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Sample records for ablatively accelerated targets

  1. Accelerator target

    DOEpatents

    Schlyer, D.J.; Ferrieri, R.A.; Koehler, C.

    1999-06-29

    A target includes a body having a depression in a front side for holding a sample for irradiation by a particle beam to produce a radioisotope. Cooling fins are disposed on a backside of the body opposite the depression. A foil is joined to the body front side to cover the depression and sample therein. A perforate grid is joined to the body atop the foil for supporting the foil and for transmitting the particle beam therethrough. A coolant is circulated over the fins to cool the body during the particle beam irradiation of the sample in the depression. 5 figs.

  2. Accelerator target

    DOEpatents

    Schlyer, David J.; Ferrieri, Richard A.; Koehler, Conrad

    1999-01-01

    A target includes a body having a depression in a front side for holding a sample for irradiation by a particle beam to produce a radioisotope. Cooling fins are disposed on a backside of the body opposite the depression. A foil is joined to the body front side to cover the depression and sample therein. A perforate grid is joined to the body atop the foil for supporting the foil and for transmitting the particle beam therethrough. A coolant is circulated over the fins to cool the body during the particle beam irradiation of the sample in the depression.

  3. Laser-ablation-assisted microparticle acceleration for drug delivery

    NASA Astrophysics Data System (ADS)

    Menezes, V.; Takayama, K.; Ohki, T.; Gopalan, J.

    2005-10-01

    Localized drug delivery with minimal tissue damage is desired in some of the clinical procedures such as gene therapy, treatment of cancer cells, treatment of thrombosis, etc. We present an effective method for delivering drug-coated microparticles using laser ablation on a thin metal foil containing particles. A thin metal foil, with a deposition of a layer of microparticles is subjected to laser ablation on its backface such that a shock wave propagates through the foil. Due to shock wave loading, the surface of the foil containing microparticles is accelerated to very high speeds, ejecting the deposited particles at hypersonic speeds. The ejected particles have sufficient momentum to penetrate soft body tissues, and the penetration depth observed is sufficient for most of the pharmacological treatments. We have tried delivering 1μm tungsten particles into gelatin models that represent soft tissues, and liver tissues of an experimental rat. Sufficient penetration depths have been observed in these experiments with minimum target damage.

  4. A study of ablation effects for an axisymmetric electromagnetic accelerator

    SciTech Connect

    Ikuta, K. . Inst. of Plasma Physics)

    1989-01-01

    In order to give the additional forward thrust to the projectile other than the electromagnetic force, the axial symmetric launcher called ablation mass driver (AMD) has been proposed using sequential z pinches in a cylindrical electrode array. The additional driving force originates from the reaction of ablating hot gas from the ablator on the rear of the projectile, since the Joule heating by the high electric current for electromagnetic acceleration is not negligiblly small. The ablated gas becomes plasma which propagates along the field-null line of z pinch, giving the forward thrust to the projectile. A proto type AMD has been built at Texas Tech University in order to see the capabilities of AMD as a launcher, although a study on the effect of ablation will remain as a future work. This paper describes a device of accelerating water blob for the study of ablation effect during acceleration together with the experimental results.

  5. Guiding and Ionization Blueshift in Ablative Capillary Waveguide Accelerators

    SciTech Connect

    McGuffey, Chris; Matsuoka, Takeshi; Bulanov, Stepan; Chvykov, Vladimir; Kalintchenko, Galina; Rousseau, Pascal; Yanovsky, Victor; Maksimchuk, Anatoly; Krushelnick, Karl; Levin, Michael; Zigler, Arie

    2009-01-22

    Laser wakefield acceleration (LWFA) in plasmas has been demonstrated with gradients which are orders of magnitude greater than the limit on conventional Radio Frequency accelerators. However, the acceleration length is limited by two factors, the dephasing length and the Rayleigh range of the laser pulse. Dephasing length is the distance in which electrons overtake the laser pulse and can be increased by decreasing plasma density. Alternatively the interaction length can be extended by orders of magnitude by using ablative wall discharge capillary targets, in which a plasma is preformed with a transverse density profile capable of guiding the focused laser. We have demonstrated guiding of high intensity laser pulses from the HERCULES laser over 3 cm for powers up to 35 TW. The quality of the laser spot can be retained and the intensity remains high even at the exit of the capillary. The transmitted laser spectrum shows blueshifting due to field ionization by the laser pulse. This ionization might enhance electron injection at low electron density for LWFA GeV accelerators. The field ionization affects carbon atoms and ions from the ablated capillary, which are not present in hydrogen-filled capillaries. This creates an additional challenge to guiding compared to hydrogen-filled capillaries. However, the setup and materials are easier to come by. The use of these capillary targets may also be of interest to other high intensity laser-plasma interactions requiring long interaction lengths such as high harmonic generation from gases and plasmas, or x-ray lasing in underdense plasmas.

  6. Pellet acceleration using an ablation-controlled electrothermal launcher

    SciTech Connect

    Kincaid, R.W.; Bourham, M.A.; Gilligan, J.G.

    1995-12-31

    The NCSU ablation-controlled electrothermal launcher SIRENS has been used to accelerate plastic (Lexan polycarbonate) pellets to investigate the possibility of using electrothermal launchers as frozen pellet injectors for tokamak fueling. Successful installation of such a device would include a protective shell (sabot) to shield the hydrogenic pellet from ablation and allow it to maintain its integrity throughout the acceleration. The SIRENS device has been modified to include specially designed barrel sections equipped with diagnostic ports.

  7. Flyer Acceleration by Pulsed Ion Beam Ablation and Application for Space Propulsion

    SciTech Connect

    Harada, Nobuhiro; Buttapeng, Chainarong; Yazawa, Masaru; Kashine, Kenji; Jiang Weihua; Yatsui, Kiyoshi

    2004-02-04

    Flyer acceleration by ablation plasma pressure produced by irradiation of intense pulsed ion beam has been studied. Acceleration process including expansion of ablation plasma was simulated based on fluid model. And interaction between incident pulsed ion beam and a flyer target was considered as accounting stopping power of it. In experiments, we used ETIGO-II intense pulsed ion beam generator with two kinds of diodes; 1) Magnetically Insulated Diode (MID, power densities of <100 J/cm2) and 2) Spherical-focused Plasma Focus Diode (SPFD, power densities of up to 4.3 kJ/cm2). Numerical results of accelerated flyer velocity agreed well with measured one over wide range of incident ion beam energy density. Flyer velocity of 5.6 km/s and ablation plasma pressure of 15 GPa was demonstrated by the present experiments. Acceleration of double-layer target consists of gold/aluminum was studied. For adequate layer thickness, such a flyer target could be much more accelerated than a single layer. Effect of waveform of ion beam was also examined. Parabolic waveform could accelerate more efficiently than rectangular waveform. Applicability of ablation propulsion was discussed. Specific impulse of 7000{approx}8000 seconds and time averaged thrust of up to 5000{approx}6000N can be expected. Their values can be controllable by changing power density of incident ion beam and pulse duration.

  8. Density Profile of a Foil Accelerated by Laser Ablation

    NASA Astrophysics Data System (ADS)

    Knauer, J. P.; Hu, S. X.; Goncharov, V. N.; Haberberger, D.

    2016-10-01

    An experiment to measure the density profile of a foil accelerated by laser ablation has been designed and is underway. High-density material is measured with x-ray radiography and low-density plasma is measured using 251-nm interferometry. Two-dimensional hydrodynamic simulation results from the code DRACO will be compared to these data. The accelerated foil is an 80- μm-thick CH target with Ge and Si-doped layers. The incident laser is a 351-nm, 5-ns pulse with a total energy of 6.2 kJ. Si and Ti x rays are used for the radiography measurement. A 1-D image versus time data are recorded with an x-ray streak camera and 2-D image data at specific times are recorded with an x-ray framing camera using point-projection backlighting. Foil acceleration is measured with the 1-D data. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  9. Thermal Convection on an Ablating Target

    NASA Astrophysics Data System (ADS)

    Mehmedagic, Igbal; Thangam, Siva

    2015-11-01

    Modeling and analysis of thermal convection of a metallic targets subject to radiative flux is of relevance to various manufacturing processes as well as for the development of protective shields. The present work involves the computational modeling of metallic targets subject to high heat fluxes that are both steady and pulsed. Modeling of the ablation and associated fluid dynamics when metallic surfaces are exposed to high intensity pulsed laser fluence at normal atmospheric conditions is considered. The incident energy from the laser is partly absorbed and partly reflected by the surface during ablation and subsequent vaporization of the convecting melt also participates in the radiative exchange. The energy distribution during the process between the bulk and vapor phase strongly depends on optical and thermodynamic properties of the irradiated material, radiation wavelength, and laser pulse intensity and duration. Computational findings based on effective representation and prediction of the heat transfer, melting and vaporization of the targeting material as well as plume formation and expansion are presented and discussed in the context of various ablation mechanisms, variable thermo-physical and optical properties, plume expansion and surface geometry. Funded in part by U. S. Army ARDEC, Picatinny Arsenal, NJ.

  10. Experimental setup for the laboratory investigation of micrometeoroid ablation using a dust accelerator

    NASA Astrophysics Data System (ADS)

    Thomas, Evan; Simolka, Jonas; DeLuca, Michael; Horányi, Mihály; Janches, Diego; Marshall, Robert A.; Munsat, Tobin; Plane, John M. C.; Sternovsky, Zoltan

    2017-03-01

    A facility has been developed to simulate the ablation of micrometeoroids in laboratory conditions. An electrostatic dust accelerator is used to generate iron particles with velocities of 10-70 km/s. The particles are then introduced into a chamber pressurized with a target gas, where the pressure is adjustable between 0.01 and 0.5 Torr, and the particle partially or completely ablates over a short distance. An array of biased electrodes above and below the ablation path is used to collect the generated ions/electrons with a spatial resolution of 2.6 cm along the ablating particles' path, thus allowing the study of the spatiotemporal evolution of the process. For completely ablated particles, the total collected charge directly yields the ionization coefficient of a given dust material-target gas combination. The first results of this facility measured the ionization coefficient of iron atoms with N2, air, CO2, and He target gases for impact velocities >20 km/s, and are reported by Thomas et al. [Geophys. Res. Lett. 43, 3645 (2016)]. The ablation chamber is also equipped with four optical ports that allow for the detection of the light emitted by the ablating particle. A multichannel photomultiplier tube system is used to observe the ablation process with a spatial and temporal resolution of 0.64 cm and 90 ns. The preliminary results indicate that it is possible to calculate the velocity of the ablating particle from the optical observations, and in conjunction with the spatially resolved charge measurements allow for experimental validation of ablation models in future studies.

  11. Modeling of beam-target interaction during pulsed electron beam ablation of graphite: Case of melting

    NASA Astrophysics Data System (ADS)

    Ali, Muddassir; Henda, Redhouane

    2017-02-01

    A one-dimensional thermal model based on a two-stage heat conduction equation is employed to investigate the ablation of graphite target during nanosecond pulsed electron beam ablation. This comprehensive model accounts for the complex physical phenomena comprised of target heating, melting and vaporization upon irradiation with a polyenergetic electron beam. Melting and vaporization effects induced during ablation are taken into account by introducing moving phase boundaries. Phase transition induced during ablation is considered through the temperature dependent thermodynamic properties of graphite. The effect of electron beam efficiency, power density, and accelerating voltage on ablation is analyzed. For an electron beam operating at an accelerating voltage of 15 kV and efficiency of 0.6, the model findings show that the target surface temperature can reach up to 7500 K at the end of the pulse. The surface begins to melt within 25 ns from the pulse start. For the same process conditions, the estimated ablation depth and ablated mass per unit area are about 0.60 μm and 1.05 μg/mm2, respectively. Model results indicate that ablation takes place primarily in the regime of normal vaporization from the surface. The results obtained at an accelerating voltage of 15 kV and efficiency factor of 0.6 are satisfactorily in good accordance with available experimental data in the literature.

  12. Deflection of uncooperative targets using laser ablation

    NASA Astrophysics Data System (ADS)

    Thiry, Nicolas; Vasile, Massimiliano

    2015-09-01

    Owing to their ability to move a target in space without requiring propellant, laser-based deflection methods have gained attention among the research community in the recent years. With laser ablation, the vaporized material is used to push the target itself allowing for a significant reduction in the mass requirement for a space mission. Specifically, this paper addresses two important issues which are thought to limit seriously the potential efficiency of a laser-deflection method: the impact of the tumbling motion of the target as well as the impact of the finite thickness of the material ablated in the case of a space debris. In this paper, we developed a steady-state analytical model based on energetic considerations in order to predict the efficiency range theoretically allowed by a laser deflection system in absence of the two aforementioned issues. A numerical model was then implemented to solve the transient heat equation in presence of vaporization and melting and account for the tumbling rate of the target. This model was also translated to the case where the target is a space debris by considering material properties of an aluminium 6061-T6 alloy and adapting at every time-step the size of the computational domain along with the recession speed of the interface in order to account for the finite thickness of the debris component. The comparison between the numerical results and the analytical predictions allow us to draw interesting conclusions regarding the momentum coupling achievable by a given laser deflection system both for asteroids and space debris in function of the flux, the rotation rate of the target and its material properties. In the last section of this paper, we show how a reasonably small spacecraft could deflect a 56m asteroid with a laser system requiring less than 5kW of input power.

  13. Cooled particle accelerator target

    DOEpatents

    Degtiarenko, Pavel V.

    2005-06-14

    A novel particle beam target comprising: a rotating target disc mounted on a retainer and thermally coupled to a first array of spaced-apart parallel plate fins that extend radially inwardly from the retainer and mesh without physical contact with a second array of spaced-apart parallel plate fins that extend radially outwardly from and are thermally coupled to a cooling mechanism capable of removing heat from said second array of spaced-apart fins and located within the first array of spaced-apart parallel fins. Radiant thermal exchange between the two arrays of parallel plate fins provides removal of heat from the rotating disc. A method of cooling the rotating target is also described.

  14. Numerical Studies of Ablative Mass Loss from Wind Accelerated Clouds.

    NASA Astrophysics Data System (ADS)

    Knerr, Jeffrey Matthew

    1993-01-01

    We have used numerical hydrodynamics to study the acceleration of dense gas clouds via wind ram pressure. Our goal has been to examine a model for the explanation of broad absorption lines (BALs) seen in the spectra of a certain fraction of observed QSOs. This model postulates cool dense clouds moving at very high speeds as the source of the BALs. Furthermore, it invokes simple wind ram pressure as the acceleration mechanism for the clouds. A crucial question is whether the clouds can survive potentially disruptive fluid instabilities, allowing time for acceleration to speeds comparable to the wind velocity. Linear stability arguments imply Rayleigh-Taylor (RT) instability growth occurs on time scales much shorter than the acceleration time scale. These arguments conclude acceleration via ram pressure cannot produce bulk cloud velocities in excess of the cloud's internal sound speed. Our simulations show this is simply not true. We present two-dimensional slab-symmetric simulations where clouds are accelerated to speeds close to an order of magnitude greater than their internal sound speed. Ablative mass loss by the flow of shocked wind gas around the periphery of the clouds acts to limit the growth of potentially disruptive instabilities. Simulations run at different computational grid resolutions clearly show the stabilizing effect ablation has on the evolution of the clouds. Simplified models for line profiles have been developed using mass-velocity histograms generated from the numerical simulations. There is good qualitative agreement between the simulated line profiles and observed BAL profiles.

  15. Automated planning of ablation targets in atrial fibrillation treatment

    NASA Astrophysics Data System (ADS)

    Keustermans, Johannes; De Buck, Stijn; Heidbüchel, Hein; Suetens, Paul

    2011-03-01

    Catheter based radio-frequency ablation is used as an invasive treatment of atrial fibrillation. This procedure is often guided by the use of 3D anatomical models obtained from CT, MRI or rotational angiography. During the intervention the operator accurately guides the catheter to prespecified target ablation lines. The planning stage, however, can be time consuming and operator dependent which is suboptimal both from a cost and health perspective. Therefore, we present a novel statistical model-based algorithm for locating ablation targets from 3D rotational angiography images. Based on a training data set of 20 patients, consisting of 3D rotational angiography images with 30 manually indicated ablation points, a statistical local appearance and shape model is built. The local appearance model is based on local image descriptors to capture the intensity patterns around each ablation point. The local shape model is constructed by embedding the ablation points in an undirected graph and imposing that each ablation point only interacts with its neighbors. Identifying the ablation points on a new 3D rotational angiography image is performed by proposing a set of possible candidate locations for each ablation point, as such, converting the problem into a labeling problem. The algorithm is validated using a leave-one-out-approach on the training data set, by computing the distance between the ablation lines obtained by the algorithm and the manually identified ablation points. The distance error is equal to 3.8+/-2.9 mm. As ablation lesion size is around 5-7 mm, automated planning of ablation targets by the presented approach is sufficiently accurate.

  16. Dynamics of Laser Driven, Ablatively Accelerated Targets

    DTIC Science & Technology

    1981-05-08

    Tenierature Hydrodynamic Phenomena," V.I. II. pg. 676. Academic Press NY (1966) 21. R. Resnick , and 1). lHalliday, "Physics." Vol. I. pg. 178, J. Wiley...Attn: Prof. Gan Fu-xi GI. Barifi Prof. Yu Wen-yan Istituto Fisica Application Prof. Xu Zhi-2han Universita di Paria Prof. Deng Xi-ming Pavia 27100 Italy

  17. Observations of multimode perturbation decay at non-accelerating, soft x-ray driven ablation fronts

    NASA Astrophysics Data System (ADS)

    Loomis, E. N.; Braun, D.; Batha, S. H.; Landen, O. L.

    2012-12-01

    Minimizing the growth of hydrodynamic instabilities is a fundamental design issue facing the achievement of thermonuclear ignition and burn with Inertial Confinement Fusion (ICF). The thin capsules and extreme accelerations found in ICF make it an inherently unstable system primarily to Rayleigh-Taylor (RT) occurring at the ablation front. A potential mechanism by which perturbations at the outer capsule surface can be reduced lies in the already present ablative Richtmyer-Meshkov (RM) effect, which operates during the first shock transit of the ablator. At present, the available Equation of State (EOS) models predict a wide range of behavior for the ablative RM oscillations of multimode isolated defects on plastic (CH) capsules. To resolve these differences, we conducted experiments at the OMEGA Laser Facility [T. R. Boehly et al., Optics Comm. 133 (1997)] that measured the evolution of gaussian-shaped bumps driven by soft x-ray ablation from a halfraum. Shock speeds in the CH target were measured to reach 15 μm/ns for halfraum radiation temperatures of 70 eV lasting for up to 7 ns. The evolution of gaussian-shaped bumps of different widths and heights were measured using on-axis x-ray radiography at up to 37× magnification. Bumps with initial widths of 34 and 44 μm FWHM were found to grow by 3× their initial areal density and then saturate out to 6 ns due to lateral compression of the bump characteristic of the formation of a rippled shock front propagating into the solid target. Narrower 17 μm FWHM bumps, on the other hand, grew by roughly 2× followed immediately by a decrease back to initial values of areal density out to 7 ns, which largely agrees with both LEOS 5310 and SESAME 7592 EOS predictions. The difference in observed behavior suggests that high spatial frequency modes found in narrower bumps are needed to significantly affect the ablation front profile on shorter time scales.

  18. Ultrafast laser ablation for targeted atherosclerotic plaque removal

    NASA Astrophysics Data System (ADS)

    Lanvin, Thomas; Conkey, Donald B.; Descloux, Laurent; Frobert, Aurelien; Valentin, Jeremy; Goy, Jean-Jacques; Cook, Stéphane; Giraud, Marie-Noelle; Psaltis, Demetri

    2015-07-01

    Coronary artery disease, the main cause of heart disease, develops as immune cells and lipids accumulate into plaques within the coronary arterial wall. As a plaque grows, the tissue layer (fibrous cap) separating it from the blood flow becomes thinner and increasingly susceptible to rupturing and causing a potentially lethal thrombosis. The stabilization and/or treatment of atherosclerotic plaque is required to prevent rupturing and remains an unsolved medical problem. Here we show for the first time targeted, subsurface ablation of atherosclerotic plaque using ultrafast laser pulses. Excised atherosclerotic mouse aortas were ablated with ultrafast near-infrared (NIR) laser pulses. The physical damage was characterized with histological sections of the ablated atherosclerotic arteries from six different mice. The ultrafast ablation system was integrated with optical coherence tomography (OCT) imaging for plaque-specific targeting and monitoring of the resulting ablation volume. We find that ultrafast ablation of plaque just below the surface is possible without causing damage to the fibrous cap, which indicates the potential use of ultrafast ablation for subsurface atherosclerotic plaque removal. We further demonstrate ex vivo subsurface ablation of a plaque volume through a catheter device with the high-energy ultrafast pulse delivered via hollow-core photonic crystal fiber.

  19. Materials considerations in accelerator targets

    SciTech Connect

    Peacock, H.B. Jr.; Iyer, N.C.; Louthan, M.R. Jr.

    1994-08-01

    Future nuclear materials production and/or the burn-up of long lived radioisotopes may be accomplished through the capture of spallation produced neutrons in accelerators. Aluminum clad-lead and/or lead alloys has been proposed as a spallation target. Aluminum was the cladding choice because of the low neutron absorption cross section, fast radioactivity decay, high thermal conductivity, and excellent fabricability. Metallic lead and lead oxide powders were considered for the target core with the fabrication options being casting or powder metallurgy (PM). Scoping tests to evaluate gravity casting, squeeze casting, and casting and swaging processes showed that, based on fabricability and heat transfer considerations, squeeze casting was the preferred option for manufacture of targets with initial core cladding contact. Thousands of aluminum clad aluminum-lithium alloy core targets and control rods for tritium production have been fabricated by coextrusion processes and successfully irradiated in the SRS reactors. Tritium retention in, and release from the coextruded product was modeled from experimental and operational data. Newly produced tritium atoms were trapped by lithium atoms to form a lithium tritide. The effective tritium pressure required for trap or tritide stability was the equilibrium decomposition pressure of tritium over a lithium tritide-aluminum mixture. The temperature dependence of tritium release was determined by the permeability of the cladding to tritium and the local equilibrium at the trap sites. The model can be used to calculate tritium release from aluminum clad, aluminum-lithium alloy targets during postulated accelerator operational and accident conditions. This paper describes the manufacturing technologies evaluated and presents the model for tritium retention in aluminum clad, aluminum-lithium alloy tritium production targets.

  20. Materials considerations in accelerator targets

    SciTech Connect

    Peacock, H. B. Jr.; Iyer, N. C.; Louthan, M. R. Jr.

    1995-09-15

    Future nuclear materials production and/or the burn-up of long lived radioisotopes may be accomplished through the capture of spallation produced neutrons in accelerators. Aluminum clad-lead and/or lead alloys has been proposed as a spallation target. Aluminum was the cladding choice because of the low neutron absorption cross section, fast radioactivity decay, high thermal conductivity, and excellent fabricability. Metallic lead and lead oxide powders were considered for the target core with the fabrication options being casting or powder metallurgy (PM). Scoping tests to evaluate gravity casting, squeeze casting, and casting and swaging processes showed that, based on fabricability and heat transfer considerations, squeeze casting was the preferred option for manufacture of targets with initial core cladding contact. Thousands of aluminum clad aluminum-lithium alloy core targets and control rods for tritium production have been fabricated by coextrusion processes and successfully irradiated in the SRS reactors. Tritium retention in, and release from, the coextruded product was modeled from experimental and operational data. The model assumed that tritium atoms, formed by the 6Li(n,a)3He reaction, were produced in solid solution in the Al-Li alloy. Because of the low solubility of hydrogen isotopes in aluminum alloys, the irradiated Al-Li rapidly became supersaturated in tritium. Newly produced tritium atoms were trapped by lithium atoms to form a lithium tritide. The effective tritium pressure required for trap or tritide stability was the equilibrium decomposition pressure of tritium over a lithium tritide-aluminum mixture. The temperature dependence of tritium release was determined by the permeability of the cladding to tritium and the local equilibrium at the trap sites. The model can be used to calculate tritium release from aluminum clad, aluminum-lithium alloy targets during postulated accelerator operational and accident conditions. This paper describes

  1. Materials considerations in accelerator targets

    NASA Astrophysics Data System (ADS)

    Peacock, H. B.; Iyer, N. C.; Louthan, M. R.

    1995-09-01

    Future nuclear materials production and/or the burn-up of long lived radioisotopes may be accomplished through the capture of spallation produced neutrons in accelerators. Aluminum clad-lead and/or lead alloys has been proposed as a spallation target. Aluminum was the cladding choice because of the low neutron absorption cross section, fast radioactivity decay, high thermal conductivity, and excellent fabricability. Metallic lead and lead oxide powders were considered for the target core with the fabrication options being casting or powder metallurgy (PM). Scoping tests to evaluate gravity casting, squeeze casting, and casting and swaging processes showed that, based on fabricability and heat transfer considerations, squeeze casting was the preferred option for manufacture of targets with initial core cladding contact. Thousands of aluminum clad aluminum-lithium alloy core targets and control rods for tritium production have been fabricated by coextrusion processes and successfully irradiated in the SRS reactors. Tritium retention in, and release from, the coextruded product was modeled from experimental and operational data. The model assumed that tritium atoms, formed by the 6Li(n,a)3He reaction, were produced in solid solution in the Al-Li alloy. Because of the low solubility of hydrogen isotopes in aluminum alloys, the irradiated Al-Li rapidly became supersaturated in tritium. Newly produced tritium atoms were trapped by lithium atoms to form a lithium tritide. The effective tritium pressure required for trap or tritide stability was the equilibrium decomposition pressure of tritium over a lithium tritide-aluminum mixture. The temperature dependence of tritium release was determined by the permeability of the cladding to tritium and the local equilibrium at the trap sites. The model can be used to calculate tritium release from aluminum clad, aluminum-lithium alloy targets during postulated accelerator operational and accident conditions. This paper describes

  2. A novel laser ablation plasma thruster with electromagnetic acceleration

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Zhang, Daixian; Wu, Jianjun; He, Zhen; Zhang, Hua

    2016-10-01

    A novel laser ablation plasma thruster accelerated by electromagnetic means was proposed and investigated. The discharge characteristics and thrust performance were tested with different charged energy, structural parameters and propellants. The thrust performance was proven to be improved by electromagnetic acceleration. In contrast with the pure laser propulsion mode, the thrust performance in electromagnetic acceleration modes was much better. The effects of electrodes distance and the off-axis distance between ceramic tube and cathode were tested, and it's found that there were optimal structural parameters for achieving optimal thrust performance. It's indicated that the impulse bit and specific impulse increased with increasing charged energy. In our experiments, the thrust performance of the thruster was optimal in large charged energy modes. With the charged energy 25 J and the use of metal aluminum, a maximal impulse bit of 600 μNs, a specific impulse of approximate 8000 s and thrust efficiency of about 90% were obtained. For the PTFE propellant, a maximal impulse bit of about 350 μNs, a specific impulse of about 2400 s, and thrust efficiency of about 16% were obtained. Besides, the metal aluminum was proven to be the better propellant than PTFE for the thruster.

  3. Study of Cu ions acceleration via UV laser ablation

    NASA Astrophysics Data System (ADS)

    Belloni, F.; Doria, D.; Lorusso, A.; Nassisi, Vincenzo; Torrisi, Lorenzo

    2005-03-01

    In this work an ion acceleration system based on a laser ion source was studied. It was able to generate ion beams utilizing as a source a laser plasma produced by a XeCl laser from a copper target. The focused laser beam provided a power density on the target surface of about 3.5x108 W/cm2. Laser wavelength and pulse duration were 308 nm and 20 ns, respectively. The experimental apparatus consisted substantially of a plasma generation chamber, a drift tube and an expansion chamber mounted on the target stem inside the generation chamber. The expansion chamber end formed the acceleration gap together with a grounded bored electrode, placed in front of it at a distance of 1.3 cm. A Faraday cup placed at the end of the drift tube was used to reveal the ion intensity. Many attempts were done in order to accelerate plasma ions without the expansion chamber, but arcs were present. The maximum accelerating voltage applied to the extraction gap was 18 kV, resulting in an ion bunch of about 4.2 nC and a peak current of 220 μA.

  4. Observations of multimode perturbation decay at non-accelerating, soft x-ray driven ablation fronts

    SciTech Connect

    Loomis, E. N.; Batha, S. H.; Braun, D.; Landen, O. L.

    2012-12-15

    Minimizing the growth of hydrodynamic instabilities is a fundamental design issue facing the achievement of thermonuclear ignition and burn with Inertial Confinement Fusion (ICF). The thin capsules and extreme accelerations found in ICF make it an inherently unstable system primarily to Rayleigh-Taylor (RT) occurring at the ablation front. A potential mechanism by which perturbations at the outer capsule surface can be reduced lies in the already present ablative Richtmyer-Meshkov (RM) effect, which operates during the first shock transit of the ablator. At present, the available Equation of State (EOS) models predict a wide range of behavior for the ablative RM oscillations of multimode isolated defects on plastic (CH) capsules. To resolve these differences, we conducted experiments at the OMEGA Laser Facility [T. R. Boehly et al., Optics Comm. 133 (1997)] that measured the evolution of gaussian-shaped bumps driven by soft x-ray ablation from a halfraum. Shock speeds in the CH target were measured to reach 15 {mu}m/ns for halfraum radiation temperatures of 70 eV lasting for up to 7 ns. The evolution of gaussian-shaped bumps of different widths and heights were measured using on-axis x-ray radiography at up to 37 Multiplication-Sign magnification. Bumps with initial widths of 34 and 44 {mu}m FWHM were found to grow by 3 Multiplication-Sign their initial areal density and then saturate out to 6 ns due to lateral compression of the bump characteristic of the formation of a rippled shock front propagating into the solid target. Narrower 17 {mu}m FWHM bumps, on the other hand, grew by roughly 2 Multiplication-Sign followed immediately by a decrease back to initial values of areal density out to 7 ns, which largely agrees with both LEOS 5310 and SESAME 7592 EOS predictions. The difference in observed behavior suggests that high spatial frequency modes found in narrower bumps are needed to significantly affect the ablation front profile on shorter time scales.

  5. Laboratory Measurements of Micrometeoroid Impacts into Solid Ice and Gas Ablation Targets

    NASA Astrophysics Data System (ADS)

    Munsat, T. L.; Britt, D. T.; Dee, R.; Gudipati, M. S.; Horanyi, M.; James, D.; Janches, D.; Kempf, S.; Nelson, A. O.; Plane, J. M. C.; Shu, A. J.; Sternovsky, Z.; Thomas, E.; Ulibarri, Z.

    2015-12-01

    The dust accelerator facility at the SSERVI Institute for Modeling Plasma, Atmospheres, and Cosmic Dust (IMPACT) has recently implemented two major target upgrades: a cryogenic ice target and a high-pressure gas target. Each target can be exposed to micron and submicron particles accelerated to speeds up to 100 km/s. The ice target consists of a LN2 cryogenic system connected to both a water-ice deposition system and a movable freezer/holder for a pre-mixed liquid cartridge. Impact products and chemistry are assessed with an integrated time-of-flight mass spectrometer. Such a system enables a program of research into the evolution of ice under micrometeoroid bombardment and the synthesis of complex organic molecules through micrometeoroid impacts. We present the early results from studies of hypervelocity iron particle impacts into frozen mixtures of H2O, NH3, and olivine grains which contain nanophase Fe, a possible catalyst for organic chemical reactions, under conditions of low-pressure background CO or CO2 gas. The gas target consists of a differentially pumped chamber kept at pressures up to 0.5 Torr, such that high-velocity (~10-60 km/s) micrometeoroids are completely ablated within the 40 cm long measurement region. The chamber is configured with segmented electrodes to perform temporally- and spatially-resolved measurements of charge production during ablation, and localized light-collection optics enable an assessment of the light production. We present the latest results of experiments to determine the ionization efficiency of Fe particles ablating in N2, air, CO2, and He gas, and modifications to standard ablation models made possible from these experimental results. Such studies are critical for the interpretation of remote sensing measurements, including radar and lidar, which in turn make possible the assessment of the interplanetary dust particle flux.

  6. Laser backwriting process on glass via ablation of metal targets

    NASA Astrophysics Data System (ADS)

    Castelo, A.; Nieto, D.; Bao, C.; Flores-Arias, M. T.; Pérez, M. V.; Gómez-Reino, C.; López-Gascón, C.; de la Fuente, G. F.

    2007-05-01

    Ablation of metal targets onto pyrex glass substrates, using a Q-switched Nd:YAG laser working at 355 nm, was used to study the potential of a laser backwriting process for the fabrication of optical waveguides via an index of refraction change. Metal foils of stainless steel, aluminum, copper, brass and gold have been used as blanks and irradiated by focusing the laser beam through a cylindrical lens under continuous movement in a direction perpendicular to the irradiation. An horizontal setup was found suitable to improve the effect of the plume in the sample. Results were obtained for two different configurations. Transversal profiles were analysed using a contact profilometer, comparing results obtained for the different configurations, traverse speeds and metal targets used. Two ablation regimes were identified, which are related to a critical laser fluence value of 2.7 J/cm 2. Surface micrographs obtained by scanning electron microscopy are discussed, together with the characteristics of the structures attained, taking into account the optical and thermal properties of the ablated metal blanks.

  7. Energy balance in laser ablation of metal targets

    SciTech Connect

    Sobral, H.; Villagran-Muniz, M.; Bredice, F.

    2005-10-15

    Laser-generated plasma was induced on metallic targets glued to a piezoelectric microphone and placed between the plates of a planar charged capacitor. The plasma generates a temporal redistribution of electric charge on the plates that can easily be measured by a resistor connected to the ground plate; this signal is proportional to the total number of ions removed by breakdown. Both the absorbed and scattered energies were simultaneously monitored by the photoacoustic signal and an energy meter. From these signals it was possible to determine the energy involved in each of the processes. Just above the ablation threshold most of the delivered energy is absorbed and the acoustic signal prevails compared to other contributions. Above this region, the electric signal, which is proportional to the energy involved in the ablation process, becomes dominant.

  8. Enhancing proton acceleration by using composite targets

    SciTech Connect

    Bulanov, S. S.; Esarey, E.; Schroeder, C. B.; Bulanov, S. V.; Esirkepov, T. Zh.; Kando, M.; Pegoraro, F.; Leemans, W. P.

    2015-07-10

    Efficient laser ion acceleration requires high laser intensities, which can only be obtained by tightly focusing laser radiation. In the radiation pressure acceleration regime, where the tightly focused laser driver leads to the appearance of the fundamental limit for the maximum attainable ion energy, this limit corresponds to the laser pulse group velocity as well as to another limit connected with the transverse expansion of the accelerated foil and consequent onset of the foil transparency. These limits can be relaxed by using composite targets, consisting of a thin foil followed by a near critical density slab. Such targets provide guiding of a laser pulse inside a self-generated channel and background electrons, being snowplowed by the pulse, compensate for the transverse expansion. The use of composite targets results in a significant increase in maximum ion energy, compared to a single foil target case.

  9. Surface Modification of ICF Target Capsules by Pulsed Laser Ablation

    SciTech Connect

    Carlson, Lane C.; Johnson, Michael A.; Bunn, Thomas L.

    2016-06-30

    Topographical modifications of spherical surfaces are imprinted on National Ignition Facility (NIF) target capsules by extending the capabilities of a recently developed full surface (4π) laser ablation and mapping apparatus. The laser ablation method combines the precision, energy density and long reach of a focused laser beam to pre-impose sinusoidal modulations on the outside surface of High Density Carbon (HDC) capsules and the inside surface of Glow Discharge Polymer (GDP) capsules. Sinusoidal modulations described in this paper have sub-micron to 10’s of microns vertical scale and wavelengths as small as 30 μm and as large as 200 μm. The modulated patterns are created by rastering a focused laser fired at discrete capsule surface locations for a specified number of pulses. The computer program developed to create these raster patterns uses inputs such as laser beam intensity profile, the material removal function, the starting surface figure and the desired surface figure. The patterns are optimized to minimize surface roughness. Lastly, in this paper, simulated surfaces are compared with actual ablated surfaces measured using confocal microscopy.

  10. Surface Modification of ICF Target Capsules by Pulsed Laser Ablation

    DOE PAGES

    Carlson, Lane C.; Johnson, Michael A.; Bunn, Thomas L.

    2016-06-30

    Topographical modifications of spherical surfaces are imprinted on National Ignition Facility (NIF) target capsules by extending the capabilities of a recently developed full surface (4π) laser ablation and mapping apparatus. The laser ablation method combines the precision, energy density and long reach of a focused laser beam to pre-impose sinusoidal modulations on the outside surface of High Density Carbon (HDC) capsules and the inside surface of Glow Discharge Polymer (GDP) capsules. Sinusoidal modulations described in this paper have sub-micron to 10’s of microns vertical scale and wavelengths as small as 30 μm and as large as 200 μm. The modulatedmore » patterns are created by rastering a focused laser fired at discrete capsule surface locations for a specified number of pulses. The computer program developed to create these raster patterns uses inputs such as laser beam intensity profile, the material removal function, the starting surface figure and the desired surface figure. The patterns are optimized to minimize surface roughness. Lastly, in this paper, simulated surfaces are compared with actual ablated surfaces measured using confocal microscopy.« less

  11. ACCELERATOR TARGET POSITIONER AND CONTROL CIRCUIT THEREFOR

    DOEpatents

    Stone, K.F.; Force, R.J.; Olson, W.W.; Cagle, D.S.

    1959-12-15

    An apparatus is described for inserting and retracting a target material with respect to the internal beam of a charged particle accelerator and to circuitry for controlling the timing and motion of the target placement. Two drive coils are mounted on the shaft of a target holder arm and disposed within the accelerator magnetic field with one coil at right angles to the other. Control circuitry alternately connects each coil to a current source and to a varying shorting resistance whereby the coils interchangeably produce driving and braking forces which swing the target arm within a ninety degree arc. The target is thus moved into the beam and away from it at high speeds and is brought to rest after each movement without whiplash or vibration.

  12. Radiative shocking and acceleration of polycrystalline slabs for investigation of ablative Rayleigh-Taylor instability triggered by ablator microstructure

    SciTech Connect

    Hoffman, N. M.; Tubbs, D. L.; Swift, D. C.; Cobble, J. A.; Kyrala, George A.; Tierney, T.

    2002-01-01

    It is vital to identify and control all perturbation sources that could trigger ablative Rayleigh-Taylor instability One obvious perturbation 'seed' is surface roughness computed perturbation growth, validated by experiments - Specification for allowable roughness of NIF ignition capsule' is based on But what about infernal microstructure of shell materials? - Beryllium shells are composed of individual crystalline grains with - Polymer shells are composed of long molecular chains that might 'stack like an isotropic elastic/plastic properties logs' with a preferred orientation What happens when shock waves transit anisotropic material? What happens when such material is accelerated by radiation drive? We need a specification for allowable internal anisotropy.

  13. Rapid revelation of radiocarbon records with laser ablation Accelerator Mass Spectrometry.

    PubMed

    Münsterer, Caroline; Wacker, Lukas; Hattendorf, Bodo; Christl, Marcus; Koch, Joachim; Dietiker, Rolf; Synal, Hans-Arno; Günther, Detlef

    2014-01-01

    By focusing high-intensity laser pulses on carbonate samples carbon dioxide is generated and can be directly introduced into the gas ion source (GIS) of an Accelerator Mass Spectrometer (AMS). This new technique allows rapid radiocarbon analyses at high spatial resolution. The design of the deignated laser ablation cell as well as first results on a stalagmite sample are presented.

  14. Accelerated Taylor plumes for MIF targets

    NASA Astrophysics Data System (ADS)

    Brown, M. R.; Schaffner, D. A.; Parks, H. L.; Rock, A. B.

    2015-11-01

    The SSX plasma device has been converted to a 2.5 m merging plasma wind tunnel configuration. Experiments are underway to study merging and stagnation of high density, helical Taylor states to employ as a potential target for magneto-inertial fusion. Eventually, SSX Taylor states will be accelerated to over 100 km / s and compressed to small volumes either by stagnation or merging. Initial un-accelerated merging studies produce peak proton densities of 5 ×1015cm-3 . Densities are measured with a precision quadrature He-Ne laser interferometer. Typical merged plasma parameters are Ti = 20 eV, Te = 10 eV, B = 0 . 4 T with lifetimes of 100 μs. Results from a single prototype acceleration coil will be presented, as well as initial simulation studies of Taylor state plasma acceleration using multiple staged, pulsed theta-pinch coils. Work supported by DOE ARPA-E ALPHA program.

  15. Target and accelerator developments at CTI

    NASA Astrophysics Data System (ADS)

    Alvord, C. W.; Mendez, A. J.; Wittner, D. E.

    2001-07-01

    The accelerator products marketed by CTI have exclusively focused on proton-only, low energy (11 MeV) designs. This choice best suited the research customer, interested in producing several doses a day of a variety of positron emitting compounds. The PET cyclotron market has evolved into a high output, cost driven, competitive radiotracer production environment. A thoughtful analysis of the choices of energy and particle reveals that an 11 MeV proton accelerator outfitted with target changers and automated target loading and unloading equipment is still the best choice for FDG distribution. However technological innovations are required to face the challenges of the rapidly growing PET radiotracer business. Modifications to the CTI line of accelerators developed to face this evolving need will be presented.

  16. Numerical investigation on target implosions driven by radiation ablation and shock compression in dynamic hohlraums

    SciTech Connect

    Xiao, Delong; Sun, Shunkai; Zhao, Yingkui; Ding, Ning; Wu, Jiming; Dai, Zihuan; Yin, Li; Zhang, Yang; Xue, Chuang

    2015-05-15

    In a dynamic hohlraum driven inertial confinement fusion (ICF) configuration, the target may experience two different kinds of implosions. One is driven by hohlraum radiation ablation, which is approximately symmetric at the equator and poles. The second is caused by the radiating shock produced in Z-pinch dynamic hohlraums, only taking place at the equator. To gain a symmetrical target implosion driven by radiation ablation and avoid asymmetric shock compression is a crucial issue in driving ICF using dynamic hohlraums. It is known that when the target is heated by hohlraum radiation, the ablated plasma will expand outward. The pressure in the shocked converter plasma qualitatively varies linearly with the material temperature. However, the ablation pressure in the ablated plasma varies with 3.5 power of the hohlraum radiation temperature. Therefore, as the hohlraum temperature increases, the ablation pressure will eventually exceed the shock pressure, and the expansion of the ablated plasma will obviously weaken the shock propagation and decrease its velocity after propagating into the ablator plasma. Consequently, longer time duration is provided for the symmetrical target implosion driven by radiation ablation. In this paper these processes are numerically investigated by changing drive currents or varying load parameters. The simulation results show that a critical hohlraum radiation temperature is needed to provide a high enough ablation pressure to decelerate the shock, thus providing long enough time duration for the symmetric fuel compression driven by radiation ablation.

  17. Targeted p120-catenin ablation disrupts dental enamel development.

    PubMed

    Bartlett, John D; Dobeck, Justine M; Tye, Coralee E; Perez-Moreno, Mirna; Stokes, Nicole; Reynolds, Albert B; Fuchs, Elaine; Skobe, Ziedonis

    2010-09-16

    Dental enamel development occurs in stages. The ameloblast cell layer is adjacent to, and is responsible for, enamel formation. When rodent pre-ameloblasts become tall columnar secretory-stage ameloblasts, they secrete enamel matrix proteins, and the ameloblasts start moving in rows that slide by one another. This movement is necessary to form the characteristic decussating enamel prism pattern. Thus, a dynamic system of intercellular interactions is required for proper enamel development. Cadherins are components of the adherens junction (AJ), and they span the cell membrane to mediate attachment to adjacent cells. p120 stabilizes cadherins by preventing their internalization and degradation. So, we asked if p120-mediated cadherin stability is important for dental enamel formation. Targeted p120 ablation in the mouse enamel organ had a striking effect. Secretory stage ameloblasts detached from surrounding tissues, lost polarity, flattened, and ameloblast E- and N-cadherin expression became undetectable by immunostaining. The enamel itself was poorly mineralized and appeared to be composed of a thin layer of merged spheres that abraded from the tooth. Significantly, p120 mosaic mouse teeth were capable of forming normal enamel demonstrating that the enamel defects were not a secondary effect of p120 ablation. Surprisingly, blood-filled sinusoids developed in random locations around the developing teeth. This has not been observed in other p120-ablated tissues and may be due to altered p120-mediated cell signaling. These data reveal a critical role for p120 in tooth and dental enamel development and are consistent with p120 directing the attachment and detachment of the secretory stage ameloblasts as they move in rows.

  18. Neutral atomic jet generation by laser ablation of copper targets

    SciTech Connect

    Matos, J. B. de; Rodrigues, N. A. S.

    2014-08-15

    This work aimed the obtainment of a neutral atomic jet departing from a plume generated by laser ablation of copper targets. A pair of electrodes together with a transducer pressure sensor was used to study the ablated plume charge composition and also to measure the ion extraction from the plasma plume. The neutral beam was produced with this setup and the relative abundance of neutrals in the plasma was measured, it decreases from 30% to 8% when the laser fluence is varied from 20 J/cm{sup 2} to 32 J/cm{sup 2}. The necessary voltage to completely remove the ions from the plume varied from 10 V to 230 V in the same fluence range. TOF analysis resulted in center of mass velocities between 3.4 and 4.6 km/s, longitudinal temperature in the range from 1 × 10{sup 4} K to 2.4 × 10{sup 4} K and a Mach number of M = 2.36, calculated using purely hydrodynamic expansion approximation.

  19. Accelerator Science: Collider vs. Fixed Target

    SciTech Connect

    Lincoln, Don

    2016-09-07

    Particle physics experiments employ high energy particle accelerators to make their measurements. However there are many kinds of particle accelerators with many interesting techniques. One important dichotomy is whether one takes a particle beam and have it hit a stationary target of atoms, or whether one takes two counter rotating beams of particles and smashes them together head on. In this video, Fermilab’s Dr. Don Lincoln explains the pros and cons of these two powerful methods of exploring the rules of the universe.

  20. Accelerator Science: Collider vs. Fixed Target

    ScienceCinema

    Lincoln, Don

    2016-09-21

    Particle physics experiments employ high energy particle accelerators to make their measurements. However there are many kinds of particle accelerators with many interesting techniques. One important dichotomy is whether one takes a particle beam and have it hit a stationary target of atoms, or whether one takes two counter rotating beams of particles and smashes them together head on. In this video, Fermilab’s Dr. Don Lincoln explains the pros and cons of these two powerful methods of exploring the rules of the universe.

  1. Feasibility of Image-Based Simulation to Estimate Ablation Target in Human Ventricular Arrhythmia

    PubMed Central

    Ashikaga, Hiroshi; Arevalo, Hermenegild; Vadakkumpadan, Fijoy; Blake, Robert C.; Bayer, Jason D.; Nazarian, Saman; Zviman, M. Muz; Tandri, Harikrishna; Berger, Ronald D.; Calkins, Hugh; Herzka, Daniel A.; Trayanova, Natalia A.; Halperin, Henry R.

    2013-01-01

    Background Previous studies suggest that MRI with late gadolinium enhancement (LGE) may identify slowly conducting tissues in scar-related ventricular tachycardia (VT). Objective We tested the feasibility of image-based simulation based on LGE to estimate ablation targets in VT. Methods We conducted a retrospective study in 13 patients who had pre-ablation MRI for scar-related VT ablation. We used image-based simulation to induce VT and estimate target regions according to the simulated VT circuit. The estimated target regions were co-registered with the LGE scar map and the ablation sites from the electroanatomical map in the standard ablation approach. Results In image-based simulation, VT was inducible in 12 patients (92.3%). All VTs showed macro-reentrant propagation patterns, and the narrowest width of estimated target region that an ablation line should span to prevent VT recurrence was 5.0 ± 3.4 mm. Out of 11 patients who underwent ablation, the results of image-based simulation and the standard approach were consistent in 9 patients (82%), where ablation within the estimated target region was associated with acute success (n=8) and ablation outside the estimated target region was associated with failure (n=1). In one case (9%), the results of image-based simulation and the standard approach were inconsistent, where ablation outside the estimated target region was associated with acute success. Conclusions The image-based simulation can be used to estimate potential ablation targets of scar-related VT. The image-based simulation may be a powerful noninvasive tool for pre-procedural planning of ablation procedures to potentially reduce the procedure time and complication rates. PMID:23608593

  2. Targeted cellular ablation based on the morphology of malignant cells

    PubMed Central

    Ivey, Jill W.; Latouche, Eduardo L.; Sano, Michael B.; Rossmeisl, John H.; Davalos, Rafael V.; Verbridge, Scott S.

    2015-01-01

    Treatment of glioblastoma multiforme (GBM) is especially challenging due to a shortage of methods to preferentially target diffuse infiltrative cells, and therapy-resistant glioma stem cell populations. Here we report a physical treatment method based on electrical disruption of cells, whose action depends strongly on cellular morphology. Interestingly, numerical modeling suggests that while outer lipid bilayer disruption induced by long pulses (~100 μs) is enhanced for larger cells, short pulses (~1 μs) preferentially result in high fields within the cell interior, which scale in magnitude with nucleus size. Because enlarged nuclei represent a reliable indicator of malignancy, this suggested a means of preferentially targeting malignant cells. While we demonstrate killing of both normal and malignant cells using pulsed electric fields (PEFs) to treat spontaneous canine GBM, we proposed that properly tuned PEFs might provide targeted ablation based on nuclear size. Using 3D hydrogel models of normal and malignant brain tissues, which permit high-resolution interrogation during treatment testing, we confirmed that PEFs could be tuned to preferentially kill cancerous cells. Finally, we estimated the nuclear envelope electric potential disruption needed for cell death from PEFs. Our results may be useful in safely targeting the therapy-resistant cell niches that cause recurrence of GBM tumors. PMID:26596248

  3. Targeted cellular ablation based on the morphology of malignant cells.

    PubMed

    Ivey, Jill W; Latouche, Eduardo L; Sano, Michael B; Rossmeisl, John H; Davalos, Rafael V; Verbridge, Scott S

    2015-11-24

    Treatment of glioblastoma multiforme (GBM) is especially challenging due to a shortage of methods to preferentially target diffuse infiltrative cells, and therapy-resistant glioma stem cell populations. Here we report a physical treatment method based on electrical disruption of cells, whose action depends strongly on cellular morphology. Interestingly, numerical modeling suggests that while outer lipid bilayer disruption induced by long pulses (~100 μs) is enhanced for larger cells, short pulses (~1 μs) preferentially result in high fields within the cell interior, which scale in magnitude with nucleus size. Because enlarged nuclei represent a reliable indicator of malignancy, this suggested a means of preferentially targeting malignant cells. While we demonstrate killing of both normal and malignant cells using pulsed electric fields (PEFs) to treat spontaneous canine GBM, we proposed that properly tuned PEFs might provide targeted ablation based on nuclear size. Using 3D hydrogel models of normal and malignant brain tissues, which permit high-resolution interrogation during treatment testing, we confirmed that PEFs could be tuned to preferentially kill cancerous cells. Finally, we estimated the nuclear envelope electric potential disruption needed for cell death from PEFs. Our results may be useful in safely targeting the therapy-resistant cell niches that cause recurrence of GBM tumors.

  4. Targeted cellular ablation based on the morphology of malignant cells

    NASA Astrophysics Data System (ADS)

    Ivey, Jill W.; Latouche, Eduardo L.; Sano, Michael B.; Rossmeisl, John H.; Davalos, Rafael V.; Verbridge, Scott S.

    2015-11-01

    Treatment of glioblastoma multiforme (GBM) is especially challenging due to a shortage of methods to preferentially target diffuse infiltrative cells, and therapy-resistant glioma stem cell populations. Here we report a physical treatment method based on electrical disruption of cells, whose action depends strongly on cellular morphology. Interestingly, numerical modeling suggests that while outer lipid bilayer disruption induced by long pulses (~100 μs) is enhanced for larger cells, short pulses (~1 μs) preferentially result in high fields within the cell interior, which scale in magnitude with nucleus size. Because enlarged nuclei represent a reliable indicator of malignancy, this suggested a means of preferentially targeting malignant cells. While we demonstrate killing of both normal and malignant cells using pulsed electric fields (PEFs) to treat spontaneous canine GBM, we proposed that properly tuned PEFs might provide targeted ablation based on nuclear size. Using 3D hydrogel models of normal and malignant brain tissues, which permit high-resolution interrogation during treatment testing, we confirmed that PEFs could be tuned to preferentially kill cancerous cells. Finally, we estimated the nuclear envelope electric potential disruption needed for cell death from PEFs. Our results may be useful in safely targeting the therapy-resistant cell niches that cause recurrence of GBM tumors.

  5. Three-dimensional simulations of ablative hydrodynamic instabilities in indirectly driven targets

    SciTech Connect

    Marinak, M.M.; Tipton, R.E.; Remington, B.A.

    1996-06-01

    To model ignition in a National Ignition Facility (NIF) capsule implosion, the authors must understand the behavior of instabilities that can cause breakup of the pellet shell. During a capsule implosion, shocks that transit the shell cause growth of perturbations at the surface or at an interface because of a Richtmyer-Meshkov type of instability. Following shock breakout, or earlier for a shaped pulse, the low-density ablated plasma accelerates the pusher, and the ablation front is Rayleigh-Taylor (RT) unstable. Ablation and finite density gradients have the effect of stabilizing the short wavelength modes. Unstable modes present on the outer surface grow and feed through to the inner surface. Once the shell encounters the rebounding shock from the capsule center, it decelerates and the inner surface becomes RT unstable. If perturbations grow large enough, pusher material mixes into the core, degrading implosion performance. Capsule designs for the NIF depend on ablative stabilization and saturation to prevent perturbations initially present on the capsule surface from growing large enough to quench ignition. Here, the authors examine the first simulations and experiments to study the effect of 3-D perturbation shape on instability growth and saturation in indirectly driven targets. The first section discusses HYDRA, the radiation hydrodynamics code developed for these simulations. The subsequent section examines 3-D shape effects in single-mode perturbations in planar foil simulations and experiments. A discussion of the evolution of multimode perturbations on planar foils is followed by a discussion of 3-D simulations of instability growth in Nova capsule implosions.

  6. Gas-dynamic acceleration of laser-ablation plumes: Hyperthermal particle energies under thermal vaporization

    SciTech Connect

    Morozov, A. A.; Evtushenko, A. B.; Bulgakov, A. V.

    2015-02-02

    The expansion of a plume produced by low-fluence laser ablation of graphite in vacuum is investigated experimentally and by direct Monte Carlo simulations in an attempt to explain hyperthermal particle energies for thermally vaporized materials. We demonstrate that the translation energy of neutral particles, ∼2 times higher than classical expectations, is due to two effects, hydrodynamic plume acceleration into the forward direction and kinetic selection of fast particles in the on-axis region. Both effects depend on the collision number within the plume and on the particles internal degrees of freedom. The simulations allow ablation properties to be evaluated, such as ablation rate and surface temperature, based on time-of-flight measurements. Available experimental data on kinetic energies of various laser-produced particles are well described by the presented model.

  7. Theory and numerical modeling of the accelerated expansion of laser-ablated materials near a solid surface

    NASA Astrophysics Data System (ADS)

    Chen, K. R.; King, T. C.; Hes, J. H.; Leboeuf, J. N.; Geohegan, D. B.; Wood, R. F.; Puretzky, A. A.; Donato, J. M.

    1999-09-01

    A self-similar theory and numerical hydrodynamic modeling is developed to investigate the effects of dynamic source and partial ionization on the acceleration of the unsteady expansion of laser-ablated material near a solid target surface. The dynamic source effect accelerates the expansion in the direction perpendicular to the target surface, while the dynamic partial ionization effect accelerates the expansion in all directions. The vaporized material during laser ablation provides a nonadiabatic dynamic source at the target surface into the unsteady expanding fluid. For studying the dynamic source effect, the self-similar theory begins with an assumed profile of plume velocity, u=v/vm=α+(1-α)ξ, where vm is the maximum expansion velocity, α is a constant, and ξ=x/vmt. The resultant profiles of plume density and plume temperature are derived. The relations obtained from the conservations of mass, momentum, and energy, respectively, all show that the maximum expansion velocity is inversely proportional to α, where 1-α is the slope of plume velocity profile. The numerical hydrodynamic simulation is performed with the Rusanov method and the Newton Raphson method. The profiles and scalings obtained from numerical hydrodynamic modeling are in good agreement with the theory. The dynamic partial ionization requires ionization energy from the heat at the expansion front, and thus reduces the increase of front temperature. The reduction of thermal motion would increase the flow velocity to conserve the momentum. This dynamic partial ionization effect is studied with the numerical hydrodynamic simulation including the Saha equation. With these effects, α is reduced from its value of conventional free expansion. This reduction on α increases the flow velocity slope, decreases the flow velocity near the surface, and reduces the thermal motion of plume, such that the maximum expansion velocity is significantly increased over that found from conventional models. The

  8. Nonlinear spectrum of the ablative Rayleigh-Taylor instability in laser-accelerated planar plasmas

    SciTech Connect

    Keskinen, M. J.; Schmitt, A.

    2007-01-15

    A model for the nonlinear spectrum of the ablative Rayleigh-Taylor instability in laser-accelerated planar plasmas has been developed for a wide range of Froude numbers and scale sizes. It is found that the spectrum can be characterized by an inverse power law with spectral index of approximately 2 in the limit of small-wavenumber spectrum cutoffs and small-scale density gradient scale lengths. Comparison of the model spectrum with recent experimental observations is made with good agreement.

  9. Accelerator breeder with uranium, thorium target

    SciTech Connect

    Takahashi, H.; Powell, J.; Kouts, H.

    1983-01-01

    An accelerator breeder, that uses a low-enriched fuel as the target material, can produce substantial amounts of fissile material and electric power. A study of H/sub 2/O- and D/sub 2/O-cooled, UO/sub 2/, U, (depleted U), or thorium indicates that U-metal fuel produces a good fissile production rate and electrical power of about 60% higher than UO/sub 2/ fuel. Thorium fuel has the same order of magnitude as UO/sub 2/ fuel for fissile-fuel production, but the generating electric power is substantially lower than in a UO/sub 2/ reactor. Enriched UO/sub 2/ fuel increases the generating electric power but not the fissile-material production rate. The Na-cooled breeder target has many advantages over the H/sub 2/O-cooled breeder target.

  10. Ablation of NIF Targets and Diagnostic Components by High Power Lasers and X-Rays from High Temperature Plasmas

    SciTech Connect

    Eder, D.C; Anderson, A.T.; Braun, D.G; Tobin, M.T.

    2000-04-19

    The National Ignition Facility (NIF) will consist of 192 laser beams that have a total energy of up to 1.8 MJ in the 3rd harmonic ({lambda} = 0.35 {micro}m) with the amount of 2nd harmonic and fundamental light depending on the pulse shape. Material near best focus of the 3rd harmonic light will be vaporized/ablated very rapidly, with a significant fraction of the laser energy converted into plasma x rays. Additional plasma x rays can come from imploding/igniting capsule inside Inertial Confinement Fusion (ICF) hohlraums. Material from outer portions of the target, diagnostic components, first-wall material, and optical components, are ablated by the plasma x rays. Material out to a radius of order 3 cm from target center is also exposed to a significant flux of 2nd harmonic and fundamental laser light. Ablation can accelerate the remaining material to high velocities if it has been fragmented or melted. In addition, the high velocity debris wind of the initially vaporized material pushes on the fragments/droplets and increases their velocity. The high velocity shrapnel fragments/droplets can damage the fused silica shields protecting the final optics in NIF. We discuss modeling efforts to calculate vaporization/ablation, x-ray generation, shrapnel production, and ways to mitigate damage to the shields.

  11. A spectroscopic study of laser ablation plasma from Mo target

    NASA Astrophysics Data System (ADS)

    Jakubowska, Katarzyna; Kubkowska, Monika; Blagoev, Alexander; Rosiński, Marcin; Parys, Piotr; Gąsior, Paweł

    2014-05-01

    The goal of this contribution is to present time-resolved optical spectroscopy studies of laser ablation of the Mo target with ˜ 3.5 ns, 0.4 J pulses delivered by the Nd-YAG laser system at 1.06 μm. The sample was placed in a vacuum chamber under 5 × 10-5 mbar pressure and irradiated, with power densities varied up to 22.7 GW cm-2. The ion emission from the plasma plume was measured using an electrostatic ion energy analyzer (IEA) and ion collector, which allowed us to estimate the ion kinetic energy and charge independent of the applied power densities. The signal collected by the IEA indicated the presence of molybdenum ions up to eight-ion charge. Simultaneously after the ion emission, the optical spectra acquired within 2 μs of exposure time were observed in the wavelength range from 200 to 1000 nm with a Mechelle 5000 spectrometer equipped with an iCCD (iStar) detector. The plasma electron temperature was estimated from a Boltzmann plot based on the registered spectra as well as from the ion measurements.

  12. Sputter-deposited Be ablators for NIF target capsules

    SciTech Connect

    McEachern, R.; Clford, C.; Cook, R.; Makowiecki, E.; Wallace, R.

    1997-03-26

    We have performed a series of preliminary experiments to determine whether sputter deposition of doped Be is a practical route to producing NIF target capsules with Be ablators. Films ranging in thickness from 7 to {approximately} 120 {micro}m have been deposited on spherical polymer mandrels using a bounce pan to ensure uniform coating. With no voltage bias applied to the pan, relatively porous coatings were formed that were highly permeable to hydrogen. The surface finish of these films ranged from {approximately}250 nm rms for 13-{micro}m-thick films to a minimum of {approximately}75 nm rms for an 80-{micro}m-thick film. Application of a voltage bias was found to significantly modify the film morphology. At a bias of 120 V, 7-{micro}m-thick films with a dense, fine-grained microstructure were produced. These capsules had a reflective surface with a 50 nm rms roughness. Finally, to demonstrate the ability to produce a graded dopant profile, a coating was produced in which the concentration of added Cu was varied from 2.5 atom % at the beginning to zero after 40 {micro}m of deposition.

  13. Intercepting accelerated moving targets: effects of practice on movement performance.

    PubMed

    Fialho, João V A P; Tresilian, James R

    2017-02-14

    When performing a rapid manual interception, targets moving under constant motion are often intercepted with greater accuracy when compared to targets moving under accelerated motion. Usually, accelerated targets are timed too late and decelerating ones too early. The present experiment sought to investigate whether these differences in performance when intercepting targets moving under constant and accelerated motions change after a short period of practice. The task involved striking targets that moved along a straight track by moving forward a manipulandum that moved along a slide perpendicular to the target's motion. Participants were allocated to one of the three experimental groups, defined according to the type of motion of the moving targets: constant speed, constant acceleration, and constant deceleration. Results showed that after some practice participants were able to intercept (positive and negative) accelerating moving targets as accurately as constant speed targets. These results suggest that people might be able to learn how to intercept accelerating targets, corroborating the results of some recent studies.

  14. Targeted Vessel Ablation for More Efficient Magnetic Resonance-Guided High-Intensity Focused Ultrasound Ablation of Uterine Fibroids

    SciTech Connect

    Voogt, Marianne J.; Stralen, Marijn van; Ikink, Marlijne E.; Deckers, Roel; Vincken, Koen L.; Bartels, Lambertus W.; Mali, Willem P. Th. M.; Bosch, Maurice A. A. J. van den

    2012-10-15

    Purpose: To report the first clinical experience with targeted vessel ablation during magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) treatment of symptomatic uterine fibroids. Methods: Pretreatment T1-weighted contrast-enhanced magnetic resonance angiography was used to create a detailed map of the uterine arteries and feeding branches to the fibroids. A three-dimensional overlay of the magnetic resonance angiography images was registered on 3D T2-weighted pretreatment imaging data. Treatment was focused primarily on locations where supplying vessels entered the fibroid. Patients were followed 6 months after treatment with a questionnaire to assess symptoms and quality of life (Uterine Fibroid Symptom and Quality of Life) and magnetic resonance imaging to quantify shrinkage of fibroid volumes. Results: In two patients, three fibroids were treated with targeted vessel ablation during MR-HIFU. The treatments resulted in almost total fibroid devascularization with nonperfused volume to total fibroid volume ratios of 84, 68, and 86%, respectively, of treated fibroids. The predicted ablated volumes during MR-HIFU in patients 1 and 2 were 45, 40, and 82 ml, respectively, while the nonperfused volumes determined immediately after treatment were 195, 92, and 190 ml respectively, which is 4.3 (patient 1) and 2.3 (patient 2) times higher than expected based on the thermal dose distribution. Fibroid-related symptoms reduced after treatment, and quality of life improved. Fibroid volume reduction ranged 31-59% at 6 months after treatment. Conclusion: Targeted vessel ablation during MR-HIFU allowed nearly complete fibroid ablation in both patients. This technique may enhance the use of MR-HIFU for fibroid treatment in clinical practice.

  15. Ablative Acceleration of Planar Targets to High Velocities.

    DTIC Science & Technology

    1982-03-30

    N RIPI UNCLASSIFIED NRL-MR4747 M DEEEMIEEEE - 11111.25 -4 IIt8 AM I () "I’ R I 1 " 11) ŕ t IAI4 SECURITY CLASSIFICATION OF THIS PAGE ("o Date E.te...Ebrahim, C. Joshi , D.M. Villeneuve, N.H. Burnett, and M.C. Richardson, Phys. Rev. Lett. 43, 1996 (1979). 17. C.M. Armstrong, B.H. Ripin, F.C. Young, R ...E. Storm Dr. T . Spieziali INRS Energie Dr. A. Glass Case Postale 1020 Varennes, Quebec TRW Corp. Attn: Dr. T . Johnston 1 Space Park Dr. R . Decoste

  16. Evaluation of a Novel Thermal Accelerant for Augmentation of Microwave Energy during Image-guided Tumor Ablation

    PubMed Central

    Park, William Keun Chan; Maxwell, Aaron Wilhelm Palmer; Frank, Victoria Elizabeth; Primmer, Michael Patrick; Collins, Scott Andrew; Baird, Grayson Luderman; Dupuy, Damian Edward

    2017-01-01

    The primary challenge in thermal ablation of liver tumors (e.g. hepatocellular carcinoma and hepatic colorectal cancer) is the relatively high recurrence rate (~30%) for which incomplete ablation at the periphery of the tumor is the most common reason. In an attempt to overcome this, we have developed a novel thermal accelerant (TA) agent capable of augmenting microwave energy from a distance normally unattainable by a single microwave ablation antenna. This cesium-based block co-polymer compound transforms from a liquid to a gel at body temperature and is intrinsically visible by computed tomography. Using an agarose phantom model, herein we demonstrate that both the rate and magnitude of temperature increase during microwave ablation were significantly greater in the presence of TA when compared with controls. These results suggest robust augmentation of microwave energy, and may translate into larger ablation zone volumes within biologic tissues. Further work using in vivo techniques is necessary to confirm these findings. PMID:28382173

  17. Electron acceleration in collisionless shocks and magnetic reconnection by laser-produced plasma ablation

    NASA Astrophysics Data System (ADS)

    Park, Jaehong; Spitkovksy, Anatoly; Fox, Will; Bhattacharjee, Amitava

    2016-10-01

    We perform particle-in-cell simulations of collisionless shocks and magnetic reconnection generated by ablated plasma expanding into a magnetized background plasma. We find: (1) The simulated proton radiography produces different morphology of the shock structure depending on the orientation of the magnetic field and can be used to identify a shock in the experiment. Electrons are accelerated by the whistler waves generated at oblique sites of the shock. (2) Forced collisionless magnetic reconnection is induced when the expanding plumes carry opposite magnetic polarities and interact with a background plasma. Electrons are accelerated at the reconnection X line and reveal a power-law distribution as the plasma beta is lowered, β = 0.08 . As the plasma beta is increased, β = 0.32 , the 1st order Fermi mechanism against the two plasma plumes contributes to the electron acceleration as well as the X line acceleration. Using 3-D simulations, we also explore the effect of 3-D instabilities (Weibel instability or drift-kink) on particle acceleration and magnetic field annihilation between the colliding magnetized plumes

  18. Numerical simulations of the ablative Rayleigh-Taylor instability in planar inertial-confinement-fusion targets using the FastRad3D code

    NASA Astrophysics Data System (ADS)

    Bates, J. W.; Schmitt, A. J.; Karasik, M.; Zalesak, S. T.

    2016-12-01

    The ablative Rayleigh-Taylor (RT) instability is a central issue in the performance of laser-accelerated inertial-confinement-fusion targets. Historically, the accurate numerical simulation of this instability has been a challenging task for many radiation hydrodynamics codes, particularly when it comes to capturing the ablatively stabilized region of the linear dispersion spectrum and modeling ab initio perturbations. Here, we present recent results from two-dimensional numerical simulations of the ablative RT instability in planar laser-ablated foils that were performed using the Eulerian code FastRad3D. Our study considers polystyrene, (cryogenic) deuterium-tritium, and beryllium target materials, quarter- and third-micron laser light, and low and high laser intensities. An initial single-mode surface perturbation is modeled in our simulations as a small modulation to the target mass density and the ablative RT growth-rate is calculated from the time history of areal-mass variations once the target reaches a steady-state acceleration. By performing a sequence of such simulations with different perturbation wavelengths, we generate a discrete dispersion spectrum for each of our examples and find that in all cases the linear RT growth-rate γ is well described by an expression of the form γ = α [ k g / ( 1 + ɛ k L m ) ] 1 / 2 - β k V a , where k is the perturbation wavenumber, g is the acceleration of the target, Lm is the minimum density scale-length, Va is the ablation velocity, and ɛ is either one or zero. The dimensionless coefficients α and β in the above formula depend on the particular target and laser parameters and are determined from two-dimensional simulation results through the use of a nonlinear curve-fitting procedure. While our findings are generally consistent with those of Betti et al. (Phys. Plasmas 5, 1446 (1998)), the ablative RT growth-rates predicted in this investigation are somewhat smaller than the values previously reported for the

  19. Fabrication of nanostructured targets for improved laser-driven proton acceleration

    NASA Astrophysics Data System (ADS)

    Barberio, M.; Scisciò, M.; Veltri, S.; Antici, P.

    2016-07-01

    In this work, we present a novel realization of nanostructured targets suitable for improving laser-driven proton acceleration experiments, in particular with regard to the Target-Normal-Sheath Acceleration (TNSA) acceleration mechanism. The nanostructured targets, produced as films, are realized by a simpler and cheaper method than using conventional lithographic techniques. The growth process includes a two step approach for the production of the gold nanoparticle layers: 1) Laser Ablation in Solution and 2) spray-dry technique using a colloidal solution on target surfaces (Aluminum, Mylar and Multi Walled Carbon Nanotube). The obtained nanostructured films appear, at morphological and chemical analysis, uniformly nanostructured and the nanostructure distributed on the target surfaces without presence of oxides or external contaminants. The obtained targets show a broad optical absorption in all the visible region and a surface roughness that is two times greater than non-nanostructured targets, enabling a greater laser energy absorption during the laser-matter interaction experiments producing the laser-driven proton acceleration.

  20. Formation of periodic structures upon laser ablation of metal targets in liquids

    SciTech Connect

    Kazakevich, Pavel V; Simakin, Aleksandr V; Shafeev, Georgii A

    2005-09-30

    Experimental data on the formation of ordered microstructures produced upon ablation of metal targets in liquids irradiated by a copper vapour laser or a pulsed Nd:YAG laser are presented. The structures were obtained on brass, bronze, copper, and tungsten substrates immersed in distilled water or ethanol. As a result of multiple-pulse laser ablation by a scanning beam, ordered microcones with pointed vertexes are formed on the target surface. The structures are separated by deep narrow channels. The structure period was experimentally shown to increase linearly with diameter of the laser spot on the target surface. (interaction of laser radiation with matter)

  1. Progress of laser ablation for accelerator mass spectroscopy at ATLAS utilizing an ECRIS

    NASA Astrophysics Data System (ADS)

    Scott, R.; Palchan, T.; Pardo, R.; Vondrasek, R.; Kondev, F.; Nusair, O.; Peters, C.; Paul, M.; Bauder, W.; Collon, P.

    2014-02-01

    Beams of ions from the laser ablation method of solid materials into an electron cyclotron resonance ion source (ECRIS) plasma have been used for the first time in experiments at ATLAS. Initial accelerator mass spectroscopy experiments using laser ablation for actinides and samarium have been performed. Initial results of coupling the laser system to the ECR source have guided us in making a number of changes to the original design. The point of laser impact has been moved off axis from the center of the ECR injection side. Motor control of the laser positioning mirror has been replaced with a faster and more reliable piezo-electric system, and different raster scan patterns have been tested. The use of the laser system in conjunction with a multi-sample changer has been implemented. Two major problems that are being confronted at this time are beam stability and total beam intensity. The status of the development will be presented and ideas for further improvements will be discussed.

  2. Progress of laser ablation for accelerator mass spectroscopy at ATLAS utilizing an ECRIS.

    PubMed

    Scott, R; Palchan, T; Pardo, R; Vondrasek, R; Kondev, F; Nusair, O; Peters, C; Paul, M; Bauder, W; Collon, P

    2014-02-01

    Beams of ions from the laser ablation method of solid materials into an electron cyclotron resonance ion source (ECRIS) plasma have been used for the first time in experiments at ATLAS. Initial accelerator mass spectroscopy experiments using laser ablation for actinides and samarium have been performed. Initial results of coupling the laser system to the ECR source have guided us in making a number of changes to the original design. The point of laser impact has been moved off axis from the center of the ECR injection side. Motor control of the laser positioning mirror has been replaced with a faster and more reliable piezo-electric system, and different raster scan patterns have been tested. The use of the laser system in conjunction with a multi-sample changer has been implemented. Two major problems that are being confronted at this time are beam stability and total beam intensity. The status of the development will be presented and ideas for further improvements will be discussed.

  3. The Current Beryllium Ablator NIF Ignition Target Design

    NASA Astrophysics Data System (ADS)

    Salmonson, Jay; Milovich, Jose; Haan, Steven; Ho, Darwin

    2012-10-01

    We report the results of our effort to optimize and control sensitivities for the Beryllium (Be) ablator NIF ignition capsule design. We will show recent work on the latest (Revision 6) Be capsule with a maximum hohlraum radiation temperature of 295 eV and capsule radius 1.2 mm. In particular we will highlight recent efforts to mitigate against an elevated non-thermal, hard X-ray (> 1.8 keV) component to the radiation drive that is predicted by current hohlraum simulations. These efforts include exploration of a variety of different dopants other than the traditional Copper. We particularly seek dopant materials that include Silicon (Si) due to its fortuitously placed absorption K-edge (1.8 keV). Candidates under consideration include SiC and SiO2. We also explore various dopant radial concentration profiles including i) a uniform dopant throughout the ablator, ii) a graded, ``Olympic podium'' set of three layers of varying concentration, iii) as well as a hybrid combination of these two profiles. LLNL-ABS-563631

  4. High-intensity interstitial ultrasound for thermal ablation of focal cancer targets in prostate

    NASA Astrophysics Data System (ADS)

    Salgaonkar, Vasant A.; Scott, Serena; Kurhanewicz, John; Diederich, Chris J.

    2017-03-01

    Recent advances in image based techniques such as multi-parametric MRI (MP-MRI) can provide precise targeting of focal disease in the prostate. Thermal ablation of such cancer targets while avoiding rectum, urethra, neurovascular bundles (NVB) and sphincter is clinically challenging. The approach described here employs multi-element ultrasound linear arrays designed for transperineal placement within prostate. They consist of independently powered sectored tubular transducers (6.5 - 8.0 MHz) that provide spatial control of energy deposition in angle and length. Volumetric ablation strategies were investigated through patient-specific biothermal models based on Pennes bioheat transfer equation. The acoustic and heat transfer models used here have been validated in several previous simulation and experimental studies. Focal disease sites in prostate were identified through multi-parametric MR images of representative patient cases (n=3). Focal cancer lesions and critical anatomy (prostate, urethra, rectum, bladder, seminal vesicles) were manually segmented (Mimics, Materialise) and converted to 3D finite element meshes (3-Matic, Materialise). The chosen test cases consisted of patients with medium and large sized glands and models of bulk tissue ablation covered volumes in a single quadrant in posterior prostate, hemi-gland targets and "hockey-stick" targets (lesions in three quadrants). Ultrasound applicator placement was determined such that devices were positioned along the prostate periphery while avoiding surrounding anatomy. Transducer sector angles were chosen based on applicator location within limits of fabrication practicability. Thermal models were numerically solved using finite element methods (FEM) in COMSOL Multiphysics. Temperature and thermal dose distributions were calculated to determine treated volumes (> 240 CEM43C, >52 °C) and safety profiles (<10 CEM43C, <45 °C) for nerve, rectal and urethral sparing. Modeling studies indicated that focal

  5. Investigations of the Cavitation and Damage Thresholds of Histotripsy and Applications in Targeted Tissue Ablation

    NASA Astrophysics Data System (ADS)

    Vlaisavljevich, Eli

    Histotripsy is a noninvasive ultrasound therapy that controls acoustic cavitation to mechanically fractionate soft tissue. This dissertation investigates the physical thresholds to initiate cavitation and produce tissue damage in histotripsy and factors affecting these thresholds in order to develop novel strategies for targeted tissue ablation. In the first part of this dissertation, the effects of tissue properties on histotripsy cavitation thresholds and damage thresholds were investigated. Results demonstrated that the histotripsy shock scattering threshold using multi-cycle pulses increases in stiffer tissues, while the histotripsy intrinsic threshold using single-cycle pulses is independent of tissue stiffness. Further, the intrinsic threshold slightly decreases with lower frequencies and significantly decreases with increasing temperature. The effects of tissue properties on the susceptibility to histotripsy-induced tissue damage were also investigated, demonstrating that stiffer tissues are more resistant to histotripsy. Two strategies were investigated for increasing the effectiveness of histotripsy for the treatment of stiffer tissues, with results showing that thermal preconditioning may be used to alter tissue susceptibility to histotripsy and that lower frequency treatments may increase the efficiency of histotripsy tissue ablation due to enhanced bubble expansion. In the second part of this dissertation, the feasibility of using histotripsy for targeted liver ablation was investigated in an intact in vivo porcine model, with results demonstrating that histotripsy was capable of non-invasively creating precise lesions throughout the entire liver. Additionally, a tissue selective ablation approach was developed, where histotripsy completely fractionated the liver tissue surrounding the major hepatic vessels and gallbladder while being self-limited at the boundaries of these critical structures. Finally, the long-term effects of histotripsy liver

  6. INFN - P.L.A.I.A. PROJECT (Plasma Laser Ablation for Ion Acceleration)

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Gammino, S.; Andò, L.; Ciavola, G.; Mezzasalma, A. M.; Nassisi, V.; Wolowski, J.; Parys, P.; Laska, L.; Krasa, J.; Boody, F. P.

    2004-10-01

    The INFN-Gr.V PLAIA (Plasma Laser Ablation for Ion Acceleration) Project is presented and discussed. The project is developing at LNS of Catania, Messina and Lecce Laboratories as Italian centers of research and it see as European partners the PALS Laboratory of Prague and the group of researchers coordinated by Prof. Wolowsky from IPPLM of Warsaw. PLAIA concerns the study of pulsed plasma produced by pulsed lasers and some special applications of this physics to the new generation of ion sources. Different lasers are employed at LNS of Catania, LEA of Lecce and PALS of Prague. Their fluences range from about 10 J/cm2 for the excimer lasers of LEA up to about 100 kj/cm2 for the iodine laser of PALS. The Nd:Yag laser of LNS, operating at 1064 nm, 9 ns pulse width and 900 mJ maximum pulse energy shows peculiar properties, specially if it is employed at 30 Hz repetition rate, at which it may produce stabile current of ions ejected from a dense plasma. Such laser has the optimum compromise between power density and repetition rate to be used as injector of ions in ECR sources or as source of a new generation of ion implanters which can be employed to accelerate multi-energetic ion beams useful to treat the surface of different materials. Results and projects are discussed in detail.

  7. Laser ablation of carbon targets placed in a liquid

    SciTech Connect

    Antipov, A A; Arakelyan, S M; Kutrovskaya, S V; Kucherik, A O; Nogtev, D S; Osipov, A V; Garnov, S V

    2015-08-31

    We report experimental results on laser formation of carbon nanostructures produced during irradiation of a target placed in water. We have performed comparative experiments on laser heating of carbon targets by millisecond and femtosecond laser pulses. It is shown that under different conditions of laser irradiation of targets made of schungite, glassy carbon and pyrolytic graphite, different morphological types of micro- and nanostructured carbon are formed. (interaction of laser radiation with matter)

  8. Optimizing laser-driven proton acceleration from overdense targets

    PubMed Central

    Stockem Novo, A.; Kaluza, M. C.; Fonseca, R. A.; Silva, L. O.

    2016-01-01

    We demonstrate how to tune the main ion acceleration mechanism in laser-plasma interactions to collisionless shock acceleration, thus achieving control over the final ion beam properties (e. g. maximum energy, divergence, number of accelerated ions). We investigate this technique with three-dimensional particle-in-cell simulations and illustrate a possible experimental realisation. The setup consists of an isolated solid density target, which is preheated by a first laser pulse to initiate target expansion, and a second one to trigger acceleration. The timing between the two laser pulses allows to access all ion acceleration regimes, ranging from target normal sheath acceleration, to hole boring and collisionless shock acceleration. We further demonstrate that the most energetic ions are produced by collisionless shock acceleration, if the target density is near-critical, ne ≈ 0.5 ncr. A scaling of the laser power shows that 100 MeV protons may be achieved in the PW range. PMID:27435449

  9. Optimizing laser-driven proton acceleration from overdense targets.

    PubMed

    Stockem Novo, A; Kaluza, M C; Fonseca, R A; Silva, L O

    2016-07-20

    We demonstrate how to tune the main ion acceleration mechanism in laser-plasma interactions to collisionless shock acceleration, thus achieving control over the final ion beam properties (e. g. maximum energy, divergence, number of accelerated ions). We investigate this technique with three-dimensional particle-in-cell simulations and illustrate a possible experimental realisation. The setup consists of an isolated solid density target, which is preheated by a first laser pulse to initiate target expansion, and a second one to trigger acceleration. The timing between the two laser pulses allows to access all ion acceleration regimes, ranging from target normal sheath acceleration, to hole boring and collisionless shock acceleration. We further demonstrate that the most energetic ions are produced by collisionless shock acceleration, if the target density is near-critical, ne ≈ 0.5 ncr. A scaling of the laser power shows that 100 MeV protons may be achieved in the PW range.

  10. Beamed Energy Propulsion by Means of Target Ablation

    NASA Astrophysics Data System (ADS)

    Rosenberg, Benjamin A.

    2004-03-01

    This paper describes hundreds of pendulum tests examining the beamed energy conversion efficiency of different metal targets coated with multiple liquid enhancers. Preliminary testing used a local laser with photographic paper targets, with no liquid, water, canola oil, or methanol additives. Laboratory experimentation was completed at Wright-Patterson AFB using a high-powered laser, and ballistic pendulums of aluminum, titanium, or copper. Dry targets, and those coated with water, methanol and oil were repeatedly tested in laboratory conditions. Results were recorded on several high-speed digital video cameras, and the conversion efficiency was calculated. Paper airplanes successfully launched using BEP were likewise recorded.

  11. Beamed Energy Propulsion by Means of Target Ablation

    SciTech Connect

    Rosenberg, Benjamin A.

    2004-03-30

    This paper describes hundreds of pendulum tests examining the beamed energy conversion efficiency of different metal targets coated with multiple liquid enhancers. Preliminary testing used a local laser with photographic paper targets, with no liquid, water, canola oil, or methanol additives. Laboratory experimentation was completed at Wright-Patterson AFB using a high-powered laser, and ballistic pendulums of aluminum, titanium, or copper. Dry targets, and those coated with water, methanol and oil were repeatedly tested in laboratory conditions. Results were recorded on several high-speed digital video cameras, and the conversion efficiency was calculated. Paper airplanes successfully launched using BEP were likewise recorded.

  12. CO{sub 2} Laser Ablation Area Scaling And Redeposition On Flat Polyoxymethylene Targets

    SciTech Connect

    Sinko, John E.; Scharring, Stefan; Eckel, Hans-Albert; Tsukiyama, Yosuke; Umehara, Noritsugu; Ichihashi, Katsuhiro; Ogita, Naoya; Sasoh, Akihiro; Roeser, Hans-Peter

    2010-10-08

    One of the remaining unknown subjects of laser propulsion involves whether special benefits or challenges exist for applying laser ablation propulsion to targets with particularly large or small spot areas. This subject is of high importance for a wide range of topics ranging from laser removal of space debris to micropropulsion for laser propulsion vehicles. Analysis is complex since different ablation phenomena are dominant between atmosphere and vacuum conditions. Progress has also been impeded by the difficulty of setting control parameters (particularly fluence) constant while the spot area is adjusted. It is also usually difficult for one group to address small- and large-area effects using a single high-power laser system. Recent collaborative experiments on laser ablation area scaling at several institutions, using 100-J class and 10-J class CO{sub 2} lasers, have advanced the understanding of laser propulsion area scaling. The spot area-dependence of laser propulsion parameters has been investigated over an area range covering approximately 0.05-50 cm{sup 2} at low fluence of about 0.6 J/cm{sup 2}. The experiments were conducted well below the threshold for plasma formation, and provide an estimate of the ablation threshold for CO{sub 2} laser ablation of POM.

  13. Targeted ablation of cholinergic interneurons in the dorsolateral striatum produces behavioral manifestations of Tourette syndrome.

    PubMed

    Xu, Meiyu; Kobets, Andrew; Du, Jung-Chieh; Lennington, Jessica; Li, Lina; Banasr, Mounira; Duman, Ronald S; Vaccarino, Flora M; DiLeone, Ralph J; Pittenger, Christopher

    2015-01-20

    Gilles de la Tourette syndrome (TS) is characterized by tics, which are transiently worsened by stress, acute administration of dopaminergic drugs, and by subtle deficits in motor coordination and sensorimotor gating. It represents the most severe end of a spectrum of tic disorders that, in aggregate, affect ∼ 5% of the population. Available treatments are frequently inadequate, and the pathophysiology is poorly understood. Postmortem studies have revealed a reduction in specific striatal interneurons, including the large cholinergic interneurons, in severe disease. We tested the hypothesis that this deficit is sufficient to produce aspects of the phenomenology of TS, using a strategy for targeted, specific cell ablation in mice. We achieved ∼ 50% ablation of the cholinergic interneurons of the striatum, recapitulating the deficit observed in patients postmortem, without any effect on GABAergic markers or on parvalbumin-expressing fast-spiking interneurons. Interneuron ablation in the dorsolateral striatum (DLS), corresponding roughly to the human putamen, led to tic-like stereotypies after either acute stress or d-amphetamine challenge; ablation in the dorsomedial striatum, in contrast, did not. DLS interneuron ablation also led to a deficit in coordination on the rotorod, but not to any abnormalities in prepulse inhibition, a measure of sensorimotor gating. These results support the causal sufficiency of cholinergic interneuron deficits in the DLS to produce some, but not all, of the characteristic symptoms of TS.

  14. Development of the C{sup 6+} laser ablation ion source for the KEK digital accelerator

    SciTech Connect

    Munemoto, Naoya; Takayama, Ken; Takano, Susumu; Okamura, Masahiro; Kumaki, Masahumi

    2014-02-15

    A laser ion source that provides a fully ionized carbon ion beam is under joint development at the High Energy Accelerator Research Organization and Brookhaven National Laboratory. Long-pulse (6 ns) and short-pulse (500 ps) laser systems were tested by using them to irradiate a graphite target. Notable differences between the systems were observed in these experiments. Preliminary experimental results, such as the charge-state spectrum, beam intensity, and stability, are discussed.

  15. Cavitation-enhanced nonthermal ablation in deep brain targets: feasibility in a large animal model.

    PubMed

    Arvanitis, Costas D; Vykhodtseva, Natalia; Jolesz, Ferenc; Livingstone, Margaret; McDannold, Nathan

    2016-05-01

    OBJECT Transcranial MRI-guided focused ultrasound (TcMRgFUS) is an emerging noninvasive alternative to surgery and radiosurgery that is undergoing testing for tumor ablation and functional neurosurgery. The method is currently limited to central brain targets due to skull heating and other factors. An alternative ablative approach combines very low intensity ultrasound bursts and an intravenously administered microbubble agent to locally destroy the vasculature. The objective of this work was to investigate whether it is feasible to use this approach at deep brain targets near the skull base in nonhuman primates. METHODS In 4 rhesus macaques, targets near the skull base were ablated using a clinical TcMRgFUS system operating at 220 kHz. Low-duty-cycle ultrasound exposures (sonications) were applied for 5 minutes in conjunction with the ultrasound contrast agent Definity, which was administered as a bolus injection or continuous infusion. The acoustic power level was set to be near the inertial cavitation threshold, which was measured using passive monitoring of the acoustic emissions. The resulting tissue effects were investigated with MRI and with histological analysis performed 3 hours to 1 week after sonication. RESULTS Thirteen targets were sonicated in regions next to the optic tract in the 4 animals. Inertial cavitation, indicated by broadband acoustic emissions, occurred at acoustic pressure amplitudes ranging from 340 to 540 kPa. MRI analysis suggested that the lesions had a central region containing red blood cell extravasations that was surrounded by edema. Blood-brain barrier disruption was observed on contrast-enhanced MRI in the lesions and in a surrounding region corresponding to the prefocal area of the FUS system. In histology, lesions consisting of tissue undergoing ischemic necrosis were found in all regions that were sonicated above the inertial cavitation threshold. Tissue damage in prefocal areas was found in several cases, suggesting that in

  16. Endometrial ablation

    MedlinePlus

    Hysteroscopy-endometrial ablation; Laser thermal ablation; Endometrial ablation-radiofrequency; Endometrial ablation-thermal balloon ablation; Rollerball ablation; Hydrothermal ablation; Novasure ablation

  17. Study of ablation by laser irradiation of plane targets at wavelengths 1. 05, 0. 53, and 0. 35. mu. m

    SciTech Connect

    Key, M.H.; Toner, W.T.; Goldsack, T.J.; Kilkenny, J.D.; Veats, S.A.; Cunningham, P.F.; Lewis, C.L.S.

    1983-07-01

    Ablation by laser irradiation at wavelengths lambda = 1.05, 0.53, and 0.35 ..mu..m has been studied from analysis of time-resolved x-ray spectra of layered targets and of ion emission. Irradiance was varied in the range 2 x 10/sup 13/ to 2 x 10/sup 15/ W cm/sup -2/ with constant laser power and variable focal spot size. Deductions include the effect of lateral energy transport from small focal spots and ablation rates and ablation pressures obtained both in the limit of negligible transport and when lateral transport is significant. Advantages of short wavelengths for ablatively driven implosions are quantified.

  18. The target laboratory of the Pelletron Accelerator's facilities

    SciTech Connect

    Ueta, Nobuko; Pereira Engel, Wanda Gabriel

    2013-05-06

    A short report on the activities developed in the Target Laboratory, since 1970, will be presented. Basic target laboratory facilities were provided to produce the necessary nuclear targets as well as the ion beam stripper foils. Vacuum evaporation units, a roller, a press and an analytical balance were installed in the Oscar Sala building. A brief historical report will be presented in commemoration of the 40{sup th} year of the Pelletron Accelerator.

  19. Broadening of the spectral lines of a buffer gas and target substance in laser ablation

    SciTech Connect

    Kask, Nikolai E; Michurin, Sergei V

    2012-11-30

    The broadening of discrete spectral lines from the plasma produced in the laser ablation of metal targets in a broad pressure range (10{sup 2} - 10{sup 7} Pa) of the ambient gas (Ar, He, H{sub 2}) was studied experimentally. The behaviour of spectral line broadening for the buffer gases was found to be significantly different from that for the atoms and ions of the target material. In comparison with target atoms, the atoms of buffer gases radiate from denser plasma layers, and their spectral line profiles are complex in shape. (interaction of laser radiation with matter. laser plasma)

  20. Modification of the argon stripping target of the tandem accelerator.

    PubMed

    Makarov, A; Ostreinov, Yu; Taskaev, S; Vobly, P

    2015-12-01

    The tandem accelerator with vacuum insulation has been proposed and developed in Budker Institute of Nuclear Physics. Negative hydrogen ions are accelerated by the positive 1MV potential of the high-voltage electrode, converted into protons in the gas stripping target inside the electrode, and then protons are accelerated again by the same potential. A stationary proton beam with 2 MeV energy, 1.6 mA current, 0.1% energy monochromaticity, and 0.5% current stability is obtained now. To conduct Boron Neutron Capture Therapy it is planned to increase the proton beam current to at least 3 mA. The paper presents the results of experimental studies clarifying the reasons for limiting the current, and gives suggestions for modifying the gas stripping target in order to increase the proton beam current along with the stability of the accelerator.

  1. Preparation of germanium doped plasma polymerized coatings as ICF target ablators

    SciTech Connect

    Brusasco, R M; Saculla, M D; Cook, R C

    1994-10-05

    Targets for Inertial Confinement Fusion (ICF) experiments at the Lawrence Livermore National Laboratory (LLNL) utilize an organic (CH) ablator coating prepared by plasma polymerization. Some of these experiments require a mid-Z dopant in the ablator coating to modify the opacity of the shell. Bromine had been used in the past, but the surface finish of brominated CH degrades rapidly with time upon exposure to air. This paper describes the preparation and characterization of plasma polymer layers containing germanium as a dopant at concentrations of between 1.25 and 2.25 atom percent. The coatings are stable in air and have an rms surface roughness of 7--9 nm (modes 10--1,000) which is similar to that obtained with undoped coatings. High levels of dopant result in cracking of the inner mandrel during target assembly. Possible explanations for the observed cracking behavior will be discussed.

  2. Solid hydrogen target for laser driven proton acceleration

    NASA Astrophysics Data System (ADS)

    Perin, J. P.; Garcia, S.; Chatain, D.; Margarone, D.

    2015-05-01

    The development of very high power lasers opens up new horizons in various fields, such as laser plasma acceleration in Physics and innovative approaches for proton therapy in Medicine. Laser driven proton acceleration is commonly based on the so-called Target Normal Sheath Acceleration (TNSA) mechanisms: a high power laser is focused onto a solid target (thin metallic or plastic foil) and interact with matter at very high intensity, thus generating a plasma; as a consequence "hot" electrons are produced and move into the forward direction through the target. Protons are generated at the target rear side, electrons try to escape from the target and an ultra-strong quasi-electrostatic field (~1TV/m) is generated. Such a field can accelerate protons with a wide energy spectrum (1-200 MeV) in a few tens of micrometers. The proton beam characteristics depend on the laser parameters and on the target geometry and nature. This technique has been validated experimentally in several high power laser facilities by accelerating protons coming from hydrogenated contaminant (mainly water) at the rear of metallic target, however, several research groups are investigating the possibility to perform experiments by using "pure" hydrogen targets. In this context, the low temperature laboratory at CEA-Grenoble has developed a cryostat able to continuously produce a thin hydrogen ribbon (from 40 to 100 microns thick). A new extrusion concept, without any moving part has been carried out, using only the thermodynamic properties of the fluid. First results and perspectives are presented in this paper.

  3. Influence of the embryonic preplate on the organization of the cerebral cortex: a targeted ablation model.

    PubMed

    Xie, Y; Skinner, E; Landry, C; Handley, V; Schonmann, V; Jacobs, E; Fisher, R; Campagnoni, A

    2002-10-15

    Transgenic mice were generated to permit the targeted ablation of cortical preplate cells at the time they are born. In these mice, the 1.3 kb golli promoter of the myelin basic protein gene was used to drive the herpes simplex virus thymidine kinase (TK) transgene in cortical preplate cells. Heterozygous transgenic pairs were bred, and pregnant dams were treated with ganciclovir at embryonic days 11-12 to ablate preplate cells at the time the preplate was forming. This paradigm exposed control (TK-) and experimental (TK+) littermates to exactly the same conditions. Embryological ablation of preplate cells led to an early disruption of the radial glial framework and subplate structure in the developing cortex and dramatically altered the cellular lamination and connectivity of the cortical plate. The disturbed radial glial network contributed to an impaired radial migration of neurons into the cortical plate from the ventricular zone. The cortical plate became dyslaminated, and there was a substantial reduction in short- and long-range cortical projections within the cortex and to subcortical regions. Cell death within the cortical plate and the proliferative zones was substantially increased in the ablated animals. After birth, a cortical lesion developed, which became exacerbated with the secondary onset of hydrocephaly in the second postnatal week. The results underscore the critical importance of the preplate in cortex formation, mediated through its guidance of the formation of radial glial scaffolding, subsequent neuronal migration into the incipient cortical plate, and the final arrangement of its vertical organization and cellular connectivity.

  4. Accelerated nonlinear multichannel ultrasonic tomographic imaging using target sparseness.

    PubMed

    Chengdong Dong; Yuanwei Jin; Enyue Lu

    2014-03-01

    This paper presents an accelerated iterative Landweber method for nonlinear ultrasonic tomographic imaging in a multiple-input multiple-output (MIMO) configuration under a sparsity constraint on the image. The proposed method introduces the emerging MIMO signal processing techniques and target sparseness constraints in the traditional computational imaging field, thus significantly improves the speed of image reconstruction compared with the conventional imaging method while producing high quality images. Using numerical examples, we demonstrate that incorporating prior knowledge about the imaging field such as target sparseness accelerates significantly the convergence of the iterative imaging method, which provides considerable benefits to real-time tomographic imaging applications.

  5. Enhanced Ion Acceleration from Micro-tube Structured Targets

    NASA Astrophysics Data System (ADS)

    Snyder, Joseph; Ji, Liangliang; Akli, Kramer

    2015-11-01

    We present an enhanced ion acceleration method that leverages recent advancements in 3D printing for target fabrication. Using the three-dimensional Particle-in-Cell simulation code Virtual Laser-Plasma Lab (VLPL), we model the interaction of a short pulse, high intensity laser with a micro-tube plasma (MTP) structured target. When compared to flat foils, the MTP target enhances the maximum proton energy by a factor of about 4. The ion enhancement is attributed to two main factors: high energy electrons extracted from the tube structure enhancing the accelerating field and light intensification within the MTP target increasing the laser intensity at the location of the foil. We also present results on ion energy scaling with micro-tube diameter and incident laser pulse intensity. This work was supported by the AFOSR under contract No. FA9550-14-1-0085.

  6. A Phase II Trial of Stereotactic Ablative Body Radiotherapy for Low-Risk Prostate Cancer Using a Non-Robotic Linear Accelerator and Real-Time Target Tracking: Report of Toxicity, Quality of Life, and Disease Control Outcomes with 5-Year Minimum Follow-Up

    PubMed Central

    Mantz, Constantine

    2014-01-01

    Purpose/Objective(s): Herein, we report the results of an IRB-approved phase II trial of Varian Trilogy/TrueBeam-based stereotactic ablative body radiotherapy (SABR) monotherapy for low-risk prostate cancer using the Calypso® System to provide real-time electromagnetic tracking of the prostate’s position during treatment delivery. Materials/Methods: A total of 102 low-risk patients completed protocol treatment between January 2007 and May 2009. A total dose of 40.0 Gy in 5 every-other-day fractions of 8.0 Gy was prescribed to the planning target volume. Target setup and tracking procedures were as follows: (1) the Calypso® System was used to achieve target setup prior to each fraction; (2) conebeam CT imaging was then used for correction of setup error and for assessment of target and organs-at-risk deformations; (3) after treatment delivery was initiated, the Calypso® System then provided real-time intrafractional target tracking. The NCI CTCAE v3.0 was used to assess urinary and rectal toxicity during treatment and at defined follow-up time points. Biochemical response and quality of life measurements were made at concurrent follow-up points. Results: Urinary toxicities were most common. At 6 months, 19.6, 2.9, and 4.9% of patients reported grades 1–2 urinary frequency, dysuria, and retention, respectively. Rectal toxicities were uncommon. By 12 months, 2.9% of patients reported painless rectal bleeding with subsequent symptom resolution without requiring invasive interventions. Quality of life measurements demonstrated a significant decline over baseline in urinary irritative/obstructive scores at 1 month following SABR but otherwise did not demonstrate any difference for bowel, bladder, and sexual function scores at any other follow-up time point. One patient suffered biochemical recurrence at 6 years following SABR. Conclusion: At 5 years, minimum follow-up for this favorable patient cohort, prostate SABR resulted in favorable toxicity

  7. Target Material Irradiation Studies for High-Intensity Accelerator Beams

    SciTech Connect

    Simos, N.; Kirk, H.; Ludewig, H.; Thieberger, P.; Weng, W.T.; McDonald, K.; Sheppard, J.; Evangelakis, G.; Yoshimura, K.; /KEK, Tsukuba

    2005-08-16

    This paper presents results of recent experimental studies focusing on the behavior of special materials and composites under irradiation conditions and their potential use as accelerator targets. The paper also discusses the approach and goals of on-going investigations on an expanded material matrix geared toward the neutrino superbeam and muon collider initiatives.

  8. SERS detection and targeted ablation of lymphoma cells using functionalized Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Yao, Qian; Cao, Fei; Feng, Chao; Zhao, Yan; Wang, Xiuhong

    2016-03-01

    Lymphoma is a heterogeneous group of malignancies of the lymphoid tissue, and is prevalent worldwide affecting both children and adults with a high mortality rate. There is in dire need of accurate and noninvasive approaches for early detection of the disease. Herein, we report a facile way to fabricate silver nanoparticle based nanoprobe by incorporating the corner-stone immunotherapeutic drug Rituxan for simultaneous detection and ablation of lymphoma cells in vitro. The fabricated nanoprobe can detect CD20 positive single lymphoma cell by surface enhanced Raman scattering technique with high specificity. The engineered nanoprobe retains the same antibody property as intact drug via Antibody-Dependent Cell-mediated Cytotoxicity (ADCC) analysis. The nanoprobe efficiently eradicates lymphoma cells in vitro. By integrating the advantages of sensitive SERS detection with targeted ablation capabilities of immunotherapeutic drug through site specificity, this nanoprobe can be applied as outstanding tools in living imaging, cancer diagnosis and treatment.

  9. Ion acceleration by femtosecond laser pulses in small multispecies targets

    NASA Astrophysics Data System (ADS)

    Psikal, J.; Tikhonchuk, V. T.; Limpouch, J.; Andreev, A. A.; Brantov, A. V.

    2008-05-01

    Ion acceleration by ultrashort intense femtosecond laser pulses (˜4×1019W/cm2, ˜30fs) in small targets of uniform chemical composition of two ion species (protons and carbon C4+ ions) is studied theoretically via a particle-in-cell code with two spatial and three velocity components. Energy spectra of accelerated ions, the number and divergence of fast protons, are compared for various target shapes (cylinder, flat foil, curved foil) and density profiles. Dips and peaks are observed in proton energy spectra due to mutual interaction between two ion species. The simulations demonstrate that maximum energy of fast protons depends on the efficiency of laser absorption and the cross section of the hot electron cloud behind the target. A rear-side plasma density ramp can substantially decrease the energy of fast ions and simultaneously enhance their number. These results are compared with analytical estimates and with previously published experiments.

  10. Design of a deuterium and tritium-ablator shock ignition target for the National Ignition Facility

    SciTech Connect

    Terry, Matthew R.; Perkins, L. John; Sepke, Scott M.

    2012-11-15

    Shock ignition presents a viable path to ignition and high gain on the National Ignition Facility (NIF). In this paper, we describe the development of the 1D design of 0.5 MJ class, all-deuterium and tritium (fuel and ablator) shock ignition target that should be reasonably robust to Rayleigh-Taylor fluid instabilities, mistiming, and hot electron preheat. The target assumes 'day one' NIF hardware and produces a yield of 31 MJ with reasonable allowances for laser backscatter, absorption efficiency, and polar drive power variation. The energetics of polar drive laser absorption require a beam configuration with half of the NIF quads dedicated to launching the ignitor shock, while the remaining quads drive the target compression. Hydrodynamic scaling of the target suggests that gains of 75 and yields 70 MJ may be possible.

  11. Thermal infrared images to quantify thermal ablation effects of acid and base on target tissues

    NASA Astrophysics Data System (ADS)

    Liu, Ran; Wang, Jia; Liu, Jing

    2015-07-01

    Hyperthermia (42-46°C), treatment of tumor tissue through elevated temperature, offers several advantages including high cost-effectiveness, highly targeted ablation and fewer side effects and hence higher safety level over traditional therapies such as chemotherapy and radiotherapy. Recently, hyperthermia using heat release through exothermic acid-base neutralization comes into view owing to its relatively safe products of salt and water and highly confined ablation. However, lack of quantitative understanding of the spatial and temporal temperature profiles that are produced by simultaneous diffusion of liquid chemical and its chemical reaction within tumor tissue impedes the application of this method. This article is dedicated to quantify thermal ablation effects of acid and base both individually and as in neutralization via infrared captured thermal images. A theoretical model is used to approximate specific heat absorption rate (SAR) based on experimental measurements that contrast two types of tissue, normal pork and pig liver. According to the computation, both pork and liver tissue has a higher ability in absorbing hydrochloric acid (HCl) than sodium hydroxide, hence suggesting that a reduced dosage for HCl is appropriate in a surgery. The heating effect depends heavily on the properties of tissue types and amount of chemical reagents administered. Given thermal parameters such as SAR for different tissues, a computational model can be made in predicting temperature transitions which will be helpful in planning and optimizing surgical hyperthermia procedures.

  12. Thermal infrared images to quantify thermal ablation effects of acid and base on target tissues

    SciTech Connect

    Liu, Ran E-mail: liuran@tsinghua.edu.cn; Liu, Jing E-mail: liuran@tsinghua.edu.cn; Wang, Jia

    2015-07-15

    Hyperthermia (42-46°C), treatment of tumor tissue through elevated temperature, offers several advantages including high cost-effectiveness, highly targeted ablation and fewer side effects and hence higher safety level over traditional therapies such as chemotherapy and radiotherapy. Recently, hyperthermia using heat release through exothermic acid-base neutralization comes into view owing to its relatively safe products of salt and water and highly confined ablation. However, lack of quantitative understanding of the spatial and temporal temperature profiles that are produced by simultaneous diffusion of liquid chemical and its chemical reaction within tumor tissue impedes the application of this method. This article is dedicated to quantify thermal ablation effects of acid and base both individually and as in neutralization via infrared captured thermal images. A theoretical model is used to approximate specific heat absorption rate (SAR) based on experimental measurements that contrast two types of tissue, normal pork and pig liver. According to the computation, both pork and liver tissue has a higher ability in absorbing hydrochloric acid (HCl) than sodium hydroxide, hence suggesting that a reduced dosage for HCl is appropriate in a surgery. The heating effect depends heavily on the properties of tissue types and amount of chemical reagents administered. Given thermal parameters such as SAR for different tissues, a computational model can be made in predicting temperature transitions which will be helpful in planning and optimizing surgical hyperthermia procedures.

  13. Electron Beam/Converter Target Interactions in Radiographic Accelerators

    SciTech Connect

    McCarrick, J; Caporaso, G; Chambers, F; Chen, Y-J; Falabella, S; Goldin, F; Guethlein, G; Ho, D; Richardson, R; Weir, J

    2003-05-27

    Linear induction accelerators used in X-ray radiography have single-pulse parameters of the order 20 MeV of electron beam energy, 2 kA of beam current, pulse lengths of 50-100 ns, and spot sizes of 1-2 mm. The thermal energy deposited in a bremsstrahlung converter target made of tantalum from such a pulse is {approx}80 kJ/cc, more than enough to bring the target material to a partially ionized state. The tail end of a single beam pulse, or any subsequent pulse in a multi-pulse train, undergoes a number of interactions with the target that can affect beam transport and radiographic performance. Positive ions extracted from the target plasma by the electron beam space charge can affect the beam focus and centroid stability. As the target expands on the inter-pulse time scale, the integrated line density of material decreases, eventually affecting the X-ray output of the system. If the target plume becomes sufficiently large, beam transport through it is affected by macroscopic charge and current neutralization effects and microscopic beam/plasma instability mechanisms. We will present a survey of some of these interactions, as well as some results of an extensive experimental and theoretical campaign to understand the practical amelioration of these effects, carried out at the ETA-II accelerator facility at the Lawrence Livermore National Laboratory.

  14. Experiments on Dynamic Overpressure Stabilization of Ablative Richtmyer--Meshkov Growth in ICF Targets on OMEGA

    NASA Astrophysics Data System (ADS)

    Gotchev, O. V.; Goncharov, V. N.; Jaanimagi, P. A.; Knauer, J. P.; Meyerhofer, D. D.

    2002-11-01

    Dynamic overpressure sets the growth rate of the ablative Richtmyer--Meshkov (RM) instability and the late-time imprint levels in directly driven ICF targets. It leads to temporal oscillations of the perturbed ablation front, which have been predicted analytically and observed experimentally,(Y. Aglitskiy et al.), Phys. Plasmas 9, 2264 (2002). and in 2-D ORCHID simulations. These predictions were verified on OMEGA by measuring the perturbation amplitudes and frequencies directly with an x-ray framing camera through face-on x-ray radiography. Planar plastic targets with variable thickness (20 to 60 μm) and single-mode (λ = 10 to 30 μm) ripples on the front surface were irradiated with 1.5-ns square UV laser pulses at maximum energy. Results clearly indicate a phase reversal in the evolution of the target areal density perturbations, in good agreement with theory and simulation. Nonlinearity in the evolution of the preimposed mode, resulting in an enriched spectrum, was observed for initial amplitudes previously believed to develop linearly with time. Upcoming experiments with a high-resolution, streaked imager, will allow for the detailed recording of the evolution of the RM instability and the competing stabilization effect. This work was supported by the U.S. DOE Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  15. Tbx18 targets dermal condensates for labeling, isolation, and gene ablation during embryonic hair follicle formation.

    PubMed

    Grisanti, Laura; Clavel, Carlos; Cai, Xiaoqiang; Rezza, Amelie; Tsai, Su-Yi; Sennett, Rachel; Mumau, Melanie; Cai, Chen-Leng; Rendl, Michael

    2013-02-01

    How cell fate decisions of stem and progenitor cells are regulated by their microenvironment or niche is a central question in stem cell and regenerative biology. Although functional analysis of hair follicle epithelial stem cells by gene targeting is well established, the molecular and genetic characterization of the dermal counterpart during embryonic morphogenesis has been lacking because of the absence of cell type-specific drivers. Here, we report that T-box transcription factor Tbx18 specifically marks dermal papilla (DP) precursor cells during embryonic hair follicle morphogenesis. With Tbx18(LacZ), Tbx18(H2BGFP), and Tbx18(Cre) knock-in mouse models, we demonstrate LacZ and H2BGFP (nuclear green fluorescent protein) expression and Cre activity in dermal condensates of nascent first-wave hair follicles at E14.5. As Tbx18 expression becomes more widespread throughout the dermis at later developmental stages, we use tamoxifen-inducible Cre-expressing mice, Tbx18(MerCreMer), to exclusively target DP precursor cells and their progeny. Finally, we ablate Tbx18 in full knockout mice, but find no perturbations in hair follicle formation, suggesting that Tbx18 is dispensable for normal DP function. In summary, our study establishes Tbx18 as a genetic driver to target for the first time embryonic DP precursors for labeling, isolation, and gene ablation that will greatly enhance investigations into their molecular functions during hair follicle morphogenesis.

  16. Rare Isotope Accelerator - Conceptual Design of Target Areas

    SciTech Connect

    Bollen, Georg; Baek, Inseok; Blideanu, Valentin; Lawton, Don; Mantica, Paul F.; Morrissey, David J.; Ronningen, Reginald M.; Sherrill, Bradley S.; Zeller, Albert; Beene, James R; Burgess, Tom; Carter, Kenneth; Carrol, Adam; Conner, David; Gabriel, Tony A; Mansur, Louis K; Remec, Igor; Rennich, Mark J; Stracener, Daniel W; Wendel, Mark W; Ahle, Larry; Boles, Jason; Reyes, Susana; Stein, Werner; Heilbronn, Lawrence

    2006-01-01

    The planned rare isotope accelerator facility RIA in the US would become the most powerful radioactive beam facility in the world. RIA s driver accelerator will be a device capable of providing beams from protons to uranium at energies of at least 400MeV per nucleon, with beam power up to 400 kW. Radioactive beam production relies on both the in-flight separation of fast beam fragments and on the ISOL technique. In both cases the high beam power poses major challenges for target technology and handling and on the design of the beam production areas. This paper will give a brief overview of RIA and discuss aspects of ongoing conceptual design work for the RIA target areas.

  17. Nonthermal ablation of deep brain targets: A simulation study on a large animal model

    PubMed Central

    Top, Can Barış; White, P. Jason; McDannold, Nathan J.

    2016-01-01

    Purpose: Thermal ablation with transcranial MRI-guided focused ultrasound (FUS) is currently limited to central brain targets because of heating and other beam effects caused by the presence of the skull. Recently, it was shown that it is possible to ablate tissues without depositing thermal energy by driving intravenously administered microbubbles to inertial cavitation using low-duty-cycle burst sonications. A recent study demonstrated that this ablation method could ablate tissue volumes near the skull base in nonhuman primates without thermally damaging the nearby bone. However, blood–brain disruption was observed in the prefocal region, and in some cases, this region contained small areas of tissue damage. The objective of this study was to analyze the experimental model with simulations and to interpret the cause of these effects. Methods: The authors simulated prior experiments where nonthermal ablation was performed in the brain in anesthetized rhesus macaques using a 220 kHz clinical prototype transcranial MRI-guided FUS system. Low-duty-cycle sonications were applied at deep brain targets with the ultrasound contrast agent Definity. For simulations, a 3D pseudospectral finite difference time domain tool was used. The effects of shear mode conversion, focal steering, skull aberrations, nonlinear propagation, and the presence of skull base on the pressure field were investigated using acoustic and elastic wave propagation models. Results: The simulation results were in agreement with the experimental findings in the prefocal region. In the postfocal region, however, side lobes were predicted by the simulations, but no effects were evident in the experiments. The main beam was not affected by the different simulated scenarios except for a shift of about 1 mm in peak position due to skull aberrations. However, the authors observed differences in the volume, amplitude, and distribution of the side lobes. In the experiments, a single element passive

  18. Powder Metallurgy Fabrication of Molybdenum Accelerator Target Disks

    SciTech Connect

    Lowden, Richard Andrew; Kiggans Jr., James O.; Nunn, Stephen D.; Parten, Randy J.

    2015-07-01

    Powder metallurgy approaches for the fabrication of accelerator target disks are being examined to support the development of Mo-99 production by NorthStar Medical Technologies, LLC. An advantage of powder metallurgy is that very little material is wasted and, at present, dense, quality parts are routinely produced from molybdenum powder. The proposed targets, however, are thin wafers, 29 mm in diameter with a thickness of 0.5 mm, with very stringent dimensional tolerances. Although tooling can be machined to very high tolerance levels, the operations of powder feed, pressing and sintering involve complicated mechanisms, each of which affects green density and shrinkage, and therefore the dimensions and shape of the final product. Combinations of powder morphology, lubricants and pressing technique have been explored to produce target disks with minimal variations in thickness and little or no distortion. In addition, sintering conditions that produce densities for optimum target dissolvability are being determined.

  19. INTERACTION OF LASER RADIATION WITH MATTER: Formation of periodic structures upon laser ablation of metal targets in liquids

    NASA Astrophysics Data System (ADS)

    Kazakevich, Pavel V.; Simakin, Aleksandr V.; Shafeev, Georgii A.

    2005-09-01

    Experimental data on the formation of ordered microstructures produced upon ablation of metal targets in liquids irradiated by a copper vapour laser or a pulsed Nd:YAG laser are presented. The structures were obtained on brass, bronze, copper, and tungsten substrates immersed in distilled water or ethanol. As a result of multiple-pulse laser ablation by a scanning beam, ordered microcones with pointed vertexes are formed on the target surface. The structures are separated by deep narrow channels. The structure period was experimentally shown to increase linearly with diameter of the laser spot on the target surface.

  20. Neutron producing target for accelerator based neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Bayanov, B.; Belov, V.; Taskaev, S.

    2006-05-01

    Pilot innovative accelerator based neutron source for neutron capture therapy of cancer is under construction now at the Budker Institute. One of the main elements of the facility is lithium target producing neutrons via threshold 7Li(p, n)7Be reaction at 10 mA proton beam with energies of 1.915 MeV or 2.5 MeV. In the present report, choice of target was substantiated. The main problems of lithium target were determined to be: 7Be radioactive isotope activation, keeping lithium layer solid, presence of photons resulted from proton inelastic scattering on lithium nuclei, and radiation blistering. The results of thermal testing of target prototype, investigation of radiation blistering and several simulations are presented. It becomes clear that water is preferable for cooling this target, and that the lithium target 10 cm in diameter is able to run up to 25 kW proton beam before melting. The conception of optimal target is proposed: thin and easy to detach metal disk 10 cm in diameter, evaporated with thin layer of pure lithium from the side of proton beam exposure: its back is intensively cooled with turbulent water flow to maintain lithium layer solid. Design of target for the neutron source constructed at BINP is shown. Conceptions of radiation protection and neutrons, γ-rays and α- particles diagnostics are presented. The immediate plans on obtaining epithermal neutron beam are declared.

  1. Pulsed laser ablation of borax target in vacuum and hydrogen DC glow discharges

    NASA Astrophysics Data System (ADS)

    Kale, A. N.; Miotello, A.; Mosaner, P.

    2006-09-01

    The aim of our experiment was to produce a material with B sbnd H bonds for applications in hydrogen storage and generation. By using KrF excimer laser ( λ = 248 nm) ablation of borax (Na 2B 4O 7) target, thin films were deposited on KBr and silicon substrates. Ablation was performed both in vacuum and in hydrogen atmosphere. DC glow discharge technique was utilized to enhance hydrogen gas ionization. Experiments were performed using laser fluence from 5 to 20 J/cm 2. Films were deposited under gas pressure of 1 × 10 -5 to 5 × 10 -2 mbar and substrate temperatures of 130-450 °C. Scanning electron microscopy analysis of films showed presence of circular particulates. Film thickness, roughness and particulates number increased with increase in laser fluence. Energy dispersive X-ray spectroscopy analysis shows that sodium content in the particulates is higher than in the target. This effect is discussed in terms of atomic arrangements (both at surface and bulk) in systems where ionic and covalent bonds are present and by looking at the increased surface/bulk ratio of the particulates with respect to the deposited films. The Fourier transform infrared spectroscopy measurements showed presence of B sbnd O stretching and B sbnd O sbnd B bending bonds. Possible reasons for absence of B sbnd H bonds are attributed to binding enthalpy of the competing molecules.

  2. Laser ablation of Drosophila embryonic motoneurons causes ectopic innervation of target muscle fibers

    NASA Technical Reports Server (NTRS)

    Chang, T. N.; Keshishian, H.

    1996-01-01

    We have tested the effects of neuromuscular denervation in Drosophila by laser-ablating the RP motoneurons in intact embryos before synaptogenesis. We examined the consequences of this ablation on local synaptic connectivity in both 1st and 3rd instar larvae. We find that the partial or complete loss of native innervation correlates with the appearance of alternate inputs from neighboring motor endings and axons. These collateral inputs are found at ectopic sites on the denervated target muscle fibers. The foreign motor endings are electrophysiologically functional and are observed on the denervated muscle fibers by the 1st instar larval stage. Our data are consistent with the existence of a local signal from the target environment, which is regulated by innervation and influences synaptic connectivity. Our results show that, despite the stereotypy of Drosophila neuromuscular connections, denervation can induce local changes in connectivity in wild-type Drosophila, suggesting that mechanisms of synaptic plasticity may also be involved in normal Drosophila neuromuscular development.

  3. Streaked Imaging of Ablative Richtmyer--Meshkov Growth in ICF Targets on OMEGA

    NASA Astrophysics Data System (ADS)

    Gotchev, O. V.; Goncharov, V. N.; Jaanimagi, P. A.; Knauer, J. P.; Meyerhofer, D. D.

    2003-10-01

    Dynamic overpressure sets the growth rate of the ablative Richtmyer--Meshkov (RM) instability and the seeds for subsequent growth of perturbations due to the Rayleigh--Taylor instability in directly driven ICF targets. It leads to temporal oscillations of the perturbed ablation front, which have been predicted analytically,(V.N. Goncharov, Phys. Rev. Lett. 82), 2091 (1999). observed in 2-D ORCHID hydrodynamic simulations, and measured experimentally.(Y. Aglitskiy et al.), Phys. Plasmas 9, 2264 (2002). These predictions were verified on OMEGA by measuring the perturbation amplitudes and frequencies directly, through face-on x-ray radiography. Experiments with a high-resolution, Ir-coated Kirkpatrick--Baez microscope, coupled to a high-current streak tube, provided a continuous record of the target areal density during shock transit, while it was dominated by the evolution of the RM instability. Planar plastic targets with variable thicknesses (30 to 60 μm) and single-mode (λ = 10 to 30 μm) ripples on the front surface were irradiated with 1.5-ns square UV laser pulses with intensities---ranging from 5 × 10^13 W/cm^2 to 4 × 10^14 W/cm^2. Results clearly indicate a phase reversal in the evolution of the target areal density perturbations, in good agreement with theory and simulation. The predicted dependence of the oscillation period on laser intensity and modulation wavelength was quantified. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  4. The importance of cellular internalization of antibody-targeted carbon nanotubes in the photothermal ablation of breast cancer cells

    NASA Astrophysics Data System (ADS)

    Marches, Radu; Mikoryak, Carole; Wang, Ru-Hung; Pantano, Paul; Draper, Rockford K.; Vitetta, Ellen S.

    2011-03-01

    Single-walled carbon nanotubes (CNTs) convert absorbed near infrared (NIR) light into heat. The use of CNTs in the NIR-mediated photothermal ablation of tumor cells is attractive because the penetration of NIR light through normal tissues is optimal and the side effects are minimal. Targeted thermal ablation with minimal collateral damage can be achieved by using CNTs attached to tumor-specific monoclonal antibodies (MAbs). However, the role that the cellular internalization of CNTs plays in the subsequent sensitivity of the target cells to NIR-mediated photothermal ablation remains undefined. To address this issue, we used CNTs covalently coupled to an anti-Her2 or a control MAb and tested their ability to bind, internalize, and photothermally ablate Her2 + but not Her2 - breast cancer cell lines. Using flow cytometry, immunofluorescence, and confocal Raman microscopy, we observed the gradual time-dependent receptor-mediated endocytosis of anti-Her2-CNTs whereas a control MAb-CNT conjugate did not bind to the cells. Most importantly, the Her2 + cells that internalized the MAb-CNTs were more sensitive to NIR-mediated photothermal damage than cells that could bind to, but not internalize the MAb-CNTs. These results suggest that both the targeting and internalization of MAb-CNTs might result in the most effective thermal ablation of tumor cells following their exposure to NIR light.

  5. Target studies for accelerator-based boron neutron capture therapy

    SciTech Connect

    Powell, J.R.; Ludewig, H.; Todosow, M.; Reich, M.

    1996-03-01

    Two new concepts, NIFTI and DISCOS, are described. These concepts enable the efficient production of epithermal neutrons for BNCT (Boron Neutron Capture Therapy) medical treatment, utilizing a low current, low energy proton beam impacting on a lithium target. The NIFTI concept uses an iron layer that strongly impedes the transmission of neutrons with energies above 24 KeV. Lower energy neutrons readily pass through this iron ``filter``, which has a deep ``window`` in its scattering cross section at 24 KeV. The DISCOS concept uses a rapidly rotating, high g disc to create a series of thin ({approximately} 1 micron thickness) liquid lithium targets in the form of continuous films through which the proton beam passes. The average energy lost by a proton as it passes through a single target is small, approximately 10 KeV. Between the targets, the proton beam is reaccelerated by an applied DC electric field. The DISCOS approach enables the accelerator -- target facility to operate with a beam energy only slightly above the threshold value for neutron production -- resulting in an output beam of low-energy epithermal neutrons -- while achieving a high yield of neutrons per milliamp of proton beam current.

  6. Laser Ablation - Accelerator Mass Spectrometry: An Approach for Rapid Radiocarbon Analyses of Carbonate Archives at High Spatial Resolution.

    PubMed

    Welte, Caroline; Wacker, Lukas; Hattendorf, Bodo; Christl, Marcus; Fohlmeister, Jens; Breitenbach, Sebastian F M; Robinson, Laura F; Andrews, Allen H; Freiwald, André; Farmer, Jesse R; Yeman, Christiane; Synal, Hans-Arno; Günther, Detlef

    2016-09-06

    A new instrumental setup, combining laser ablation (LA) with accelerator mass spectrometry (AMS), has been investigated for the online radiocarbon ((14)C) analysis of carbonate records. Samples were placed in an in-house designed LA-cell, and CO2 gas was produced by ablation using a 193 nm ArF excimer laser. The (14)C/(12)C abundance ratio of the gas was then analyzed by gas ion source AMS. This configuration allows flexible and time-resolved acquisition of (14)C profiles in contrast to conventional measurements, where only the bulk composition of discrete samples can be obtained. Three different measurement modes, i.e. discrete layer analysis, survey scans, and precision scans, were investigated and compared using a stalagmite sample and, subsequently, applied to terrestrial and marine carbonates. Depending on the measurement mode, a precision of typically 1-5% combined with a spatial resolution of 100 μm can be obtained. Prominent (14)C features, such as the atomic bomb (14)C peak, can be resolved by scanning several cm of a sample within 1 h. Stalagmite, deep-sea coral, and mollusk shell samples yielded comparable signal intensities, which again were comparable to those of conventional gas measurements. The novel LA-AMS setup allowed rapid scans on a variety of sample materials with high spatial resolution.

  7. Laser-ablated loading of solid target through foams of overcritical density

    SciTech Connect

    De Angelis, R. Consoli, F.; Andreoli, P.; Cristofari, G.; Di Giorgio, G.; Gus'kov, S. Yu.; Rupasov, A. A.

    2015-07-15

    The main objective of the work is to study the conversion of the laser pulse energy into the energy of the hydrodynamic motion of matter in a solid target following the initial absorption of laser radiation in a layer of porous material. Results of experiments on plane massive aluminum targets, coated with a layer of porous plastic with density greater than the critical density of the plasma created, are presented. Experiments were carried out on the laser installation ABC of the Research Center ENEA-Frascati; the targets were irradiated by a beam of the fundamental harmonic of Nd-laser radiation with an energy of about 50 kJ, intensity of 10{sup 13 }W/cm{sup 2}, and 3 ns duration. The experimental method consisted in measuring the volume of the craters created on the aluminum surface behind various thicknesses and densities of the porous absorber of laser radiation. On the basis of these measurements and of an advanced analytical model, quantitative conclusions are made on how the efficiency of laser energy transfer to the solid part of the target (laser-ablated loading) depends on thickness and density of the porous absorber.

  8. Preparation of oriented silicon carbide films by laser ablation of ceramic silicon carbide targets

    NASA Astrophysics Data System (ADS)

    Rimai, L.; Ager, R.; Logothetis, E. M.; Weber, W. H.; Hangas, J.

    1991-10-01

    Stoichiometric films of SiC, 60-150 nm thick, were deposited on 001-line and 111-line Si wafers by laser ablation of ceramic stoichiometric SiC targets. Films grown at substrate temperatures above 1050 C show orientation epitaxial to the Si substrate along the film normal. Depending on the deposition conditions, the oriented crystalline dimension along this direction ranges from 20 nm up to the film thickness. The crystallite dimensions in the film plane range from 20 to 70 nm. Raman spectra indicate that the films often contain material other than crystalline SiC. Some of that is in the form of small (3-5 nm) graphitic inclusions.

  9. Minimization of target positioning error in accelerator-based radiosurgery.

    PubMed

    Low, D A; Li, Z; Drzymala, R E

    1995-04-01

    The stereotactic radiosurgery system used at the Mallinckrodt Institute of Radiology is patterned after that developed at the Joint Center for Radiation Therapy (Brigham & Women's Hospital, Boston, MA) and uses the Brown-Roberts-Wells computed tomography (CT) stereotactic system. The patient's head is attached to a stand that rotates with the treatment couch. The irradiation is conducted using a set of converging arcs of irradiation. Because of mechanical limitations, no accelerator or treatment couch is capable of placing the center of the radiation beam at precisely the same point for all gantry and couch angles and a compromise must be made when locating the nominal isocenter. The stand settings are checked by placing a radiopaque QA sphere at the desired target location. The QA sphere is imaged using a series of eight films exposed at a set of couch and gantry angles that encompass the treatment angles. The distances between the QA sphere image and the center of the radiation field indicate if the correct coordinates were set on the stand and if the radiation beam converges to a sufficiently small region (< 0.1-cm diameter) for treatment. A mathematical procedure has been developed to use the film-measured position errors to determine a stand offset that will minimize the distance between the accelerator isocenter and the target. The technique is capable of reducing the average placement error, as measured by imaging the QA sphere, to 0.035 cm with a maximum deviation of 0.07 cm.

  10. Prospects of target nanostructuring for laser proton acceleration

    NASA Astrophysics Data System (ADS)

    Lübcke, Andrea; Andreev, Alexander A.; Höhm, Sandra; Grunwald, Ruediger; Ehrentraut, Lutz; Schnürer, Matthias

    2017-03-01

    In laser-based proton acceleration, nanostructured targets hold the promise to allow for significantly boosted proton energies due to strong increase of laser absorption. We used laser-induced periodic surface structures generated in-situ as a very fast and economic way to produce nanostructured targets capable of high-repetition rate applications. Both in experiment and theory, we investigate the impact of nanostructuring on the proton spectrum for different laser–plasma conditions. Our experimental data show that the nanostructures lead to a significant enhancement of absorption over the entire range of laser plasma conditions investigated. At conditions that do not allow for efficient laser absorption by plane targets, i.e. too steep plasma gradients, nanostructuring is found to significantly enhance the proton cutoff energy and conversion efficiency. In contrast, if the plasma gradient is optimized for laser absorption of the plane target, the nanostructure-induced absorption increase is not reflected in higher cutoff energies. Both, simulation and experiment point towards the energy transfer from the laser to the hot electrons as bottleneck.

  11. Prospects of target nanostructuring for laser proton acceleration

    PubMed Central

    Lübcke, Andrea; Andreev, Alexander A.; Höhm, Sandra; Grunwald, Ruediger; Ehrentraut, Lutz; Schnürer, Matthias

    2017-01-01

    In laser-based proton acceleration, nanostructured targets hold the promise to allow for significantly boosted proton energies due to strong increase of laser absorption. We used laser-induced periodic surface structures generated in-situ as a very fast and economic way to produce nanostructured targets capable of high-repetition rate applications. Both in experiment and theory, we investigate the impact of nanostructuring on the proton spectrum for different laser–plasma conditions. Our experimental data show that the nanostructures lead to a significant enhancement of absorption over the entire range of laser plasma conditions investigated. At conditions that do not allow for efficient laser absorption by plane targets, i.e. too steep plasma gradients, nanostructuring is found to significantly enhance the proton cutoff energy and conversion efficiency. In contrast, if the plasma gradient is optimized for laser absorption of the plane target, the nanostructure-induced absorption increase is not reflected in higher cutoff energies. Both, simulation and experiment point towards the energy transfer from the laser to the hot electrons as bottleneck. PMID:28290479

  12. MUC1-Targeted Cancer Cell Photothermal Ablation Using Bioinspired Gold Nanorods

    PubMed Central

    Zelasko-Leon, Daria C.; Fuentes, Christina M.; Messersmith, Phillip B.

    2015-01-01

    Recent studies have highlighted the overexpression of mucin 1 (MUC1) in various epithelial carcinomas and its role in tumorigenesis. These mucins present a novel targeting opportunity for nanoparticle-mediated photothermal cancer treatments due to their unique antenna-like extracellular extension. In this study, MUC1 antibodies and albumin were immobilized onto the surface of gold nanorods using a “primer” of polydopamine (PD), a molecular mimic of catechol- and amine-rich mussel adhesive proteins. PD forms an adhesive platform for the deposition of albumin and MUC1 antibodies, achieving a surface that is stable, bioinert and biofunctional. Two-photon luminescence confocal and darkfield scattering imaging revealed targeting of MUC1-BSA-PD-NRs to MUC1+ MCF-7 breast cancer and SCC-15 squamous cell carcinoma cells lines. Treated cells were exposed to a laser encompassing the near-infrared AuNR longitudinal surface plasmon and assessed for photothermal ablation. MUC1-BSA-PD-NRs substantially decreased cell viability in photoirradiated MCF-7 cell lines vs. MUC1- MDA-MB-231 breast cancer cells (p < 0.005). Agents exhibited no cytotoxicity in the absence of photothermal treatment. The facile nature of the coating method, combined with targeting and photoablation efficacy, are attractive features of these candidate cancer nanotherapeutics. PMID:26147830

  13. Enhancing Target Normal Sheath Accelerated Ions with Micro-structured Targets

    NASA Astrophysics Data System (ADS)

    George, Kevin; Snyder, Joseph; Ji, Liangliang; Rubin, Trevor; Handler, Abraham; Poole, Patrick; Willis, Christopher; Daskalova, Rebecca; Cochran, Ginevra; Schumacher, Douglass

    2016-10-01

    Laser driven target normal sheath acceleration (TNSA) of ions has been widely studied due to its fundamental importance, use as a probe, and for possible applications such as cancer therapy and neutron generation. Much of this work has been conducted on thin foils with peak ion energy and yield optimized using laser parameters such as energy and spot size. Micro-structured targets, however, have demonstrated increased peak ion energy and yield by controlling and enhancing mechanisms preferential to TNSA. Novel micro-structured targets were developed using optical lithography techniques on thin substrates at the OSU NanoSystem Laboratory. Variable structure height (0.5-2 micron) and transverse patterning (up to 1 micron resolution) permit the survey of a range of structured target variables in the study of ion acceleration. We describe the development of these targets and an experiment investigating the enhancement of TNSA ions from lithography produced micro-structured targets conducted at the Scarlet Laser Facility. Experimental results show increased proton and Carbon yield >2 MeV and higher peak Carbon energy from structured targets. This work was supported by the Air Force Office of Scientific Research.

  14. Characterization of particulates accompanying laser ablation of pressed polytetrafluorethylene (PTFE) targets

    NASA Astrophysics Data System (ADS)

    Heitz, J.; Dickinson, J. T.

    We present observations of sub-micron- to micron-sized particles generated by high fluence ( 2 J/cm2) 248-nm laser ablation of pressed polytetrafluorethylene (PTFE) targets in air at atmospheric pressure. The original target material was hydrostatically compressed 7 μm PTFE powder, sintered at 275 °C. Collected ejecta due to laser irradiation consists of four basic particle morphologies ranging from small particles 50-200 nm in diameter to larger particles 10 μm in diameter. Many particles formed in air carry electric charge. Using charged electrodes we are able to collect charged particles to determine relative numbers of +/- charge. We observe roughly equal numbers of positively and negatively charged particles except for the largest particles which were predominantly negative. For a range of particle sizes we are able to measure the sign and magnitude of this charge with a Millikan-oil-drop technique and determine surface charge densities. The implications of these observations with respect to pulsed laser deposition of PTFE thin films and coatings are discussed.

  15. Cardiomyocyte-specific ablation of CD36 accelerates the progression from compensated cardiac hypertrophy to heart failure.

    PubMed

    Sung, Miranda M; Byrne, Nikole J; Kim, Ty T; Levasseur, Jody; Masson, Grant; Boisvenue, Jamie J; Febbraio, Maria; Dyck, Jason R B

    2017-03-01

    Previous studies have shown that loss of CD36 protects the heart from dysfunction induced by pressure overload in the presence of diet-induced insulin resistance and/or obesity. The beneficial effects of CD36 ablation in this context are mediated by preventing excessive cardiac fatty acid (FA) entry and reducing lipotoxic injury. However, whether or not the loss of CD36 can prevent pressure overload-induced cardiac dysfunction in the absence of chronic exposure to high circulating FAs is presently unknown. To address this, we utilized a tamoxifen-inducible cardiomyocyte-specific CD36 knockout (icCD36KO) mouse and genetically deleted CD36 in adulthood. Control mice (CD36 floxed/floxed mice) and icCD36KO mice were treated with tamoxifen and subsequently subjected to transverse aortic constriction (TAC) surgery to generate pressure overload-induced cardiac hypertrophy. Consistent with CD36 mediating a significant proportion of FA entry into the cardiomyocyte and subsequent FA utilization for ATP production, hearts from icCD36KO mice were metabolically inefficient and displayed signs of energetic stress, including activation of the energetic stress kinase, AMPK. In addition, impaired energetics in icCD36KO mice contributed to a rapid progression from compensated hypertrophy to heart failure. However, icCD36KO mice fed a medium-chain FA diet, whereby medium-chain FAs can enter into the cardiomyocyte independent from CD36, were protected from TAC-induced heart failure. Together these data suggest that limiting FA uptake and partial inhibition of FA oxidation in the heart via CD36 ablation may be detrimental for the compensated hypertrophic heart in the absence of sufficiently elevated circulating FAs to provide an adequate energy source.NEW & NOTEWORTHY Limiting CD36-mediated fatty acid uptake in the setting of obesity and/or insulin resistance protects the heart from cardiac hypertrophy and dysfunction. However, cardiomyocyte-specific CD36 ablation in the absence of

  16. The Nitroreductase System of Inducible Targeted Ablation Facilitates Cell-specific Regenerative Studies in Zebrafish

    PubMed Central

    White, David T.; Mumm, Jeff S.

    2013-01-01

    At the turn of the 20th century, classical regenerative biology – the study of organismal/tissue/limb regeneration in animals such as crayfish, snails, and planaria – garnered much attention. However, scientific luminaries such as Thomas Hunt Morgan eventually turned to other fields after concluding that inquiries into regenerative mechanisms were largely intractable beyond observational intrigues. The field of regeneration has enjoyed a resurgence in research activity at the turn of the 21st century, in large part due to “the promise” of cultured stem cells regarding reparative therapeutic approaches. Additionally, genomics-based methods that allow sophisticated genetic/molecular manipulations to be carried out in nearly any species have extended organismal regenerative biology well beyond observational limits. Throughout its history, complex paradigms such as limb regeneration – involving multiple tissue/cell types, thus, potentially multiple stem cell subtypes – have predominated the regenerative biology field. Conversely, cellular regeneration – the replacement of specific cell types – has been studied from only a few perspectives (predominantly muscle and mechanosensory hair cells). Yet, many of the degenerative diseases that regenerative biology hopes to address involve the loss of individual cell types; thus, a primary emphasis of the embryonic/induced stem cell field is defining culture conditions which promote cell-specific differentiation. Here we will discuss recent methodological approaches that promote the study of cell-specific regeneration. Such paradigms can reveal how the differentiation of specific cell types and regenerative potential of discrete stem cell niches are regulated. In particular, we will focus on how the nitroreductase (NTR) system of inducible targeted cell ablation facilitates: 1) large-scale genetic and chemical screens for identifying factors that regulate regeneration and, 2) in vivo time-lapse imaging

  17. Ultra-High-Contrast Laser Acceleration of Relativistic Electrons in Solid Targets

    SciTech Connect

    Higginson, Drew Pitney

    2013-01-01

    The cone-guided fast ignition approach to Inertial Con nement Fusion requires laser-accelerated relativistic electrons to deposit kilojoules of energy within an imploded fuel core to initiate fusion burn. One obstacle to coupling electron energy into the core is the ablation of material, known as preplasma, by laser energy proceeding nanoseconds prior to the main pulse. This causes the laser-absorption surface to be pushed back hundreds of microns from the initial target surface; thus increasing the distance that electrons must travel to reach the imploded core. Previous experiments have shown an order of magnitude decrease in coupling into surrogate targets when intentionally increasing the amount of preplasma. Additionally, for electrons to deposit energy within the core, they should have kinetic energies on the order of a few MeV, as less energetic electrons will be stopped prior to the core and more energetic electrons will pass through the core without depositing much energy. Thus a quantitative understanding of the electron energy spectrum and how it responds to varied laser parameters is paramount for fast ignition. For the rst time, this dissertation quantitatively investigates the acceleration of electrons using an ultra-high-contrast laser. Ultra-high-contrast lasers reduce the laser energy that reaches the target prior to the main pulse; drastically reducing the amount of preplasma. Experiments were performed in a cone-wire geometry relevant to fast ignition. These experiments irradiated the inner-tip of a Au cone with the laser and observed electrons that passed through a Cu wire attached to the outer-tip of the cone. The total emission of K x-rays is used as a diagnostic to infer the electron energy coupled into the wire. Imaging the x-ray emission allowed an e ective path-length of electrons within the wire to be determined, which constrained the electron energy spectrum. Experiments were carried out on the ultra-high-contrast Trident laser at Los

  18. Inhibition of ischemic cardiomyocyte apoptosis through targeted ablation of Bnip3 restrains postinfarction remodeling in mice

    PubMed Central

    Diwan, Abhinav; Krenz, Maike; Syed, Faisal M.; Wansapura, Janaka; Ren, Xiaoping; Koesters, Andrew G.; Li, Hairong; Kirshenbaum, Lorrie A.; Hahn, Harvey S.; Robbins, Jeffrey; Jones, W. Keith; Dorn, Gerald W.

    2007-01-01

    Following myocardial infarction, nonischemic myocyte death results in infarct expansion, myocardial loss, and ventricular dysfunction. Here, we demonstrate that a specific proapoptotic gene, Bnip3, minimizes ventricular remodeling in the mouse, despite having no effect on early or late infarct size. We evaluated the effects of ablating Bnip3 on cardiomyocyte death, infarct size, and ventricular remodeling after surgical ischemia/reperfusion (IR) injury in mice. Immediately following IR, no significant differences were observed between Bnip3–/– and WT mice. However, at 2 days after IR, apoptosis was diminished in Bnip3–/– periinfarct and remote myocardium, and at 3 weeks after IR, Bnip3–/– mice exhibited preserved LV systolic performance, diminished LV dilation, and decreased ventricular sphericalization. These results suggest myocardial salvage by inhibition of apoptosis. Forced cardiac expression of Bnip3 increased cardiomyocyte apoptosis in unstressed mice, causing progressive LV dilation and diminished systolic function. Conditional Bnip3 overexpression prior to coronary ligation increased apoptosis and infarct size. These studies identify postischemic apoptosis by myocardial Bnip3 as a major determinant of ventricular remodeling in the infarcted heart, suggesting that Bnip3 may be an attractive therapeutic target. PMID:17909626

  19. Development of Targeted Nanobubbles for Ultrasound Imaging and Ablation of Metastatic Prostate Cancer Lesions

    DTIC Science & Technology

    2013-08-01

    upon incubation with BSA for 24 hours at 37ºC, which prove their promise for cancer cell ablation and warrant their future testing in vivo. All...concentration upon incubation with BSA for 24 hours at 37ºC, which prove their promise for cancer cell ablation and warrant their future testing in vivo...hours at 37ºC, which prove their promise for cancer cell ablation and warrant their future testing in vivo. 14 6. References [1] a) M

  20. Accelerated search for materials with targeted properties by adaptive design

    PubMed Central

    Xue, Dezhen; Balachandran, Prasanna V.; Hogden, John; Theiler, James; Xue, Deqing; Lookman, Turab

    2016-01-01

    Finding new materials with targeted properties has traditionally been guided by intuition, and trial and error. With increasing chemical complexity, the combinatorial possibilities are too large for an Edisonian approach to be practical. Here we show how an adaptive design strategy, tightly coupled with experiments, can accelerate the discovery process by sequentially identifying the next experiments or calculations, to effectively navigate the complex search space. Our strategy uses inference and global optimization to balance the trade-off between exploitation and exploration of the search space. We demonstrate this by finding very low thermal hysteresis (ΔT) NiTi-based shape memory alloys, with Ti50.0Ni46.7Cu0.8Fe2.3Pd0.2 possessing the smallest ΔT (1.84 K). We synthesize and characterize 36 predicted compositions (9 feedback loops) from a potential space of ∼800,000 compositions. Of these, 14 had smaller ΔT than any of the 22 in the original data set. PMID:27079901

  1. A unified model to determine the energy partitioning between target and plasma in nanosecond laser ablation of silicon

    SciTech Connect

    Galasso, G.; Kaltenbacher, M.; Tomaselli, A.; Scarpa, D.

    2015-03-28

    In semiconductor industry, pulsed nanosecond lasers are widely applied for the separation of silicon wafers. Here, the high intensities employed activate a cascade of complex multi-physical and multi-phase mechanisms, which finally result in the formation of a laser induced plasma, shielding the target from the incoming laser beam. Such induced plasma plume, by preventing the laser to effectively reach the target, reduces the overall efficiency and controllability of the ablation process. Modelling can be a useful tool in the optimization of industrial laser applications, allowing a deeper understanding of the way the laser energy distributes between target and induced plasma. Nevertheless, the highly multi-physical character of laser ablation poses serious challenges on the implementation of the various mechanisms underlying the process within a common modelling framework. A novel strategy is here proposed in order to simulate in a simplified, yet physically consistent way, a typical industrial application as laser ablation of silicon wafers. Reasonable agreement with experimental findings is obtained. Three fundamental mechanisms have been identified as the main factors influencing the accuracy of the numerical predictions: the transition from evaporative to volumetric mass removal occurring at critical temperature, the collisional and radiative processes underlying the initial plasma formation stage and the increased impact of the liquid ejection mechanism when a sub-millimeter laser footprint is used.

  2. Cavitation-free CW laser ablation from a solid target to synthesize low size-dispersed Au nanoparticles.

    PubMed

    Kabashin, Andrei V; Kucherik, Alexei; Ryabchikov, Yury; Kutrovskaya, Stella; Al-Kattan, Ahmed; Arakelyan, Sergei; Itina, Tatiana

    2017-02-27

    Continuous wave (CW) radiation from Yb-fiber laser (central wave length is 1064 nm, power 1-200 W) is used to initiate ablation of material Au target in deionized water and synthesize bare (unprotected) Au nanoparticles. We show that the formed nanoparticles present a single low-size-dispersed population with the mean size of the order of 10 nm, which contrasts to previously reported data on dual populations of nanoparticles during pulsed laser ablation in liquids. The lacking second population of nanoparticles is explained by the absence of cavitation-related mechanism of material ablation, which typically takes place under pulsed laser action on a solid target in liquid ambience, and this supposition is confirmed by plume visualization tests. We also observe a gradual growth of mean nanoparticles size from 8-10 to 20-25 nm under the increase of laser power for 532 nm pumping wavelength, while for 1064 nm pumping wavelength the mean size 8-10 nm is independent of radiation power. The growth of the nanoparticles observed for 532 nm wavelength is attributed to the enhanced target melting and splashing followed by an additional heating due to an efficient excitation of plasmons over Au nanoparticles. Bare, low-size-dispersed Au nanoparticles are of importance for a variety of applications, including biomedicine, catalysis, photovoltaics etc., whereas the employment of CW radiation for nanomaterial production promises an improvement of cost-efficiency of this technology.

  3. Bioavailable nanoparticles obtained in laser ablation of a selenium target in water

    SciTech Connect

    Kuzmin, P G; Shafeev, Georgii A; Voronov, Valerii V; Raspopov, R V; Arianova, E A; Trushina, E N; Gmoshinskii, I V; Khotimchenko, S A

    2012-11-30

    The process of producing colloidal solutions of selenium nanoparticles in water using the laser ablation method is described. The prospects of using nanoparticles of elementary selenium as a nutrition source of this microelement are discussed. (nanoparticles)

  4. Self-assembled tumor-targeting hyaluronic acid nanoparticles for photothermal ablation in orthotopic bladder cancer.

    PubMed

    Lin, Tingsheng; Yuan, Ahu; Zhao, Xiaozhi; Lian, Huibo; Zhuang, Junlong; Chen, Wei; Zhang, Qing; Liu, Guangxiang; Zhang, Shiwei; Chen, Wei; Cao, Wenmin; Zhang, Chengwei; Wu, Jinhui; Hu, Yiqiao; Guo, Hongqian

    2017-02-15

    Bladder cancer is one of the most frequent malignancies in the urinary system. Radical cystectomy is inevitable when bladder cancer progresses to a muscle-invasive disease. However, cystectomy still causes a high risk of death and a low quality of life (such as ureter-abdomen ostomy, uroclepsia for ileal-colon neobladder). Therefore, more effective treatments as well as bladder preservation are needed. We developed self-assembled tumor-targeting hyaluronic acid-IR-780 nanoparticles for photothermal ablation in over-expressing CD44 (the receptor for HA) bladder cancer, which show high tumor selectivity, high treatment efficacy, good bioavailability, and excellent biocompatibility. The nanoparticles demonstrated a stable spherical nanostructure in aqueous conditions with good mono-dispersity, and their average size was 171.3±9.14nm. The nanoparticles can be degraded by hyaluronidase when it is over-expressed in bladder cells; therefore, they appear to have a hyaluronidase-responsive "OFF/ON" behavior of a fluorescence signal. HA-IR-780 NPs also showed high photothermal efficiency; 2.5, 5, 10 and 20μg/mL of NPs had a maximum temperature increase of 11.2±0.66°C, 18.6±0.75°C, 26.8±1.11°C and 32.3±1.42°C. The in vitro cell viability showed that MB-49 cells could be efficiently ablated by combining HA-IR-780 NPs with 808nm laser irradiation. Then, in vivo biodistribution showed the HA-IR-780 NPs are targeted for accumulation in bladder cancer cells but have negligible accumulation in normal bladder wall. The photothermal therapeutic efficacy of HA-IR-780 NPs in the orthotopic bladder cancer model showed tumors treated with NPs had a maximum temperature of 48.1±1.81°C after 6min of laser irradiation. The tumor volume was approximately 65-75mm(3) prior to treatment. After 12days, the tumor sizes for the PBS, PBS plus laser irradiation and HA-IR-780 NPs-treated groups were 784.75mm(3), 707.5mm(3), and 711.37mm(3), respectively. None of the tumors in the HA-IR-780

  5. The influence of laser ablation plume at different laser incidence angle on the impulse coupling coefficient with metal target

    NASA Astrophysics Data System (ADS)

    Zhao, Xiong-Tao; Tang, Feng; Han, Bing; Ni, Xiao-Wu

    2016-12-01

    A calibrated pendulum measuring device and a dimensionless analysis method were used to measure the impulse coupling coefficient at different laser intensities with aluminum, steel, and iron targets. The experiment was performed with a pulsed laser with the wavelength of 1.06 μm and the pulse duration of 7 ns. The experimental measurements of the variation of the impulse coupling coefficient versus the laser energy density agree with the theoretical prediction, and the optimum laser energy density correlated with the maximum impulse coupling coefficient corresponding to the theoretical predictions. The impulse coupling coefficients with laser incidence angles of 0 ° and 45 ° are compared for understanding of the effects of the ablation plume on the impulse coupling effect, and the experimental result shows that the impulse coupling effect grows as the incidence angle changes from 0 ° to 45 ° . Furthermore, the transmittance of the incident laser through the ablation plume in front of the target is deduced from the impulse measurements, and the effect of the ablation plume on the impulse coupling at high laser intensity is discussed. In order to investigate the weak impulse coupling effect, which is difficult to obtain from the experiments, the impulse coupling coefficient at low laser energy density was calculated by the finite element simulation.

  6. Interaction of a converging laser beam with a Ag colloidal solution during the ablation of a Ag target in water

    NASA Astrophysics Data System (ADS)

    Resano-Garcia, Amandine; Battie, Yann; Naciri, Aotmane En; Chaoui, Nouari

    2016-05-01

    We studied the nanosecond laser-induced shape modifications of Ag colloids exposed to a converging laser beam during the ablation of a Ag target in water. To this end, we performed a series of laser ablation experiments in which the laser energy was varied while all other parameters were kept constant. In addition to transmission electron microscopy (TEM), the shape distribution of the Ag nanoparticles was determined by modelling the extinction spectra of the final colloidal solutions using theoretical calculations based on shape distributed effective medium theory (SDEMT). From these calculations, two physical parameters named sphericity and dispersity were introduced and used to gauge the evolution of the shape distribution of the particles. As the laser energy on the target was increased from 5 to 20 mJ/pulse, an apparently abrupt modification of the shape distribution of the particles was evidenced by both TEM and SDEMT calculations. This change is explained in terms of competitive fragmentation, growth and reshaping processes. On the basis the heating-melting-vaporization model, we demonstrate how the competition between these processes, occurring at different locations of the converging beam, determines the shape distribution of the final product. We highlight the relevance of the fluence gradient along the beam path and the laser interaction volume on the laser-induced modifications of the suspended particles during the ablation process.

  7. Planarization of Isolated Defects on ICF Target Capsule Surfaces by Pulsed Laser Ablation

    SciTech Connect

    Alfonso, Noel; Carlson, Lane C.; Bunn, Thomas L.

    2016-08-09

    Demanding surface quality requirements for inertial confinement fusion (ICF) capsules motivated the development of a pulsed laser ablation method to reduce or eliminate undesirable surface defects. The pulsed laser ablation technique takes advantage of a full surface (4π) capsule manipulation system working in combination with an optical profiling (confocal) microscope. Based on the defect topography, the material removal rate, the laser pulse energy and its beam profile, a customized laser raster pattern is derived to remove the defect. The pattern is a table of coordinates and number of pulses that dictate how the defect will be vaporized until its height is level with the capsule surface. This paper explains how the raster patterns are optimized to minimize surface roughness and how surface roughness after laser ablation is simulated. The simulated surfaces are compared with actual ablated surfaces. Large defects are reduced to a size regime where a tumble finishing process produces very high quality surfaces devoid of high mode defects. The combined polishing processes of laser ablation and tumble finishing have become routine fabrication steps for National Ignition Facility capsule production.

  8. Planarization of Isolated Defects on ICF Target Capsule Surfaces by Pulsed Laser Ablation

    DOE PAGES

    Alfonso, Noel; Carlson, Lane C.; Bunn, Thomas L.

    2016-08-09

    Demanding surface quality requirements for inertial confinement fusion (ICF) capsules motivated the development of a pulsed laser ablation method to reduce or eliminate undesirable surface defects. The pulsed laser ablation technique takes advantage of a full surface (4π) capsule manipulation system working in combination with an optical profiling (confocal) microscope. Based on the defect topography, the material removal rate, the laser pulse energy and its beam profile, a customized laser raster pattern is derived to remove the defect. The pattern is a table of coordinates and number of pulses that dictate how the defect will be vaporized until its heightmore » is level with the capsule surface. This paper explains how the raster patterns are optimized to minimize surface roughness and how surface roughness after laser ablation is simulated. The simulated surfaces are compared with actual ablated surfaces. Large defects are reduced to a size regime where a tumble finishing process produces very high quality surfaces devoid of high mode defects. The combined polishing processes of laser ablation and tumble finishing have become routine fabrication steps for National Ignition Facility capsule production.« less

  9. Targeted ablation of diverse cell classes in the nervous system in vivo.

    PubMed

    Nirenberg, S; Cepko, C

    1993-08-01

    The study of both the function and development of complex neural systems would be greatly facilitated by a means for systematically blocking intercell communication. One way of preventing cells from signaling each other is to remove them from the system by ablation. Here we present a general technique for visualizing and ablating selected cell classes in vivo. The cells of interest are genetically engineered so that they can be selectively labeled with a photoactivatable dye and visualized in living preparations; the dye-labeled cells can then be photoablated. This approach is applicable to a broad range of cell types, in organisms amenable to gene transfer, and permits ablations to be performed at different developmental stages or in the adult. We demonstrate the use of this technique on several cell types in the mouse retina and cerebral cortex, and in the zebrafish embryo.

  10. Generation of heavy ion beams using femtosecond laser pulses in the target normal sheath acceleration and radiation pressure acceleration regimes

    NASA Astrophysics Data System (ADS)

    Petrov, G. M.; McGuffey, C.; Thomas, A. G. R.; Krushelnick, K.; Beg, F. N.

    2016-06-01

    Theoretical study of heavy ion acceleration from sub-micron gold foils irradiated by a short pulse laser is presented. Using two dimensional particle-in-cell simulations, the time history of the laser pulse is examined in order to get insight into the laser energy deposition and ion acceleration process. For laser pulses with intensity 3 × 10 21 W / cm 2 , duration 32 fs, focal spot size 5 μm, and energy 27 J, the calculated reflection, transmission, and coupling coefficients from a 20 nm foil are 80%, 5%, and 15%, respectively. The conversion efficiency into gold ions is 8%. Two highly collimated counter-propagating ion beams have been identified. The forward accelerated gold ions have average and maximum charge-to-mass ratio of 0.25 and 0.3, respectively, maximum normalized energy 25 MeV/nucleon, and flux 2 × 10 11 ions / sr . An analytical model was used to determine a range of foil thicknesses suitable for acceleration of gold ions in the radiation pressure acceleration regime and the onset of the target normal sheath acceleration regime. The numerical simulations and analytical model point to at least four technical challenges hindering the heavy ion acceleration: low charge-to-mass ratio, limited number of ions amenable to acceleration, delayed acceleration, and high reflectivity of the plasma. Finally, a regime suitable for heavy ion acceleration has been identified in an alternative approach by analyzing the energy absorption and distribution among participating species and scaling of conversion efficiency, maximum energy, and flux with laser intensity.

  11. Table-top laser-based proton acceleration in nanostructured targets

    NASA Astrophysics Data System (ADS)

    Blanco, M.; Flores-Arias, M. T.; Ruiz, C.; Vranic, M.

    2017-03-01

    The interaction of ultrashort, high intensity laser pulses with thin foil targets leads to ion acceleration on the target rear surface. To make this ion source useful for applications, it is important to optimize the transfer of energy from the laser into the accelerated ions. One of the most promising ways to achieve this consists in engineering the target front by introducing periodic nanostructures. In this paper, the effect of these structures on ion acceleration is studied analytically and with multi-dimensional particle-in-cell simulations. We assessed the role of the structure shape, size, and the angle of laser incidence for obtaining the efficient energy transfer. Local control of electron trajectories is exploited to maximize the energy delivered into the target. Based on our numerical simulations, we propose a precise range of parameters for fabrication of nanostructured targets, which can increase the energy of the accelerated ions without requiring a higher laser intensity.

  12. Mass Limited Target Effects on Proton Acceleration with Femtosecond Laser Plasma Interactions

    NASA Astrophysics Data System (ADS)

    Zulick, Calvin; Raymond, A.; McKelvey, A.; Willingale, L.; Chvykov, V.; Maksimchuk, A.; Thomas, A. G. R.; Yanovsky, V.; Krushelnick, K.

    2014-10-01

    Experiments at the HERCULES laser facility have been performed to measure the effect of reduced mass targets on proton acceleration through the use of foil, grid, and wire targets in femtosecond laser plasma interactions. The target thickness was held approximately constant at 12 . 5 μm, while the lateral extent of the target was varied. The electron current density was measured with an imaging Cu Kα crystal. Higher current densities were observed as the target mass was reduced which corresponded to an increase in the temperature of the accelerated proton beam. Additionally, a line focusing feature was observed in the spatial distribution of protons accelerated to from the wire target, believed to be a result of azimuthal magnetic fields generated by electron currents in the wire. Particle-in-cell and Vlasov-Fokker-Plank simulations were performed in order to investigate the focusing magnetic field as well as the complex sheath formation dynamics on the mesh target.

  13. Design options for improved performance with high-density carbon ablators and low-gas fill hohlraum targets

    NASA Astrophysics Data System (ADS)

    Berzak Hopkins, L.; Divol, L.; Lepape, S.; Meezan, N. B.; Dewald, E.; Ho, D.; Khan, S.; Pak, A.; Ralph, J.; Ross, J. S.

    2016-10-01

    Recent simulation-based and experimental work using high-density carbon ablators in unlined uranium hohlraums with 0.3 mg/cc helium fill have demonstrated round implosions with minimal evolution of Legendre moment P2 during burn. To extend this promising work, design studies have been performed to explore potential performance improvements with larger capsules, while maintaining similar case-to-capsule target ratios. We present here the results of these design studies, which will motivate a series of upcoming experiments at the National Ignition Facility. Prepared by LLNL under Contract DE-AC52-07NA27344.

  14. Acceleration of high charge-state target ions in high-intensity laser interactions with sub-micron targets

    NASA Astrophysics Data System (ADS)

    McGuffey, C.; Raymond, A.; Batson, T.; Hua, R.; Petrov, G. M.; Kim, J.; Krauland, C. M.; Maksimchuk, A.; Thomas, A. G. R.; Yanovsky, V.; Krushelnick, K.; Beg, F. N.

    2016-11-01

    We have studied laser acceleration of ions from Si3N4 and Al foils ranging in thickness from 1800 to 8 nm with particular interest in acceleration of ions from the bulk of the target. The study includes results of experiments conducted with the HERCULES laser with pulse duration 40 fs and intensity 3 × 1020 W cm-2 and corresponding two-dimensional particle-in-cell simulations. When the target thickness was reduced the distribution of ion species heavier than protons transitioned from being dominated by carbon contaminant ions of low ionization states to being dominated by high ionization states of bulk ions (such as Si12+) and carbon. Targets in the range 50-150 nm yielded dramatically greater particle number and higher ion maximum energy for these high ionization states compared to thicker targets typifying the Target Normal Sheath Acceleration (TNSA) regime. The high charge states persisted for the thinnest targets, but the accelerated particle numbers decreased for targets 35 nm and thinner. This transition to an enhanced ion TNSA regime, which more efficiently generates ion beams from the bulk target material, is also seen in the simulations.

  15. Optimization of the combined proton acceleration regime with a target composition scheme

    SciTech Connect

    Yao, W. P.; Li, B. W.; Zheng, C. Y.; Liu, Z. J.; Yan, X. Q.; Qiao, B.

    2016-01-15

    A target composition scheme to optimize the combined proton acceleration regime is presented and verified by two-dimensional particle-in-cell simulations by using an ultra-intense circularly polarized (CP) laser pulse irradiating an overdense hydrocarbon (CH) target, instead of a pure hydrogen (H) one. The combined acceleration regime is a two-stage proton acceleration scheme combining the radiation pressure dominated acceleration (RPDA) stage and the laser wakefield acceleration (LWFA) stage sequentially together. Protons get pre-accelerated in the first stage when an ultra-intense CP laser pulse irradiating an overdense CH target. The wakefield is driven by the laser pulse after penetrating through the overdense CH target and propagating in the underdense tritium plasma gas. With the pre-accelerate stage, protons can now get trapped in the wakefield and accelerated to much higher energy by LWFA. Finally, protons with higher energies (from about 20 GeV up to about 30 GeV) and lower energy spreads (from about 18% down to about 5% in full-width at half-maximum, or FWHM) are generated, as compared to the use of a pure H target. It is because protons can be more stably pre-accelerated in the first RPDA stage when using CH targets. With the increase of the carbon-to-hydrogen density ratio, the energy spread is lower and the maximum proton energy is higher. It also shows that for the same laser intensity around 10{sup 22} W cm{sup −2}, using the CH target will lead to a higher proton energy, as compared to the use of a pure H target. Additionally, proton energy can be further increased by employing a longitudinally negative gradient of a background plasma density.

  16. Enhanced target normal sheath acceleration of protons from intense laser interaction with a cone-tube target

    SciTech Connect

    Xiao, K. D.; Huang, T. W.; Zhou, C. T.; Qiao, B.; Wu, S. Z.; Ruan, S. C.; He, X. T.

    2016-01-15

    Laser driven proton acceleration is proposed to be greatly enhanced by using a cone-tube target, which can be easily manufactured by current 3D-print technology. It is observed that energetic electron bunches are generated along the tube and accelerated to a much higher temperature by the combination of ponderomotive force and longitudinal electric field which is induced by the optical confinement of the laser field. As a result, a localized and enhanced sheath field is produced at the rear of the target and the maximum proton energy is about three-fold increased based on the two-dimentional particle-in-cell simulation results. It is demonstrated that by employing this advanced target scheme, the scaling of the proton energy versus the laser intensity is much beyond the normal target normal sheath acceleration (TNSA) case.

  17. Experiments on the Dynamics and Hydrodynamic Instabilities of Ablatively Accelerated Targets.

    DTIC Science & Technology

    1983-02-01

    CILCUILATION C BS’D ON INJPUT CALORIMET~rC ihUL ROgAL~~wl INTEnCER C4AR r-IND E Q UIVAL EN CE !- AIS ’A R R i) E P. NVANR3) s WIR ITLU(5, 0) a 0 FO;RMAT...approximated by show-. the fluid flow pattern are only to appear soon. I the solution to Laplace’s equation subject to the boundary In thE present work, a...in the plasma. As indicated in Fig. 8. the method relies upon the steady-state mass conservation equation , which tells us that the product of the

  18. Micro-physical properties of carbonaceous aerosol particles generated by laser ablation of a graphite target

    NASA Astrophysics Data System (ADS)

    Ajtai, T.; Utry, N.; Pintér, M.; Tápai, Cs.; Kecskeméti, G.; Smausz, T.; Hopp, B.; Bozóki, Z.; Szabó, G.

    2014-09-01

    In this work the authors propose laser ablation as a highly versatile tool for carbonaceous aerosol generation. The generated carbonaceous particles can be used as a model aerosol for atmospheric black carbon. Various microphysical properties including mass concentration, size distribution and morphology of aerosol particles generated by laser ablation of a high purity graphite sample were investigated in detail. These measurements proved that the proposed method can be used to generate both primary particles and fractal aggregates with a high yield. As a further advantage of the method the size distribution of the generated aerosol can cover a wide range, and can be tuned accurately with laser fluence, the ambient composition or with the volumetric flow rate of the carrier gas.

  19. SATIF-2 shielding aspects of accelerators, targets and irradiation facilities

    SciTech Connect

    1995-12-31

    Particle accelerators have evolved over the last 50 years from simple devices to powerful machines, and will continue to have an important impact on research, technology and lifestyle. Today they cover a wide range of applications, from television and computer displays in households to the investigation of the origin and structure of matter. It has become common practice to use them for material science and medical applications. In recent years, requirements from new technological and research applications have emerged, such as increased particle beams intensities, higher flexibility, etc., giving rise to new radiation shielding aspects and problems. These proceedings review recent progress in radiation shielding of accelerator facilities, and evaluate advancements with respect to international co-operation in this field.

  20. Targeted multifunctional gold-based nanoshells for magnetic resonance-guided laser ablation of head and neck cancer.

    PubMed

    Melancon, Marites P; Lu, Wei; Zhong, Meng; Zhou, Min; Liang, Gan; Elliott, Andrew M; Hazle, John D; Myers, Jeffrey N; Li, Chun; Stafford, R Jason

    2011-10-01

    Image-guided thermal ablation of tumors is becoming a more widely accepted minimally invasive alternative to surgery for patients who are not good surgical candidates, such as patients with advanced head and neck cancer. In this study, multifunctional superparamagnetic iron oxide coated with gold nanoshell (SPIO@Au NS) that have both optical and magnetic properties was conjugated with the targeting agent, C225 monoclonal antibody, against epidermal growth factor receptor (EGFR). C225-SPIO@Au NS have an average a diameter of 82 ± 4.4 nm, contain 142 ± 15 antibodies per nanoshell, have an absorption peak in the near infrared (~800 nm), and have transverse relaxivity (r(2)) of 193 and 353 mM(-1) s(-1) versus Feridex™ of 171 and 300 mM(-1) s(-1), using 1.5 T and 7 T MR scanners, respectively. Specific targeting of the synthesized C225-SPIO@Au NS was tested in vitro using A431 cells and oral cancer cells, FaDu, OSC19, and HN5, all of which overexpress EGFR. Selective binding was achieved using C225-SPIO@Au NS but not with the non-targeting PEG-SPIO@Au NS and blocking group (excess of C225 + C225-SPIO@Au NS). In vivo biodistribution on mice bearing A431 tumors also showed selective targeting of C225-SPIO@Au NS compared with the non-targeting and blocking groups. The selective photothermal ablation of the nanoshells shows that without laser treatment there were no cell death and among the groups that were treated with laser at a power of 36 W/cm(2) for 3 min, only the cells treated with C225-SPIO@Au NS had cell killing (p < 0.001). In summary, successful synthesis and characterization of targeted C225-SPIO@Au NS demonstrating both superparamagnetic and optical properties has been achieved. We have shown both in vitro and in vivo that these nanoshells are MR-active and can be selectively heated up for simultaneous imaging and photothermal ablation therapy.

  1. Ablative skin resurfacing.

    PubMed

    Chwalek, Jennifer; Goldberg, David J

    2011-01-01

    Ablative skin resurfacing has remained the gold standard for treating photodamage and acne scars since the development of the first CO(2) lasers. CO(2) and Er:YAG lasers emit infrared light, which targets water resulting in tissue contraction and collagen formation. The first ablative laser systems created significant thermal damage resulting in unacceptably high rates of scarring and prolonged healing. Newer devices, such as high-energy pulsed lasers and fractional ablative lasers, are capable of achieving significant improvements with fewer side effects and shorter recovery times. While ablative resurfacing has become safer, careful patient selection is still important to avoid post-treatment scarring, dyspigmentation, and infections. Clinicians utilizing ablative devices need to be aware of possible side effects in order to maximize results and patient satisfaction. This chapter reviews the background of ablative lasers including the types of ablative lasers, mechanism of action, indications for ablative resurfacing, and possible side effects.

  2. Streaked X-Ray Imager for Observation of Oscillations of Perturbed Ablation Fronts in Planar ICF Targets During Shock Transit

    NASA Astrophysics Data System (ADS)

    Gotchev, O. V.; Goncharov, V. N.; Jaanimagi, P. A.; Knauer, J. P.; Meyerhofer, D. D.

    2001-10-01

    The dynamic overpressure effect sets the growth rate of the ablative Richtmyer-Meshkov instability and the late imprint levels in directly driven targets. It leads to temporal oscillations of the perturbed ablation front that have been predicted analytically and observed in 2-D ORCHID simulations. These predictions will be verified on OMEGA by measuring the perturbation amplitudes and frequencies directly with a high-resolution, IR-coated Kirkpatrick-Baez (KB) microscope, coupled to a high-current streak tube. The construction and characterization of this new diagnostic tool are described. The optic has up to three-orders-of-magnitude-higher throughput than conventional pinhole arrays, mainly due to the single-layer IR coating and an optimized grazing angle of 2.1^o. Resolution is 3-μm over a 120-μm field of view, as determined by ray tracing. Signal-level calculations for competing theoretical models treating these phenomena were performed to optimize target design, laser pulse shape, and backlighter. Preliminary experimental results may be shown. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  3. Ultra-High-Contrast Laser Acceleration of Relativistic Electrons in Solid Targets

    NASA Astrophysics Data System (ADS)

    Higginson, Drew Pitney

    The cone-guided fast ignition approach to Inertial Confinement Fusion requires laser-accelerated relativistic electrons to deposit kilojoules of energy within an imploded fuel core to initiate fusion burn. One obstacle to coupling electron energy into the core is the ablation of material, known as preplasma, by laser energy proceeding nanoseconds prior to the main pulse. This causes the laser-absorption surface to be pushed back hundreds of microns from the initial target surface; thus increasing the distance that electrons must travel to reach the imploded core. Previous experiments have shown an order of magnitude decrease in coupling into surrogate targets when intentionally increasing the amount of preplasma. Additionally, for electrons to deposit energy within the core, they should have kinetic energies on the order of a few MeV, as less energetic electrons will be stopped prior to the core and more energetic electrons will pass through the core without depositing much energy. Thus a quantitative understanding of the electron energy spectrum and how it responds to varied laser parameters is paramount for fast ignition. For the first time, this dissertation quantitatively investigates the acceleration of electrons using an ultra-high-contrast laser. Ultra-high-contrast lasers reduce the laser energy that reaches the target prior to the main pulse; drastically reducing the amount of preplasma. Experiments were performed in a cone-wire geometry relevant to fast ignition. These experiments irradiated the inner-tip of a Au cone with the laser and observed electrons that passed through a Cu wire attached to the outer-tip of the cone. The total emission of Kalpha x-rays is used as a diagnostic to infer the electron energy coupled into the wire. Imaging the x-ray emission allowed an effective path-length of electrons within the wire to be determined, which constrained the electron energy spectrum. Experiments were carried out on the ultra-high-contrast Trident laser

  4. Efficient ion acceleration by relativistic self-induced transparency in subwavelength targets

    NASA Astrophysics Data System (ADS)

    Choudhary, Shivani; Holkundkar, Amol R.

    2016-10-01

    We studied the effect of target thickness on relativistic self-induced transparency (RSIT) and observed that, for subwavelength targets, the corresponding threshold target density (beyond which the target is opaque to an incident laser pulse of given intensity) increases. The accelerating longitudinal electrostatic field created by RSIT from the subwavelength target is then used to accelerate the ions from a thin, low density layer behind the main target to 100 MeV using a 6 cycle flat-top (with rise and fall of one cycle each) circularly polarized laser with peak dimensionless amplitude of 20. A suitable scaling law for optimum laser and target conditions is also deduced. We observed that, as far as energy spectrum is concerned, an extra low density layer is more advantageous than relying on target ions alone.

  5. Closed loop spray cooling apparatus. [for particle accelerator targets

    NASA Technical Reports Server (NTRS)

    Alger, D. L.; Schwab, W. B.; Furman, E. R. (Inventor)

    1978-01-01

    A closed loop apparatus for spraying coolant against the back of a radiation target is described. The coolant was circulated through a closed loop with a bubble of inert gas being maintained around the spray. Mesh material was disposed between the bubble and the surface of the liquid coolant which was below the bubble at a predetermined level. In a second embodiment, no inert gas was used, the bubble consisting of a vapor produced when the coolant was sprayed against the target.

  6. Proton acceleration in the interaction of high power laser and cryogenic hydrogen targets

    NASA Astrophysics Data System (ADS)

    Mishra, Rohini; Fiuza, Frederico; Glenzer, Siegfried

    2014-10-01

    High intensity laser driven ion acceleration has attracted great interest due to many prospective applications ranging from inertial confinement fusion, cancer therapy, particle accelerators. Particle-in-Cell (PIC) simulations are performed to model and design experiments at MEC for high power laser interaction with cryogenic hydrogen targets of tunable density and thickness. Preliminary 1D and 2D simulations, using fully relativistic particle-in-cell code PICLS, show a unique regime of proton acceleration, e.g. ~ 300 MeV peak energy protons are observed in the 1D run for interaction of ~1020 W/cm2, 110 fs intense laser with 6nc dense (nc = 1021 cm-3) and 2 micron thin target. The target is relativistically under-dense for the laser and we observe that a strong (multi-terawatt) shock electric field is produced and protons are reflected to high velocities by this field. Further, the shock field and the laser field keep propagating through the hydrogen target and meets up with target normal sheath acceleration (TNSA) electric field produced at the target rear edge and vacuum interface and this superposition amplifies the TNSA fields resulting in higher proton energy. In addition, the electrons present at the rear edge of the target continue to gain energy via strong interaction with laser that crosses the target and these accelerated electrons maintains higher electric sheath fields which further provides acceleration to protons. We will also present detailed investigation with 2D PICLS simulations to gain a better insight of such physical processes to characterize multidimensional effects and establish analytical scaling between laser and target conditions for the optimization of proton acceleration.

  7. Investigation on target normal sheath acceleration through measurements of ions energy distribution

    SciTech Connect

    Tudisco, S. Cirrone, G. A. P.; Mascali, D.; Schillaci, F.; Altana, C.; Lanzalone, G.; Muoio, A.; Brandi, F.; Cristoforetti, G.; Ferrara, P.; Fulgentini, L.; Koester, P.; Labate, L.; Gizzi, L. A.; and others

    2016-02-15

    An experimental campaign aiming at investigating the ion acceleration mechanisms through laser-matter interaction in femtosecond domain has been carried out at the Intense Laser Irradiation Laboratory facility with a laser intensity of up to 2 × 10{sup 19} W/cm{sup 2}. A Thomson parabola spectrometer was used to obtain the spectra of the ions of the different species accelerated. Here, we show the energy spectra of light-ions and we discuss their dependence on structural characteristics of the target and the role of surface and target bulk in the acceleration process.

  8. Generation of quasi-monoenergetic carbon ions accelerated parallel to the plane of a sandwich target

    SciTech Connect

    Wang, J. W.; Murakami, M.; Weng, S. M.; Xu, H.; Ju, J. J.; Luan, S. X.; Yu, W.

    2014-12-15

    A new ion acceleration scheme, namely, target parallel Coulomb acceleration, is proposed in which a carbon plate sandwiched between gold layers is irradiated with intense linearly polarized laser pulses. The high electrostatic field generated by the gold ions efficiently accelerates the embedded carbon ions parallel to the plane of the target. The ion beam is found to be collimated by the concave-shaped Coulomb potential. As a result, a quasi-monoenergetic and collimated C{sup 6+}-ion beam with an energy exceeding 10 MeV/nucleon is produced at a laser intensity of 5 × 10{sup 19} W/cm{sup 2}.

  9. Enhancement of proton acceleration field in laser double-layer target interaction

    SciTech Connect

    Gu, Y. J.; Kong, Q.; Li, X. F.; Yu, Q.; Wang, P. X.; Kawata, S.; Izumiyama, T.; Ma, Y. Y.

    2013-07-15

    A mechanism is proposed to enhance a proton acceleration field in laser plasma interaction. A double-layer plasma with different densities is illuminated by an intense short pulse. Electrons are accelerated to a high energy in the first layer by the wakefield. The electrons accelerated by the laser wakefield induce the enhanced target normal sheath (TNSA) and breakout afterburner (BOA) accelerations through the second layer. The maximum proton energy reaches about 1 GeV, and the total charge with an energy higher than 100 MeV is about several tens of μC/μm. Both the acceleration gradient and laser energy transfer efficiency are higher than those in single-target-based TNSA or BOA. The model has been verified by 2.5D-PIC simulations.

  10. Enhancement of proton acceleration field in laser double-layer target interaction

    NASA Astrophysics Data System (ADS)

    Gu, Y. J.; Kong, Q.; Kawata, S.; Izumiyama, T.; Li, X. F.; Yu, Q.; Wang, P. X.; Ma, Y. Y.

    2013-07-01

    A mechanism is proposed to enhance a proton acceleration field in laser plasma interaction. A double-layer plasma with different densities is illuminated by an intense short pulse. Electrons are accelerated to a high energy in the first layer by the wakefield. The electrons accelerated by the laser wakefield induce the enhanced target normal sheath (TNSA) and breakout afterburner (BOA) accelerations through the second layer. The maximum proton energy reaches about 1 GeV, and the total charge with an energy higher than 100 MeV is about several tens of μC/μm. Both the acceleration gradient and laser energy transfer efficiency are higher than those in single-target-based TNSA or BOA. The model has been verified by 2.5D-PIC simulations.

  11. Increased laser-accelerated proton energies via direct laser-light-pressure acceleration of electrons in microcone targets

    SciTech Connect

    Gaillard, S. A.; Kluge, T.; Bussmann, M.; Cowan, T. E.; Flippo, K. A.; Offermann, D. T.; Gall, B.; Lockard, T.; Sentoku, Y.; Geissel, M.; Schollmeier, M.

    2011-05-15

    We present experimental results showing a laser-accelerated proton beam maximum energy cutoff of 67.5 MeV, with more than 5 x 10{sup 6} protons per MeV at that energy, using flat-top hollow microcone targets. This result was obtained with a modest laser energy of {approx}80 J, on the high-contrast Trident laser at Los Alamos National Laboratory. From 2D particle-in-cell simulations, we attribute the source of these enhanced proton energies to direct laser-light-pressure acceleration of electrons along the inner cone wall surface, where the laser light wave accelerates electrons just outside the surface critical density, in a potential well created by a shift of the electrostatic field maximum with respect to that of the magnetic field maximum. Simulations show that for an increasing acceleration length, the continuous loading of electrons into the accelerating phase of the laser field yields an increase in high-energy electrons.

  12. Multistage ion acceleration in the interaction of intense short laser pulse with ultrathin target

    NASA Astrophysics Data System (ADS)

    Mirzanejhad, Saeed; Joulaei, Atefeh; Babaei, Javad

    2016-12-01

    New analytical formalism is invented in the description of ion acceleration in the interaction of intense high-contrast short laser pulse with ultrathin target. The electrostatic shock wave acceleration is our fundamental point of view, but different criteria are obtained for description of various acceleration phenomenon. Acceleration condition for an ion with a definite charge to mass ratio ( z / m ) and initial velocity β0 is obtained in the electrostatic shock (ES) field in front side of the foil. According to this point of view, self organized multistage ion acceleration formalism is proposed and confirmed by the 1D3V particle in cell simulation results. In this formalism, ions may be re-accelerated repeatedly in the developing ES field.

  13. Inertial effects in laser-driven ablation

    SciTech Connect

    Harrach, R.J.; Szeoke, A.; Howard, W.M.

    1983-07-15

    The gasdynamic partial differential equations (PDE's) governing the motion of an ablatively accelerated target (rocket) contain an inertial force term that arises from acceleration of the reference frame in which the PDE's are written. We give a simple, intuitive description of this effect, and estimate its magnitude and parametric dependences by means of approximate analytical formulas inferred from our computer hydrocode calculations. Often this inertial term is negligible, but for problems in the areas of laser fusion and laser equation of state studies we find that it can substantially reduce the attainable hydrodynamic efficiency of acceleration and implosion.

  14. HIGH POWER BEAM DUMP AND TARGET / ACCELERATOR INTERFACE PROCEDURES

    SciTech Connect

    Blokland, Willem; Plum, Michael A; Peters, Charles C; Brown, David L; Galambos, John D

    2013-01-01

    Satisfying operational procedures and limits for the beam target interface is a critical concern for high power operation at spallation neutron sources. At the Oak Ridge Spallation Neutron Source (SNS) a number of protective measures are instituted to ensure that the beam position, beam size and peak intensity are within acceptable limits at the target and high power Ring Injection Dump (RID). The high power beam dump typically handles up to 50 100 kW of beam power and its setup is complicated by the fact that there are two separate beam components simultaneously directed to the dump. The beam on target is typically in the 800-1000 kW average power level, delivered in sub- s 60 Hz pulses. Setup techniques using beam measurements to quantify the beam parameters at the target and dump will be described. However, not all the instrumentation used for the setup and initial qualification is available during high power operation. Additional techniques are used to monitor the beam during high power operation to ensure the setup conditions are maintained, and these are also described.

  15. Graphics processing unit-accelerated non-rigid registration of MR images to CT images during CT-guided percutaneous liver tumor ablations

    PubMed Central

    Tokuda, Junichi; Plishker, William; Torabi, Meysam; Olubiyi, Olutayo I; Zaki, George; Tatli, Servet; Silverman, Stuart G.; Shekhar, Raj; Hata, Nobuhiko

    2015-01-01

    Rationale and Objectives Accuracy and speed are essential for the intraprocedural nonrigid MR-to-CT image registration in the assessment of tumor margins during CT-guided liver tumor ablations. While both accuracy and speed can be improved by limiting the registration to a region of interest (ROI), manual contouring of the ROI prolongs the registration process substantially. To achieve accurate and fast registration without the use of an ROI, we combined a nonrigid registration technique based on volume subdivision with hardware acceleration using a graphical processing unit (GPU). We compared the registration accuracy and processing time of GPU-accelerated volume subdivision-based nonrigid registration technique to the conventional nonrigid B-spline registration technique. Materials and Methods Fourteen image data sets of preprocedural MR and intraprocedural CT images for percutaneous CT-guided liver tumor ablations were obtained. Each set of images was registered using the GPU-accelerated volume subdivision technique and the B-spline technique. Manual contouring of ROI was used only for the B-spline technique. Registration accuracies (Dice Similarity Coefficient (DSC) and 95% Hausdorff Distance (HD)), and total processing time including contouring of ROIs and computation were compared using a paired Student’s t-test. Results Accuracy of the GPU-accelerated registrations and B-spline registrations, respectively were 88.3 ± 3.7% vs 89.3 ± 4.9% (p = 0.41) for DSC and 13.1 ± 5.2 mm vs 11.4 ± 6.3 mm (p = 0.15) for HD. Total processing time of the GPU-accelerated registration and B-spline registration techniques was 88 ± 14 s vs 557 ± 116 s (p < 0.000000002), respectively; there was no significant difference in computation time despite the difference in the complexity of the algorithms (p = 0.71). Conclusion The GPU-accelerated volume subdivision technique was as accurate as the B-spline technique and required significantly less processing time. The GPU-accelerated

  16. Simulation of Rayleigh-Taylor instability growth rate of laser accelerated plant target. Final report

    SciTech Connect

    Bel`kov, S.A.; Bondarenko, S.V.; Vinokurov, O.A.; Kochemasov, G.G.; Mkhitarian, L.S.

    1996-09-01

    This report presents the research results for the time point when the Rayleigh-Taylor instability converts to the nonlinear stage as well as the computational results for the interaction of two modes of Rayleigh-Taylor instability when initial perturbations are concentrated at the ablation front (problem (a)) and on the rear side (problem (b)) of the plane target. As was shown in the report for the first phase, for a target of 3 {mu}m thick the existence time of the nonlinear stage is extremely low and does not allow to track the evolution pattern. In it was shown that the plane target with {Delta}{sub 0}=5 {mu}m is more preferable for this goal. Therefore all the computations presented here relate to the target with the indicated thickness. The laser pulse parameters are remained unchanged J{sub L}=10{sup 15} W/cm{sup 2}, {lambda}=0.35 {mu}m.

  17. Resistively enhanced proton acceleration via high-intensity laser interactions with cold foil targets

    SciTech Connect

    Gibbon, Paul

    2005-08-01

    The acceleration of MeV protons by high-intensity laser interaction with foil targets is studied using a recently developed plasma simulation technique. Based on a hierarchical N-body tree algorithm, this method provides a natural means of treating three-dimensional, collisional transport effects hitherto neglected in conventional explicit particle-in-cell simulations. For targets with finite resistivity, hot electron transport is strongly inhibited, even at temperatures in the MeV range. This leads to suppression of ion acceleration from the rear of the target and an enhancement in energies and numbers of protons originating from the front.

  18. The analytic model of a laser-accelerated plasma target and its stability

    NASA Astrophysics Data System (ADS)

    Khudik, V.; Yi, S. A.; Siemon, C.; Shvets, G.

    2014-01-01

    A self-consistent kinetic theory of a laser-accelerated plasma target with distributed electron/ion densities is developed. The simplified model assumes that after an initial transition period the bulk of cold ions are uniformly accelerated by the self-consistent electric field generated by hot electrons trapped in combined ponderomotive and electrostatic potentials. Several distinct target regions (non-neutral ion tail, non-neutral electron sheath, and neutral plasma bulk) are identified and analytically described. It is shown analytically that such laser-accelerated finite-thickness target is susceptible to Rayleigh-Taylor (RT) instability. Particle-in-cell simulations of the seeded perturbations of the plasma target reveal that, for ultra-relativistic laser intensities, the growth rate of the RT instability is depressed from the analytic estimates.

  19. The analytic model of a laser-accelerated plasma target and its stability

    SciTech Connect

    Khudik, V. Yi, S. A.; Siemon, C.; Shvets, G.

    2014-01-15

    A self-consistent kinetic theory of a laser-accelerated plasma target with distributed electron/ion densities is developed. The simplified model assumes that after an initial transition period the bulk of cold ions are uniformly accelerated by the self-consistent electric field generated by hot electrons trapped in combined ponderomotive and electrostatic potentials. Several distinct target regions (non-neutral ion tail, non-neutral electron sheath, and neutral plasma bulk) are identified and analytically described. It is shown analytically that such laser-accelerated finite-thickness target is susceptible to Rayleigh-Taylor (RT) instability. Particle-in-cell simulations of the seeded perturbations of the plasma target reveal that, for ultra-relativistic laser intensities, the growth rate of the RT instability is depressed from the analytic estimates.

  20. Slow positron target concepts for the Advanced Photon Source (APS) linear accelerator

    SciTech Connect

    White, M.; Lessner, E.

    1997-09-01

    The APS linear accelerator (linac) system consists of a 200-MeV, 2856-MHz S-band electron linac, followed by a 450-Mev positron linac. The linac is available for other uses upon completion of the storage ring injection cycle. Nominal linac beam power is 480 W but the power can be increased substantially, making it suitable for production of slow positrons. Simulation studies for the design of a slow-positron target-moderator system that is optimized for operation with the APS linac are presented. Results of simulations of various target configurations indicate that a suitably designed multilayer target can result in a higher positron yield than a single-block target. Use of an integrated, multilayer target moderator is suggested. Some possibilities for extracting slow positrons between target layers by means of electromagnetic fields are discussed. First results from recent accelerator studies aimed at increasing the linac beam power are also presented.

  1. Plasma block acceleration via double targets driven by an ultraintense circularly polarized laser pulse

    NASA Astrophysics Data System (ADS)

    Xu, Yanxia; Wang, Jiaxiang; Qi, Xin; Li, Meng; Xing, Yifan; Yang, Lei; Zhu, Wenjun

    2017-03-01

    By using two-dimensional particle-in-cell simulations, plasma block acceleration via radiation pressure from an ultraintense circularly polarized laser pulse with intensity I ≈ 10 22 W / cm 2 is investigated based on a double-target scheme, in which the targets are composed of a pre-target with a relatively low plasma density and a main target with a high plasma density. It has been demonstrated that an appropriately selected pre-target can help to greatly enhance the charge separation field in the main target, which then leads to generation of a strongly accelerated and well directed plasma block with proton energy in GeV magnitude. This result can have potential applications in the plasma block ignition of proton-born fusion.

  2. Asymmetric partitioning of metals among cluster anions and cations generated via laser ablation of mixed aluminum/Group 6 transition metal targets.

    PubMed

    Waller, Sarah E; Mann, Jennifer E; Jarrold, Caroline Chick

    2013-02-28

    While high-power laser ablation of metal alloys indiscriminately produces gas-phase atomic ions in proportion to the abundance of the various metals in the alloy, gas-phase ions produced by moderate-power laser ablation sources coupled with molecular beams are formed by more complicated mechanisms. A mass spectrometric study that directly compares the mass distributions of cluster anions and cations generated from laser ablation of pure aluminum, an aluminum/molybdenum mixed target, and an aluminum/tungsten mixed target is detailed. Mass spectra of anionic species generated from the mixed targets showed that both tungsten and molybdenum were in higher abundance in the negatively charged species than in the target material. Mass spectra of the cationic species showed primarily Al(+) and aluminum oxide and hydroxide cluster cations. No molybdenum- or tungsten-containing cluster cations were definitively assigned. The asymmetric distribution of aluminum and Group 6 transition metals in cation and anion cluster composition is attributed to the low ionization energy of atomic aluminum and aluminum suboxide clusters. In addition, the propensity of both molybdenum and tungsten to form metal oxide cluster anions under the same conditions that favor metallic aluminum cluster anions is attributed to differences in the optical properties of the surface oxide that is present in the metal powders used to prepare the ablation targets. Mechanisms of mixed metal oxide clusters are considered.

  3. Highly collimated monoenergetic target-surface electron acceleration in near-critical-density plasmas

    SciTech Connect

    Mao, J. Y.; Chen, L. M.; Huang, K.; Ma, Y.; Zhao, J. R.; Yan, W. C.; Ma, J. L.; Wei, Z. Y.; Li, D. Z.; Aeschlimann, M.; Zhang, J.

    2015-03-30

    Optimized-quality monoenergetic target surface electron beams at MeV level with low normalized emittance (0.03π mm mrad) and high charge (30 pC) per shot have been obtained from 3 TW laser-solid interactions at a grazing incidence. The 2-Dimension particle-in-cell simulations suggest that electrons are wake-field accelerated in a large-scale, near-critical-density preplasma. It reveals that a bubble-like structure as an accelerating cavity appears in the near-critical-density plasma region and travels along the target surface. A bunch of electrons are pinched transversely and accelerated longitudinally by the wake field in the bubble. The outstanding normalized emittance and monochromaticity of such highly collimated surface electron beams could make it an ideal beam for fast ignition or may serve as an injector in traditional accelerators.

  4. Sequence heterogeneity accelerates protein search for targets on DNA

    NASA Astrophysics Data System (ADS)

    Shvets, Alexey A.; Kolomeisky, Anatoly B.

    2015-12-01

    The process of protein search for specific binding sites on DNA is fundamentally important since it marks the beginning of all major biological processes. We present a theoretical investigation that probes the role of DNA sequence symmetry, heterogeneity, and chemical composition in the protein search dynamics. Using a discrete-state stochastic approach with a first-passage events analysis, which takes into account the most relevant physical-chemical processes, a full analytical description of the search dynamics is obtained. It is found that, contrary to existing views, the protein search is generally faster on DNA with more heterogeneous sequences. In addition, the search dynamics might be affected by the chemical composition near the target site. The physical origins of these phenomena are discussed. Our results suggest that biological processes might be effectively regulated by modifying chemical composition, symmetry, and heterogeneity of a genome.

  5. Sequence heterogeneity accelerates protein search for targets on DNA

    SciTech Connect

    Shvets, Alexey A.; Kolomeisky, Anatoly B.

    2015-12-28

    The process of protein search for specific binding sites on DNA is fundamentally important since it marks the beginning of all major biological processes. We present a theoretical investigation that probes the role of DNA sequence symmetry, heterogeneity, and chemical composition in the protein search dynamics. Using a discrete-state stochastic approach with a first-passage events analysis, which takes into account the most relevant physical-chemical processes, a full analytical description of the search dynamics is obtained. It is found that, contrary to existing views, the protein search is generally faster on DNA with more heterogeneous sequences. In addition, the search dynamics might be affected by the chemical composition near the target site. The physical origins of these phenomena are discussed. Our results suggest that biological processes might be effectively regulated by modifying chemical composition, symmetry, and heterogeneity of a genome.

  6. Targeted ablation and reorganization of the principal preplate neurons and their neuroblasts identified by golli promoter transgene expression in the neocortex of mice

    PubMed Central

    Xie, Yuan-Yun; Jacobs, Erin; Fisher, Robin

    2009-01-01

    The present study delineates the cellular responses of dorsal pallium to targeted genetic ablation of the principal preplate neurons of the neocortex. Ganciclovir treatment during prenatal development (E11–E13; where E is embryonic day) of mice selectively killed cells with shared S-phase vulnerability and targeted expression of a GPT [golli promoter transgene, linked to HSV-TK (herpes simplex virus-thymidine kinase), τ-eGFP (τ-enhanced green fluorescent protein) and lacZ (lacZ galactosidase) reporters] localized in preplate neurons. Morphogenetic fates of attacked neurons and neuroblasts, and their successors, were assessed by multiple labelling in time-series comparisons between ablated (HSV-TK+/0) and control (HSV-TK0/0) littermates. During ablation generation, neocortical growth was suppressed, and compensatory reorganization of non-GPT ventricular zone progenitors of dorsal pallium produced replacements for killed GPT neuroblasts. Replacement and surviving GPT neuroblasts then produced replacements for killed GPT neurons. Near-normal restoration of their complement delayed the settlement of GPT neurons into the reconstituted preplate, which curtailed the outgrowth of pioneer corticofugal axons. Based on this evidence, we conclude that specific cell killing in ablated mice can eliminate a major fraction of GPT neurons, with insignificant bystander killing. Also, replacement GPT neurons in ablated mice originate exclusively by proliferation from intermediate progenitor GPT neuroblasts, whose complement is maintained by non-GPT progenitors for inductive regulation of the total complement of GPT neurons. Finally, GPT neurons in both normal and ablated mice meet all morphogenetic criteria, including the ‘outside-in’ vertical gradient of settlement, presently used to identify principal preplate neurons. In ablated mice, delayed organization of these neurons desynchronizes and isolates developing neocortex from the rest of the brain, and permanently impairs

  7. High excitation of the species in nitrogen-aluminum plasma generated by electron cyclotron resonance microwave discharge of N2 gas and pulsed laser ablation of Al target

    NASA Astrophysics Data System (ADS)

    Liang, Peipei; Li, Yanli; Cai, Hua; You, Qinghu; Yang, Xu; Huang, Feiling; Sun, Jian; Xu, Ning; Wu, Jiada

    2014-11-01

    A reactive nitrogen-aluminum plasma generated by electron cyclotron resonance (ECR) microwave discharge of N2 gas and pulsed laser ablation of an Al target is characterized spectroscopically by time-integrated and time-resolved optical emission spectroscopy (OES). The vibrational and rotational temperatures of N2 species are determined by spectral simulation. The generated plasma strongly emits radiation from a variety of excited species including ambient nitrogen and ablated aluminum and exhibits unique features in optical emission and temperature evolution compared with the plasmas generated by a pure ECR discharge or by the expansion of the ablation plume. The working N2 gas is first excited by ECR discharge and the excitation of nitrogen is further enhanced due to the fast expansion of the aluminum plume induced by target ablation, while the excitation of the ablated aluminum is prolonged during the plume expansion in the ECR nitrogen plasma, resulting in the formation of strongly reactive nitrogen-aluminum plasma which contains highly excited species with high vibrational and rotational temperatures. The enhanced intensities and the prolonged duration of the optical emissions of the combined plasma would provide an improved analytical capability for spectrochemical analysis.

  8. On the numerical simulation of the ablative Rayleigh-Taylor instability in laser-driven ICF targets using the FastRad3D code

    NASA Astrophysics Data System (ADS)

    Bates, Jason; Schmitt, Andrew; Zalesak, Steve

    2015-11-01

    The ablative Rayleigh-Taylor (RT) instability is a key factor in the performance of directly-drive inertial-confinement-fusion (ICF) targets. Although this subject has been studied for quite some time, the accurate simulation of the ablative RT instability has proven to be a challenging task for many radiation hydrodynamics codes, particularly when it comes to capturing the ablatively-stabilized region of the linear dispersion spectrum and modeling ab initio perturbations. In this poster, we present results from recent two-dimensional numerical simulations of the ablative RT instability that were performed using the Eulerian code FastRad3D at the U.S. Naval Research Laboratory. We consider both planar and spherical geometries, low and moderate-Z target materials, different laser wavelengths and where possible, compare our findings with experiment data, linearized theory and/or results from other radiation hydrodynamics codes. Overall, we find that FastRad3D is capable of simulating the ablative RT instability quite accurately, although some uncertainties/discrepancies persist. We discuss these issues, as well as some of the numerical challenges associated with modeling this class of problems. Work supported by U.S. DOE/NNSA.

  9. Studies of Ion Acceleration from Thin Solid-Density Targets on High-Intensity Lasers

    NASA Astrophysics Data System (ADS)

    Willis, Christopher R.

    Over the past two decades, a number of experiments have been performed demonstrating the acceleration of ions from the interaction of an intense laser pulse with a thin, solid density target. These ions are accelerated by quasi-static electric fields generated by energetic electrons produced at the front of the target, resulting in ion energies up to tens of MeV. These ions have been widely studied for a variety of potential applications ranging from treatment of cancer to the production of neutrons for advanced radiography techniques. However, realization of these applications will require further optimization of the maximum energy, spectrum, or species of the accelerated ions, which has been a primary focus of research to date. This thesis presents two experiments designed to optimize several characteristics of the accelerated ion beam. The first of these experiments took place on the GHOST laser system at the University of Texas at Austin, and was designed to demonstrate reliable acceleration of deuterium ions, as needed for the most efficient methods of neutron generation from accelerated ions. This experiment leveraged cryogenically cooled targets coated in D2 O ice to suppress the protons which typically dominate the accelerated ions, producing as many as 2 x 1010 deuterium ions per 1 J laser shot, exceeding the proton yield by an average ratio of 5:1. The second major experiment in this work was performed on the Scarlet laser system at The Ohio State University, and studied the accelerated ion energy, yield, and spatial distribution as a function of the target thickness. In principle, the peak energy increases with decreasing target thickness, with the thinnest targets accessing additional acceleration mechanisms which provide favorable scaling with the laser intensity. However, laser prepulse characteristics provide a lower bound for the target thickness, yielding an optimum target thickness for ion acceleration which is dependent on the laser system. This

  10. Fermilab Project X nuclear energy application: Accelerator, spallation target and transmutation technology demonstration

    SciTech Connect

    Gohar, Yousry; Johnson, David; Johnson, Todd; Mishra, Shekhar; /Fermilab

    2011-04-01

    The recent paper 'Accelerator and Target Technology for Accelerator Driven Transmutation and Energy Production' and report 'Accelerators for America's Future' have endorsed the idea that the next generation particle accelerators would enable technological breakthrough needed for nuclear energy applications, including transmutation of waste. In the Fall of 2009 Fermilab sponsored a workshop on Application of High Intensity Proton Accelerators to explore in detail the use of the Superconducting Radio Frequency (SRF) accelerator technology for Nuclear Energy Applications. High intensity Continuous Wave (CW) beam from the Superconducting Radio Frequency (SRF) Linac (Project-X) at beam energy between 1-2 GeV will provide an unprecedented experimental and demonstration facility in the United States for much needed nuclear energy Research and Development. We propose to carry out an experimental program to demonstrate the reliability of the accelerator technology, Lead-Bismuth spallation target technology and a transmutation experiment of spent nuclear fuel. We also suggest that this facility could be used for other Nuclear Energy applications.

  11. Target optimization for desired X-ray spectra produced by laser plasma accelerated electrons

    NASA Astrophysics Data System (ADS)

    Lobok, Maxim; Brantov, Andrey; Bychenkov, Valery

    2016-10-01

    Different regimes of electron acceleration from low-density targets are investigated using three-dimensional numerical simulations. Multiple spatial target density profiles were examined, including laser pre-pulse modified targets. The size of the plasma corona is shown to be one of the main parameters characterizing the temperature and number of hot electrons, which determine the yield of X-ray radiation and its hardness. The generation of X-ray radiation by laser accelerated electrons, which impact the converter target located behind the laser target, was studied. The X-ray spectra were computed using Monte-Carlo simulations. This work was partially supported by the Russian Foundation for Basic Research 16-02-00088-a.

  12. Physics of Double Pulse Irradiation of Targets For Proton Acceleration

    NASA Astrophysics Data System (ADS)

    Kerr, S.; Mo, M.; Masud, R.; Manzoor, L.; Tiedje, H.; Tsui, Y.; Fedosejevs, R.; Link, A.; Patel, P.; McLean, H.; Hazi, A.; Chen, H.; Ceurvorst, L.; Norreys, P.

    2016-10-01

    Experiments have been carried out on double-pulse irradiation of um-scale foil targets with varying preplasma conditions. Our experiment at the Titan Laser facility utilized two 700 fs, 1054 nm pulses, separated by 1 to 5 ps with a total energy of 100 J, and with 5-20% of the total energy contained within the first pulse. The proton spectra were measured with radiochromic film stacks and magnetic spectrometers. The prepulse energy was on the order of 10 mJ, which appears to have a moderating effect on the double pulse enhancement of proton beam. We have performed LSP PIC simulations to understand the double pulse enhancement mechanism, as well as the role of preplasma in modifying the interaction. A 1D parameter study was done to isolate various aspects of the interaction, while 2D simulations provide more detailed physical insight and a better comparison with experimental data. Work by the Univ. of Alberta was supported by the Natural Sciences and Engineering Research Council of Canada. Work by LLNL was performed under the auspices of U.S. DOE under contract DE-AC52-07NA27344.

  13. Sequence Heterogeneity Accelerates Protein Search for Targets on DNA

    NASA Astrophysics Data System (ADS)

    Shvets, Alexey; Kolomeisky, Anatoly

    The process of protein search for specific binding sites on DNA is fundamentally important since it marks the beginning of all major biological processes. We present a theoretical investigation that probes the role of DNA sequence symmetry, heterogeneity and chemical composition in the protein search dynamics. Using a discrete-state stochastic approach with a first-passage events analysis, which takes into account the most relevant physical-chemical processes, a full analytical description of the search dynamics is obtained. It is found that, contrary to existing views, the protein search is generally faster on DNA with more heterogeneous sequences. In addition, the search dynamics might be affected by the chemical composition near the target site. The physical origins of these phenomena are discussed. Our results suggest that biological processes might be effectively regulated by modifying chemical composition, symmetry and heterogeneity of a genome. The work was supported by the Welch Foundation (Grant C-1559), by the NSF (Grant CHE-1360979), and by the Center for Theoretical Biological Physics sponsored by the NSF (Grant PHY-1427654).

  14. Stability analysis of unsteady ablation fronts

    NASA Astrophysics Data System (ADS)

    Betti, R.; McCrory, R. L.; Verdon, C. P.

    1993-08-01

    The linear stability analysis of unsteady ablation fronts is carried out for a semi-infinite uniform medium. For a laser accelerated target, it is shown that a properly selected modulation of the laser intensity can lead to the dynamic stabilization or growth-rate reduction of a large portion of the unstable spectrum. The theory is in qualitative agreement with the numerical results obtained by using the two-dimensional hydrodynamic code ORCHID.

  15. Stability analysis of unsteady ablation fronts

    SciTech Connect

    Betti, R.; McCrory, R.L.; Verdon, C.P. )

    1993-11-08

    The linear stability analysis of unsteady ablation fronts is carried out for a semi-infinite uniform medium. For a laser accelerated target, it is shown that a properly selected modulation of the laser intensity can lead to the dynamic stabilization or growth-rate reduction of a large portion of the unstable spectrum. The theory is in qualitative agreement with the numerical results obtained by using the two-dimensional hydrodynamic code ORCHID.

  16. Stability analysis of unsteady ablation fronts

    NASA Astrophysics Data System (ADS)

    Betti, R.; McCrory, R. L.; Verdon, C. P.

    1993-11-01

    The linear stability analysis of unsteady ablation fronts is carried out for a semi-infinite uniform medium. For a laser accelerated target, it is shown that a properly selected modulation of the laser intensity can lead to the dynamic stabilization or growth-rate reduction of a large portion of the unstable spectrum. The theory is in qualitative agreement with the numerical results obtained by using the two-dimensional hydrodynamic code orchid.

  17. Stability analysis of unsteady ablation fronts

    SciTech Connect

    Betti, R.; McCrory, R.L.; Verdon, C.P.

    1993-08-01

    The linear stability analysis of unsteady ablation fronts, is carried out for a semi-infinite uniform medium. For a laser accelerated target, it is shown that a properly selected modulation of the laser intensity can lead to the dynamic stabilization or growth-rate reduction of a large portion of the unstable spectrum. The theory is in qualitative agreement with the numerical results obtained by using the two-dimensional hydrodynamic code ORCHID.

  18. Microstructured snow targets for high energy quasi-monoenergetic proton acceleration

    NASA Astrophysics Data System (ADS)

    Schleifer, E.; Nahum, E.; Eisenmann, S.; Botton, M.; Baspaly, A.; Pomerantz, I.; Abricht, F.; Branzel, J.; Priebe, G.; Steinke, S.; Andreev, A.; Schnuerer, M.; Sandner, W.; Gordon, D.; Sprangle, P.; Ledingham, K. W. D.; Zigler, A.

    2013-05-01

    Compact size sources of high energy protons (50-200MeV) are expected to be key technology in a wide range of scientific applications 1-8. One promising approach is the Target Normal Sheath Acceleration (TNSA) scheme 9,10, holding record level of 67MeV protons generated by a peta-Watt laser 11. In general, laser intensity exceeding 1018 W/cm2 is required to produce MeV level protons. Another approach is the Break-Out Afterburner (BOA) scheme which is a more efficient acceleration scheme but requires an extremely clean pulse with contrast ratio of above 10-10. Increasing the energy of the accelerated protons using modest energy laser sources is a very attractive task nowadays. Recently, nano-scale targets were used to accelerate ions 12,13 but no significant enhancement of the accelerated proton energy was measured. Here we report on the generation of up to 20MeV by a modest (5TW) laser system interacting with a microstructured snow target deposited on a Sapphire substrate. This scheme relax also the requirement of high contrast ratio between the pulse and the pre-pulse, where the latter produces the highly structured plasma essential for the interaction process. The plasma near the tip of the snow target is subject to locally enhanced laser intensity with high spatial gradients, and enhanced charge separation is obtained. Electrostatic fields of extremely high intensities are produced, and protons are accelerated to MeV-level energies. PIC simulations of this targets reproduce the experimentally measured energy scaling and predict the generation of 150 MeV protons from laser power of 100TW laser system18.

  19. Spectral control of laser accelerated ions via deuterium vapour deposition onto cryogenically cooled targets

    NASA Astrophysics Data System (ADS)

    Scott, Graeme

    2016-10-01

    A widely perceived criticism of the best understood laser driven ion acceleration mechanism, TNSA, is that the energy spectra routinely obtained are Maxwellian in nature, and are non-ideal for some of the long term envisaged applications of a laser accelerated ion source such as ion driven fast ignition or hadrontherapy. We, however, demonstrate a novel method to accelerate a quasi-monoenergetic deuterium beam in the TNSA regime of ion acceleration. This is made possible by recent developments in cryogenic targetry at the Central Laser Facility, and is achieved by cooling a gold target to approximately 7-8 K and introducing overcoats of isotopic deuterium layers on top of the hydrogen contaminant layer present on the original target. The presence of a lower charge to mass ion on top of the high charge to mass hydrogen, alters the sheath dynamics during the acceleration such that the high energy portion of the deuterium beam exhibits a full width at half maximum energy spread of δɛ / ɛ 0.3-0.5. Experimental results and multidimensional numerical modelling will be presented describing this effect. Further than this, experimental results show that the accelerated deuterium beam is found to significantly enhance the number of neutrons produced when fielded in a pitcher/catcher configuration, and provides avenues for investigation on the production of a high brightness neutron source.

  20. Morphology and pathophysiology of target anatomical sites for ablation procedures in patients with atrial fibrillation: part II: pulmonary veins, caval veins, ganglionated plexi, and ligament of Marshall.

    PubMed

    Corradi, Domenico; Callegari, Sergio; Gelsomino, Sandro; Lorusso, Roberto; Macchi, Emilio

    2013-10-03

    The inadequate long-term efficacy of anti-arrhythmic therapy has been one of the main reasons for the development of non-pharmacological interventions for patients with atrial fibrillation such as catheter and surgical ablation. This has greatly increased interest in the functional morphology and electrophysiological properties of the atria and related anatomical structures. This article is the second of a two-part review that aims to provide anatomical and functional details concerning some of the principal anatomical sites commonly targeted by ablative procedures for treating atrial fibrillation, and covers pulmonary veins, ganglionated plexi, caval veins, and the ligament of Marshall. It also provides some general information about site-specific ablation procedures.

  1. The impact of subcellular location on the near infrared-mediated thermal ablation of cells by targeted carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Murali, Vasanth S.; Wang, Ruhung; Mikoryak, Carole A.; Pantano, Paul; Draper, Rockford K.

    2016-10-01

    Single-walled carbon nanotubes (SWNTs) are used in the near infrared (NIR)-mediated thermal ablation of tumor cells because they efficiently convert absorbed NIR light into heat. Despite the therapeutic potential of SWNTs, there have been no published studies that directly quantify how many SWNTs need be associated with a cell to achieve a desired efficiency of killing, or what is the most efficient subcellular location of SWNTs for killing cells. Herein we measured dose response curves for the efficiency of killing correlated to the measured amounts of folate-targeted SWNTs that were either on the surface or within the vacuolar compartment of normal rat kidney cells. Folate-targeted SWNTs on the cell surface were measured after different concentrations of SWNTs in medium were incubated with cells for 30 min at 4 °C. Folate-targeted SWNTs within the vacuolar compartments were measured after cells were incubated with different concentrations of SWNTs in medium for 6 h at 37 °C. It was observed that a SWNT load of ∼13 pg/cell when internalized was sufficient to kill 90% of the cells under standardized conditions of NIR light irradiation. When ∼3.5 pg/cell of SWNTs were internalized within the endosomal/lysosomal compartments, ∼50% of the cells were killed, but when ∼3.5 pg/cell of SWNTs were confined to the cell surface only ∼5% of the cells were killed under the same NIR irradiation conditions. The SWNT subcellular locations were verified using Raman imaging of SWNTs merged with fluorescence images of known subcellular markers. To our knowledge, this is the first time that SWNT amounts at known subcellular locations have been correlated with a dose-normalized efficacy of thermal ablation and the results support the idea that SWNTs confined to the plasma membrane are not as effective in NIR-mediated cell killing as an equivalent amount of SWNTs when internalized within the endosomal/lysosomal vesicles.

  2. LANL sunnyside experiment: Study of neutron production in accelerator-driven targets

    NASA Astrophysics Data System (ADS)

    Morgan, G.; Butler, G.; Cappiello, M.; Carius, S.; Daemen, L.; DeVolder, B.; Frehaut, J.; Goulding, C.; Grace, R.; Green, R.; Lisowski, P.; Littleton, P.; King, J.; King, N.; Prael, R.; Stratton, T.; Turner, S.; Ullmann, J.; Venneri, F.; Yates, M.

    1995-09-01

    Measurements have been made of the neutron production in prototypic targets for accelerator driven systems. Studies were conducted on four target assemblies containing lead, lithium, tungsten, and a thorium-salt mixture. Integral data on total neutron production were obtained as well as more differential data on neutron leakage and neutron flux profiles in the blanket/moderator region. Data analysis on total neutron production is complete and shows excellent agreement with calculations using the LAHET/MCNP code system.

  3. Studies on subcritical and overcritical density laser ablated TAC foam targets

    NASA Astrophysics Data System (ADS)

    Chaurasia, S.; Leshma, P.; Murali, C. G.; Borisenko, N. G.; Munda, D. S.; Orekhov, A.; Gromov, A. I.; Merkuliev, Yu. A.; Dhareshwar, L. J.

    2015-05-01

    In this paper, the interaction of high power laser with low density polymer foam with density as low as 2 mg/cm3, 4 mg/cm3, 20 mg/cm3 30 mg/cm3 and 50 mg/cm3 targets are investigated and compared with solid polymer targets. An understanding of such interaction is important from fusion research point of view. Low density foam coating of fusion capsule has been proposed in order to smooth in direct drive scheme and also it is being used as efficient x-ray converter in indirect drive scheme. It is observed that about 75-80% of the laser energy is absorbed in the subcritical (with density <4 mg/cm3) foam targets and the soft x-ray yield in this case is almost two times that measured in the over dense (supper critical) targets. The optical shadowgraphy of the targets shows that the laser coupling in low density foam is associated with a supersonic heat wave while, with increasing density this phenomenon is replaced by subsonic absorption and shock formation. In the case of a 50 mg/cm3 foams the foil velocity reduced by 35% (i.e. 5×106 cm/s), which further reduced to 3.8×106 cm/s in case solid polymer targets.

  4. Measurements of ablation-front hydrodynamic instability growth in high-density carbon (HDC) ignition targets at the National Ignition Facility (NIF)

    NASA Astrophysics Data System (ADS)

    Casey, D.; Smalyuk, V.; Peterson, L.; Berzak Hopkins, L.; Bunn, T.; Carlson, L.; Haan, S.; Ho, D.; Hoover, D.; Kroll, J.; Landen, O.; Le Pape, S.; MacKinnon, A.; Macphee, A.; Meezan, N.; Milovich, J.; Nikroo, A.; Remington, B.; Robey, H.; Ross, S.

    2014-10-01

    High-density carbon (HDC) has emerged as a promising ablator for ignition experiments at the National Ignition Facility (NIF) partly because of its efficient coupling of the drive energy to fuel. Experiments during the National Ignition Campaign using a CH plastic ablator have shown that instability growth and the resultant mix of plastic into the hotspot was a significant source of overall the observed performance degradation. Likewise, mix of HDC ablator into the hotspot may also be a concern, as growth rates for HDC are comparable to CH and ablator/dopant is higher Z than CH ablators making the consequences potentially more severe. To help understand this issue, we plan to perform the first instability growth measurements of W-doped HDC implosions with preimposed mode 60 and mode 90 perturbations in convergent geometry using actual ignition targets and drives. These results will be presented and compared to ignition design simulations. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  5. Effective Targeted Photothermal Ablation of Multidrug Resistant Bacteria and Their Biofilms with NIR-Absorbing Gold Nanocrosses.

    PubMed

    Teng, Choon Peng; Zhou, Tielin; Ye, Enyi; Liu, Shuhua; Koh, Leng Duei; Low, Michelle; Loh, Xian Jun; Win, Khin Yin; Zhang, Lianhui; Han, Ming-Yong

    2016-08-01

    With the rapid evolution of antibiotic resistance in bacteria, antibiotic-resistant bacteria (in particular, multidrug-resistant bacteria) and their biofilms have been becoming more and more difficult to be effectively treated with conventional antibiotics. As such, there is a great demand to develop a nonantibiotic approach in efficiently eliminating such bacteria. Here, multibranched gold nanocrosses with strong near-infrared absorption falling in the biological window, which heat up quickly under near-infrared-light irradiation are presented. The gold nanocrosses are conjugated to secondary and primary antibodies for targeting PcrV, a type III secretion protein, which is uniquely expressed on the bacteria superbug, Pseudomonas aeruginosa. The conjugated gold nanocrosses are capable of completely destroying P. aeruginosa and its biofilms upon near-infrared-light irradiation for 5 min with an 800 nm laser at a low power density of ≈3.0 W cm(-2) . No bacterial activity is detected after 48 h postirradiation, which indicates that the heat generated from the irradiated plasmonic gold nanocrosses attached to bacteria is effective in eliminating and preventing the re-growth of the bacteria. Overall, the conjugated gold nanocrosses allow targeted and effective photothermal ablation of multidrug-resistant bacteria and their biofilms in the localized region with reduced nonspecific damage to normal tissue.

  6. Ultraintense laser interaction with nanoscale target: a simple model for layer expansion and ion acceleration

    SciTech Connect

    Albright, Brian J; Yin, Lin; Hegelich, Bjoorn M; Bowers, Kevin J; Huang, Chengkun; Fernandez, Juan C; Flippo, Kirk A; Gaillard, Sandrine; Kwan, Thomas J T; Henig, Andreas; Yan, Xue Q; Tajima, Toshi; Habs, Dieter

    2009-01-01

    A simple model has been derived for the expansion of a thin (up to 100s of nm thickness), solid-density target driven by an u.ltraintense laser. In this regime, new ion acceleration mechanisms, such as the Break-Out Afterburner (BOA) [1], emerge with the potential to dramatically improve energy, efficiency, and energy spread of laser-driven ion beams. Such beams have been proposed [2] as drivers for fast ignition inertial confinement fusion [3]. Analysis of kinetic simulations of the BOA shows two dislinct times that bound the period of enhanced acceleration: t{sub 1}, when the target becomes relativistically transparent to the laser, and t{sub 2}, when the target becomes classically underdense and the enhanced acceleration terminates. A silllple dynamical model for target expansion has been derived that contains both the early, one-dimensional (lD) expansion of the target as well as three-dimensional (3D) expansion of the plasma at late times, The model assumes that expansion is slab-like at the instantaneous ion sound speed and requires as input target composition, laser intensity, laser spot area, and the efficiency of laser absorption into electron thermal energy.

  7. Laser acceleration of protons with an optically shaped, near-critical hydrogen gas target

    NASA Astrophysics Data System (ADS)

    Chen, Yu-hsin; Helle, Michael; Ting, Antonio; Gordon, Daniel; Dover, Nicholas; Ettlinger, Oliver; Najmudin, Zulfikar; Polyanskiy, Mikhail; Pogorelsky, Igor; Babzien, Marcus

    2017-03-01

    We report our recent experimental results on CO2 laser acceleration of protons, with a near-critical hydrogen gas target tailored by a Nd:YAG laser-produced blast wave. Monoenergetic protons with energies up to 2.5 MeV were observed.

  8. Direct-drive–ignition designs with mid-Z ablators

    SciTech Connect

    Lafon, M.; Betti, R.; Anderson, K. S.; Collins, T. J. B.; Epstein, R.; McKenty, P. W.; Myatt, J. F.; Shvydky, A.; Skupsky, S.

    2015-03-15

    Achieving thermonuclear ignition using direct laser illumination relies on the capability to accelerate spherical shells to high implosion velocities while maintaining shell integrity. Ablator materials of moderate atomic number Z reduce the detrimental effects of laser–plasma instabilities in direct-drive implosions. To validate the physics of moderate-Z ablator materials for ignition target designs on the National Ignition Facility (NIF), hydro-equivalent targets are designed using pure plastic (CH), high-density carbon, and glass (SiO{sub 2}) ablators. The hydrodynamic stability of these targets is investigated through two-dimensional (2D) single-mode and multimode simulations. The overall stability of these targets to laser-imprint perturbations and low-mode asymmetries makes it possible to design high-gain targets. Designs using polar-drive illumination are developed within the NIF laser system specifications. Mid-Z ablator targets are an attractive candidate for direct-drive ignition since they present better overall performance than plastic ablator targets through reduced laser–plasma instabilities and a similar hydrodynamic stability.

  9. Direct-drive–ignition designs with mid-Z ablators

    SciTech Connect

    Lafon, M.; Betti, R.; Anderson, K. S.; Collins, T. J. B.; Epstein, R.; McKenty, P. W.; Myatt, J. F.; Shvydky, A.; Skupsky, S.

    2015-03-01

    Achieving thermonuclear ignition using direct laser illumination relies on the capability to accelerate spherical shells to high implosion velocities while maintaining shell integrity. Ablator materials of moderate atomic number Z reduce the detrimental effects of laser–plasma instabilities in direct-drive implosions. To validate the physics of moderate-Z ablator materials for ignition target designs on the National Ignition Facility (NIF), hydro-equivalent targets are designed using pure plastic (CH), high-density carbon, and glass (SiO2) ablators. The hydrodynamic stability of these targets is investigated through two-dimensional (2D) single-mode and multimode simulations. The overall stability of these targets to laser-imprint perturbations and low-mode asymmetries makes it possible to design high-gain targets. Designs using polar-drive illumination are developed within the NIF laser system specifications. Mid-Z ablator targets are an attractive candidate for direct-drive ignition since they present better overall performance than plastic ablator targets through reduced laser–plasma instabilities and a similar hydrodynamic stability.

  10. Laser beam-profile impression and target thickness impact on laser-accelerated protons

    NASA Astrophysics Data System (ADS)

    Schollmeier, M.; Harres, K.; Nürnberg, F.; Blažević, A.; Audebert, P.; Brambrink, E.; Fernández, J. C.; Flippo, K. A.; Gautier, D. C.; Geißel, M.; Hegelich, B. M.; Schreiber, J.; Roth, M.

    2008-05-01

    Experimental results on the influence of the laser focal spot shape onto the beam profile of laser-accelerated protons from gold foils are reported. The targets' microgrooved rear side, together with a stack of radiochromic films, allowed us to deduce the energy-dependent proton source-shape and size, respectively. The experiments show, that shape and size of the proton source depend only weakly on target thickness as well as shape of the laser focus, although they strongly influence the proton's intensity distribution. It was shown that the laser creates an electron beam that closely follows the laser beam topology, which is maintained during the propagation through the target. Protons are then accelerated from the rear side with an electron created electric field of a similar shape. Simulations with the Sheath-Accelerated Beam Ray-tracing for IoN Analysis code SABRINA, which calculates the proton distribution in the detector for a given laser-beam profile, show that the electron distribution during the transport through a thick target (50μm Au) is only modified due to multiple small angle scattering. Thin targets (10μm) show large source sizes of over 100μm diameter for 5MeV protons, which cannot be explained by multiple scattering only and are most likely the result of refluxing electrons.

  11. Laser beam-profile impression and target thickness impact on laser-accelerated protons

    SciTech Connect

    Schollmeier, M.; Harres, K.; Nuernberg, F.; Roth, M.; Blazevic, A.; Audebert, P.; Brambrink, E.; Fernandez, J. C.; Flippo, K. A.; Gautier, D. C.; Geissel, M.; Hegelich, B. M.; Schreiber, J.

    2008-05-15

    Experimental results on the influence of the laser focal spot shape onto the beam profile of laser-accelerated protons from gold foils are reported. The targets' microgrooved rear side, together with a stack of radiochromic films, allowed us to deduce the energy-dependent proton source-shape and size, respectively. The experiments show, that shape and size of the proton source depend only weakly on target thickness as well as shape of the laser focus, although they strongly influence the proton's intensity distribution. It was shown that the laser creates an electron beam that closely follows the laser beam topology, which is maintained during the propagation through the target. Protons are then accelerated from the rear side with an electron created electric field of a similar shape. Simulations with the Sheath-Accelerated Beam Ray-tracing for IoN Analysis code SABRINA, which calculates the proton distribution in the detector for a given laser-beam profile, show that the electron distribution during the transport through a thick target (50 {mu}m Au) is only modified due to multiple small angle scattering. Thin targets (10 {mu}m) show large source sizes of over 100 {mu}m diameter for 5 MeV protons, which cannot be explained by multiple scattering only and are most likely the result of refluxing electrons.

  12. Influence of laser parameters in generating the NiTi nanoparticles with a rotating target using underwater solid state Nd: YAG laser ablation

    NASA Astrophysics Data System (ADS)

    Gagrani, Rohit; Patra, Nandini; Rajagopalan, P.; Singh, Vipul; Palani, I. A.

    2016-09-01

    The great effort that the scientific community has put in the last decade in the study of nanoscience and nanotechnology has been leading the research toward the development of new methodologies of nanostructures synthesis. Among them, Pulsed Laser Ablation in Liquid, PLAL, is gaining an increasing interest thanks to several promising advantages, which include: environmental sustainability, easy experimental set-up (which does not require extreme conditions of the ambient of synthesis), long-lasting stability of the nanoparticles, which are produced completely free of undesired contaminants or dangerous synthesis reactants. In this work, a drop wise flow of deionized water on the periphery of NiTi rotating target was tested as a procedure for the significant production of NiTi nanoparticles. This is a novel technique to improve the ablation efficiency of nanoparticles than the existing techniques of laser ablation. The influence of varying external parameters like laser wavelengths and laser fluences on the size distribution of nanoparticle was investigated. Second harmonic and third harmonics of Nd: YAG nanosecond laser with three different laser fluences of 30 J/cm2, 40 J/cm2 and 50 J/cm2 was used to ablate the nitinol (Ni-55%, Ti-45%) target. The average particle size and redistribution was characterized by dynamic light scattering (DLS) and the crystalline formation of NiTi nanoparticles were analyzed by X-ray diffraction, where it confirms the alloy formation of NiTi nanoparticles.

  13. Control of target-normal-sheath-accelerated protons from a guiding cone

    SciTech Connect

    Zou, D. B.; Zhuo, H. B.; Yang, X. H.; Yu, T. P.; Shao, F. Q.; Pukhov, A.

    2015-06-15

    It is demonstrated through particle-in-cell simulations that target-normal-sheath-accelerated protons can be well controlled by using a guiding cone. Compared to a conventional planar target, both the collimation and number density of proton beams are substantially improved, giving a high-quality proton beam which maintained for a longer distance without degradation. The effect is attributed to the radial electric field resulting from the charge due to the hot target electrons propagating along the cone surface. This electric field can effectively suppress the spatial spread of the protons after the expansion of the hot electrons.

  14. Preparation of liposomal amiodarone and investigation of its cardiomyocyte-targeting ability in cardiac radiofrequency ablation rat model

    PubMed Central

    Zhuge, Ying; Zheng, Zhi-Feng; Xie, Mu-Qing; Li, Lin; Wang, Fang; Gao, Feng

    2016-01-01

    The objective of this study was to develop an amiodarone hydrochloride (ADHC)-loaded liposome (ADHC-L) formulation and investigate its potential for cardiomyocyte targeting after cardiac radiofrequency ablation (CA) in vivo. The ADHC-L was prepared by thin-film method combined with ultrasonication and extrusion. The preparation process was optimized by Box–Behnken design with encapsulation efficiency as the main evaluation index. The optimum formulation was quantitatively obtained with a diameter of 99.9±0.4 nm, a zeta potential of 35.1±10.9 mV, and an encapsulation efficiency of 99.5%±13.3%. Transmission electron microscopy showed that the liposomes were spherical particles with integrated bilayers and well dispersed with high colloidal stability. Pharmacokinetic studies were investigated in rats after intravenous administration, which revealed that compared with free ADHC treatment, ADHC-L treatment showed a 5.1-fold increase in the area under the plasma drug concentration–time curve over a period of 24 hours (AUC0–24 h) and an 8.5-fold increase in mean residence time, suggesting that ADHC-L could facilitate drug release in a more stable and sustained manner while increasing the circulation time of ADHC, especially in the blood. Biodistribution studies of ADHC-L demonstrated that ADHC concentration in the heart was 4.1 times higher after ADHC-L treatment in CA rat model compared with ADHC-L sham-operated treatment at 20 minutes postinjection. Fluorescence imaging studies further proved that the heart-targeting ability of ADHC-L was mainly due to the CA in rats. These results strongly support that ADHC-L could be exploited as a potential heart-targeting drug delivery system with enhanced bioavailability and reduced side effects for arrhythmia treatment after CA. PMID:27313453

  15. Monoenergetic and GeV ion acceleration from the laser breakout afterburner using ultrathin targets

    SciTech Connect

    Yin, L.; Albright, B. J.; Hegelich, B. M.; Bowers, K. J.; Flippo, K. A.; Kwan, T. J. T.; Fernandez, J. C.

    2007-05-15

    A new laser-driven ion acceleration mechanism using ultrathin targets has been identified from particle-in-cell simulations. After a brief period of target normal sheath acceleration (TNSA) [S. P. Hatchett et al., Phys. Plasmas 7, 2076 (2000)], two distinct stages follow: first, a period of enhanced TNSA during which the cold electron background converts entirely to hot electrons, and second, the ''laser breakout afterburner'' (BOA) when the laser penetrates to the rear of the target where a localized longitudinal electric field is generated with the location of the peak field co-moving with the ions. During this process, a relativistic electron beam is produced by the ponderomotive drive of the laser. This beam is unstable to a relativistic Buneman instability, which rapidly converts the electron energy into ion energy. This mechanism accelerates ions to much higher energies using laser intensities comparable to earlier TNSA experiments. At a laser intensity of 10{sup 21} W/cm{sup 2}, the carbon ions accelerate as a quasimonoenergetic bunch to 100 s of MeV in the early stages of the BOA with conversion efficiency of order a few percent. Both are an order of magnitude higher than those realized from TNSA in recent experiments [Hegelich et al., Nature 441, 439 (2006)]. The laser-plasma interaction then evolves to produce a quasithermal energy distribution with maximum energy of {approx}2 GeV.

  16. On the dose to a moving target in stereotactic ablative body radiotherapy to lung tumors

    NASA Astrophysics Data System (ADS)

    Feygelman, V.; Dilling, T. J.; Moros, E. G.; Zhang, G. G.

    2017-01-01

    This review summarizes the hierarchy of potential dose inaccuracies in lung SABR in terms of their expected clinical impact. The two main terms are targeting accuracy and adequacy of the dose calculation algorithm. One can associate dose-errors at the 50-100% (zero order) and 10-20% (first order) levels with the former and the latter, respectively. At the first order level, strong evidence exists that using dose algorithms which do not account for 3D density scaling is associated with diminished local control. On the other hand, the second-order target dose-errors due to either static approximations to full 4D calculations, or interplay during modulated delivery, are rather unlikely to rise above 5% (conservatively, ≤ 1% tumor control probability change).

  17. Laser-driven shock acceleration of ion beams from spherical mass-limited targets.

    PubMed

    Henig, A; Kiefer, D; Geissler, M; Rykovanov, S G; Ramis, R; Hörlein, R; Osterhoff, J; Major, Zs; Veisz, L; Karsch, S; Krausz, F; Habs, D; Schreiber, J

    2009-03-06

    We report on experimental studies of ion acceleration from spherical targets of diameter 15 microm irradiated by ultraintense (1x10(20) W/cm2) pulses from a 20-TW Ti:sapphire laser system. A highly directed proton beam with plateau-shaped spectrum extending to energies up to 8 MeV is observed in the laser propagation direction. This beam arises from acceleration in a converging shock launched by the laser, which is confirmed by 3-dimensional particle-in-cell simulations. The temporal evolution of the shock-front curvature shows excellent agreement with a two-dimensional radiation pressure model.

  18. Robust energy enhancement of ultrashort pulse laser accelerated protons from reduced mass targets

    NASA Astrophysics Data System (ADS)

    Zeil, K.; Metzkes, J.; Kluge, T.; Bussmann, M.; Cowan, T. E.; Kraft, S. D.; Sauerbrey, R.; Schmidt, B.; Zier, M.; Schramm, U.

    2014-08-01

    This paper reports on a systematic investigation of the ultrashort pulse laser driven acceleration of protons from thin targets of finite size, so-called reduced mass targets (RMTs). Reproducible series of targets, manufactured with lithographic techniques, and varying in size, thickness, and mounting geometry, were irradiated with ultrashort (30 fs) laser pulses of intensities of about 8 × 1020 W cm-2. A robust maximum energy enhancement of almost a factor of two was found when comparing gold RMTs to reference irradiations of plain gold foils of the same thickness. Furthermore, a change of the thickness of these targets has less influence on the measured maximum proton energy when compared to standard foils, which, based on detailed particle-in-cell simulations, can be explained by the influence of the RMT geometry on the electron sheath. The performance gain was, however, restricted to lateral target sizes of greater than 50 µm, which can be attributed to edge and mounting structure influences.

  19. Tomographic characterisation of gas-jet targets for laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Couperus, J. P.; Köhler, A.; Wolterink, T. A. W.; Jochmann, A.; Zarini, O.; Bastiaens, H. M. J.; Boller, K. J.; Irman, A.; Schramm, U.

    2016-09-01

    Laser wakefield acceleration (LWFA) has emerged as a promising concept for the next generation of high energy electron accelerators. The acceleration medium is provided by a target that creates a local well-defined gas-density profile inside a vacuum vessel. Target development and analysis of the resulting gas-density profiles is an important aspect in the further development of LWFA. Gas-jet targets are widely used in regimes where relatively high electron densities over short interaction lengths are required (up to several millimetres interaction length, plasma densities down to 1018cm-3). In this paper we report a precise characterisation of such gas-jet targets by a laser interferometry technique. We show that phase shifts down to 4 mrad can be resolved. Tomographic phase reconstruction enables detection of non-axisymmetrical gas-density profiles which indicates defects in cylindrical nozzles, analysis of slit-nozzles and nozzles with an induced shock-wave density step. In a direct comparison between argon and helium jets we show that it cannot automatically be assumed, as is often done, that a nozzle measured with argon will provide the same gas density with helium.

  20. Creation of Pure Frozen Gas Targets for Ion Acceleration using Short Pulse Lasers

    NASA Astrophysics Data System (ADS)

    McCary, Edward; Stehr, Florian; Jiao, Xuejing; Quevedo, Hernan; Franke, Philip; Agustsson, Ronald; Oshea, Finn; Berry, Robert; Chao, Dennis; Woods, Kayley; Gautier, Donald; Letzring, Sam; Hegelich, Bjorn

    2015-11-01

    A system for shooting interchangeable frozen gas targets was developed at the University of Texas and will be tested at Los Alamos National Lab. A target holder which can hold up to five substrates used for target growing was cryogenically cooled to temperatures below 14 K. The target substrates consist of holes with diameters ranging from 15 μm-500 μm and TEM grids with micron scale spacing, across which films of ice are frozen by releasing small amounts of pure gas molecules directly into the vacuum target chamber. Frozen gas targets comprised of simple molecules like methane and single element gasses like hydrogen and deuterium will provide novel target configuations that will be compared with laser plasma interaction simulations. The targets will be shot with the ultra-intense short-pulse Trident laser. Accelerated ion spectra will be characterized using a Thomson Parabola with magnetic field strength of 0.92T and electric field strength of 30kV. Hydrogen targets will be additionally characterized using stacks of copper which become activated upon exposure to energetic protons resulting in a beta decay signal which be imaged on electron sensitive imaging plates to provide an energy spectrum and spacial profile of the proton beam. Details of target creation and pre-shot characterization will be presented.

  1. Monoenergetic acceleration of a target foil by circularly polarized laser pulse in RPA regime without thermal heating

    SciTech Connect

    Khudik, V.; Yi, S. A.; Siemon, C.; Shvets, G.

    2012-12-21

    A kinetic model of the monoenergetic acceleration of a target foil irradiated by the circularly polarized laser pulse is developed. The target moves without thermal heating with constant acceleration which is provided by chirping the frequency of the laser pulse and correspondingly increasing its intensity. In the accelerated reference frame, bulk plasma in the target is neutral and its parameters are stationary: cold ions are immobile while nonrelativistic electrons bounce back and forth inside the potential well formed by ponderomotive and electrostatic potentials. It is shown that a positive charge left behind of the moving target in the ion tail and a negative charge in front of the target in the electron sheath form a capacitor whose constant electric field accelerates the ions of the target. The charge separation is maintained by the radiation pressure pushing electrons forward. The scalings of the target thickness and electromagnetic radiation with the electron temperature are found.

  2. CO2 laser pulse shortening by laser ablation of a metal target.

    PubMed

    Donnelly, T; Mazoyer, M; Lynch, A; O'Sullivan, G; O'Reilly, F; Dunne, P; Cummins, T

    2012-03-01

    A repeatable and flexible technique for pulse shortening of laser pulses has been applied to transversely excited atmospheric (TEA) CO(2) laser pulses. The technique involves focusing the laser output onto a highly reflective metal target so that plasma is formed, which then operates as a shutter due to strong laser absorption and scattering. Precise control of the focused laser intensity allows for timing of the shutter so that different temporal portions of the pulse can be reflected from the target surface before plasma formation occurs. This type of shutter enables one to reduce the pulse duration down to ~2 ns and to remove the low power, long duration tails that are present in TEA CO(2) pulses. The transmitted energy is reduced as the pulse duration is decreased but the reflected power is ~10 MW for all pulse durations. A simple laser heating model verifies that the pulse shortening depends directly on the plasma formation time, which in turn is dependent on the applied laser intensity. It is envisaged that this plasma shutter will be used as a tool for pulse shaping in the search for laser pulse conditions to optimize conversion efficiency from laser energy to useable extreme ultraviolet (EUV) radiation for EUV source development.

  3. CO2 laser pulse shortening by laser ablation of a metal target

    NASA Astrophysics Data System (ADS)

    Donnelly, T.; Mazoyer, M.; Lynch, A.; O'Sullivan, G.; O'Reilly, F.; Dunne, P.; Cummins, T.

    2012-03-01

    A repeatable and flexible technique for pulse shortening of laser pulses has been applied to transversely excited atmospheric (TEA) CO2 laser pulses. The technique involves focusing the laser output onto a highly reflective metal target so that plasma is formed, which then operates as a shutter due to strong laser absorption and scattering. Precise control of the focused laser intensity allows for timing of the shutter so that different temporal portions of the pulse can be reflected from the target surface before plasma formation occurs. This type of shutter enables one to reduce the pulse duration down to ˜2 ns and to remove the low power, long duration tails that are present in TEA CO2 pulses. The transmitted energy is reduced as the pulse duration is decreased but the reflected power is ˜10 MW for all pulse durations. A simple laser heating model verifies that the pulse shortening depends directly on the plasma formation time, which in turn is dependent on the applied laser intensity. It is envisaged that this plasma shutter will be used as a tool for pulse shaping in the search for laser pulse conditions to optimize conversion efficiency from laser energy to useable extreme ultraviolet (EUV) radiation for EUV source development.

  4. Targeted ablation of the WW domain-containing oxidoreductase tumor suppressor leads to impaired steroidogenesis.

    PubMed

    Aqeilan, Rami I; Hagan, John P; de Bruin, Alain; Rawahneh, Maysoon; Salah, Zaidoun; Gaudio, Eugenio; Siddiqui, Hasan; Volinia, Stefano; Alder, Hansjuerg; Lian, Jane B; Stein, Gary S; Croce, Carlo M

    2009-03-01

    The WW domain-containing oxidoreductase (WWOX) gene encodes a 46-kDa tumor suppressor. The Wwox protein contains two N-terminal WW domains that interact with several transcriptional activators containing proline-tyrosine motifs and a central short-chain dehydrogenase/reductase domain that has been suggested to play a role in steroid metabolism. Recently, we have shown that targeted deletion of the Wwox gene in mice leads to postnatal lethality and defects in bone growth. Here, we report that Wwox-deficient mice display impaired steroidogenesis. Mutant homozygous mice are born with gonadal abnormalities, including failure of Leydig cell development in testis and reduced theca cell proliferation in ovary. Furthermore, Wwox(-/-) mice displayed impaired gene expression of key steroidogenesis enzymes. Affymetrix microarray gene analysis revealed differentially expressed related genes in steroidogenesis in knockout mice testis and ovary as compared with control mice. These results demonstrate the essential requirement for the Wwox tumor suppressor in proper steroidogenesis.

  5. Spectral modification of shock accelerated ions using a hydrodynamically shaped gas target

    SciTech Connect

    Tresca, O.; Polyanskiy, M. N.; Dover, N. P.; Cook, N.; Maharjan, C.; Najmudin, Z.; Shkolnikov, P.; Pogorelsky, I.

    2015-08-28

    We report on reproducible shock acceleration from irradiation of a λ=10 μm CO2 laser on optically shaped H2 and He gas targets. A low energy laser prepulse (I≲1014 W cm–2) is used to drive a blast wave inside the gas target, creating a steepened, variable density gradient. This is followed, after 25 ns, by a high intensity laser pulse (I>1016 W cm–2) that produces an electrostatic collisionless shock. Upstream ions are accelerated for a narrow range of prepulse energies. For long density gradients (≳40 μm), broadband beams of He+ and H+ were routinely produced, whilst for shorter gradients (≲20 μm), quasimonoenergetic acceleration of protons is observed. These measurements indicate that the properties of the accelerating shock and the resultant ion energy distribution, in particular the production of narrow energy spread beams, is highly dependent on the plasma density profile. These findings are corroborated by 2D particle-in-cell simulations.

  6. Spectral modification of shock accelerated ions using a hydrodynamically shaped gas target

    DOE PAGES

    Tresca, O.; Polyanskiy, M. N.; Dover, N. P.; ...

    2015-08-28

    We report on reproducible shock acceleration from irradiation of a λ=10 μm CO2 laser on optically shaped H2 and He gas targets. A low energy laser prepulse (I≲1014 W cm–2) is used to drive a blast wave inside the gas target, creating a steepened, variable density gradient. This is followed, after 25 ns, by a high intensity laser pulse (I>1016 W cm–2) that produces an electrostatic collisionless shock. Upstream ions are accelerated for a narrow range of prepulse energies. For long density gradients (≳40 μm), broadband beams of He+ and H+ were routinely produced, whilst for shorter gradients (≲20 μm),more » quasimonoenergetic acceleration of protons is observed. These measurements indicate that the properties of the accelerating shock and the resultant ion energy distribution, in particular the production of narrow energy spread beams, is highly dependent on the plasma density profile. These findings are corroborated by 2D particle-in-cell simulations.« less

  7. Quasi-mono-energetic ion acceleration from a homogeneous composite target by an intense laser pulse

    SciTech Connect

    Brantov, A. V.; Tikhonchuk, V. T.; Klimo, O.; Romanov, D. V.; Ter-Avetisyan, S.; Schnuerer, M.; Sokollik, T.; Nickles, P. V.

    2006-12-15

    The paper presents an analytical model and particle-in-cell simulations of the quasi-mono-energetic ion acceleration by an intense laser pulse in a multispecies target and the corresponding experimental observations. Homogeneous and heterogeneous targets are considered, and it is shown that the formation of the energy spectrum proceeds in three stages: (1) the initial light ion acceleration in the sheath electric field, (2) the ion species separation followed by the electrostatic shock formation, and (3) the interaction of spatially separated ion bunches accompanied by electron cooling. The field ionization of heavy ions and interaction between the heavy and light species play an important role in the formation and preservation of the energy spectrum of light ions. The simulation results are compared with the theoretical predictions and the experiments.

  8. Laser irradiations of advanced targets promoting absorption resonance for ion acceleration in TNSA regime

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Calcagno, L.; Giulietti, D.; Cutroneo, M.; Zimbone, M.; Skala, J.

    2015-07-01

    Advanced targets based on Au nanoparticles embedded in polymers films show high absorption coefficient in the UV-visible and infrared region. They can be employed to enhance the proton and ion acceleration from the laser-generated plasma in TNSA regime. In conditions of "p" polarized laser irradiations at 1015 W/cm2 intensity, in these films can be induced resonant absorption due to plasma wave excitation. Plasma on-line diagnostics is based on SiC detectors, Thomson spectrometry and X-ray streak camera imaging. Measurements of kinetic energy of accelerated ions indicate a significant increment using polymer targets containing gold nanoparticles and "p" polarized laser light with respect to pure polymers and unpolarized light irradiation.

  9. Investigation of Lead Target Nuclei Used on Accelerator-Driven Systems for Tritium Production

    NASA Astrophysics Data System (ADS)

    Tel, E.; Aydin, A.

    2012-02-01

    High-current proton accelerators are being researched at Los Alamos National Laboratory and other laboratories for accelerator production of tritium, transmuting long-lived radioactive waste into shorter-lived products, converting excess plutonium, and producing energy. These technologies make use of spallation neutrons produced in ( p,xn) and ( n,xn) nuclear reactions on high-Z targets. Through ( p,xn) and ( n,xn) nuclear reactions, neutrons are produced and are moderated by heavy water. These moderated neutrons are subsequently captured on 3He to produce tritium via the ( n,p) reaction. Tritium self-sufficiency must be maintained for a commercial fusion power plant. Rubbia succeeded in a proposal of a full scale demonstration plant of the Energy Amplifier. This plant is to be known the accelerator-driven system (ADS). The ADS can be used for production of neutrons in spallation neutron source and they can act as an intense neutron source in accelerator-driven subcritical reactors, capable of incinerating nuclear waste and of producing energy. Thorium and Uranium are nuclear fuels and Lead, Bismuth, Tungsten are the target nuclei in these reactor systems. The spallation targets can be Pb, Bi, W, etc. isotopes and these target material can be liquid or solid. Naturally Lead includes the 204Pb (%1.42), 206Pb (%24.1), 207Pb (%22.1) and 208Pb (%52.3) isotopes. The design of ADS systems and also a fusion-fission hybrid reactor systems require the knowledge of a wide range of better data. In this study, by using Hartree-Fock method with an effective nucleon-nucleon Skyrme interactions rms nuclear charge radii, rms nuclear mass radii, rms nuclear proton, neutron radii and neutron skin thickness were calculated for the 204, 206, 208Pb isotopes . The calculated results have been compared with those of the compiled experimental and theoretical values of other studies.

  10. Targeted ablation of IKK2 improves skeletal muscle strength, maintains mass, and promotes regeneration

    PubMed Central

    Mourkioti, Foteini; Kratsios, Paschalis; Luedde, Tom; Song, Yao-Hua; Delafontaine, Patrick; Adami, Raffaella; Parente, Valeria; Bottinelli, Roberto; Pasparakis, Manolis; Rosenthal, Nadia

    2006-01-01

    NF-κB is a major pleiotropic transcription factor modulating immune, inflammatory, cell survival, and proliferative responses, yet the relevance of NF-κB signaling in muscle physiology and disease is less well documented. Here we show that muscle-restricted NF-κB inhibition in mice, through targeted deletion of the activating kinase inhibitor of NF-κB kinase 2 (IKK2), shifted muscle fiber distribution and improved muscle force. In response to denervation, IKK2 depletion protected against atrophy, maintaining fiber type, size, and strength, increasing protein synthesis, and decreasing protein degradation. IKK2-depleted mice with a muscle-specific transgene expressing a local Igf-1 isoform (mIgf-1) showed enhanced protection against muscle atrophy. In response to muscle damage, IKK2 depletion facilitated skeletal muscle regeneration through enhanced satellite cell activation and reduced fibrosis. Our results establish IKK2/NF-κB signaling as an important modulator of muscle homeostasis and suggest a combined role for IKK inhibitors and growth factors in the therapy of muscle diseases. PMID:17080195

  11. Nonlinear surface plasma wave induced target normal sheath acceleration of protons

    SciTech Connect

    Liu, C. S.; Tripathi, V. K. Shao, Xi; Liu, T. C.

    2015-02-15

    The mode structure of a large amplitude surface plasma wave (SPW) over a vacuum–plasma interface, including relativistic and ponderomotive nonlinearities, is deduced. It is shown that the SPW excited by a p-polarized laser on a rippled thin foil target can have larger amplitude than the transmitted laser amplitude and cause stronger target normal sheath acceleration of protons as reported in a recent experiment. Substantial enhancement in proton number also occurs due to the larger surface area covered by the SPW.

  12. Design of photon converter and photoneutron target for High power electron accelerator based BNCT.

    PubMed

    Rahmani, Faezeh; Seifi, Samaneh; Anbaran, Hossein Tavakoli; Ghasemi, Farshad

    2015-12-01

    An electron accelerator, ILU-14, with current of 10 mA and 100 kW in power has been considered as one of the options for neutron source in Boron Neutron Capture Therapy (BNCT). The final design of neutron target has been obtained using MCNPX to optimize the neutron production. Tungsten in strip shape and D2O in cylindrical form have been proposed as the photon converter and the photoneutron target, respectively. In addition calculation of heat deposition in the photon target design has been considered to ensure mechanical stability of target. The results show that about 8.37×10(12) photoneutron/s with average energy of 615 keV can be produced by this neutron source design. In addition, using an appropriate beam shaping assembly an epithermal neutron flux of the order of 1.24×10(8) cm(-2) s(-1) can be obtained for BNCT applications.

  13. Size of lethality target in mouse immature oocytes determined with accelerated heavy ions.

    PubMed

    Straume, T; Dobson, R L; Kwan, T C

    1989-01-01

    Mouse immature oocytes were irradiated in vivo with highly charged, heavy ions from the Bevalac accelerator at the Lawrence Berkeley Laboratory. The particles used were 670-MeV/nucleon Si14+, 570-MeV/nucleon Ar18+, and 450-MeV/nucleon Fe26+. The cross-sectional area of the lethality target in these extremely radiosensitive cells was determined from fluence-response curves and information on energy deposition by delta rays. Results indicate a target cross-section larger than that of the nucleus, one which closely approximates the cross-sectional area of the entire oocyte. For 450-MeV/nucleon Fe26+ particles, the predicted target cross-sectional area is 120 +/- 16 microns2, comparing well with the microscopically determined cross-sectional area of 111 +/- 12 microns2 for these cells. The present results are in agreement with our previous target studies which implicate the oocyte plasma membrane.

  14. Magnetic–optical nanohybrid for targeted detection, separation, and photothermal ablation of drug-resistant pathogens

    PubMed Central

    Ondera, Thomas J.

    2015-01-01

    A rapid, sensitive and quantitative immunoassay for the targeted detection and decontamination of E. coli based on Fe3O4 magnetic nanoparticles (MNPs) and plasmonic popcorn-shaped gold nanostructures attached single-walled carbon nanotubes (AuNP@SWCNT) is presented. The MNPs were synthesized as the support for the monoclonal antibody (mAb@MNP). E. coli (49979) was captured and rapidly preconcentrated from sample with the mAb@MNP, followed by binding with Raman-tagged concanavalin A-AuNP@SWCNT (Con A-AuNP@SWCNT) as detector nanoprobes. A Raman tag 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) generated Raman signal upon 670 nm Laser excitation enabling detection and quantification of E. coli concentration with a limit of detection of 102 CFU/mL and a linear logarithmic response range of 1.0 × 102 to 1.0 × 107 CFU/mL. The mAb@MNP could remove more than 98% of E. coli (initial concentration of 1.3 × 104 CFU/mL) from water. The potential of the immunoassay to detect E. coli bacteria in real water samples was investigated and the results were compared with the experimental results from classical count method. There was no statistically significant difference between the two methods (p > 0.05). Furthermore, the MNP/AuNP@SWCNT hybrid system exhibits enhanced photothermal killing effect. The sandwich-like immunoassay possesses the potential for rapid bioanalysis and simultaneous biosensing of multiple pathogenic agents. PMID:26469636

  15. Magnetic-optical nanohybrids for targeted detection, separation, and photothermal ablation of drug-resistant pathogens.

    PubMed

    Ondera, Thomas J; Hamme, Ashton T

    2015-12-07

    A rapid, sensitive and quantitative immunoassay for the targeted detection and decontamination of E. coli based on Fe3O4 magnetic nanoparticles (MNPs) and plasmonic popcorn-shaped gold nanostructure attached single-walled carbon nanotubes (AuNP@SWCNT) is presented. The MNPs were synthesized as the support for a monoclonal antibody (mAb@MNP). E. coli (49979) was captured and rapidly preconcentrated from the sample with the mAb@MNP, followed by binding with Raman-tagged concanavalin A-AuNP@SWCNTs (Con A-AuNP@SWCNTs) as detector nanoprobes. A Raman tag 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) generated a Raman signal upon 670 nm laser excitation enabling the detection and quantification of E. coli concentration with a limit of detection of 10(2) CFU mL(-1) and a linear logarithmic response range of 1.0 × 10(2) to 1.0 × 10(7) CFU mL(-1). The mAb@MNP could remove more than 98% of E. coli (initial concentration of 1.3 × 10(4) CFU mL(-1)) from water. The potential of the immunoassay to detect E. coli bacteria in real water samples was investigated and the results were compared with the experimental results from the classical count method. There was no statistically significant difference between the two methods (p > 0.05). Furthermore, the MNP/AuNP@SWCNT hybrid system exhibits an enhanced photothermal killing effect. The sandwich-like immunoassay possesses potential for rapid bioanalysis and the simultaneous biosensing of multiple pathogenic agents.

  16. Hydrodynamic Efficiency of Ablation Propulsion with Pulsed Ion Beam

    SciTech Connect

    Buttapeng, Chainarong; Yazawa, Masaru; Harada, Nobuhiro; Suematsu, Hisayuki; Jiang Weihua; Yatsui, Kiyoshi

    2006-05-02

    This paper presents the hydrodynamic efficiency of ablation plasma produced by pulsed ion beam on the basis of the ion beam-target interaction. We used a one-dimensional hydrodynamic fluid compressible to study the physics involved namely an ablation acceleration behavior and analyzed it as a rocketlike model in order to investigate its hydrodynamic variables for propulsion applications. These variables were estimated by the concept of ablation driven implosion in terms of ablated mass fraction, implosion efficiency, and hydrodynamic energy conversion. Herein, the energy conversion efficiency of 17.5% was achieved. In addition, the results show maximum energy efficiency of the ablation process (ablation efficiency) of 67% meaning the efficiency with which pulsed ion beam energy-ablation plasma conversion. The effects of ion beam energy deposition depth to hydrodynamic efficiency were briefly discussed. Further, an evaluation of propulsive force with high specific impulse of 4000s, total impulse of 34mN and momentum to energy ratio in the range of {mu}N/W was also analyzed.

  17. Implementation of the Polarized HD target at the Thomas Jefferson National Accelerator Facility

    SciTech Connect

    Chaden Djalali; David Tedeschi

    2007-01-30

    The original goal of this proposal was to study frozen spin polarized targets (HD target and other technologies) and produce a conceptual design report for the implementation of such a target in the HALL B detector of the Thomas Jefferson National Accelerator Facility (JLab). During the first two years of the proposal, we came to the conclusion that the best suited target for JLab was a frozen spin target and helped with the design of such a target. We have not only achieved our original goal but have exceeded it by being involved in the actual building and testing of parts the target. The main reason for this success has been the hiring of a senior research associate, Dr. Oleksandr Dzyubak, who had more than 10 years of experience in the field of frozen spin polarized targets. The current grant has allowed the USC nuclear physics group to strengthen its role in the JLab collaboration and make important contribution to both the detector development and the scientific program.

  18. Improved therapeutic outcomes of thermal ablation on rat orthotopic liver allograft sarcoma models by radioiodinated hypericin induced necrosis targeted radiotherapy

    PubMed Central

    Gao, Long; Zhang, Jian; Ma, Tengchuang; Yao, Nan; Gao, Meng; Shan, Xin; Ni, Yicheng; Shao, Haibo; Xu, Ke

    2016-01-01

    Residual tumor resulting in tumor recurrence after various anticancer therapies is an unmet challenge in current clinical oncology. This study aimed to investigate the hypothesis that radioiodinated hypericin (131I-Hyp) may inhibit residual tumor recurrence after microwave ablation (MWA) on rat orthotopic liver allograft sarcoma models. Thirty Sprague-Dawley (SD) rats with hepatic tumors were divided into three groups: Group A received laparotomy MWA and sequential intravenous injection (i.v.) of 131I labelled hypericin (131I-Hyp) in a time interval of 24 h; Group B received only laparotomy MWA; Group C was a blank control. Tumor inhibitory effects were monitored with in vivo magnetic resonance imaging (MRI) and these findings were compared to histopathology data before (baseline, day 0) and 1, 4, and 8 days after MWA. In addition, biodistribution of 131I-Hyp was assessed with in vivo single-photon emission computed tomography-computed tomography (SPECT-CT) imaging, in vitro autoradiography, fluorescent microscopy, and gamma counting. A fast clearance of 131I-Hyp and increasing deposit in necrotic tumors appeared over time, with a significantly higher radioactivity than other organs (0.9169 ± 1.1138 % ID/g, P < 0.01) on day 9. Tumor growth was significantly slowed down in group A compared to group B and C according to MRI images and corresponding tumor doubling time (12.13 ± 1.99, 4.09 ± 0.97, 3.36 ± 0.72 days respectively). The crescent tagerability of 131I-Hyp to necrosis was visualized consistently by autoradiography and fluorescence microscopy. In conclusion, 131I-Hyp induced necrosis targeted radiotherapy improved therapeutic outcomes of MWA on rat orthotopic liver allograft sarcoma models. PMID:27285983

  19. Gold nanorods coupled with upconverting nanophosphors for targeted thermal ablation and imaging of bladder cancer cells (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Cho, Suehyun K.; Su, Lih-Jen; Flaig, Thomas W.; Park, Wounjhang

    2016-09-01

    NaYF4:Yb3+,Er3+ upconverting nanophosphors (UCNPs) are robust and stable nanoparticles that absorb near-infrared (NIR) photons and emit green and red visible photons through energy transfer upconversion. This mechanism provides UCNPs several advantages as a bioimaging agent over traditional fluorescence imaging agent in that NIR excitation allows high-contrast imaging without autofluorescence and that they can be used for deep-tissue imaging. However, additional surface modification of UCNPs is necessary for them to be biocompatible. We use an amphiphilic polymer (poly(maleic anhydride-alt-octadecene) (PMAO) and a hetero-functional polyethylene glycol with amine and thiol ends (NH2-PEG-SH)) to make the UCNPs water-soluble. This reaction yields a carboxylic group that allows functionalization with anti-epidermal growth factor receptor (aEGFR), which provides specific binding of UCNPs to EGFR-expressing bladder cancer cells. Additionally, the thiol ends of the PEGylated UCNPs are able to bind with gold nanorods (AuNRs) to create UCNP-AuNR complexes. The localized surface plasmon of the AuNR then allow localized heating of HTB9 bladder cancer cells, enabling in situ cell killing upon detection by UCNP fluorescence. Here, we report a successful synthesis, surface modification and conjugation of aEGFR functionalized UCNP-AuNR complexes and in vitro imaging and thermal ablation studies using them. Synthesis and surface modification of UCNP-AuNR complexes are confirmed by electron microscopy. Then, a combination of brightfield, NIR confocal fluorescence, and darkfield microscopy on the UCNP-AuNR treated bladder cancer cells revealed successful cancer targeting and imaging capabilities of the complex. Finally, cell viability assay showed that NIR irradiation of UCNP-AuNR conjugated cells resulted highly selective cell killing.

  20. Acceleration Mechanism Of Pulsed Laser-Electromagnetic Hybrid Thruster

    SciTech Connect

    Horisawa, Hideyuki; Mashima, Yuki; Yamada, Osamu

    2011-11-10

    A fundamental study of a newly developed rectangular pulsed laser-electromagnetic hybrid thruster was conducted. Laser-ablation plasma in the thruster was induced through laser beam irradiation onto a solid target and accelerated by electrical means instead of direct acceleration only by using a laser beam. The performance of the thrusters was evaluated by measuring the ablated mass per pulse and impulse bit. As results, significantly high specific impulses up to 7,200 s were obtained at charge energies of 8.6 J. Moreover, from the Faraday cup measurement, it was confirmed that the speed of ions was accelerated with addition of electric energy.

  1. Assessment of candidates for target window material in accelerator-driven molybdenum-99 production

    SciTech Connect

    Strons, Philip; Bailey, James; Makarashvili, Vakhtang; Chemerisov, Sergey; Gromov, Roman; Vandegrift, George

    2016-10-01

    NorthStar Medical Technologies is pursuing production of an important medical isotope, Mo-99, through a photo-nuclear reaction of a Mo-100 target using a high-power electron accelerator. The current target utilizes an Inconel 718 window. The purpose of this study was to evaluate other candidate materials for the target window, which separates the high-pressure helium gas inside the target from the vacuum inside the accelerator beamline and is subjected to significant stress. Our initial analysis assessed the properties (density, thermal conductivity, maximum stress, minimum window thickness, maximum temperature, and figure of merit) for a range of materials, from which the three most promising were chosen: Inconel 718, 250 maraging steel, and standard-grade beryllium. These materials were subjected to further analysis to determine the effects of thermal and mechanical strain versus beam power at varying thicknesses. Both beryllium and the maraging steel were calculated to withstand more than twice as high beam power than Inconel 718.

  2. The effect of asteroid topography on surface ablation deflection

    NASA Astrophysics Data System (ADS)

    McMahon, Jay W.; Scheeres, Daniel J.

    2017-02-01

    Ablation techniques for deflecting hazardous asteroids deposit energy into the asteroid's surface, causing an effective thrust on the asteroid as the ablating material leaves normal to the surface. Although it has long been recognized that surface topography plays an important role in determining the deflection capabilities, most studies to date have ignored this aspect of the model. This paper focuses on understanding the topography for real asteroid shapes, and how this topography can change the deflection performance of an ablation technique. The near Earth asteroids Golevka, Bennu, and Itokawa are used as the basis for this study, as all three have high-resolution shape models available. This paper shows that naive targeting of an ablation method without accounting for the surface topography can lower the deflection performance by up to 20% in the cases studied in terms of the amount of acceleration applied in the desired direction. If the ablation thrust level is assumed to be 100 N, as used elsewhere in the literature, this misapplication of thrust translates to tens of kilometers per year in decreased semimajor axis change. However, if the ablation method can freely target any visible point on the surface of the asteroid, almost all of this performance can be recovered.

  3. Density characterization of tapered super-sonic gas jet targets for laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Golovin, Gregory; Grace, Emily; Banerjee, Sudeep; Petersen, Chad; Brown, Kevin; Mills, Jared; Chen, Shouyuan; Liu, Cheng; Umstadter, Donald

    2012-10-01

    Phase slippage between plasma wave and electron bunch limits maximum energy gain in laser-wakefield acceleration. Plasma-density spatial tailoring has been proposed as a way to overcome this dephasing problem [1]. In practice, such tailoring can be achieved in super-sonic gas jets by use of a nozzle with a tapered orifice. We have developed a 3-D temporally-resolved interferometric tomography technique to characterize dynamical density distribution of such gas jets. The SIRT (Simultaneous Iterative Reconstructive Technique) algorithm [2] was implemented. We also present preliminarily results on laser wakefield acceleration in the tailored gradient density profiles resulting from use of the characterized jets as targets. [4pt] [1] W. Rittershofer, C. B. Schroeder, E. Esarey, F. J. Gr"uner, and W. P. Leemans, ``Tapered plasma channels to phase-lock accelerating and focusing forces in laser-plasma accelerators,'' Physics of Plasmas 17, 063104, (2010). [0pt] [2] P. Gilbert, ``Iterative methods for the three-dimensional reconstruction of an object from projections,'' Journal of Theoretical Biology 36, 105 (1972).

  4. A Fast, Electromagnetically Driven Supersonic Gas Jet Target For Laser Wakefield Acceleration

    SciTech Connect

    Krishnan, Mahadevan; Wright, Jason; Ma, Timothy

    2009-01-22

    Laser-Wakefield acceleration (LWFA) promises electron accelerators with unprecedented electric field gradients. Gas jets and gas-filled capillary discharge waveguides are two primary targets of choice for LWFA. Present gas jets have lengths of only 2-4 mm at densities of 1-4x10{sup 19} /cm{sup 3}, sufficient for self-trapping and acceleration to energies up to {approx}150 MeV. While 3 cm capillary structures have been used to accelerate beams up to 1 GeV, gas jets require a well-collimated beam that is {>=}10 mm in length and <500 {mu}m in width, with a tunable gas density profile to optimize the LWFA process. This paper describes the design of an electromagnetically driven, fast supersonic gas valve that opens in <100 {mu}s, closes in <500 {mu}s and can operate at pressures beyond 1000 psia. The motion of the valve seat (flyer plate) is measured using a laser probe and compared with predictions of a model. The valve design is based on an optimization of many parameters: flyer plate mass and durability, driver bank speed and stored energy for high rep-rate (>10 Hz) operation, return spring non-linearity and materials selection for various components. Optimization of the valve dynamics and preliminary designs of the supersonic flow patterns are described.

  5. Thermal-hydraulic design of the target/blanket for the accelerator production of tritium conceptual design

    SciTech Connect

    Willcutt, G.J.E. Jr.; Kapernick, R.J.

    1997-11-01

    A conceptual design was developed for the target/blanket system of an accelerator-based system to produce tritium. The target/blanket system uses clad tungsten rods for a spallation target and clad lead rods as a neutron multiplier in a blanket surrounding the target. The neutrons produce tritium in {sup 3}He, which is contained in aluminum tubes located in the decoupler and blanket regions. This paper presents the thermal-hydraulic design of the target, decoupler, and blanket developed for the conceptual design of the Accelerator Production of Tritium Project, and demonstrates there is adequate margin in the design at full power operation.

  6. Measurement of Neutrons Produced by Beam-Target Interactions via a Coaxial Plasma Accelerator

    NASA Astrophysics Data System (ADS)

    Cauble, Scott; Poehlmann, Flavio; Rieker, Gregory; Cappelli, Mark

    2011-10-01

    This poster presents a method to measure neutron yield from a coaxial plasma accelerator. Stored electrical energies between 1 and 19 kJ are discharged within a few microseconds across the electrodes of the coaxial gun, accelerating deuterium gas samples to plasma beam energies well beyond the keV energy range. The focus of this study is to examine the interaction of the plasma beam with a deuterated target by designing and fabricating a detector to measure neutron yield. Given the strong electromagnetic pulse associated with our accelerator, indirect measurement of neutrons via threshold-dependent nuclear activation serves as both a reliable and definitive indicator of high-energy particles for our application. Upon bombardment with neutrons, discs or stacks of metal foils placed near the deuterated target undergo nuclear activation reactions, yielding gamma-emitting isotopes whose decay is measured by a scintillation detector system. By collecting gamma ray spectra over time and considering nuclear cross sections, the magnitude of the original neutron pulse is inferred.

  7. Production of 64Cu and 67Cu radiopharmaceuticals using zinc target irradiated with accelerator neutrons

    NASA Astrophysics Data System (ADS)

    Kawabata, Masako; Hashimoto, Kazuyuki; Saeki, Hideya; Sato, Nozomi; Motoishi, Shoji; Nagai, Yasuki

    2014-09-01

    Copper radioisotopes have gained a lot of attention in radiopharmaceuticals owing to their unique decay characteristics. The longest half-life β emitter, 67Cu, is thought to be suitable for targeted radio-immunotherapy. Adequate production of 67Cu to meet the demands of clinical studies has not been fully established. Another attractive copper isotope, 64Cu has possible applications as a diagnostic imaging tracer combined with a therapeutic effect. This work proposes a production method using accelerator neutrons in which two copper radioisotopes can be produced: 1) 68Zn(n,x)67Cu and 2) 64Zn(n,p)64Cu using ~14 MeV neutrons generated by natC(d, n) reaction, both from natural or enriched zinc oxides. The generated 64,67Cu were separated from the target zinc oxide using a chelating and an anion exchange columns and were labelled with two widely studied chelators where the labelling efficiency was found to be acceptably good. The major advantage of this method is that a significant amount of 64,67Cu with a very few impurity radionuclides are produced which also makes the separation procedure simple. Provided an accelerator supplying an Ed = ~ 40 MeV, a wide application of 64,67Cu based drugs in nuclear medicine is feasible in the near future. We will present the characteristics of this production method using accelerator neutrons including the chemical separation processes.

  8. Simulations of ion acceleration from ultrathin targets with the VEGA petawatt laser

    NASA Astrophysics Data System (ADS)

    Stockhausen, Luca C.; Torres, Ricardo; Conejero Jarque, Enrique

    2015-05-01

    The Spanish Pulsed Laser Centre (CLPU) is a new high-power laser facility for users. Its main system, VEGA, is a CPA Ti:Sapphire laser which, in its final phase, will be able to reach petawatt peak powers in pulses of 30 fs with a pulse contrast of 1 : 1010 at 1 ps. The extremely low level of pre-pulse intensity makes this system ideally suited for studying the laser interaction with ultrathin targets. We have used the particle-in-cell (PIC) code OSIRIS to carry out 2D simulations of the acceleration of ions from ultrathin solid targets under the unique conditions provided by VEGA, with laser intensities up to 1022Wcm-2 impinging normally on 5 - 40 nm thick overdense plasmas, with different polarizations and pre-plasma scale lengths. We show how signatures of the radiation pressure dominated regime, such as layer compression and bunch formation, are only present with circular polarization. By passively shaping the density gradient of the plasma, we demonstrate an enhancement in peak energy up to tens of MeV and monoenergetic features. On the contrary linear polarization at the same intensity level causes the target to blow up, resulting in much lower energies and broader spectra. One limiting factor of Radiation Pressure Acceleration is the development of Rayleigh-Taylor like instabilities at the interface of the plasma and photon fluid. This results in the formation of bubbles in the spatial profile of laser-accelerated proton beams. These structures were previously evidenced both experimentally and theoretically. We have performed 2D simulations to characterize this bubble-like structure and report on the dependency on laser and target parameters.

  9. Targeted Ablation Reveals a Novel Role of FKBP52 in Gene-Specific Regulation of Glucocorticoid Receptor Transcriptional Activity

    PubMed Central

    Wolf, Irene M.; Periyasamy, Sumudra; Hinds, Terry; Yong, Weidong; Shou, Weinian; Sanchez, Edwin R.

    2009-01-01

    FKBP52 is a tetratricopeptide repeat (TPR) protein with peptidyl-prolyl isomerase activity and is found in steroid receptor complexes, including glucocorticoid receptor (GR). It is generally accepted that FKBP52 has a stimulatory effect on GR transcriptional activity. However, the mechanism by which FKBP52 controls GR is not yet clear, with reports showing effects on GR hormone-binding affinity and/or hormone-induced nuclear translocation. To address this issue, we have generated mice with targeted ablation of the FKBP52 gene. To date, no overt defects of GR-regulated physiology have been found in these animals, demonstrating that FKBP52 is not an essential regulator of global GR activity. To better assess the impact of FKBP52 on GR, mouse embryonic fibroblasts (MEFs) were generated from wild-type (WT) and FKBP52-deficient (KO) animals. Analysis of GR activity at reporter genes showed an approximate 70% reduction of activity in 52KO MEF cells, with no effect of FKBP52 loss on thyroid receptor. Interestingly, GR activity at endogenous genes was not globally affected in 52KO cells, with reduced activity at GILZ and FKBP51, but not at SGK and p21. Thus, FKBP52 appears to be a gene-specific modulator of GR. To investigate the mechanism of this action, analyses of GR heterocomplex composition, hormone-binding affinity, and ability to undergo hormone-induced nuclear translocation and DNA-binding were performed. Interestingly, no effect of FKBP52 loss was found for any of these GR properties, suggesting that the main function of FKBP52 is a heretofore-unknown ability to control GR activity at target genes. Lastly, loss of FKBP52 did not affect the ability of GR to undergo hormone-induced autologous down-regulation, showing that FKBP52 does not contribute to all branches of GR signaling. The implications of these results to the potential actions of FKBP52 on GR activity in vivo are discussed. PMID:19073255

  10. Critical Density Target Design for Ion Acceleration on the T-Cubed Laser

    NASA Astrophysics Data System (ADS)

    Kordell, Peter; Campbell, Paul; Maksimchuk, Anatoly; Willingale, Louise; Krushelnick, Karl

    2016-10-01

    The interaction of an intense laser pulse with a critical density target can form a high Mach number electrostatic shock. Recent experiments on CO2 lasers have demonstrated that such shocks can be used to produce directional, quasi-monoenergetic proton beams. PIC simulations indicate that the our single pulse system, the T-Cubed laser (1.053 μm, 6J in 400fs), is both capable of both producing these shocks and accelerating protons to MeV energies. Shock formation and propagation with our system has challenging target peak density and density gradient requirements. We present our target design, an interferometric characterization of its density profile and preliminary experiments on T-Cubed.

  11. ACCELERATOR SYSTEMS MODIFICATIONS FOR A SECOND TARGET STATION AT THE OAK RIDGE SPALLATION NEUTRON SOURCE

    SciTech Connect

    Galambos, John D; Kim, Sang-Ho; Plum, Michael A

    2014-01-01

    A second target station is planned for the Oak Ridge Spallation Neutron Source. The ion source will be upgraded to increase the peak current from 38 to 49 mA, additional superconducting RF cavities will be added to the linac to increase the H beam energy from 938 to 1300 MeV, and the accumulator ring will receive modifications to the injection and extraction systems to accommodate the higher beam energy. After pulse compression in the storage ring one sixth of the beam pulses (10 out of 60 Hz) will be diverted to the second target by kicker and septum magnets added to the existing Ring to Target Beam Transport (RTBT) line. No further modifications will be made to the RTBT so that when the kicker and septum magnets are turned off the original beam transport lattice will be unaffected. In this paper we will discuss these and other planned modifications and upgrades to the accelerator facility.

  12. High-intensity laser-accelerated ion beam produced from cryogenic micro-jet target.

    PubMed

    Gauthier, M; Kim, J B; Curry, C B; Aurand, B; Gamboa, E J; Göde, S; Goyon, C; Hazi, A; Kerr, S; Pak, A; Propp, A; Ramakrishna, B; Ruby, J; Willi, O; Williams, G J; Rödel, C; Glenzer, S H

    2016-11-01

    We report on the successful operation of a newly developed cryogenic jet target at high intensity laser-irradiation. Using the frequency-doubled Titan short pulse laser system at Jupiter Laser Facility, Lawrence Livermore National Laboratory, we demonstrate the generation of a pure proton beam a with maximum energy of 2 MeV. Furthermore, we record a quasi-monoenergetic peak at 1.1 MeV in the proton spectrum emitted in the laser forward direction suggesting an alternative acceleration mechanism. Using a solid-density mixed hydrogen-deuterium target, we are also able to produce pure proton-deuteron ion beams. With its high purity, limited size, near-critical density, and high-repetition rate capability, this target is promising for future applications.

  13. High-intensity laser-accelerated ion beam produced from cryogenic micro-jet target

    NASA Astrophysics Data System (ADS)

    Gauthier, M.; Kim, J. B.; Curry, C. B.; Aurand, B.; Gamboa, E. J.; Göde, S.; Goyon, C.; Hazi, A.; Kerr, S.; Pak, A.; Propp, A.; Ramakrishna, B.; Ruby, J.; Willi, O.; Williams, G. J.; Rödel, C.; Glenzer, S. H.

    2016-11-01

    We report on the successful operation of a newly developed cryogenic jet target at high intensity laser-irradiation. Using the frequency-doubled Titan short pulse laser system at Jupiter Laser Facility, Lawrence Livermore National Laboratory, we demonstrate the generation of a pure proton beam a with maximum energy of 2 MeV. Furthermore, we record a quasi-monoenergetic peak at 1.1 MeV in the proton spectrum emitted in the laser forward direction suggesting an alternative acceleration mechanism. Using a solid-density mixed hydrogen-deuterium target, we are also able to produce pure proton-deuteron ion beams. With its high purity, limited size, near-critical density, and high-repetition rate capability, this target is promising for future applications.

  14. High-intensity laser-accelerated ion beam produced from cryogenic micro-jet target

    DOE PAGES

    Gauthier, M.; Kim, J. B.; Curry, C. B.; ...

    2016-08-24

    Here, we report on the successful operation of a newly developed cryogenic jet target at high intensity laser-irradiation. Using the frequency-doubled Titan short pulse laser system at Jupiter Laser Facility, Lawrence Livermore National Laboratory, we demonstrate the generation of a pure proton beam a with maximum energy of 2 MeV. Furthermore, we record a quasi-monoenergetic peak at 1.1 MeV in the proton spectrum emitted in the laser forward direction suggesting an alternative acceleration mechanism. Using a solid-density mixed hydrogen-deuterium target, we are also able to produce pure proton-deuteron ion beams. With its high purity, limited size, near-critical density, and high-repetitionmore » rate capability, this target is promising for future applications.« less

  15. High-intensity laser-accelerated ion beam produced from cryogenic micro-jet target

    SciTech Connect

    Gauthier, M.; Kim, J. B.; Curry, C. B.; Aurand, B.; Gamboa, E. J.; Göde, S.; Goyon, C.; Hazi, A.; Kerr, S.; Pak, A.; Propp, A.; Ramakrishna, B.; Ruby, J.; Willi, O.; Williams, G. J.; Rödel, C.; Glenzer, S. H.

    2016-08-24

    Here, we report on the successful operation of a newly developed cryogenic jet target at high intensity laser-irradiation. Using the frequency-doubled Titan short pulse laser system at Jupiter Laser Facility, Lawrence Livermore National Laboratory, we demonstrate the generation of a pure proton beam a with maximum energy of 2 MeV. Furthermore, we record a quasi-monoenergetic peak at 1.1 MeV in the proton spectrum emitted in the laser forward direction suggesting an alternative acceleration mechanism. Using a solid-density mixed hydrogen-deuterium target, we are also able to produce pure proton-deuteron ion beams. With its high purity, limited size, near-critical density, and high-repetition rate capability, this target is promising for future applications.

  16. CFD Analysis and Design of Detailed Target Configurations for an Accelerator-Driven Subcritical System

    SciTech Connect

    Kraus, Adam; Merzari, Elia; Sofu, Tanju; Zhong, Zhaopeng; Gohar, Yousry

    2016-08-01

    High-fidelity analysis has been utilized in the design of beam target options for an accelerator driven subcritical system. Designs featuring stacks of plates with square cross section have been investigated for both tungsten and uranium target materials. The presented work includes the first thermal-hydraulic simulations of the full, detailed target geometry. The innovative target cooling manifold design features many regions with complex flow features, including 90 bends and merging jets, which necessitate three-dimensional fluid simulations. These were performed using the commercial computational fluid dynamics code STAR-CCM+. Conjugate heat transfer was modeled between the plates, cladding, manifold structure, and fluid. Steady-state simulations were performed but lacked good residual convergence. Unsteady simulations were then performed, which converged well and demonstrated that flow instability existed in the lower portion of the manifold. It was established that the flow instability had little effect on the peak plate temperatures, which were well below the melting point. The estimated plate surface temperatures and target region pressure were shown to provide sufficient margin to subcooled boiling for standard operating conditions. This demonstrated the safety of both potential target configurations during normal operation.

  17. High heat flux accelerator targets cooling with liquid-metal jet impingement

    NASA Astrophysics Data System (ADS)

    Silverman, I.; Arenshtam, A.; Kijel, D.; Nagler, A.

    2005-12-01

    Accelerator targets for radioisotope production generate very high density of thermal energy in the target material, which absorbs the particles beam. The design of these targets requires efficient heat removal techniques in order to preserve the integrity of the target. Normal average heat fluxes from these targets are around 1 kW/cm2 and may reach order of magnitude higher values at hot spots. Few techniques exist to deal with such high heat fluxes. One of them is jet impingement that has been proved to be able to deal with heat fluxes as high as 40 kW/cm2 using water as coolant. However, this requires very high jet velocities of more than 100 m/s. A few theoretical and experimental studies indicate that liquid-metal coolants (e.g., gallium or gallium alloys) can improve the heat transfer efficiency in this configuration. Experimental cooling loops based on water and liquid-metal jet impingement have been designed and built at Soreq to evaluate this method. For the current liquid-metal system an eutectic alloy of gallium and indium (GaIn) is used. Initial experiments demonstrate that the GaIn cooling system can deal with heat flux of about 2 kW/cm2 over an area of 1 cm2. The jet velocity is less than 4 m/s and the required differential pressure from the pump is less than 1 bar.

  18. Doppler-shifted optical absorption characterization of plume-lateral expansion in laser ablation of a cerium target

    NASA Astrophysics Data System (ADS)

    Miyabe, M.; Oba, M.; Iimura, H.; Akaoka, K.; Maruyama, Y.; Ohba, H.; Tampo, M.; Wakaida, I.

    2012-12-01

    The temporal evolution of the ablation plume of cerium was investigated by absorption spectroscopy. Cerium oxide pellets were ablated in a helium atmosphere by second-harmonic radiation (532 nm) from a Nd:YAG laser at a fluence of 0.5 J/cm2. The lateral velocity (expansion velocity horizontal to the sample surface) of the plume was determined from the magnitude of the Doppler splitting of the absorption spectra measured close to the sample surface. The lateral velocities of neutral and singly ionized atoms were systematically investigated by varying several parameters, such as ambient gas pressure, ablation laser fluence, observation timing, and observation height. In addition, temporal profiles of the absorption signal were measured by detuning the probe laser frequency from the atomic resonant frequency in order to obtain the temporal variation of the velocity. On the basis of the drag force model, the slowing coefficients for atomic and ionic species in a helium atmosphere were evaluated along with lateral velocity in a vacuum. This study may help in understanding the plume dynamics effect on deposited film properties as well as optimizing experimental conditions for ablation-based spectroscopic analysis.

  19. Target/Blanket Design for the Accelerator Production of Tritium Plant

    SciTech Connect

    Cappiello, M. W.

    1997-12-31

    The Accelerator Production of Tritium Target/Blanket (T/B) system is comprised of the T/B assembly and the attendant heat removal systems. The T/B assembly produces tritium using a high energy proton beam, and a spallation neutron source. The supporting heat removal systems safely remove the heat deposited by the proton beam during both normal and off-normal conditions. All systems reside within the T/B building, which is located at the end of a linear accelerator. Protons are accelerated to an energy of 1700 MeV at a current of 100 mA and are directed onto the T/B assembly. The protons interact with tungsten and lead nuclei to produce neutrons through the process of nuclear spallation. Neutron capture in {sup 3}He gas produces tritium which is removed on a continual basis in an adjacent Tritium Separation Facility (TSF). The T/B assembly is modular to allow for replacement of spent components and minimization of waste. Systems and components are designed with safety as a primary consideration to minimize risk to the workers and the public.

  20. Laser-Driven Ion Acceleration from Plasma Micro-Channel Targets

    PubMed Central

    Zou, D. B.; Pukhov, A.; Yi, L. Q.; Zhou, H. B.; Yu, T. P.; Yin, Y.; Shao, F. Q.

    2017-01-01

    Efficient energy boost of the laser-accelerated ions is critical for their applications in biomedical and hadron research. Achiev-able energies continue to rise, with currently highest energies, allowing access to medical therapy energy windows. Here, a new regime of simultaneous acceleration of ~100 MeV protons and multi-100 MeV carbon-ions from plasma micro-channel targets is proposed by using a ~1020 W/cm2 modest intensity laser pulse. It is found that two trains of overdense electron bunches are dragged out from the micro-channel and effectively accelerated by the longitudinal electric-field excited in the plasma channel. With the optimized channel size, these “superponderomotive” energetic electrons can be focused on the front surface of the attached plastic substrate. The much intense sheath electric-field is formed on the rear side, leading to up to ~10-fold ionic energy increase compared to the simple planar geometry. The analytical prediction of the optimal channel size and ion maximum energies is derived, which shows good agreement with the particle-in-cell simulations. PMID:28218247

  1. Laser-Driven Ion Acceleration from Plasma Micro-Channel Targets.

    PubMed

    Zou, D B; Pukhov, A; Yi, L Q; Zhou, H B; Yu, T P; Yin, Y; Shao, F Q

    2017-02-20

    Efficient energy boost of the laser-accelerated ions is critical for their applications in biomedical and hadron research. Achiev-able energies continue to rise, with currently highest energies, allowing access to medical therapy energy windows. Here, a new regime of simultaneous acceleration of ~100 MeV protons and multi-100 MeV carbon-ions from plasma micro-channel targets is proposed by using a ~10(20) W/cm(2) modest intensity laser pulse. It is found that two trains of overdense electron bunches are dragged out from the micro-channel and effectively accelerated by the longitudinal electric-field excited in the plasma channel. With the optimized channel size, these "superponderomotive" energetic electrons can be focused on the front surface of the attached plastic substrate. The much intense sheath electric-field is formed on the rear side, leading to up to ~10-fold ionic energy increase compared to the simple planar geometry. The analytical prediction of the optimal channel size and ion maximum energies is derived, which shows good agreement with the particle-in-cell simulations.

  2. Laser-Driven Ion Acceleration from Plasma Micro-Channel Targets

    NASA Astrophysics Data System (ADS)

    Zou, D. B.; Pukhov, A.; Yi, L. Q.; Zhou, H. B.; Yu, T. P.; Yin, Y.; Shao, F. Q.

    2017-02-01

    Efficient energy boost of the laser-accelerated ions is critical for their applications in biomedical and hadron research. Achiev-able energies continue to rise, with currently highest energies, allowing access to medical therapy energy windows. Here, a new regime of simultaneous acceleration of ~100 MeV protons and multi-100 MeV carbon-ions from plasma micro-channel targets is proposed by using a ~1020 W/cm2 modest intensity laser pulse. It is found that two trains of overdense electron bunches are dragged out from the micro-channel and effectively accelerated by the longitudinal electric-field excited in the plasma channel. With the optimized channel size, these “superponderomotive” energetic electrons can be focused on the front surface of the attached plastic substrate. The much intense sheath electric-field is formed on the rear side, leading to up to ~10-fold ionic energy increase compared to the simple planar geometry. The analytical prediction of the optimal channel size and ion maximum energies is derived, which shows good agreement with the particle-in-cell simulations.

  3. Optimization of radiation acceleration regime and the target structure in laser plasma interaction

    NASA Astrophysics Data System (ADS)

    Dudnikova, Galina; Lui, Chuan; Papadopoulos, Dennis; Sagdeev, Roald; Zigler, Ari

    2009-11-01

    Recent work [1,2] indicates that under proper conditions the interaction of ultra-short, high power lasers with thin foils can generate ion beams in the 100-200 MeV energy range with relatively low velocity dispersion. This technology can have major implications to medical ion proton cancer therapy since it can provide a relatively inexpensive table-top alternative to the current used traditional cyclotrons. This paper presents a simulation trade-off study of laser driven generation of quasi-monochromatic ion beams in the thin-foil Radiation Pressure Acceleration (RPA) regime. The radiation pressure accelerates the electron cloud, which in its turn transfers accelerates the ions due to the induced longitudinal charge separation fields. A series of two and three-dimensional PIC simulations are presented with emphasis on stabilizing the target plasma against Raleigh-Taylor and modulational instabilities. Such instabilities are known as the main obstacles in achieving monochromatic beams. [4pt] [1] B. Eliasson, C. Lui, et al. New Jour. Phys., 11, 2009.[0pt] [2] F. Pegoraro, S.V. Bulanov. Laser Phys., v19, N 2, 2009.

  4. Collimated proton acceleration in light sail regime with a tailored pinhole target

    NASA Astrophysics Data System (ADS)

    Wang, H. Y.; Yan, X. Q.; Zepf, M.

    2014-06-01

    A scheme for producing collimated protons from laser interactions with a diamond-like-carbon + pinhole target is proposed. The process is based on radiation pressure acceleration in the multi-species light-sail regime [B. Qiao et al., Phys. Rev. Lett. 105, 155002 (2010); T. P. Yu et al., Phys. Rev. Lett. 105, 065002 (2010)]. Particle-in-cell simulations demonstrate that transverse quasistatic electric field at TV/m level can be generated in the pinhole. The transverse electric field suppresses the transverse expansion of protons effectively, resulting in a higher density and more collimated proton beam compared with a single foil target. The dependence of the proton beam divergence on the parameters of the pinhole is also investigated.

  5. MS/MS similarity networking accelerated target profiling of triterpene saponins in Eleutherococcus senticosus leaves.

    PubMed

    Ge, Yue-Wei; Zhu, Shu; Yoshimatsu, Kayo; Komatsu, Katsuko

    2017-07-15

    The targeted mass information of compounds accelerated their discovery in a large volume of untargeted MS data. An MS/MS similarity networking is advanced in clustering the structural analogues, which benefits the collection of mass information of similar compounds. The triterpene saponins extracted from Eleutherococcus senticosus leaves (ESL), a kind of functional tea, have shown promise in the relief of Alzheimer's disease. In this work, a target-precursor list (TPL) generated using MS/MS similarity networking was employed to rapidly trace 106 triterpene saponins from the aqueous extracts of ESL, of which 49 were tentatively identified as potentially new triterpene saponins. Moreover, a compound database of triterpene saponins was established and successfully applied to uncover their distribution features in ESL samples collected from different areas.

  6. Collimated proton acceleration in light sail regime with a tailored pinhole target

    SciTech Connect

    Wang, H. Y.; Zepf, M.; Yan, X. Q.

    2014-06-15

    A scheme for producing collimated protons from laser interactions with a diamond-like-carbon + pinhole target is proposed. The process is based on radiation pressure acceleration in the multi-species light-sail regime [B. Qiao et al., Phys. Rev. Lett. 105, 155002 (2010); T. P. Yu et al., Phys. Rev. Lett. 105, 065002 (2010)]. Particle-in-cell simulations demonstrate that transverse quasistatic electric field at TV/m level can be generated in the pinhole. The transverse electric field suppresses the transverse expansion of protons effectively, resulting in a higher density and more collimated proton beam compared with a single foil target. The dependence of the proton beam divergence on the parameters of the pinhole is also investigated.

  7. Saturated ablation in metal hydrides and acceleration of protons and deuterons to keV energies with a soft-x-ray laser

    NASA Astrophysics Data System (ADS)

    Andreasson, J.; Iwan, B.; Andrejczuk, A.; Abreu, E.; Bergh, M.; Caleman, C.; Nelson, A. J.; Bajt, S.; Chalupsky, J.; Chapman, H. N.; Fäustlin, R. R.; Hajkova, V.; Heimann, P. A.; Hjörvarsson, B.; Juha, L.; Klinger, D.; Krzywinski, J.; Nagler, B.; Pálsson, G. K.; Singer, W.; Seibert, M. M.; Sobierajski, R.; Toleikis, S.; Tschentscher, T.; Vinko, S. M.; Lee, R. W.; Hajdu, J.; Tîmneanu, N.

    2011-01-01

    Studies of materials under extreme conditions have relevance to a broad area of research, including planetary physics, fusion research, materials science, and structural biology with x-ray lasers. We study such extreme conditions and experimentally probe the interaction between ultrashort soft x-ray pulses and solid targets (metals and their deuterides) at the FLASH free-electron laser where power densities exceeding 1017 W/cm2 were reached. Time-of-flight ion spectrometry and crater analysis were used to characterize the interaction. The results show the onset of saturation in the ablation process at power densities above 1016 W/cm2. This effect can be linked to a transiently induced x-ray transparency in the solid by the femtosecond x-ray pulse at high power densities. The measured kinetic energies of protons and deuterons ejected from the surface reach several keV and concur with predictions from plasma-expansion models. Simulations of the interactions were performed with a nonlocal thermodynamic equilibrium code with radiation transfer. These calculations return critical depths similar to the observed crater depths and capture the transient surface transparency at higher power densities.

  8. Saturated ablation in metal hydrides and acceleration of protons and deuterons to keV energies with a soft-x-ray laser.

    PubMed

    Andreasson, J; Iwan, B; Andrejczuk, A; Abreu, E; Bergh, M; Caleman, C; Nelson, A J; Bajt, S; Chalupsky, J; Chapman, H N; Fäustlin, R R; Hajkova, V; Heimann, P A; Hjörvarsson, B; Juha, L; Klinger, D; Krzywinski, J; Nagler, B; Pálsson, G K; Singer, W; Seibert, M M; Sobierajski, R; Toleikis, S; Tschentscher, T; Vinko, S M; Lee, R W; Hajdu, J; Tîmneanu, N

    2011-01-01

    Studies of materials under extreme conditions have relevance to a broad area of research, including planetary physics, fusion research, materials science, and structural biology with x-ray lasers. We study such extreme conditions and experimentally probe the interaction between ultrashort soft x-ray pulses and solid targets (metals and their deuterides) at the FLASH free-electron laser where power densities exceeding 10(17) W/cm(2) were reached. Time-of-flight ion spectrometry and crater analysis were used to characterize the interaction. The results show the onset of saturation in the ablation process at power densities above 10(16) W/cm(2). This effect can be linked to a transiently induced x-ray transparency in the solid by the femtosecond x-ray pulse at high power densities. The measured kinetic energies of protons and deuterons ejected from the surface reach several keV and concur with predictions from plasma-expansion models. Simulations of the interactions were performed with a nonlocal thermodynamic equilibrium code with radiation transfer. These calculations return critical depths similar to the observed crater depths and capture the transient surface transparency at higher power densities.

  9. Deuteron frozen-spin- polarized target for nd experiments at the VdG accelerator of Charles University

    NASA Astrophysics Data System (ADS)

    Borisov, N. S.; Bazhanov, N. A.; Belyaev, A. A.; Brož, J.; Černý, J.; Doležal, Z.; Fedorov, A. N.; Gurevich, G. M.; Ivanov, M. P.; Kodyš, P.; Kubík, P.; Kuzmin, E. S.; Lazarev, A. B.; Lehar, F.; Lukhanin, O. O.; Matafonov, V. N.; Neganov, A. B.; Pisarev, I. L.; Švejda, J.; Shilov, S. N.; Usov, Yu. A.; Wilhelm, I.

    2008-08-01

    A frozen-spin- polarized deuteron target cooled by the 3He/ 4He dilution refrigerator is described. Fully deuterated 1,2-propanediol was used as a target material. Deuteron vector polarization about 40% was obtained for the target in the shape of a cylinder of 2-cm diameter and 6-cm length. The target is intended for a study of 3N interactions at the polarized neutron beam generated by the Van de Graaff accelerator at the Charles University in Prague.

  10. Gadolinium-148 and other spallation production cross section measurements for accelerator target facilities

    NASA Astrophysics Data System (ADS)

    Kelley, Karen Corzine

    At the Los Alamos Neutron Science Center accelerator complex, protons are accelerated to 800 MeV and directed to two tungsten targets, Target 4 at the Weapons Neutron Research facility and the 1L target at the Lujan Center. The Department of Energy requires hazard classification analyses to be performed on these targets and places limits on certain radionuclide inventories in the targets to avoid characterizing the facilities as "nuclear facilities." Gadolinium-148 is a radionuclide created from the spallation of tungsten. Allowed isotopic inventories are particularly low for this isotope because it is an alpha-particle emitter with a 75-year half-life. The activity level of Gadolinium-148 is low, but it encompasses almost two-thirds of the total dose burden for the two tungsten targets based on present yield estimates. From a hazard classification standpoint, this severely limits the lifetime of these tungsten targets. The cross section is not well-established experimentally and this is the motivation for measuring the Gadolinium-148 production cross section from tungsten. In a series of experiments at the Weapons Neutron Research facility, Gadolinium-148 production was measured for 600- and 800-MeV protons on tungsten, tantalum, and gold. These experiments used 3 mum thin tungsten, tantalum, and gold foils and 10 mum thin aluminum activation foils. In addition, spallation yields were determined for many short-lived and long-lived spallation products with these foils using gamma and alpha spectroscopy and compared with predictions of the Los Alamos National Laboratory codes CEM2k+GEM2 and MCNPX. The cumulative Gadolinium-148 production cross section measured from tantalum, tungsten, and gold for incident 600-MeV protons were 15.2 +/- 4.0, 8.31 +/- 0.92, and 0.591 +/- 0.155, respectively. The average production cross sections measured at 800 MeV were 28.6 +/- 3.5, 19.4 +/- 1.8, and 3.69 +/- 0.50 for tantalum, tungsten, and gold, respectively. These cumulative

  11. Target normal sheath acceleration sheath fields for arbitrary electron energy distribution

    SciTech Connect

    Schmitz, Holger

    2012-08-15

    Relativistic electrons, generated by ultraintense laser pulses, travel through the target and form a space charge sheath at the rear surface which can be used to accelerate ions to high energies. If the laser pulse duration is comparable or shorter than the time needed for the electrons to travel through the target, the electrons will not have the chance to form an equilibrium distribution but must be described by a non-equilibrium distribution. We present a kinetic theory of the rear sheath for arbitrary electron distribution function f(E), where E is the electron energy, and evaluate it for different shapes of f(E). We find that the far field is mainly determined by the high energy tail of the distribution, a steep decay of f(E) for high energies results in a small electric field and vice versa. The model is extended to account for electrons escaping the sheath region thereby allowing a finite potential drop over the sheath. The consequences of the model for the acceleration of ions are discussed.

  12. Targeting of prion-infected lymphoid cells to the central nervous system accelerates prion infection

    PubMed Central

    2012-01-01

    Background Prions, composed of a misfolded protein designated PrPSc, are infectious agents causing fatal neurodegenerative diseases. We have shown previously that, following induction of experimental autoimmune encephalomyelitis, prion-infected mice succumb to disease significantly earlier than controls, concomitant with the deposition of PrPSc aggregates in inflamed white matter areas. In the present work, we asked whether prion disease acceleration by experimental autoimmune encephalomyelitis results from infiltration of viable prion-infected immune cells into the central nervous system. Methods C57Bl/6 J mice underwent intraperitoneal inoculation with scrapie brain homogenates and were later induced with experimental autoimmune encephalomyelitis by inoculation of MOG35-55 in complete Freund's adjuvant supplemented with pertussis toxin. Spleen and lymph node cells from the co-induced animals were reactivated and subsequently injected into naïve mice as viable cells or as cell homogenates. Control groups were infected with viable and homogenized scrapie immune cells only with complete Freund's adjuvant. Prion disease incubation times as well as levels and sites of PrPSc deposition were next evaluated. Results We first show that acceleration of prion disease by experimental autoimmune encephalomyelitis requires the presence of high levels of spleen PrPSc. Next, we present evidence that mice infected with activated prion-experimental autoimmune encephalomyelitis viable cells succumb to prion disease considerably faster than do mice infected with equivalent cell extracts or other controls, concomitant with the deposition of PrPSc aggregates in white matter areas in brains and spinal cords. Conclusions Our results indicate that inflammatory targeting of viable prion-infected immune cells to the central nervous system accelerates prion disease propagation. We also show that in the absence of such targeting it is the load of PrPSc in the inoculum that determines the

  13. Acceleration of thin flyer foils with a 1 MA pulsed power device for shock-wave experiments in clumpy foam targets

    NASA Astrophysics Data System (ADS)

    Neff, Stephan; Ford, Jessica; Martinez, David; Plechaty, Christopher; Wright, Sandra; Presura, Radu

    2007-11-01

    The dynamics of shock waves in clumpy media are important for understanding many astrophysical processes, including the triggering of star formation in interstellar gas clouds by passing shock waves. This phenomena can be studied in the laboratory by launching a flyer plate into a low density foam with clumps. Low density foams offer the advantage of relative low sound speeds (a few hundred meters per second) compared to normal solids, thus reducing the flyer speed required to create shock waves. In first experiments aluminum foils with thicknesses between 20 micrometer and 130 micrometer were accelerated to speeds up to 2.3 km/s. In addition, the impact of the flyers on plexiglas targets was studied. Additional measurements will focus on optimizing the flyer properties (thicker flyers, higher velocities) and on characterizing the flyer in more detail (temperature of the flyer and plasma ablation from the flyer). The results of these measurements will be used to design an experiment studying the dynamics of shock waves in clumpy foams, using the 100 TW laser system Leopard for back-lighting the foam target.

  14. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Smoothing of ablation pressure nonuniformities in the laser-plasma corona during heating of laser fusion targets

    NASA Astrophysics Data System (ADS)

    Zhurovich, M. A.; Zhitkova, O. A.; Lebo, I. G.; Mikhailov, Yu A.; Sklizkov, G. V.; Starodub, Aleksandr N.; Tishkin, V. F.

    2009-06-01

    A method for smoothing ablation pressure nonuniformities during heating of laser fusion targets is described which utilises an extra laser pulse preceding the main pulse. Theoretical and experimental data are presented on heating of thin (3-10 μm) foils (simulating the target shell) by a spatially nonuniform laser beam. In the experiments, the laser pulse width at half maximum was 2 ns and the pulse energy was 2-30 J, which ensured a power density on the target surface from 1013 to 1014 W cm-2. The experimental data are analysed using two-dimensional numerical simulations. The experimental and simulation results demonstrate that this approach is sufficiently effective. The optimal laser prepulse parameters are determined.

  15. AGS SUPER NEUTRINO BEAM FACILITY ACCELERATOR AND TARGET SYSTEM DESIGN (NEUTRINO WORKING GROUP REPORT-II).

    SciTech Connect

    DIWAN,M.; MARCIANO,W.; WENG,W.; RAPARIA,D.

    2003-04-21

    This document describes the design of the accelerator and target systems for the AGS Super Neutrino Beam Facility. Under the direction of the Associate Laboratory Director Tom Kirk, BNL has established a Neutrino Working Group to explore the scientific case and facility requirements for a very long baseline neutrino experiment. Results of a study of the physics merit and detector performance was published in BNL-69395 in October 2002, where it was shown that a wide-band neutrino beam generated by a 1 MW proton beam from the AGS, coupled with a half megaton water Cerenkov detector located deep underground in the former Homestake mine in South Dakota would be able to measure the complete set of neutrino oscillation parameters: (1) precise determination of the oscillation parameters {Delta}m{sub 32}{sup 2} and sin{sup 2} 2{theta}{sub 32}; (2) detection of the oscillation of {nu}{sub {mu}}-{nu}{sub e} and measurement of sin{sup 2} 2{theta}{sub 13}; (3) measurement of {Delta}m{sub 21}{sup 2} sin 2{theta}{sub 12} in a {nu}{sub {mu}} {yields} {nu}{sub e} appearance mode, independent of the value of {theta}{sub 13}; (4) verification of matter enhancement and the sign of {Delta}m{sub 32}{sup 2}; and (5) determination of the CP-violation parameter {delta}{sub CP} in the neutrino sector. This report details the performance requirements and conceptual design of the accelerator and the target systems for the production of a neutrino beam by a 1.0 MW proton beam from the AGS. The major components of this facility include a new 1.2 GeV superconducting linac, ramping the AGS at 2.5 Hz, and the new target station for 1.0 MW beam. It also calls for moderate increase, about 30%, of the AGS intensity per pulse. Special care is taken to account for all sources of proton beam loss plus shielding and collimation of stray beam halo particles to ensure equipment reliability and personal safety. A preliminary cost estimate and schedule for the accelerator upgrade and target system are also

  16. Very-high-growth-factor Planar Ablative Rayleigh Taylor Experiments

    SciTech Connect

    Bradley, D K; Braun, D G; Glendinning, S G; Edwards, M J; Milovich, J L; Sorce, C M; Collins, G W; Haan, S W; Page, R H

    2006-10-30

    The Rayleigh-Taylor (RT) instability is an important factor in bounding the performance envelope of ignition targets. This paper describes an experiment for ablative RT instability that for the first time achieves growth factors close to those expected to occur in ignition targets at the National Ignition Facility (NIF). The large growth allows small seed perturbations to be detected and can be used to place an upper bound on perturbation growth at the ablation front resulting from microstructure in the preferred Be ablator. The experiments were performed on the Omega laser using a halfraum 1.2 mm long by 2 mm diameter with a 75% laser entrance hole. The halfraum was filled with {approx} 1 atm of neopentane to delay gold plasma from closing the diagnostic line of sight down the axis of the halfraum. The ablator was mounted at the base of the halfraum, and was accelerated by a two stepped X-ray pulse consisting of an early time section {approx} 100 eV to emulate the NIF foot followed by an approximately constant {approx} 150 eV drive sustained over an additional 5-7ns. It is this long pulse duration and late time observation that distinguishes the present work from previous experiments, and is responsible for the large growth that is achieved. The growth of a 2D sinusoidal perturbation machined on the drive side of the ablator was measured using face-on radiography. The diagnostic view remained open until {approx} 11 ns with maximum growth factors measured to be {approx} 200. The trajectory of the ablator was measured using streaked backlit radiography. The design and analysis of the experiments is described, and implications for experiments on ignition target ablators are discussed.

  17. Thin liquid sheet target capabilities for ultra-intense laser acceleration of ions at a kHz repetition rate

    NASA Astrophysics Data System (ADS)

    Klim, Adam; Morrison, J. T.; Orban, C.; Feister, S.; Ngirmang, G. K.; Smith, J.; Frische, K.; Peterson, A. C.; Chowdhury, E. A.; Freeman, R. R.; Roquemore, W. M.

    2016-10-01

    The success of laser-accelerated ion experiments depends crucially on a number of factors including how thin the targets can be created. We present experimental results demonstrating extremely thin (under 200 nm) water sheet targets that can be used for ultra-intense laser-accelerated ion experiments conducted at the Air Force Research Laboratory at Wright-Patterson Air Force Base. Importantly, these experiments operate at a kHz repetition rate and the recovery time of the liquid targets is fast enough to allow the laser to interact with a refreshed, thin target on every shot. We present results from liquid water targets which are useful for proton acceleration experiments via the mechanism of Target Normal Sheath Acceleration (TNSA). In future work, we will create thin sheets from deuterated water in order to perform laser-accelerated deuteron experiments. This research was sponsored by the Quantum and Non-Equilibrium Processes Division of the AFOSR, under the management of Dr. Enrique Parra, and support from the DOD HPCMP Internship Program.

  18. Accelerated killing of cancer cells using a multifunctional single-walled carbon nanotube-based system for targeted drug delivery in combination with photothermal therapy.

    PubMed

    Jeyamohan, Prashanti; Hasumura, Takashi; Nagaoka, Yutaka; Yoshida, Yasuhiko; Maekawa, Toru; Kumar, D Sakthi

    2013-01-01

    The photothermal effect of single-walled carbon nanotubes (SWCNTs) in combination with the anticancer drug doxorubicin (DOX) for targeting and accelerated destruction of breast cancer cells is demonstrated in this paper. A targeted drug-delivery system was developed for selective killing of breast cancer cells with polyethylene glycol biofunctionalized and DOX-loaded SWCNTs conjugated with folic acid. In our work, in vitro drug-release studies showed that the drug (DOX) binds at physiological pH (pH 7.4) and is released only at a lower pH, ie, lysosomal pH (pH 4.0), which is the characteristic pH of the tumor environment. A sustained release of DOX from the SWCNTs was observed for a period of 3 days. SWCNTs have strong optical absorbance in the near-infrared (NIR) region. In this special spectral window, biological systems are highly transparent. Our study reports that under laser irradiation at 800 nm, SWCNTs exhibited strong light-heat transfer characteristics. These optical properties of SWCNTs open the way for selective photothermal ablation in cancer therapy. It was also observed that internalization and uptake of folate-conjugated NTs into cancer cells was achieved by a receptor-mediated endocytosis mechanism. Results of the in vitro experiments show that laser was effective in destroying the cancer cells, while sparing the normal cells. When the above laser effect was combined with DOX-conjugated SWCNTs, we found enhanced and accelerated killing of breast cancer cells. Thus, this nanodrug-delivery system, consisting of laser, drug, and SWCNTs, looks to be a promising selective modality with high treatment efficacy and low side effects for cancer therapy.

  19. Reduction of time-averaged irradiation speckle nonuniformity in laser-driven plasmas due to target ablation

    NASA Astrophysics Data System (ADS)

    Epstein, R.

    1997-09-01

    In inertial confinement fusion (ICF) experiments, irradiation uniformity is improved by passing laser beams through distributed phase plates (DPPs), which produce focused intensity profiles with well-controlled, reproducible envelopes modulated by fine random speckle. [C. B. Burckhardt, Appl. Opt. 9, 695 (1970); Y. Kato and K. Mima, Appl. Phys. B 29, 186 (1982); Y. Kato et al., Phys. Rev. Lett. 53, 1057 (1984); Laboratory for Laser Energetics LLE Review 33, NTIS Document No. DOE/DP/40200-65, 1987 (unpublished), p. 1; Laboratory for Laser Energetics LLE Review 63, NTIS Document No. DOE/SF/19460-91, 1995 (unpublished), p. 1.] A uniformly ablating plasma atmosphere acts to reduce the contribution of the speckle to the time-averaged irradiation nonuniformity by causing the intensity distribution to move relative to the absorption layer of the plasma. This occurs most directly as the absorption layer in the plasma moves with the ablation-driven flow, but it is shown that the effect of the accumulating ablated plasma on the phase of the laser light also makes a quantitatively significant contribution. Analytical results are obtained using the paraxial approximation applied to the beam propagation, and a simple statistical model is assumed for the properties of DPPs. The reduction in the time-averaged spatial spectrum of the speckle due to these effects is shown to be quantitatively significant within time intervals characteristic of atmospheric hydrodynamics under typical ICF irradiation intensities.

  20. Selection of flowing liquid lead target structural materials for accelerator driven transmutation applications

    NASA Astrophysics Data System (ADS)

    Park, John J.; Buksa, John J.

    1995-09-01

    The beam entry window and container for a liquid lead spallation target will be exposed to high fluxes of protons and neutrons that are both higher in magnitude and energy than have been experienced in proton accelerators and fission reactors, as well as in a corrosive environment. The structural material of the target should have a good compatibility with liquid lead, a sufficient mechanical strength at elevated temperatures, a good performance under an intense irradiation environment, and a low neutron absorption cross section; these factors have been used to rank the applicability of a wide range of materials for structural containment. Nb-1Zr has been selected for use as the structural container for the LANL ABC/ATW molten lead target. Corrosion and mass transfer behavior for various candidate structural materials in liquid lead are reviewed, together with the beneficial effects of inhibitors and various coatings to protect substrate against liquid lead corrosion. Mechanical properties of some candidate materials at elevated temperatures and the property changes resulting from 800 MeV proton irradiation are also reviewed.

  1. Catheter ablation.

    PubMed

    Fromer, M; Shenasa, M

    1991-02-01

    Catheter ablation is gaining increasing interest for the therapy of symptomatic, sustained arrhythmias of various origins. The scope of this review is to give an overview of the biophysical aspects and major characteristics of some of the most widely used energy sources in catheter ablation, e.g., the discharge of conventional defibrillators, modified defibrillators, laser light, and radiofrequency current application. Results from animal studies are considered to explain the basic mechanisms of catheter ablation. The recent achievements with the use of radiofrequency current to modify or ablate cardiac conduction properties are outlined in more detail.

  2. Target normal sheath acceleration of foil ions by laser-trapped hot electrons from a long subcritical-density preplasma

    SciTech Connect

    Luan, S. X.; Yu, Wei; Shen, B. F.; Xu, Z. Z.; Yu, M. Y.; Zhuo, H. B.; Xu, Han; Wong, A. Y.; Wang, J. W.

    2014-12-15

    In a long subcritical density plasma, an ultrashort ultraintense laser pulse can self-organize into a fast but sub-relativistic propagating structure consisting of the modulated laser light and a large number of trapped electrons from the plasma. Upon impact of the structure with a solid foil target placed in the latter, the remaining laser light is reflected, but the dense and hot trapped electrons pass through the foil, together with the impact-generated target-frontsurface electrons to form a dense hot electron cloud at the back of the target suitable for enhancing target normal sheath acceleration of the target-backsurface ions. The accelerated ions are well collimated and of high charge and energy densities, with peak energies a full order of magnitude higher than that from target normal sheath acceleration without the subcritical density plasma. In the latter case, the space-charge field accelerating the ions is limited since they are formed only by the target-frontsurface electrons during the very short instant of laser reflection.

  3. Micro-sphere layered targets efficiency in laser driven proton acceleration

    SciTech Connect

    Floquet, V.; Martin, Ph.; Ceccotti, T.; Klimo, O.; Psikal, J.; Limpouch, J.; Proska, J.; Novotny, F.; Stolcova, L.; Velyhan, A.; Macchi, A.; Sgattoni, A.; Vassura, L.; Labate, L.; Baffigi, F.; Gizzi, L. A.

    2013-08-28

    Proton acceleration from the interaction of high contrast, 25 fs laser pulses at >10{sup 19} W/cm{sup 2} intensity with plastic foils covered with a single layer of regularly packed micro-spheres has been investigated experimentally. The proton cut-off energy has been measured as a function of the micro-sphere size and laser incidence angle for different substrate thickness, and for both P and S polarization. The presence of micro-spheres with a size comparable to the laser wavelength allows to increase the proton cut-off energy for both polarizations at small angles of incidence (10∘). For large angles of incidence, however, proton energy enhancement with respect to flat targets is absent. Analysis of electron trajectories in particle-in-cell simulations highlights the role of the surface geometry in the heating of electrons.

  4. Suppression of instability by double ablation in tungsten doped polyvinyl alcohol foils

    NASA Astrophysics Data System (ADS)

    Peedikakkandy, Leshma; Chaurasia, S.

    2012-07-01

    In Inertial fusion Energy (IFE) research stable acceleration of fusion targets is a significant problem due to hydrodynamic instabilities. This paper presents the results of the experiments done to investigate the effects of doping 20% of Tungsten (W) (by weight) in Polyvinyl Alcohol (PVA) polymer foils for suppression of instability during laser ablative acceleration. A 20J, 1.060μm, 900ps, Nd: Glass laser system with a focusable intensity of 3 to 9.6×1013W/cm2 was used in the experiment. It is observed that the doped PVA targets yielded stable and enhanced foil acceleration as compared to the undoped PVA foils.

  5. Characterization of MeV proton acceleration from double pulse irradiation of foil targets

    NASA Astrophysics Data System (ADS)

    Kerr, S.; Mo, M. Z.; Masud, R.; Tiedje, H. F.; Tsui, Y.; Fedosejevs, R.; Link, A.; Patel, P.; McLean, H. S.; Hazi, A.; Chen, H.; Ceurvorst, L.; Norreys, P.

    2014-10-01

    We report on the experimental characterization of proton acceleration from double-pulse irradiation of um-scale foil targets. Temporally separated sub-picosecond pulses have been shown to increase the conversion efficiency of laser energy to MeV protons. Here, two 700 fs, 1 ω pulses were separated by 1 to 5 ps; total beam energy was 100 J, with 5-20% of the total energy contained within the first pulse. In contrast to the ultraclean beams used in previous experiments, prepulse energies on the order of 10 mJ were present in the current experiments which appear to have a moderating effect on the enhancement. Proton beam measurements were made with radiochromic film stacks, as well as magnetic spectrometers. The effect on electron generation was measured using Kα emission from buried Cu tracer layers, while specular light diagnostics (FROG, reflection spectralon) indicated the laser coupling efficiency into the target. The results obtained will be presented and compared to PIC simulations. Work by LLNL was performed under the auspices of U.S. DOE under contract DE-AC52-07NA27344.

  6. Skeletal Adaptation to Intramedullary Pressure-Induced Interstitial Fluid Flow Is Enhanced in Mice Subjected to Targeted Osteocyte Ablation

    PubMed Central

    Kwon, Ronald Y.; Meays, Diana R.; Meilan, Alexander S.; Jones, Jeremiah; Miramontes, Rosa; Kardos, Natalie; Yeh, Jiunn-Chern; Frangos, John A.

    2012-01-01

    Interstitial fluid flow (IFF) is a potent regulatory signal in bone. During mechanical loading, IFF is generated through two distinct mechanisms that result in spatially distinct flow profiles: poroelastic interactions within the lacunar-canalicular system, and intramedullary pressurization. While the former generates IFF primarily within the lacunar-canalicular network, the latter generates significant flow at the endosteal surface as well as within the tissue. This gives rise to the intriguing possibility that loading-induced IFF may differentially activate osteocytes or surface-residing cells depending on the generating mechanism, and that sensation of IFF generated via intramedullary pressurization may be mediated by a non-osteocytic bone cell population. To begin to explore this possibility, we used the Dmp1-HBEGF inducible osteocyte ablation mouse model and a microfluidic system for modulating intramedullary pressure (ImP) to assess whether structural adaptation to ImP-driven IFF is altered by partial osteocyte depletion. Canalicular convective velocities during pressurization were estimated through the use of fluorescence recovery after photobleaching and computational modeling. Following osteocyte ablation, transgenic mice exhibited severe losses in bone structure and altered responses to hindlimb suspension in a compartment-specific manner. In pressure-loaded limbs, transgenic mice displayed similar or significantly enhanced structural adaptation to Imp-driven IFF, particularly in the trabecular compartment, despite up to ∼50% of trabecular lacunae being uninhabited following ablation. Interestingly, regression analysis revealed relative gains in bone structure in pressure-loaded limbs were correlated with reductions in bone structure in unpressurized control limbs, suggesting that adaptation to ImP-driven IFF was potentiated by increases in osteoclastic activity and/or reductions in osteoblastic activity incurred independently of pressure loading

  7. Efficient proton acceleration and focusing by an ultraintense laser interacting with a parabolic double concave target with an extended rear

    SciTech Connect

    Bake, Muhammad Ali; Xie, Bai-Song; Aimidula, Aimierding; Wang, Hong-Yu

    2013-07-15

    A new scheme for acceleration and focusing of protons via an improved parabolic double concave target irradiated by an ultraintense laser pulse is proposed. When an intense laser pulse illuminates a concave target, the hot electrons are concentrated on the focal region of the rear cavity and they form a strong space-charge-separation field, which accelerates the protons. For a simple concave target, the proton energy spectrum becomes very broad outside the rear cavity because of transverse divergence of the electromagnetic fields. However, particle-in-cell simulations show that, when the concave target has an extended rear, the hot electrons along the wall surface induce a transverse focusing sheath field, resulting in a clear enhancement of proton focusing, which makes the lower proton energy spread, while, leads to a little reduction of the proton bunch peak energy.

  8. Thermal ablation.

    PubMed

    Webb, Heather; Lubner, Meghan G; Hinshaw, J Louis

    2011-04-01

    Image-guided tumor ablation refers to a group of treatment modalities that have emerged during the past 2 decades as important tools in the treatment of a wide range of tumors throughout the body. Although most widely recognized in the treatment of hepatic and renal malignancies, the role of thermal ablation has expanded to include lesions of the lung, breast, prostate, bone, as well as other organs and its clinical applications continue to increase. In the following article, we discuss the major thermal ablation modalities, their respective strengths and weaknesses, potential complications and how to avoid them, as well as possible future applications.

  9. Heavy-ion inertial fusion: influence of target gain on accelerator parameters for vacuum-propagation regimes in reaction chambers

    SciTech Connect

    Mark, J.W.K.; Bangerter, R.O.; Barletta, W.A.; Fawley, W.M.; Judd, D.L.

    1982-03-04

    Target physics imposes requirements on the design of inertial fusion drivers. The influence of beam propagation in near vacuum fusion reaction chambers is evaluated for the relation between target gain and the phase-space requirements of heavy-ion accelerators. Initial results suggest that neutralization of the ion beam has a much greater positive effect than the deleterious one of beam stripping provided that the fusion chamber pressure is < 10/sup -3/ torr (of Li vapor or equivalent).

  10. Acceleration of deuterons with suppression of electronic conductance in a vacuum diode with a laser target on the anode

    NASA Astrophysics Data System (ADS)

    Shikanov, A. E.; Vovchenko, E. D.; Kozlovskii, K. I.; Shatokhin, V. L.

    2016-12-01

    We report new experimental results on the acceleration of deuterons in a compact coaxial diode with the suppression of electronic conductance by a constant longitudinal magnetic field. Plasma containing deuterons is created on a laser TiD target located on the anode. The pulse of accelerating voltage is formed by means of the Arkad'ev-Marx generator. The cathode symmetrically surrounds the anode and comprises a hollow permanent ring magnet with an inner radius of no more than 0.02 m and an on-axis induction of up to 0.4 T, which provides the magnetic insulation of the accelerating gap. The experiments demonstrate the possibility of obtaining accelerated deuterons with energy of up to 300 keV and a current of up to 0.5 kA with a pulse duration of 0.2 μs.

  11. Targeted percutaneous microwave ablation at the pulmonary lesion combined with mediastinal radiotherapy with or without concurrent chemotherapy in locally advanced non-small cell lung cancer evaluation in a randomized comparison study.

    PubMed

    Xu, Xinglu; Ye, Xin; Liu, Gang; Zhang, Tingping

    2015-09-01

    Concurrent chemoradiotherapy is the standard treatment for patients with locally advanced lung cancer. The most common dose-limiting adverse effect of thoracic radiotherapy (RT) is radiation pneumonia (RP). A randomized comparison study was designed to investigate targeted percutaneous microwave ablation at pulmonary lesion combined with mediastinal RT with or without chemotherapy (ablation group) in comparison with RT (target volume includes pulmonary tumor and mediastinal node) with or without chemotherapy (RT group) for the treatment of locally advanced non-small cell lung cancers (NSCLCs). From 2009 to 2012, patients with stage IIIA or IIIB NSCLCs who refused to undergo surgery or were not suitable for surgery were enrolled. Patients were randomly assigned to the RT group (n = 47) or ablation group (n = 51). Primary outcomes were the incidence of RP and curative effectiveness (complete response, partial response, and stable disease); secondary outcome was the 2-year overall survival (OS). Fifteen patients (31.9%) in the RT and two (3.9%) in the ablation group experienced RP (P < 0.001). The ratio of effective cases was 85.1 versus 80.4% for mediastinal lymph node (P = 0.843) and 83.0 versus 100% for pulmonary tumors (P = 0.503), respectively, for the RT and ablation groups. Kaplan-Meier analysis demonstrated 2-year OS rate of NSCLC patients in ablation group was higher than RT group, but no statistical difference (log-rank test, P = 0.297). Percutaneous microwave ablation followed by RT for inoperable stage III NSCLCs may result in a lower rate of RP and better local control than radical RT treatments.

  12. Acceleration of protons to above 6 MeV using H{sub 2}O 'snow' nanowire targets

    SciTech Connect

    Pomerantz, I.; Schleifer, E.; Nahum, E.; Eisenmann, S.; Botton, M.; Gordon, D.; Sprangel, P.; Zigler, A.

    2012-07-09

    A scheme is presented for using H{sub 2}O 'snow' nanowire targets for the generation of fast protons. This novel method may relax the requirements for very high laser intensities, thus reducing the size and cost of laser based ion acceleration system.

  13. Intrafractional Target Motions and Uncertainties of Treatment Setup Reference Systems in Accelerated Partial Breast Irradiation

    SciTech Connect

    Yue, Ning J.; Goyal, Sharad; Zhou Jinghao; Khan, Atif J.; Haffty, Bruce G.

    2011-04-01

    Purpose: This study investigated the magnitude of intrafractional motion and level of accuracy of various setup strategies in accelerated partial breast irradiation (APBI) using three-dimensional conformal external beam radiotherapy. Methods and Materials: At lumpectomy, gold fiducial markers were strategically sutured to the surrounding walls of the cavity. Weekly fluoroscopy imaging was conducted at treatment to investigate the respiration-induced target motions. Daily pre- and post-RT kV imaging was performed, and images were matched to digitally reconstructed radiographs based on bony anatomy and fiducial markers, respectively, to determine the intrafractional motion magnitudes over the course of treatment. The positioning differences of the laser tattoo- and the bony anatomy-based setups compared with those of the marker-based setup (benchmark) were also determined. The study included 21 patients. Results: Although lung exhibited significant motion, the average marker motion amplitude on the fluoroscopic image was about 1 mm. Over a typical treatment time period, average intrafractional motion magnitude was 4.2 mm and 2.6 mm based on the marker and bony anatomy matching, respectively. The bony anatomy- and laser tattoo-based interfractional setup errors, with respect to the fiducial marker-based setup, were 7.1 and 9.0 mm, respectively. Conclusions: Respiration has limited effects on the target motion during APBI. Bony anatomy-based treatment setup improves the accuracy relative to that of the laser tattoo-based setup approach. Since fiducial markers are sutured directly to the surgical cavity, the marker-based approach can further improve the interfractional setup accuracy. On average, a seroma cavity exhibits intrafractional motion of more than 4 mm, a magnitude that is larger than that which is otherwise derived based on bony anatomy matching. A seroma-specific marker-based approach has the potential to improve treatment accuracy by taking the true inter

  14. Synchronized chaotic targeting and acceleration of surface chemistry in prebiotic hydrothermal microenvironments

    PubMed Central

    Priye, Aashish; Yu, Yuncheng; Hassan, Yassin A.; Ugaz, Victor M.

    2017-01-01

    Porous mineral formations near subsea alkaline hydrothermal vents embed microenvironments that make them potential hot spots for prebiotic biochemistry. But, synthesis of long-chain macromolecules needed to support higher-order functions in living systems (e.g., polypeptides, proteins, and nucleic acids) cannot occur without enrichment of chemical precursors before initiating polymerization, and identifying a suitable mechanism has become a key unanswered question in the origin of life. Here, we apply simulations and in situ experiments to show how 3D chaotic thermal convection—flows that naturally permeate hydrothermal pore networks—supplies a robust mechanism for focused accumulation at discrete targeted surface sites. This interfacial enrichment is synchronized with bulk homogenization of chemical species, yielding two distinct processes that are seemingly opposed yet synergistically combine to accelerate surface reaction kinetics by several orders of magnitude. Our results suggest that chaotic thermal convection may play a previously unappreciated role in mediating surface-catalyzed synthesis in the prebiotic milieu. PMID:28119504

  15. Targeting dendritic cells to accelerate T-cell activation overcomes a bottleneck in tuberculosis vaccine efficacy

    PubMed Central

    Griffiths, Kristin L.; Ahmed, Mushtaq; Das, Shibali; Gopal, Radha; Horne, William; Connell, Terry D.; Moynihan, Kelly D.; Kolls, Jay K.; Irvine, Darrell J.; Artyomov, Maxim N.; Rangel-Moreno, Javier; Khader, Shabaana A.

    2016-01-01

    The development of a tuberculosis (TB) vaccine that induces sterilizing immunity to Mycobacterium tuberculosis infection has been elusive. Absence of sterilizing immunity induced by TB vaccines may be due to delayed activation of mucosal dendritic cells (DCs), and subsequent delay in antigen presentation and activation of vaccine-induced CD4+ T-cell responses. Here we show that pulmonary delivery of activated M. tuberculosis antigen-primed DCs into vaccinated mice, at the time of M. tuberculosis exposure, can overcome the delay in accumulation of vaccine-induced CD4+ T-cell responses. In addition, activating endogenous host CD103+ DCs and the CD40–CD40L pathway can similarly induce rapid accumulation of vaccine-induced lung CD4+ T-cell responses and limit early M. tuberculosis growth. Thus, our study provides proof of concept that targeting mucosal DCs can accelerate vaccine-induced T-cell responses on M. tuberculosis infection, and provide insights to overcome bottlenecks in TB vaccine efficacy. PMID:28004802

  16. Catheter Ablation

    MedlinePlus

    ... you during the procedure. Machines will measure your heart’s activity. All types of ablation require cardiac catheterization to place flexible tubes, or catheters, inside your heart to make the scars. Your doctor will clean ...

  17. Theoretical Modeling for Hepatic Microwave Ablation

    PubMed Central

    Prakash, Punit

    2010-01-01

    Thermal tissue ablation is an interventional procedure increasingly being used for treatment of diverse medical conditions. Microwave ablation is emerging as an attractive modality for thermal therapy of large soft tissue targets in short periods of time, making it particularly suitable for ablation of hepatic and other tumors. Theoretical models of the ablation process are a powerful tool for predicting the temperature profile in tissue and resultant tissue damage created by ablation devices. These models play an important role in the design and optimization of devices for microwave tissue ablation. Furthermore, they are a useful tool for exploring and planning treatment delivery strategies. This review describes the status of theoretical models developed for microwave tissue ablation. It also reviews current challenges, research trends and progress towards development of accurate models for high temperature microwave tissue ablation. PMID:20309393

  18. Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator

    SciTech Connect

    Yu Haijun; Zhu Jun; Chen Nan; Xie Yutong; Jiang Xiaoguo; Jian Cheng

    2010-04-15

    Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 10{sup 21}/m{sup 3} and 2-3 mm/{mu}s, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA.

  19. Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator

    NASA Astrophysics Data System (ADS)

    Yu, Haijun; Zhu, Jun; Chen, Nan; Xie, Yutong; Jiang, Xiaoguo; Jian, Cheng

    2010-04-01

    Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 1021/m3 and 2-3 mm/μs, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA.

  20. Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator.

    PubMed

    Yu, Haijun; Zhu, Jun; Chen, Nan; Xie, Yutong; Jiang, Xiaoguo; Jian, Cheng

    2010-04-01

    Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 10(21)/m(3) and 2-3 mm/micros, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA.

  1. Low- and high-order harmonic generation in the extended plasmas produced by laser ablation of zinc and manganese targets

    SciTech Connect

    Ganeev, R. A.; Baba, M.; Suzuki, M.; Yoneya, S.; Kuroda, H.

    2014-12-28

    The systematic studies of the harmonic generation of ultrashort laser pulses in the 5-mm-long Zn and Mn plasmas (i.e., application of nanosecond, picosecond, and femtosecond pulses for ablation, comparison of harmonic generation from atomic, ionic, and cluster-contained species of plasma, variation of plasma length, two-color pump of plasmas, etc.) are presented. The conversion efficiency of the 11th–19th harmonics generated in the Zn plasma was ∼5 × 10{sup −5}. The role of the ionic resonances of Zn near the 9th and 10th harmonics on the enhancement of harmonics is discussed. The enhancement of harmonics was also analyzed using the two-color pump of extended plasmas, which showed similar intensities of the odd and even harmonics along the whole range of generation. The harmonics up to the 107th order were demonstrated in the case of manganese plasma. The comparison of harmonic generation in the 5-mm-long and commonly used short (≤0.5 mm) plasma plumes showed the advanced properties of extended media.

  2. Acceleration of protons in plasma produced from a thin plastic or aluminum target by a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Rosinski, M.; Badziak, J.; Parys, P.; Zaras-Szydlowska, A.; Ryc, L.; Torrisi, L.; Szydlowski, A.; Malinowska, A.; Kaczmarczyk, B.; Makowski, J.; Torrisi, A.

    2016-05-01

    The acceleration of protons in plasma produced from thin mylar (3.5 μ m) and aluminum (2 μm) targets by a 45-fs laser pulses with the energy of 400 mJ and the intensity of up to 1019 W/cm2 was investigated. Characteristics of forward-accelerated protons were measured by the time-of-flight method. In the measurements, special attention was paid to the dependence of proton beam parameters on the laser focus position (FP) in relation to the target surface which resulted in the intensity change within a factor of ~ 10. It was observed that in the case of using the Mylar target, the dependence of both the maximum (Epmax) and the mean (langleEprangle) proton energy on |Δx| is clearly non-symmetric with regard to the point where FP = 0 (the focal plane on the target surface) and highest proton energies are achieved when the focal plane is situated in front of the target. In particular, for the target with the thickness of 3.5 μ m Epmax reached 2.2 MeV for FP = +50 μm while for FP = 0 and FP = -100 μm the maximum proton energies reached only 1.6 MeV and 1.3 MeV, respectively. For the aluminum target of 2 μm thickness Ep changed only within ~ 40% and the highest proton energies reached 2.4 MeV.

  3. Three-Dimensional Dynamics of Breakout Afterburner Ion Acceleration Using High-Contrast Short-Pulse Laser and Nanoscale Targets

    NASA Astrophysics Data System (ADS)

    Yin, L.; Albright, B. J.; Bowers, K. J.; Jung, D.; Fernández, J. C.; Hegelich, B. M.

    2011-07-01

    Breakout afterburner (BOA) laser-ion acceleration has been demonstrated for the first time in the laboratory. In the BOA, an initially solid-density target undergoes relativistically induced transparency, initiating a period of enhanced ion acceleration. First-ever kinetic simulations of the BOA in three dimensions show that the ion beam forms lobes in the direction orthogonal to laser polarization and propagation. Analytic theory presented for the electron dynamics in the laser ponderomotive field explains how azimuthal symmetry breaks even for a symmetric laser intensity profile; these results are consistent with recent experiments at the Trident laser facility.

  4. Resolving pathobiological mechanisms relating to Huntington disease: gait, balance, and involuntary movements in mice with targeted ablation of striatal D1 dopamine receptor cells.

    PubMed

    Kim, Hyun Ah; Jiang, Luning; Madsen, Heather; Parish, Clare L; Massalas, Jim; Smardencas, Arthur; O'Leary, Claire; Gantois, Ilse; O'Tuathaigh, Colm; Waddington, John L; Ehrlich, Michelle E; Lawrence, Andrew J; Drago, John

    2014-02-01

    Progressive cell loss is observed in the striatum, cerebral cortex, thalamus, hypothalamus, subthalamic nucleus and hippocampus in Huntington disease. In the striatum, dopamine-responsive medium spiny neurons are preferentially lost. Clinical features include involuntary movements, gait and orofacial impairments in addition to cognitive deficits and psychosis, anxiety and mood disorders. We utilized the Cre-LoxP system to generate mutant mice with selective postnatal ablation of D1 dopamine receptor-expressing striatal neurons to determine which elements of the complex Huntington disease phenotype relate to loss of this neuronal subpopulation. Mutant mice had reduced body weight, locomotor slowing, reduced rearing, ataxia, a short stride length wide-based erratic gait, impairment in orofacial movements and displayed haloperidol-suppressible tic-like movements. The mutation was associated with an anxiolytic profile. Mutant mice had significant striatal-specific atrophy and astrogliosis. D1-expressing cell number was reduced throughout the rostrocaudal extent of the dorsal striatum consistent with partial destruction of the striatonigral pathway. Additional striatal changes included up-regulated D2 and enkephalin mRNA, and an increased density of D2 and preproenkephalin-expressing projection neurons, and striatal neuropeptide Y and cholinergic interneurons. These data suggest that striatal D1-cell-ablation alone may account for the involuntary movements and locomotor, balance and orofacial deficits seen not only in HD but also in HD phenocopy syndromes with striatal atrophy. Therapeutic strategies would therefore need to target striatal D1 cells to ameliorate deficits especially when the clinical presentation is dominated by a bradykinetic/ataxic phenotype with involuntary movements.

  5. Differences in Effective Target Volume Between Various Techniques of Accelerated Partial Breast Irradiation

    SciTech Connect

    Shaitelman, Simona F.; Vicini, Frank A.; Grills, Inga S.; Martinez, Alvaro A.; Yan Di; Kim, Leonard H.

    2012-01-01

    Purpose: Different cavity expansions are used to define the clinical target volume (CTV) for accelerated partial breast irradiation (APBI) delivered via balloon brachytherapy (1 cm) vs. three-dimensional conformal radiotherapy (3D-CRT) (1.5 cm). Previous studies have argued that the CTVs generated by these different margins are effectively equivalent. In this study, we use deformable registration to assess the effective CTV treated by balloon brachytherapy on clinically representative 3D-CRT planning images. Methods and Materials: Ten patients previously treated with the MammoSite were studied. Each patient had two computed tomography (CT) scans, one acquired before and one after balloon implantation. In-house deformable registration software was used to deform the MammoSite CTV onto the balloonless CT set. The deformed CTV was validated using anatomical landmarks common to both CT scans. Results: The effective CTV treated by the MammoSite was on average 7% {+-} 10% larger and 38% {+-} 4% smaller than 3D-CRT CTVs created using uniform expansions of 1 and 1.5 cm, respectively. The average effective CTV margin was 1.0 cm, the same as the actual MammoSite CTV margin. However, the effective CTV margin was nonuniform and could range from 5 to 15 mm in any given direction. Effective margins <1 cm were attributable to poor cavity-balloon conformance. Balloon size relative to the cavity did not significantly correlate with the effective margin. Conclusion: In this study, the 1.0-cm MammoSite CTV margin treated an effective volume that was significantly smaller than the 3D-CRT CTV based on a 1.5-cm margin.

  6. Diagnostic characterization of ablation plasma ion implantation

    NASA Astrophysics Data System (ADS)

    Qi, B.; Gilgenbach, R. M.; Jones, M. C.; Johnston, M. D.; Lau, Y. Y.; Wang, L. M.; Lian, J.; Doll, G. L.; Lazarides, A.

    2003-06-01

    Experiments are reported in which two configurations for ablation-plasma-ion-implantation (APII) are characterized by diagnostics and compared. The first configuration oriented the target parallel to the deposition substrate. This orientation yielded ion-beam-assisted deposition of thin films. A delay (>5 μs) between laser and high voltage was necessary for this geometry to avoid arcing between negatively biased substrate and target. The second experimental configuration oriented the target perpendicular to the deposition substrate, reducing arcing, even for zero/negative delay between the laser and the high voltage pulse. This orientation also reduced neutral atom, ballistic deposition on the substrate resulting in a pure ion implantation mode. Ion density measurements were made by resonant laser diagnostics and Langmuir probes, yielding total ion populations in the range of 1014. Implanted ion doses were estimated by electrical diagnostics, and materials analysis, including x-ray energy dispersive spectroscopy and x-ray photoelectron spectroscopy, yielding implanted doses in the range 1012 ions/cm2 per pulse. This yields an APII efficiency of order 10% for implantation of laser ablated ions. Scaling of ion dose with voltage agrees well with a theory assuming the Child-Langmuir law and that the ion current at the sheath edge is due to the uncovering of the ions by the movement of the sheath. Thin film analysis showed excellent adhesion with smoother films for an accelerating voltage of -3.2 kV; higher voltages (-7.7 kV) roughened the film.

  7. Enhanced filament ablation of metals based on plasma grating in air

    SciTech Connect

    Wang, Di; Liu, Fengjiang; Ding, Liangen; Yuan, Shuai; Zeng, Heping

    2015-09-15

    We demonstrate efficient ablation of metals with filamentary plasma grating generated by two intense blue femtosecond filaments and a third focused infrared pulse. This scheme leads to significant promotion of ablation efficiency on metal targets in air in comparison with single infrared or blue filament with equal pulse energy. The reason is that the blue plasma grating firstly provides stronger intensity and a higher density of background electrons, then the delayed infrared pulse accelerates local electrons inside the plasma grating. These two processes finally results in robustly increased electron density and highly ionized metallic atoms.

  8. Shock ion acceleration by an ultrashort circularly polarized laser pulse via relativistic transparency in an exploded target

    NASA Astrophysics Data System (ADS)

    Kim, Young-Kuk; Cho, Myung-Hoon; Song, Hyung Seon; Kang, Teyoun; Park, Hyung Ju; Jung, Moon Youn; Hur, Min Sup

    2015-10-01

    We investigated ion acceleration by an electrostatic shock in an exploded target irradiated by an ultrashort, circularly polarized laser pulse by means of one- and three-dimensional particle-in-cell simulations. We discovered that the laser field penetrating via relativistic transparency (RT) rapidly heated the upstream electron plasma to enable the formation of a high-speed electrostatic shock. Owing to the RT-based rapid heating and the fast compression of the initial density spike by a circularly polarized pulse, a new regime of the shock ion acceleration driven by an ultrashort (20-40 fs), moderately intense (1-1.4 PW) laser pulse is envisaged. This regime enables more efficient shock ion acceleration under a limited total pulse energy than a linearly polarized pulse with crystal laser systems of λ ˜1 μ m .

  9. Shock ion acceleration by an ultrashort circularly polarized laser pulse via relativistic transparency in an exploded target.

    PubMed

    Kim, Young-Kuk; Cho, Myung-Hoon; Song, Hyung Seon; Kang, Teyoun; Park, Hyung Ju; Jung, Moon Youn; Hur, Min Sup

    2015-10-01

    We investigated ion acceleration by an electrostatic shock in an exploded target irradiated by an ultrashort, circularly polarized laser pulse by means of one- and three-dimensional particle-in-cell simulations. We discovered that the laser field penetrating via relativistic transparency (RT) rapidly heated the upstream electron plasma to enable the formation of a high-speed electrostatic shock. Owing to the RT-based rapid heating and the fast compression of the initial density spike by a circularly polarized pulse, a new regime of the shock ion acceleration driven by an ultrashort (20-40 fs), moderately intense (1-1.4 PW) laser pulse is envisaged. This regime enables more efficient shock ion acceleration under a limited total pulse energy than a linearly polarized pulse with crystal laser systems of λ∼1μm.

  10. Enhanced x-ray emissions from Au-Gd mixture targets ablated by a high-power nanosecond laser

    SciTech Connect

    Dong, Yunsong; Shang, Wanli; Yang, Jiamin Zhang, Lu; Zhang, Wenhai; Li, Zhichao; Guo, Liang; Zhan, Xiayu; Du, Huabing; Deng, Bo; Pu, Yikang

    2014-01-28

    As an important x-ray source, enhancement of x-ray emissions from laser-produced plasmas is imperative for various applications. High-Z Au-Gd mixture targets are proposed to enhance the laser to x-ray conversion efficiency compared to pure Au target. In the experiments, a 1 ns frequency-tripled (351 nm wavelength) laser light was used to obtain an intensity of 3×10{sup 14} W/cm{sup 2} on the targets. The x-ray spectra, total absolute x-ray emissions of all space, M-band fraction and backscattering from pure Au and Au-Gd mixture have been measured, respectively. It is shown that the absolute laser to x-ray conversion efficiency for the Au-Gd mixture containing 60% gold by atom is 47.7%, which has a 15% enhancement compared with that of the pure Au target. The experimental results are consistent with the radiation hydrodynamic simulations.

  11. Modifications of thick-target model: re-acceleration of electron beams by static and stochastic electric fields

    NASA Astrophysics Data System (ADS)

    Varady, M.; Karlický, M.; Moravec, Z.; Kašparová, J.

    2014-03-01

    Context. The collisional thick-target model (CTTM) of the impulsive phase of solar flares, together with the famous Carmichael, Sturrock, Hirayama, and Kopp-Pneuman (CSHKP) model, presented for many years a "standard" model, which straightforwardly explained many observational aspects of flares. On the other hand, many critical issues appear when the concept is scrutinised theoretically or with the new generation of hard X-ray (HXR) observations. The famous "electron number problem" or problems related to transport of enormous particle fluxes though the corona represent only two of them. To resolve the discrepancies, several modifications of the CTTM appeared. Aims: We study two of them based on the global and local re-acceleration of non-thermal electrons by static and stochastic electric fields during their transport from the coronal acceleration site to the thick-target region in the chromosphere. We concentrate on a comparison of the non-thermal electron distribution functions, chromospheric energy deposits, and HXR spectra obtained for both considered modifications with the CTTM itself. Methods: The results were obtained using a relativistic test-particle approach. We simulated the transport of non-thermal electrons with a power-law spectrum including the influence of scattering, energy losses, magnetic mirroring, and also the effects of the electric fields corresponding to both modifications of the CTTM. Results: We show that both modifications of the CTTM change the outcome of the chromospheric bombardment in several aspects. The modifications lead to an increase in chromospheric energy deposit, change of its spatial distribution, and a substantial increase in the corresponding HXR spectrum intensity. Conclusions: The re-acceleration in both models reduces the demands on the efficiency of the primary coronal accelerator, on the electron fluxes transported from the corona downwards, and on the total number of accelerated coronal electrons during flares.

  12. Agglomeration in core-shell structure of CuAg nanoparticles synthesized by the laser ablation of Cu target in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Petrović, S.; Salatić, B.; Milovanović, D.; Lazović, V.; Živković, Lj; Trtica, M.; Jelenković, B.

    2015-02-01

    Metallic copper Cu and bimetallic copper-silver CuAg nanoparticles (NPs) are generated by the ablation of copper bulk target in water and aqueous Ag colloidal solution, respectively. The experiments were performed using nanosecond Nd:YAG laser operating at 1064 nm. The generated NPs are characterized by UV-vis absorption spectroscopy, laser-induced breakdown spectroscopy, dynamic light scattering and scanning electron microscopy. The conducted investigations can be summarized as follows: (i) CuAg NPs colloidal solution possess the absorption in UV-vis spectral region, which can be attributed to the Cu-component; (ii) the primary bimetallic CuAg NPs have near uniform dimensions with diameter of about 15 nm, and as a rule, they are grouped into larger agglomerates without defined morphology; (iii) the obtained Cu NPs have mainly spherical form with average diameters up to 20 nm. Both types of NPs show a tendency towards the formation of large agglomerates with different morphology. Bimetallic NPs show the plasmon resonance in the vicinity of 640 nm with a good coincidence with formation of the colloidal solution of pure Cu NPs. The results also demonstrate that the core-shell structure (Ag-rich core/Cu-rich shell) is important for the formation of the bimetallic NPs, also agreeing very well with theory.

  13. Role of target-substrate distance on the growth of CuInSe2 thin films by pulsed laser ablation technique

    NASA Astrophysics Data System (ADS)

    Rawat, Kusum; Dhruvashi, Shishodia, P. K.

    2016-05-01

    CuInSe2 thin films have been deposited on corning glass substrates by pulsed laser ablation technique. The chamber pressure and substrate temperature was maintained at 1 × 10-6 torr and 550°C respectively during deposition of the films. The influence of target to substrate (T-S) distance on the structural and optical properties of thin films have been investigated by grazing incidence x-ray diffraction, Raman spectroscopy, scanning electron microscope and UV-Vis-NIR spectroscopy. The study reveals that thin films crystallized in a chalcopyrite structure with highly preferential orientation along (112) plane. Optimum T-S distance has been attained for the growth of thin films with large grain size. An intense Raman peak at 174 cm-1 corresponding to dominant A1 vibration mode is gradually shifted to smaller wavenumber with the increase in T-S distance. The optical bandgap energy of the films was evaluated and found to vary with the T-S distance. The bandgap tailing was observed to obey the Urbach rule and the Urbach energy was also calculated for the films. Scanning electron micrographs depicts uniform densely packed grains and EDAX studies revealed the elemental composition of CuInSe2 thin films.

  14. Catamenial-like seizure exacerbation in mice with targeted ablation of extrasynaptic δGABA-a receptors in the brain.

    PubMed

    Clossen, Bryan L; Reddy, Doodipala Samba

    2017-02-25

    Neurosteroids play a key role in catamenial epilepsy, a menstrual cycle-related seizure clustering in women with epilepsy. While neurosteroids act on all GABA-A receptor isoforms, they cause greater effects on extrasynaptic δGABA-A receptors that mediate tonic inhibition in the brain. Previously, we identified a potential GABA-A receptor mechanism for catamenial epilepsy. However, the precise functional role of extrasynaptic δGABA-A receptors in the pathophysiology of catamenial epilepsy remains unclear. In this study, we utilized mice lacking extrasynaptic δGABA-A receptors (δKO) to investigate whether reduction of tonic inhibition affects catamenial seizure susceptibility or intensity. Intact female wildtype (WT) and δKO mice were subjected to hippocampus kindling until they exhibited stage 5 seizures. Elevated gonadal hormone-based neurosteroid levels were induced by standard gonadotropin regimen and neurosteroid withdrawal (NSW) was triggered by finasteride. NSW increased susceptibility to, as well the intensity of evoked catamenial-like seizures in WT and δKO mice. However, fully kindled δKO mice exhibited an accelerated and augmented response to NSW, with a more rapid increase in seizure susceptibility and intensity than WT mice undergoing the NSW paradigm. Moreover, δKO mice in NSW showed reduced benzodiazepine sensitivity, but in stark contrast to the increased neurosteroid sensitivity observed in WT animals, δKO mice displayed no change in neurosteroid sensitivity in response to NSW. The increased catamenial seizure exacerbation and alterations in antiseizure drug responses are consistent with NSW-induced changes in the abundance of δGABA-A receptors. Collectively, these findings provide evidence of a potential protective role for extrasynaptic δGABA-A receptors in catamenial-like seizures. © 2017 Wiley Periodicals, Inc.

  15. Dynamics of high-energy proton beam acceleration and focusing from hemisphere-cone targets by high-intensity lasers.

    PubMed

    Qiao, B; Foord, M E; Wei, M S; Stephens, R B; Key, M H; McLean, H; Patel, P K; Beg, F N

    2013-01-01

    Acceleration and focusing of high-energy proton beams from fast-ignition (FI) -related hemisphere-cone assembled targets have been numerically studied by hybrid particle-in-cell simulations and compared with those from planar-foil and open-hemisphere targets. The whole physical process including the laser-plasma interaction has been self-consistently modeled for 15 ps, at which time the protons reach asymptotic motion. It is found that the achievable focus of proton beams is limited by the thermal pressure gradients in the co-moving hot electrons, which induce a transverse defocusing electric field that bends proton trajectories near the axis. For the advanced hemisphere-cone target, the flow of hot electrons along the cone wall induces a local transverse focusing sheath field, resulting in a clear enhancement in proton focusing; however, it leads to a significant loss of longitudinal sheath potential, reducing the total conversion efficiency from laser to protons.

  16. Detection of Fast Moving and Accelerating Targets Compensating Range and Doppler Migration

    DTIC Science & Technology

    2014-06-01

    Radon -Fourier transform has been introduced to realize long- term coherent integration of the moving targets with range migration [8, 9]. Radon ...2010) Long-time coherent integration for radar target detection base on Radon -Fourier transform, in Proceedings of the IEEE Radar Conference, pp...432–436. 9. Xu, J., Yu, J., Peng, Y. & Xia, X. (2011) Radon -Fourier transform for radar target detection, I: Generalized Doppler filter bank, IEEE

  17. Quality of graphite target for biological/biomedical/environmental applications of 14C-accelerator mass spectrometry.

    PubMed

    Kim, Seung-Hyun; Kelly, Peter B; Ortalan, Volkan; Browning, Nigel D; Clifford, Andrew J

    2010-03-15

    Catalytic graphitization for (14)C-accelerator mass spectrometry ((14)C-AMS) produced various forms of elemental carbon. Our high-throughput Zn reduction method (C/Fe = 1:5, 500 degrees C, 3 h) produced the AMS target of graphite-coated iron powder (GCIP), a mix of nongraphitic carbon and Fe(3)C. Crystallinity of the AMS targets of GCIP (nongraphitic carbon) was increased to turbostratic carbon by raising the C/Fe ratio from 1:5 to 1:1 and the graphitization temperature from 500 to 585 degrees C. The AMS target of GCIP containing turbostratic carbon had a large isotopic fractionation and a low AMS ion current. The AMS target of GCIP containing turbostratic carbon also yielded less accurate/precise (14)C-AMS measurements because of the lower graphitization yield and lower thermal conductivity that were caused by the higher C/Fe ratio of 1:1. On the other hand, the AMS target of GCIP containing nongraphitic carbon had higher graphitization yield and better thermal conductivity over the AMS target of GCIP containing turbostratic carbon due to optimal surface area provided by the iron powder. Finally, graphitization yield and thermal conductivity were stronger determinants (over graphite crystallinity) for accurate/precise/high-throughput biological, biomedical, and environmental (14)C-AMS applications such as absorption, distribution, metabolism, elimination (ADME), and physiologically based pharmacokinetics (PBPK) of nutrients, drugs, phytochemicals, and environmental chemicals.

  18. Toward a physics design for NDCX-II, an ion accelerator for warm dense matter and HIF target physics studies

    SciTech Connect

    Friedman, A.; Barnard, J.J.; Briggs, R.J.; Davidson, R.C.; Dorf, M.; Grote, D.P.; Henestroza, E.; Lee, E.P.; Leitner, M.A.; Logan, B.G.; Sefkow, A.B.; Sharp, W.M.; Waldron, W.L.; Welch, D.R.; Yu, S.S.

    2008-08-01

    The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL), a collaborationof LBNL, LLNL, and PPPL, has achieved 60-fold pulse compression of ion beams on the Neutralized Drift Compression eXperiment (NDCX) at LBNL. In NDCX, a ramped voltage pulse from an induction cell imparts a velocity"tilt" to the beam; the beam's tail then catches up with its head in a plasma environment that provides neutralization. The HIFS-VNL's mission is to carry out studies of Warm Dense Matter (WDM) physics using ion beams as the energy source; an emerging thrust is basic target physics for heavy ion-driven Inertial Fusion Energy (IFE). These goals require an improved platform, labeled NDCX-II. Development of NDCX-II at modest cost was recently enabled by the availability of induction cells and associated hardware from the decommissioned Advanced Test Accelerator (ATA) facility at LLNL. Our initial physics design concept accelerates a ~;;30 nC pulse of Li+ ions to ~;;3 MeV, then compresses it to ~;;1 ns while focusing it onto a mm-scale spot. It uses the ATA cells themselves (with waveforms shaped by passive circuits) to impart the final velocity tilt; smart pulsers provide small corrections. The ATA accelerated electrons; acceleration of non-relativistic ions involves more complex beam dynamics both transversely and longitudinally. We are using analysis, an interactive one-dimensional kinetic simulation model, and multidimensional Warp-code simulations to develop the NDCX-II accelerator section. Both LSP and Warp codes are being applied to the beam dynamics in the neutralized drift and final focus regions, and the plasma injection process. The status of this effort is described.

  19. Toward a physics design for NDCX II, an ion accelerator for warm dense matter and HIF target physics studies

    SciTech Connect

    Friedman, A; Barnard, J J; Briggs, R J; Davidson, R C; Dorf, M; Grote, D P; Henestroza, E; Lee, E P; Leitner, M A; Logan, B G; Sefkow, A B; Sharp, W M; Waldron, W L; Welch, D R; Yu, S S

    2008-07-30

    The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL), a collaboration of LBNL, LLNL, and PPPL, has achieved 60-fold pulse compression of ion beams on the Neutralized Drift Compression eXperiment (NDCX) at LBNL. In NDCX, a ramped voltage pulse from an induction cell imparts a velocity 'tilt' to the beam; the beam's tail then catches up with its head in a plasma environment that provides neutralization. The HIFS-VNL's mission is to carry out studies of warm dense matter (WDM) physics using ion beams as the energy source; an emerging thrust is basic target physics for heavy ion-driven inertial fusion energy (IFE). These goals require an improved platform, labeled NDCX-II. Development of NDCX-II at modest cost was recently enabled by the availability of induction cells and associated hardware from the decommissioned advanced test accelerator (ATA) facility at LLNL. Our initial physics design concept accelerates an {approx} 30 nC pulse of Li{sup +} ions to {approx} 3 MeV, then compresses it to {approx} 1 ns while focusing it onto a mm-scale spot. It uses the ATA cells themselves (with waveforms shaped by passive circuits) to impart the final velocity tilt; smart pulsers provide small corrections. The ATA accelerated electrons; acceleration of non-relativistic ions involves more complex beam dynamics both transversely and longitudinally. We are using an interactive one-dimensional kinetic simulation model and multidimensional Warp-code simulations to develop the NDCX-II accelerator section. Both LSP and Warp codes are being applied to the beam dynamics in the neutralized drift and final focus regions, and the plasma injection process. The status of this effort is described.

  20. Demonstration of the improved rocket efficiency in direct-drive implosions using different ablator materials.

    PubMed

    Michel, D T; Goncharov, V N; Igumenshchev, I V; Epstein, R; Froula, D H

    2013-12-13

    The success of direct-drive implosions depends critically on the ability to create high ablation pressures (∼100  Mbar) and accelerating the imploding shell to ignition-relevant velocities (>3.7×10(7 ) cm/s) using direct laser illumination. This Letter reports on an experimental study of the conversion of absorbed laser energy into kinetic energy of the shell (rocket efficiency) where different ablators were used to vary the ratio of the atomic number to the atomic mass. The implosion velocity of Be shells is increased by 20% compared to C and CH shells in direct-drive implosions when a constant initial target mass is maintained. These measurements are consistent with the predicted increase in the rocket efficiency of 28% for Be and 5% for C compared to a CH ablator.

  1. Radiation-Pressure Acceleration of Ion Beams from Nanofoil Targets: The Leaky Light-Sail Regime

    SciTech Connect

    Qiao, B.; Zepf, M.; Borghesi, M.; Dromey, B.; Geissler, M.; Karmakar, A.; Gibbon, P.

    2010-10-08

    A new ion radiation-pressure acceleration regime, the 'leaky light sail', is proposed which uses sub-skin-depth nanometer foils irradiated by circularly polarized laser pulses. In the regime, the foil is partially transparent, continuously leaking electrons out along with the transmitted laser field. This feature can be exploited by a multispecies nanofoil configuration to stabilize the acceleration of the light ion component, supplementing the latter with an excess of electrons leaked from those associated with the heavy ions to avoid Coulomb explosion. It is shown by 2D particle-in-cell simulations that a monoenergetic proton beam with energy 18 MeV is produced by circularly polarized lasers at intensities of just 10{sup 19} W/cm{sup 2}. 100 MeV proton beams are obtained by increasing the intensities to 2x10{sup 20} W/cm{sup 2}.

  2. Radiation-pressure acceleration of ion beams from nanofoil targets: the leaky light-sail regime.

    PubMed

    Qiao, B; Zepf, M; Borghesi, M; Dromey, B; Geissler, M; Karmakar, A; Gibbon, P

    2010-10-08

    A new ion radiation-pressure acceleration regime, the "leaky light sail," is proposed which uses sub-skin-depth nanometer foils irradiated by circularly polarized laser pulses. In the regime, the foil is partially transparent, continuously leaking electrons out along with the transmitted laser field. This feature can be exploited by a multispecies nanofoil configuration to stabilize the acceleration of the light ion component, supplementing the latter with an excess of electrons leaked from those associated with the heavy ions to avoid Coulomb explosion. It is shown by 2D particle-in-cell simulations that a monoenergetic proton beam with energy 18 MeV is produced by circularly polarized lasers at intensities of just 10¹⁹  W/cm². 100 MeV proton beams are obtained by increasing the intensities to 2 × 10²⁰  W/cm².

  3. Enhanced proton acceleration by intense laser interaction with an inverse cone target

    NASA Astrophysics Data System (ADS)

    Bake, Muhammad Ali; Aimidula, Aimierding; Xiaerding, Fuerkaiti; Rashidin, Reyima

    2016-08-01

    The generation and control of high-quality proton bunches using focused intense laser pulse on an inverse cone target is investigated with a set of particle-in-cell simulations. The inverse cone is a high atomic number conical frustum with a thin solid top and open base, where the laser impinges onto the top surface directly, not down the open end of the cone. Results are compared with a simple planar target, where the proton angular distribution is very broad because of transverse divergence of the electromagnetic fields behind the target. For a conical target, hot electrons along the cone wall surface induce a transverse focusing sheath field. This field can effectively suppress the spatial spreading of the protons, resulting in a high-quality small-emittance, low-divergence proton beam. A slightly lower proton beam peak energy than that of a conventional planar target was also found.

  4. Targeting electrostatic interactions in accelerated molecular dynamics with application to protein partial unfolding.

    PubMed

    Flores-Canales, Jose C; Kurnikova, Maria

    2015-06-09

    Accelerated molecular dynamics (aMD) is a promising sampling method to generate an ensemble of conformations and to explore the free energy landscape of proteins in explicit solvent. Its success resides in its ability to reduce barriers in the dihedral and the total potential energy space. However, aMD simulations of large proteins can generate large fluctuations of the dihedral and total potential energy with little conformational changes in the protein structure. To facilitate wider conformational sampling of large proteins in explicit solvent, we developed a direct intrasolute electrostatic interactions accelerated MD (DISEI-aMD) approach. This method aims to reduce energy barriers within rapidly changing electrostatic interactions between solute atoms at short-range distances. It also results in improved reconstruction quality of the original statistical ensemble of the system. Recently, we characterized a pH-dependent partial unfolding of diphtheria toxin translocation domain (T-domain) using microsecond long MD simulations. In this work, we focus on the study of conformational changes of a low-pH T-domain model in explicit solvent using DISEI-aMD. On the basis of the simulations of the low-pH T-domain model, we show that the proposed sampling method accelerates conformational rearrangement significantly faster than multiple standard aMD simulations and microsecond long conventional MD simulations.

  5. Synchronized ion acceleration by ultraintense slow light and electron source for x-ray production from low-density targets

    NASA Astrophysics Data System (ADS)

    Brantov, A. V.; Bychenkov, V. Yu

    2017-03-01

    Synchronized proton acceleration by ultraintense slow light in a low-density target Brantov et al (2016 Phys. Rev. Lett. 116 085004) is studied for a circularly polarized laser pulse. This study demonstrates the advantage of circularly polarized light compared with linearly polarized light used for high-energy proton generation. At the same time, high-energy electron production for gamma-ray generation is not sensitive to the polarization of the laser pulse. Both the proton and the electron sources are considered in application to petawatt-class lasers.

  6. Depth Profiling of Polymer Composites by Ultrafast Laser Ablation

    NASA Astrophysics Data System (ADS)

    Young, Christopher; Clayton, Clive; Longtin, Jon

    2009-03-01

    Past work has shown femtosecond laser ablation to be an athermal process at low fluences in polymer systems. The ablation rate in this low fluence regime is very low, allowing for micro-scale removal of material. We have taken advantage of this fact to perform shallow depth profiling ablation on carbon fiber reinforced polymer (CFRP) composites. Neat composite and resin samples were studied to establish reference ablation profiles. These profiles and the effects of the heterogeneous distribution of carbon fibers were observed through confocal laser profilometry and optical and scanning electron microscopy. Weathered materials that have been subjected to accelerated tests in artificial sunlight or water conditions were ablated to determine the correlation between exposure and change in ablation characteristics. Preliminary Raman and micro-ATR analysis performed before and after ablation shows no chemical changes indicative of thermal effects. The low-volume-ablation property was utilized in an attempt to expose the sizing-matrix interphase for analysis.

  7. Non-Invasive Targeted Peripheral Nerve Ablation Using 3D MR Neurography and MRI-Guided High-Intensity Focused Ultrasound (MR-HIFU): Pilot Study in a Swine Model

    PubMed Central

    Huisman, Merel; Staruch, Robert M.; Ladouceur-Wodzak, Michelle; van den Bosch, Maurice A.; Burns, Dennis K.; Chhabra, Avneesh; Chopra, Rajiv

    2015-01-01

    Purpose Ultrasound (US)-guided high intensity focused ultrasound (HIFU) has been proposed for noninvasive treatment of neuropathic pain and has been investigated in in-vivo studies. However, ultrasound has important limitations regarding treatment guidance and temperature monitoring. Magnetic resonance (MR)-imaging guidance may overcome these limitations and MR-guided HIFU (MR-HIFU) has been used successfully for other clinical indications. The primary purpose of this study was to evaluate the feasibility of utilizing 3D MR neurography to identify and guide ablation of peripheral nerves using a clinical MR-HIFU system. Methods Volumetric MR-HIFU was used to induce lesions in the peripheral nerves of the lower limbs in three pigs. Diffusion-prep MR neurography and T1-weighted images were utilized to identify the target, plan treatment and immediate post-treatment evaluation. For each treatment, one 8 or 12 mm diameter treatment cell was used (sonication duration 20 s and 36 s, power 160–300 W). Peripheral nerves were extracted < 3 hours after treatment. Ablation dimensions were calculated from thermal maps, post-contrast MRI and macroscopy. Histological analysis included standard H&E staining, Masson’s trichrome and toluidine blue staining. Results All targeted peripheral nerves were identifiable on MR neurography and T1-weighted images and could be accurately ablated with a single exposure of focused ultrasound, with peak temperatures of 60.3 to 85.7°C. The lesion dimensions as measured on MR neurography were similar to the lesion dimensions as measured on CE-T1, thermal dose maps, and macroscopy. Histology indicated major hyperacute peripheral nerve damage, mostly confined to the location targeted for ablation. Conclusion Our preliminary results indicate that targeted peripheral nerve ablation is feasible with MR-HIFU. Diffusion-prep 3D MR neurography has potential for guiding therapy procedures where either nerve targeting or avoidance is desired, and may

  8. Analysis of the structure, configuration, and sizing of Cu and Cu oxide nanoparticles generated by fs laser ablation of solid target in liquids

    SciTech Connect

    Santillan, J. M. J.; Videla, F. A.; Schinca, D. C.; Scaffardi, L. B.; Fernandez van Raap, M. B.

    2013-04-07

    We report on the analysis of structure, configuration, and sizing of Cu and Cu oxide nanoparticles (Nps) produced by femtosecond (fs) laser ablation of solid copper target in liquids. Laser pulse energy ranged between 500 {mu}J and 50 {mu}J. Water and acetone were used to produce the colloidal suspensions. The study was performed through optical extinction spectroscopy using Mie theory to fit the full experimental spectra, considering free and bound electrons size dependent contributions to the metal dielectric function. Raman spectroscopy and AFM technique were also used to characterize the sample. Considering the possible oxidation of copper during the fabrication process, two species (Cu and Cu{sub 2}O) arranged in two structures (bare core or core-shell) and in two configuration types (Cu-Cu{sub 2}O or Cu{sub 2}O-Cu) were considered for the fitting depending on the laser pulse energy and the surrounding media. For water at high energy, it can be observed that a Cu-Cu{sub 2}O configuration fits the experimental spectra of the colloidal suspension, while for decreasing energy and below a certain threshold, a Cu{sub 2}O-Cu configuration needs to be included for the optimum fit. Both species coexist for energies below 170 {mu}J for water. On the other hand, for acetone at high energy, optimum fit of the full spectrum suggests the presence a bimodal Cu-Cu{sub 2}O core-shell Nps distribution while for decreasing energy and below a 70 {mu}J threshold energy value, Cu{sub 2}O-Cu core-shell Nps must be included, together with the former configuration, for the fit of the full spectrum. We discuss possible reasons for the changes in the structural configuration of the core-shell Nps.

  9. Favorable target positions for intense laser acceleration of electrons in hydrogen-like, highly-charged ions

    SciTech Connect

    Pi, Liang-Wen; Starace, Anthony F.; Hu, S. X.

    2015-09-15

    Classical relativistic Monte Carlo simulations of petawatt laser acceleration of electrons bound initially in hydrogen-like, highly-charged ions show that both the angles and energies of the laser-accelerated electrons depend on the initial ion positions with respect to the laser focus. Electrons bound in ions located after the laser focus generally acquire higher (≈GeV) energies and are ejected at smaller angles with respect to the laser beam. Our simulations assume a tightly-focused linearly-polarized laser pulse with intensity approaching 10{sup 22 }W/cm{sup 2}. Up to fifth order corrections to the paraxial approximation of the laser field in the focal region are taken into account. In addition to the laser intensity, the Rayleigh length in the focal region is shown to play a significant role in maximizing the final energy of the accelerated electrons. Results are presented for both Ne{sup 9+} and Ar{sup 17+} target ions.

  10. Effects of nanosecond-scale prepulse on generation of high-energy protons in target normal sheath acceleration

    SciTech Connect

    Wang, W. P.; Shen, B. F.; Zhang, H.; Xu, Y.; Li, Y. Y.; Lu, X. M.; Wang, C.; Liu, Y. Q.; Shi, Y.; Leng, Y. X.; Liang, X. Y.; Li, R. X.; Xu, Z. Z.; Lu, J. X.; Wang, N. Y.

    2013-06-03

    A pulse cleaner based on noncollinear optical-parametric amplification and second-harmonic generation processes is used to improve the contrast of a laser of peak intensity {approx}2 Multiplication-Sign 10{sup 19} W/cm{sup 2} to {approx}10{sup 11} at 100 ps before the peak of the main pulse. A 7 MeV proton beam is observed when a 2.5 {mu}m-thick Al foil is irradiated by this high-contrast laser. The maximum proton energy decreases to 2.9 MeV when a low-contrast ({approx}10{sup 8}) laser is used. Two-dimensional particle-in-cell simulations combined with MULTI simulations show that the maximum proton energy sensitively relies on the detecting direction. The ns-time-scale prepulse can bend a thin target before the main pulse arrives, which reduces maximum proton energy in the target normal sheath acceleration.

  11. Efficient and stable proton acceleration by irradiating a two-layer target with a linearly polarized laser pulse

    SciTech Connect

    Wang, H. Y.; Yan, X. Q.; Chen, J. E.; He, X. T.; Ma, W. J.; Bin, J. H.; Schreiber, J.; Tajima, T.; Habs, D.

    2013-01-15

    We report an efficient and stable scheme to generate {approx}200 MeV proton bunch by irradiating a two-layer targets (near-critical density layer+solid density layer with heavy ions and protons) with a linearly polarized Gaussian pulse at intensity of 6.0 Multiplication-Sign 10{sup 20} W/cm{sup 2}. Due to self-focusing of laser and directly accelerated electrons in the near-critical density layer, the proton energy is enhanced by a factor of 3 compared to single-layer solid targets. The energy spread of proton is also remarkably reduced. Such scheme is attractive for applications relevant to tumor therapy.

  12. Open Access Target Validation Is a More Efficient Way to Accelerate Drug Discovery

    PubMed Central

    Lee, Wen Hwa

    2015-01-01

    There is a scarcity of novel treatments to address many unmet medical needs. Industry and academia are finally coming to terms with the fact that the prevalent models and incentives for innovation in early stage drug discovery are failing to promote progress quickly enough. Here we will examine how an open model of precompetitive public–private research partnership is enabling efficient derisking and acceleration in the early stages of drug discovery, whilst also widening the range of communities participating in the process, such as patient and disease foundations. PMID:26042736

  13. Ion acceleration with a narrow energy spectrum by nanosecond laser-irradiation of solid target

    SciTech Connect

    Altana, C.; Lanzalone, G.; Mascali, D.; Cirrone, G. A. P.; Schillaci, F.; Tudisco, S.; Muoio, A.

    2016-02-15

    In laser-driven plasma, ion acceleration of aluminum with the production of a quasi-monoenergetic beam has occurred. A useful device to analyze the ions is the Thomson parabolas spectrometer, a well-known diagnostic that is able to obtain information on charge-to-mass ratio and energy distribution of the charged particles. At the LENS (Laser Energy for Nuclear Science) laboratory of INFN-LNS in Catania, experimental measures were carried out; the features of LENS are: Q-switched Nd:YAG laser with 2 J laser energy, 1064 nm fundamental wavelengths, and 6 ns pulse duration.

  14. Plans and status of the Beryllium ablator campaign on NIF

    NASA Astrophysics Data System (ADS)

    Kline, J. L.; Yi, S. A.; Simakov, A. N.; Wilson, D. C.; Olson, R. E.; Krasheninnikova, N. S.; Kyrala, G. A.; Perry, T. S.; Batha, S. H.; Dewald, E. L.; Edwards, M. J.; MacKinnon, A. J.; Meezan, N. B.

    2014-10-01

    Beryllium has long been known to have excellent properties for indirectly driven ICF implosions including enhanced ablation pressure, implosion velocity, and mass ablation rate. The high ablation velocity leads to stabilization of ablative hydrodynamic instabilities and higher ablation pressures. Recent ``high foot'' experiments have shown ablative Rayleigh-Taylor to be a leading cause of degraded performance for ICF implosions. While Beryllium ablators have these advantages, there are also risks associated with Beryllium target designs. A campaign is underway to design and to test these advantages for comparison with other ablator options and determine which provides the best path forward for ICF. Experiments using Beryllium ablators are expected to start in the late summer of 2014. This presentation will discuss the status of the experiments and layout the plans/goals for the campaign. This work is supported by the US DOE.

  15. Lessons from shielding retrofits at the LAMPF/LANSCE/PSR accelerator, beam lines and target facilities

    SciTech Connect

    Macek, R.J.

    1994-07-01

    The experience in the past 7 years to improve the shielding and radiation control systems at the Los Alamos Meson Physics Facility (LAMPF) and the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) provides important lessons for the design of radiation control systems at future, high beam power proton accelerator facilities. Major issues confronted and insight gained in developing shielding criteria and in the use of radiation interlocks are discussed. For accelerators and beam lines requiring hands-on-maintenance, our experience suggests that shielding criteria based on accident scenarios will be more demanding than criteria based on routinely encountered beam losses. Specification and analysis of the appropriate design basis accident become all important. Mitigation by active protection systems of the consequences of potential, but severe, prompt radiation accidents has been advocated as an alternate choice to shielding retrofits for risk management at both facilities. Acceptance of active protection systems has proven elusive primarily because of the difficulty in providing convincing proof that failure of active systems (to mitigate the accident) is incredible. Results from extensive shielding assessment studies are presented including data from experimental beam spill tests, comparisons with model estimates, and evidence bearing on the limitations of line-of-sight attenuation models in complex geometries. The scope and significant characteristics of major shielding retrofit projects at the LAMPF site are illustrated by the project to improve the shielding beneath a road over a multiuse, high-intensity beam line (Line D).

  16. Automated cell-by-cell tissue imaging and single-cell analysis for targeted morphologies by laser ablation electrospray ionization mass spectrometry.

    PubMed

    Li, Hang; Smith, Brian K; Shrestha, Bindesh; Márk, László; Vertes, Akos

    2015-01-01

    Mass spectrometry imaging (MSI) is an emerging technology for the mapping of molecular distributions in tissues. In most of the existing studies, imaging is performed by sampling on a predefined rectangular grid that does not reflect the natural cellular pattern of the tissue. Delivering laser pulses by a sharpened optical fiber in laser ablation electrospray ionization (LAESI) mass spectrometry (MS) has enabled the direct analysis of single cells and subcellular compartments. Cell-by-cell imaging had been demonstrated using LAESI-MS, where individual cells were manually selected to serve as natural pixels for tissue imaging. Here we describe a protocol for a novel cell-by-cell LAESI imaging approach that automates cell recognition and addressing for systematic ablation of individual cells. Cell types with particular morphologies can also be selected for analysis. First, the cells are recognized as objects in a microscope image. The coordinates of their centroids are used by a stage-control program to sequentially position the cells under the optical fiber tip for laser ablation. This approach increases the image acquisition efficiency and stability, and enables the investigation of extended or selected tissue areas. In the LAESI process, the ablation events result in mass spectra that represent the metabolite levels in the ablated cells. Peak intensities of selected ions are used to represent the metabolite distributions in the tissue with single-cell resolution.

  17. Transient Thermo-Hydraulic Analysis of the Windowless Target System for the Lead Bismuth Eutectic Cooled Accelerator Driven System

    SciTech Connect

    Bianchi, Fosco; Ferri, Roberta; Moreau, Vincent

    2006-07-01

    The target system, whose function is to supply an external neutron source to the ADS sub-critical core to sustain the neutron chain reaction, is the most critical part of an ADS being subject to severe thermo-mechanical loading and material damage due to accelerator protons and fission neutrons. A windowless option was chosen as reference configuration for the target system of the LBE-cooled ADS within the European PDS-XADS project in order to reduce the material damage and to increase its life. This document deals with the thermo-hydraulic results of the calculations performed with STAR-CD and RELAP5 codes for studying the behaviour of the windowless target system during off-normal operating conditions. It also reports a description of modifications properly implemented in the codes needed for this analysis. The windowless target system shows a satisfactory thermo-hydraulic behaviour for the analysed accidents, except for the loss of both pumps without proton beam shut-off and the beam trips lasting more than one second. (authors)

  18. Bright betatronlike x rays from radiation pressure acceleration of a mass-limited foil target.

    PubMed

    Yu, Tong-Pu; Pukhov, Alexander; Sheng, Zheng-Ming; Liu, Feng; Shvets, Gennady

    2013-01-25

    By using multidimensional particle-in-cell simulations, we study the electromagnetic emission from radiation pressure acceleration of ultrathin mass-limited foils. When a circularly polarized laser pulse irradiates the foil, the laser radiation pressure pushes the foil forward as a whole. The outer wings of the pulse continue to propagate and act as a natural undulator. Electrons move together with ions longitudinally but oscillate around the latter transversely, forming a self-organized helical electron bunch. When the electron oscillation frequency coincides with the laser frequency as witnessed by the electron, betatronlike resonance occurs. The emitted x rays by the resonant electrons have high brightness, short durations, and broad band ranges which may have diverse applications.

  19. Biological/biomedical accelerator mass spectrometry targets. 2. Physical, morphological, and structural characteristics.

    PubMed

    Kim, Seung-Hyun; Kelly, Peter B; Clifford, Andrew J

    2008-10-15

    The number of biological/biomedical applications that require AMS to achieve their goals is increasing, and so is the need for a better understanding of the physical, morphological, and structural traits of high quality of AMS targets. The metrics of quality included color, hardness/texture, and appearance (photo and SEM), along with FT-IR, Raman, and powder X-ray diffraction spectra that correlate positively with reliable and intense ion currents and accuracy, precision, and sensitivity of fraction modern ( F m). Our previous method produced AMS targets of gray-colored iron-carbon materials (ICM) 20% of the time and of graphite-coated iron (GCI) 80% of the time. The ICM was hard, its FT-IR spectra lacked the sp (2) bond, its Raman spectra had no detectable G' band at 2700 cm (-1), and it had more iron carbide (Fe 3C) crystal than nanocrystalline graphite or graphitizable carbon (g-C). ICM produced low and variable ion current whereas the opposite was true for the graphitic GCI. Our optimized method produced AMS targets of graphite-coated iron powder (GCIP) 100% of the time. The GCIP shared some of the same properties as GCI in that both were black in color, both produced robust ion current consistently, their FT-IR spectra had the sp (2) bond, their Raman spectra had matching D, G, G', D +G, and D '' bands, and their XRD spectra showed matching crystal size. GCIP was a powder that was easy to tamp into AMS target holders that also facilitated high throughput. We concluded that AMS targets of GCIP were a mix of graphitizable carbon and Fe 3C crystal, because none of their spectra, FT-IR, Raman, or XRD, matched exactly those of the graphite standard. Nevertheless, AMS targets of GCIP consistently produced the strong, reliable, and reproducible ion currents for high-throughput AMS analysis (270 targets per skilled analyst/day) along with accurate and precise F m values.

  20. Targeted disruption of fibrinogen like protein-1 accelerates hepatocellular carcinoma development

    PubMed Central

    Nayeb-Hashemi, Hamed; Desai, Anal; Demchev, Valeriy; Bronson, Roderick T.; Hornick, Jason L.; Cohen, David E.; Ukomadu, Chinweike

    2015-01-01

    Fibrinogen like protein-1 (Fgl1) is a predominantly liver expressed protein that has been implicated as both a hepatoprotectant and a hepatocyte mitogen. Fgl1 expression is decreased in hepatocellular carcinoma (HCC) and its loss correlates with a poorly differentiated phenotype. To better elucidate the role of Fgl1 in hepatocarcinogenesis, we treated mice wild type or null for Fgl1 with diethyl nitrosamine and monitored for incidence of hepatocellular cancer. We find that mice lacking Fgl1 develop HCC at more than twice the rate of wild type mice. We show that hepatocellular cancers from Fgl1 null mice are molecularly distinct from those of the wild type mice. In tumors from Fgl1 null mice there is enhanced activation of Akt and downstream targets of the mammalian target of rapamycin (mTOR). In addition, there is paradoxical up regulation of putative hepatocellular cancer tumor suppressors; tripartite motif-containing protein 35 (Trim35) and tumor necrosis factor super family 10b (Tnfrsf10b). Taken together, these findings suggest that Fgl1 acts as a tumor suppressor in hepatocellular cancer through an Akt dependent mechanism and supports its role as a potential therapeutic target in HCC. PMID:26225745

  1. Pellet ablation and ablation model development

    SciTech Connect

    Houlberg, W.A.

    1989-01-01

    A broad survey of pellet ablation is given, based primarily on information presented at this meeting. The implications of various experimental observations for ablation theory are derived from qualitative arguments of the physics involved. The major elements of a more complete ablation theory are then outlined in terms of these observations. This is followed by a few suggestions on improving the connections between theory and experimental results through examination of ablation data. Although this is a rather aggressive undertaking for such a brief (and undoubtedly incomplete) assessment, some of the discussion may help us advance the understanding of pellet ablation. 17 refs.

  2. Targeted disruption of fibrinogen like protein-1 accelerates hepatocellular carcinoma development

    SciTech Connect

    Nayeb-Hashemi, Hamed; Desai, Anal; Demchev, Valeriy; Bronson, Roderick T.; Hornick, Jason L.; Cohen, David E.; Ukomadu, Chinweike

    2015-09-18

    Fibrinogen like protein-1 (Fgl1) is a predominantly liver expressed protein that has been implicated as both a hepatoprotectant and a hepatocyte mitogen. Fgl1 expression is decreased in hepatocellular carcinoma (HCC) and its loss correlates with a poorly differentiated phenotype. To better elucidate the role of Fgl1 in hepatocarcinogenesis, we treated mice wild type or null for Fgl1 with diethyl nitrosamine and monitored for incidence of hepatocellular cancer. We find that mice lacking Fgl1 develop HCC at more than twice the rate of wild type mice. We show that hepatocellular cancers from Fgl1 null mice are molecularly distinct from those of the wild type mice. In tumors from Fgl1 null mice there is enhanced activation of Akt and downstream targets of the mammalian target of rapamycin (mTOR). In addition, there is paradoxical up regulation of putative hepatocellular cancer tumor suppressors; tripartite motif-containing protein 35 (Trim35) and tumor necrosis factor super family 10b (Tnfrsf10b). Taken together, these findings suggest that Fgl1 acts as a tumor suppressor in hepatocellular cancer through an Akt dependent mechanism and supports its role as a potential therapeutic target in HCC. - Highlights: • Fgl1 knockout mice (Fgl1KO) are more prone to carcinogen-induced liver cancer compared to wild type (WT) mates. • Tumors from the Fgl1KO are molecularly distinct with enhanced Akt and mTOR activity in comparison with Fgl1WT tumors. • Tumors from the Fgl1KO have enhanced expression of Trim35 and Tnfrsf10b, putative HCC tumor suppressors.

  3. Three-Dimensional Single-Mode Nonlinear Ablative Rayleigh-Taylor Instability

    NASA Astrophysics Data System (ADS)

    Yan, R.; Betti, R.; Sanz, J.; Liu, B.; Frank, A.

    2015-11-01

    The nonlinear evolution of the ablative Rayleigh-Taylor (ART) instability is studied in three dimensions for conditions relevant to inertial confinement fusion targets. The simulations are performed using our newly developed code ART3D and an astrophysical code AstroBEAR. The laser ablation can suppress the growth of the short-wavelength modes in the linear phase but may enhance their growth in the nonlinear phase because of the vortex-acceleration mechanism. As the mode wavelength approaches the cutoff of the linear spectrum (short-wavelength modes), it is found that the bubble velocity grows faster than predicted in the classical 3-D theory. When compared to 2-D results, 3-D short-wavelength bubbles grow faster and do not reach saturation. The unbounded 3-D bubble acceleration is driven by the unbounded accumulation of vorticity inside the bubble. The vorticity is transferred by mass ablation from the Rayleigh-Taylor spikes into the ablated plasma filling the bubble volume. A density plateau is observed inside a nonlinear ART bubble and the plateau density is higher for shorter-wavelength modes. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  4. Efficient neutron production from sub-nanosecond laser pulse accelerating deuterons on target front side

    SciTech Connect

    Klir, D.; Krasa, J.; Velyhan, A.; Cikhardt, J.; Rezac, K.; Dudzak, R.; Krousky, E.; Pfeifer, M.; Skala, J.; Ullschmied, J.; Sila, O.

    2015-09-15

    Neutron-producing experiments have been carried out on the Prague Asterix Laser System. At the fundamental wavelength of 1.315 μm, the laser pulse of a 600 J energy and 300 ps duration was focused on a thick deuterated-polyethylene target. Neutron yields reached (4.1 ± 0.8) × 10{sup 8} at the peak intensity of ≈3 × 10{sup 16 }W/cm{sup 2}. A more detailed analysis of neutron time-of-flight signals showed that a significant fraction of neutron yields was produced both by the {sup 2}H(d,n){sup 3}He reaction and by other neutron-producing reactions. Neutron energies together with delayed neutron and gamma emission showed that MeV deuterons escaped from a laser-produced plasma and interacted ≈50 ns later with a borosilicate blast-shield glass. In order to increase DD neutron yields and to characterize deuteron beams via nuclear reactions, a secondary deuterated polyethylene target was used in a pitcher-catcher scheme at the target front side. In this experimental arrangement, the neutron yield reached (2.0 ± 0.5) × 10{sup 9} with the peak neutron fluence of (2.5 ± 0.5) × 10{sup 8 }n/sr. From the neutron yield, it was calculated that the secondary target was bombarded by 2 × 10{sup 14} deuterons in the 0.5–2.0 MeV energy range. The neutron yield of 2 × 10{sup 9} at the laser energy of 600 J implied the production efficiency of 3 × 10{sup 6 }n/J. A very important result is that the efficient neutron production was achieved with the low contrast, sub-nanosecond laser pulse of the intensity of 10{sup 16 }W/cm{sup 2}. The latter parameters can be achieved in a rep-rate mode more easily than ultra-high intensities and contrasts.

  5. Improving beam spectral and spatial quality by double-foil target in laser ion acceleration

    NASA Astrophysics Data System (ADS)

    Huang, C.-K.; Albright, B. J.; Yin, L.; Wu, H.-C.; Bowers, K. J.; Hegelich, B. M.; Fernández, J. C.

    2011-03-01

    Mid-Z ion driven fast ignition inertial fusion requires ion beams of hundreds of MeV energy and <10% energy spread. The break-out afterburner (BOA) is one mechanism proposed to generate such beams; however, the late stages of the BOA tend to produce too large of an energy spread. Here we show how use of a second target foil placed behind a nm-scale foil can substantially reduce the temperature of the comoving electrons and improve the ion beam energy spread, leading to ion beams of energy hundreds of MeV and 6% energy spread.

  6. A small interfering RNA targeting Lnk accelerates bone fracture healing with early neovascularization.

    PubMed

    Kawakami, Yohei; Ii, Masaaki; Matsumoto, Tomoyuki; Kawamoto, Atsuhiko; Kuroda, Ryosuke; Akimaru, Hiroshi; Mifune, Yutaka; Shoji, Taro; Fukui, Tomoaki; Asahi, Michio; Kurosaka, Masahiro; Asahara, Takayuki

    2013-09-01

    Lnk, an intracellular adapter protein, is expressed in hematopoietic cell lineages, which has recently been proved as an essential inhibitory signaling molecule for stem cell self-renewal in the stem cell factor-c-Kit signaling pathway with enhanced hematopoietic and osteogenic reconstitution in Lnk-deficient mice. Moreover, the therapeutic potential of hematopoietic stem/endothelial progenitor cells (EPCs) for fracture healing has been demonstrated with mechanistic insight into vasculogenesis/angiogenesis and osteogenesis enhancement in the fracture sites. We report here, Lnk siRNA-transfected endothelial commitment of c-kit+/Sca-1+/lineage- subpopulations of bone marrow cells have high EPC colony-forming capacity exhibiting endothelial markers, VE-Cad, VEGF and Ang-1. Lnk siRNA-transfected osteoblasts also show highly osteoblastic capacity. In vivo, locally transfected Lnk siRNA could successfully downregulate the expression of Lnk at the fracture site up to 1 week, and radiological and histological examination showed extremely accelerated fracture healing in Lnk siRNA-transfected mice. Moreover, Lnk siRNA-transfected mice exhibited sufficient therapeutic outcomes with intrinstic enhancement of angiogenesis and osteogenesis, specifically, the mice demonstrated better blood flow recovery in the sites of fracture. In our series of experiments, we clarified that a negatively regulated Lnk system contributed to a favorable circumstance for fracture healing by enhancing vasculogenesis/angiogenesis and osteogenesis. These findings suggest that downregulation of Lnk system may have the clinical potential for faster fracture healing, which contributes to the reduction of delayed unions or non-unions.

  7. Accelerator mass spectrometry targets of submilligram carbonaceous samples using the high-throughput Zn reduction method.

    PubMed

    Kim, Seung-Hyun; Kelly, Peter B; Clifford, Andrew J

    2009-07-15

    The high-throughput Zn reduction method was developed and optimized for various biological/biomedical accelerator mass spectrometry (AMS) applications of mg of C size samples. However, high levels of background carbon from the high-throughput Zn reduction method were not suitable for sub-mg of C size samples in environmental, geochronology, and biological/biomedical AMS applications. This study investigated the effect of background carbon mass (mc) and background 14C level (Fc) from the high-throughput Zn reduction method. Background mc was 0.011 mg of C and background Fc was 1.5445. Background subtraction, two-component mixing, and expanded formulas were used for background correction. All three formulas accurately corrected for backgrounds to 0.025 mg of C in the aerosol standard (NIST SRM 1648a). Only the background subtraction and the two-component mixing formulas accurately corrected for backgrounds to 0.1 mg of C in the IAEA-C6 and -C7 standards. After the background corrections, our high-throughput Zn reduction method was suitable for biological (diet)/biomedical (drug) and environmental (fine particulate matter) applications of sub-mg of C samples (> or = 0.1 mg of C) in keeping with a balance between throughput (270 samples/day/analyst) and sensitivity/accuracy/precision of AMS measurement. The development of a high-throughput method for examination of > or = 0.1 mg of C size samples opens up a range of applications for 14C AMS studies. While other methods do exist for > or = 0.1 mg of C size samples, the low throughput has made them cost prohibitive for many applications.

  8. Improvements to laser wakefield accelerated electron beam stability, divergence, and energy spread using three-dimensional printed two-stage gas cell targets

    SciTech Connect

    Vargas, M.; Schumaker, W.; He, Z.-H.; Zhao, Z.; Behm, K.; Chvykov, V.; Hou, B.; Krushelnick, K.; Maksimchuk, A.; Yanovsky, V.; Thomas, A. G. R.

    2014-04-28

    High intensity, short pulse lasers can be used to accelerate electrons to ultra-relativistic energies via laser wakefield acceleration (LWFA) [T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979)]. Recently, it was shown that separating the injection and acceleration processes into two distinct stages could prove beneficial in obtaining stable, high energy electron beams [Gonsalves et al., Nat. Phys. 7, 862 (2011); Liu et al., Phys. Rev. Lett. 107, 035001 (2011); Pollock et al., Phys. Rev. Lett. 107, 045001 (2011)]. Here, we use a stereolithography based 3D printer to produce two-stage gas targets for LWFA experiments on the HERCULES laser system at the University of Michigan. We demonstrate substantial improvements to the divergence, pointing stability, and energy spread of a laser wakefield accelerated electron beam compared with a single-stage gas cell or gas jet target.

  9. Improvements to laser wakefield accelerated electron beam stability, divergence, and energy spread using three-dimensional printed two-stage gas cell targets

    NASA Astrophysics Data System (ADS)

    Vargas, M.; Schumaker, W.; He, Z.-H.; Zhao, Z.; Behm, K.; Chvykov, V.; Hou, B.; Krushelnick, K.; Maksimchuk, A.; Yanovsky, V.; Thomas, A. G. R.

    2014-04-01

    High intensity, short pulse lasers can be used to accelerate electrons to ultra-relativistic energies via laser wakefield acceleration (LWFA) [T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979)]. Recently, it was shown that separating the injection and acceleration processes into two distinct stages could prove beneficial in obtaining stable, high energy electron beams [Gonsalves et al., Nat. Phys. 7, 862 (2011); Liu et al., Phys. Rev. Lett. 107, 035001 (2011); Pollock et al., Phys. Rev. Lett. 107, 045001 (2011)]. Here, we use a stereolithography based 3D printer to produce two-stage gas targets for LWFA experiments on the HERCULES laser system at the University of Michigan. We demonstrate substantial improvements to the divergence, pointing stability, and energy spread of a laser wakefield accelerated electron beam compared with a single-stage gas cell or gas jet target.

  10. Accelerating Genome Editing in CHO Cells Using CRISPR Cas9 and CRISPy, a Web-Based Target Finding Tool

    PubMed Central

    Ronda, Carlotta; Pedersen, Lasse Ebdrup; Hansen, Henning Gram; Kallehauge, Thomas Beuchert; Betenbaugh, Michael J; Nielsen, Alex Toftgaard; Kildegaard, Helene Faustrup

    2014-01-01

    Chinese hamster ovary (CHO) cells are widely used in the biopharmaceutical industry as a host for the production of complex pharmaceutical proteins. Thus genome engineering of CHO cells for improved product quality and yield is of great interest. Here, we demonstrate for the first time the efficacy of the CRISPR Cas9 technology in CHO cells by generating site-specific gene disruptions in COSMC and FUT8, both of which encode proteins involved in glycosylation. The tested single guide RNAs (sgRNAs) created an indel frequency up to 47.3% in COSMC, while an indel frequency up to 99.7% in FUT8 was achieved by applying lectin selection. All eight sgRNAs examined in this study resulted in relatively high indel frequencies, demonstrating that the Cas9 system is a robust and efficient genome-editing methodology in CHO cells. Deep sequencing revealed that 85% of the indels created by Cas9 resulted in frameshift mutations at the target sites, with a strong preference for single base indels. Finally, we have developed a user-friendly bioinformatics tool, named “CRISPy” for rapid identification of sgRNA target sequences in the CHO-K1 genome. The CRISPy tool identified 1,970,449 CRISPR targets divided into 27,553 genes and lists the number of off-target sites in the genome. In conclusion, the proven functionality of Cas9 to edit CHO genomes combined with our CRISPy database have the potential to accelerate genome editing and synthetic biology efforts in CHO cells. Biotechnol. Bioeng. 2014; 111: 1604–1616. © 2014 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. PMID:24827782

  11. Accelerating genome editing in CHO cells using CRISPR Cas9 and CRISPy, a web-based target finding tool.

    PubMed

    Ronda, Carlotta; Pedersen, Lasse Ebdrup; Hansen, Henning Gram; Kallehauge, Thomas Beuchert; Betenbaugh, Michael J; Nielsen, Alex Toftgaard; Kildegaard, Helene Faustrup

    2014-08-01

    Chinese hamster ovary (CHO) cells are widely used in the biopharmaceutical industry as a host for the production of complex pharmaceutical proteins. Thus genome engineering of CHO cells for improved product quality and yield is of great interest. Here, we demonstrate for the first time the efficacy of the CRISPR Cas9 technology in CHO cells by generating site-specific gene disruptions in COSMC and FUT8, both of which encode proteins involved in glycosylation. The tested single guide RNAs (sgRNAs) created an indel frequency up to 47.3% in COSMC, while an indel frequency up to 99.7% in FUT8 was achieved by applying lectin selection. All eight sgRNAs examined in this study resulted in relatively high indel frequencies, demonstrating that the Cas9 system is a robust and efficient genome-editing methodology in CHO cells. Deep sequencing revealed that 85% of the indels created by Cas9 resulted in frameshift mutations at the target sites, with a strong preference for single base indels. Finally, we have developed a user-friendly bioinformatics tool, named "CRISPy" for rapid identification of sgRNA target sequences in the CHO-K1 genome. The CRISPy tool identified 1,970,449 CRISPR targets divided into 27,553 genes and lists the number of off-target sites in the genome. In conclusion, the proven functionality of Cas9 to edit CHO genomes combined with our CRISPy database have the potential to accelerate genome editing and synthetic biology efforts in CHO cells.

  12. Laser ablation studies of concrete

    SciTech Connect

    Savina, M.; Xu, Z.; Wang, Y.; Reed, C.; Pellin, M.

    1999-10-20

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. The authors present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied using cement and high density concrete as targets. Ablation efficiency and material removal rates were determined as functions of irradiance and pulse overlap. Doped samples were also ablated to determine the efficiency with which surface contaminants were removed and captured in the effluent. The results show that the cement phase of the material melts and vaporizes, but the aggregate portion (sand and rock) fragments. The effluent consists of both micron-size aerosol particles and chunks of fragmented aggregate material. Laser-induced optical emission spectroscopy was used to analyze the surface during ablation. Analysis of the effluent showed that contaminants such as cesium and strontium were strongly segregated into different regions of the particle size distribution of the aerosol.

  13. High-contrast laser acceleration of relativistic electrons in solid cone-wire targets

    SciTech Connect

    Higginson, D. P.; Link, A.; Sawada, H.; Wilks, S. C.; Chawla, S. R.; Chen, C. D.; Jarrott, L. C.; Flippo, K. A.; McLean, H. S.; Patel, P. K.; Perez, F.; Beg, F. N.; Bartal, T.; Wei, M. S.

    2015-12-31

    Optimization of electron coupling into small solid angles is of extreme importance to applications, such as Fast Ignition, that require maximum electron energy deposition within a small volume. To optimize this coupling, we use the ultra-high-contrast Trident laser, which remains below intensity of 1011 W/cm2 until < 0.1 ns before the main pulse, while still attaining high-energy, 75 J, and peak intensity of 5 x 1019 W/cm2. Using a cone-wire target, we find that the coupling into the 40 μm diameter wire is increased by a factor of 2.7x over the low-contrast Titan laser at similar peak intensity. Full-scale simulations are used to model the laser interaction and quantitatively reproduce the experimental results. These show that increase in coupling is due to both a closer interaction, as well as the reduction of laser filamentation and self-focusing.

  14. Biological/biomedical accelerator mass spectrometry targets. 1. optimizing the CO2 reduction step using zinc dust.

    PubMed

    Kim, Seung-Hyun; Kelly, Peter B; Clifford, Andrew J

    2008-10-15

    Biological and biomedical applications of accelerator mass spectrometry (AMS) use isotope ratio mass spectrometry to quantify minute amounts of long-lived radioisotopes such as (14)C. AMS target preparation involves first the oxidation of carbon (in sample of interest) to CO 2 and second the reduction of CO 2 to filamentous, fluffy, fuzzy, or firm graphite-like substances that coat a -400-mesh spherical iron powder (-400MSIP) catalyst. Until now, the quality of AMS targets has been variable; consequently, they often failed to produce robust ion currents that are required for reliable, accurate, precise, and high-throughput AMS for biological/biomedical applications. Therefore, we described our optimized method for reduction of CO 2 to high-quality uniform AMS targets whose morphology we visualized using scanning electron microscope pictures. Key features of our optimized method were to reduce CO 2 (from a sample of interest that provided 1 mg of C) using 100 +/- 1.3 mg of Zn dust, 5 +/- 0.4 mg of -400MSIP, and a reduction temperature of 500 degrees C for 3 h. The thermodynamics of our optimized method were more favorable for production of graphite-coated iron powders (GCIP) than those of previous methods. All AMS targets from our optimized method were of 100% GCIP, the graphitization yield exceeded 90%, and delta (13)C was -17.9 +/- 0.3 per thousand. The GCIP reliably produced strong (12)C (-) currents and accurate and precise F m values. The observed F m value for oxalic acid II NIST SRM deviated from its accepted F m value of 1.3407 by only 0.0003 +/- 0.0027 (mean +/- SE, n = 32), limit of detection of (14)C was 0.04 amol, and limit of quantification was 0.07 amol, and a skilled analyst can prepare as many as 270 AMS targets per day. More information on the physical (hardness/color), morphological (SEMs), and structural (FT-IR, Raman, XRD spectra) characteristics of our AMS targets that determine accurate, precise, and high-hroughput AMS measurement are in the

  15. Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy

    PubMed Central

    Kunos, Charles A.; Fabien, Jeffrey M.; Shanahan, John P.; Collen, Christine; Gevaert, Thierry; Poels, Kenneth; Van den Begin, Robbe; Engels, Benedikt; De Ridder, Mark

    2015-01-01

    Physicians considering stereotactic ablative body radiation therapy (SBRT) for the treatment of extracranial cancer targets must be aware of the sizeable risks for normal tissue injury and the hazards of physical tumor miss. A first-of-its-kind SBRT platform achieves high-precision ablative radiation treatment through a combination of versatile real-time imaging solutions and sophisticated tumor tracking capabilities. It uses dual-diagnostic kV x-ray units for stereoscopic open-loop feedback of cancer target intrafraction movement occurring as a consequence of respiratory motions and heartbeat. Image-guided feedback drives a gimbaled radiation accelerator (maximum 15 x 15 cm field size) capable of real-time ±4 cm pan-and-tilt action. Robot-driven ±60° pivots of an integrated ±185° rotational gantry allow for coplanar and non-coplanar accelerator beam set-up angles, ultimately permitting unique treatment degrees of freedom. State-of-the-art software aids real-time six dimensional positioning, ensuring irradiation of cancer targets with sub-millimeter accuracy (0.4 mm at isocenter). Use of these features enables treating physicians to steer radiation dose to cancer tumor targets while simultaneously reducing radiation dose to normal tissues. By adding respiration correlated computed tomography (CT) and 2-[18F] fluoro-2-deoxy-ᴅ-glucose (18F-FDG) positron emission tomography (PET) images into the planning system for enhanced tumor target contouring, the likelihood of physical tumor miss becomes substantially less1. In this article, we describe new radiation plans for the treatment of moving lung tumors. PMID:26131774

  16. MicroRNA-21 accelerates hepatocyte proliferation in vitro via PI3K/Akt signaling by targeting PTEN

    SciTech Connect

    Yan-nan, Bai; Zhao-yan, Yu; Li-xi, Luo; Jiang, Yi; Qing-jie, Xia

    2014-01-17

    Highlights: •miRNAs-expression patterns of primary hepatocytes under proliferative status. •miR-21 expression level peaked at 12 h after stimulated by EGF. •miR-21 drive rapid S phase entry of primary hepatocytes. •PI3K/Akt signaling was modulated via targeting PTEN by miR-21. -- Abstract: MicroRNAs (miRNAs) are involved in controlling hepatocyte proliferation during liver regeneration. In this study, we established the miRNAs-expression patterns of primary hepatocytes in vitro under stimulation of epidermal growth factor (EGF), and found that microRNA-21 (miR-21) was appreciably up-regulated and peaked at 12 h. In addition, we further presented evidences indicating that miR-21 promotes primary hepatocyte proliferation through in vitro transfecting with miR-21 mimics or inhibitor. We further demonstrated that phosphatidylinositol 3′-OH kinase (PI3K)/Akt signaling was altered accordingly, it is, by targeting phosphatase and tensin homologue deleted on chromosome 10, PI3K/Akt signaling is activated by miR-21 to accelerate hepatocyte rapid S-phase entry and proliferation in vitro.

  17. Summary of recent experiments on focusing of target-normal-sheath-accelerated proton beam with a stack of conducting foils

    SciTech Connect

    Ni, P. A.; Alexander, N.; Barnard, J. J.; Lund, S. M.

    2014-05-15

    We present a summary of recent experiments on focusing of laser target-normal-sheath-accelerated (TNSA) proton beam with a stack of thin conducting foils. The experiments were performed using the Phelix laser (GSI-Darmstadt) and the Titan laser, Lawrence Livermore National Laboratory. The phenomena consistent with self-collimation (or weak self-focusing) of TNSA protons were experimentally observed for the first time at the Phelix laser user facility, in a specially engineered structure ('lens') consisting of a stack of 300 thin aluminum foils separated by 50 μm vacuum gaps. Follow up experiments using the Titan laser obtained results consistent with the collimation/focusing observed in the initial experiments using the Phelix. The Titan experiments employed improved, 25 μm- and 50 μm-gap targets and the new fine mesh diagnostic. All the experiments were carried out in a “passive environment,” i.e., no external fields were applied, and no neutralization plasma or injection of secondary charged particles was imposed. A plausible interpretation of the observed phenomena is that the combination of magnetic self-pinch forces generated by the beam current together with the simultaneous reduction of the repulsive electrostatic forces due to the conducting foils inhibits radial expansion of the beam.

  18. Targeted Alpha Therapy: The US DOE Tri-Lab (ORNL, BNL, LANL) Research Effort to Provide Accelerator-Produced 225Ac for Radiotherapy

    NASA Astrophysics Data System (ADS)

    John, Kevin

    2017-01-01

    Targeted radiotherapy is an emerging discipline of cancer therapy that exploits the biochemical differences between normal cells and cancer cells to selectively deliver a lethal dose of radiation to cancer cells, while leaving healthy cells relatively unperturbed. A broad overview of targeted alpha therapy including isotope production methods, and associated isotope production facility needs, will be provided. A more general overview of the US Department of Energy Isotope Program's Tri-Lab (ORNL, BNL, LANL) Research Effort to Provide Accelerator-Produced 225Ac for Radiotherapy will also be presented focusing on the accelerator-production of 225Ac and final product isolation methodologies for medical applications.

  19. Laser driven ion accelerator

    DOEpatents

    Tajima, Toshiki

    2005-06-14

    A system and method of accelerating ions in an accelerator to optimize the energy produced by a light source. Several parameters may be controlled in constructing a target used in the accelerator system to adjust performance of the accelerator system. These parameters include the material, thickness, geometry and surface of the target.

  20. Laser driven ion accelerator

    DOEpatents

    Tajima, Toshiki

    2006-04-18

    A system and method of accelerating ions in an accelerator to optimize the energy produced by a light source. Several parameters may be controlled in constructing a target used in the accelerator system to adjust performance of the accelerator system. These parameters include the material, thickness, geometry and surface of the target.

  1. Radiofrequency Ablation of Liver Tumors

    MedlinePlus

    ... Site Index A-Z Radiofrequency Ablation (RFA) of Liver Tumors Radiofrequency ablation (RFA) is a treatment that ... of Liver Tumors? What is Radiofrequency Ablation of Liver Tumors? Radiofrequency ablation, sometimes referred to as RFA, ...

  2. Ablative therapies for small renal tumours.

    PubMed

    Castro, Arturo; Jenkins, Lawrence C; Salas, Nelson; Lorber, Gideon; Leveillee, Raymond J

    2013-05-01

    Improvements in imaging technology have resulted in an increase in detection of small renal masses (SRMs). Minimally invasive ablation modalities, including cryoablation, radiofrequencey ablation, microwave ablation and irreversible electroporation, are currently being used to treat SRMs in select groups of patients. Cryoablation and radiofrequency ablation have been extensively studied. Presently, cryoablation is gaining popularity because the resulting ice ball can be visualized easily using ultrasonography. Tumour size and location are strong predictors of outcome of radiofrequency ablation. One of the main benefits of microwave ablation is that microwaves can propagate through all types of tissue, including desiccated and charred tissue, as well as water vapour, which might be formed during the ablation. Irreversible electroporation has been shown in animal studies to affect only the cell membrane of undesirable target tissues and to spare adjacent structures; however, clinical studies that depict the efficacy and safety of this treatment modality in humans are still sparse. As more experience is gained in the future, ablation modalities might be utilized in all patients with tumours <4 cm in diameter, rather than just as an alternative treatment for high-risk surgical patients.

  3. High quality ion acceleration from a double-layer target dominated by the radiation pressure of a transversely Gaussian laser pulse

    SciTech Connect

    Hong Xueren; Xie Baisong; Wu Haicheng; Zhao Xueyan; Zhang Shan; Aimidula, Aimierding; Liu Mingping

    2010-10-15

    The ion acceleration from a double-layer target irradiated by a transversely Gaussian laser pulse is investigated by theoretical analysis and particle-in-cell simulations. The main idea of the double-layer target is to match the transverse areal mass density of the target with the laser intensity profile by single ion specie with two densities or by two ion species. Two-dimensional particle-in-cell simulations show that the target deformation and the transverse instability are efficiently suppressed in the double-layer scheme, ions within the laser spot are uniformly accelerated and are well collimated in the forward direction, GeV/u monoenergetic ion beams with very low divergency are observed.

  4. Overview of recent experiments on hydrodynamic instabilities at ablation front

    NASA Astrophysics Data System (ADS)

    Casner, Alexis

    2013-10-01

    Understanding and mitigating hydrodynamic instabilities is a key element for achieving ignition in Inertial Confinement Fusion (ICF). Cryogenic indirect-drive implosions on NIF have evidenced that the ablative Rayleigh-Taylor Instability (RTI) is the dominant driver of hot spot mix. This motivates in particular the switch to a more forgiving higher adiabat implosion design. After a recall of some results obtained in indirect drive (ID) on the OMEGA laser facility in the last decade, I will explain how the unique capabilities of the National Ignition Facility could be harnessed to accelerate planar samples over much larger distances and longer time periods than previously achieved. I will describe a fundamental science proposal which aims at achieving a highly nonlinear stage for the ablative RTI, a question also of crucial interest in astrophysics. The existence of a turbulent-like regime at ablation front is in fact not precluded and the late-time dynamics of single-mode RTI is a subject of theoretical investigations. On the other hand in direct drive (DD) ICF, laser intensity (and target surface) non uniformities seed the initial conditions of the ablative RTI. I will discuss DD planar experiments devoted to the study of laser imprint perturbations with special phase plates. As it is also the case in ID, simulations of the Richtmyer-Meshkov phase reversal during the shock transit phase is challenging, and of crucial interest because it sets the sign of the RTI growth factors. Future work will try to increase the accuracy of measurements when phase inversion is present, as well as to demonstrate advanced imprint mitigation using underdense foams.

  5. IR laser ablation of dental enamel

    NASA Astrophysics Data System (ADS)

    Fried, Daniel

    2000-03-01

    An overview of the basic mechanisms of IR laser ablation of dental enamel is presented. Enamel is a highly structured tissue consisting of an heterogeneous distribution of water, mineral, protein and lipid. Absorption bands of water and carbonated hydroxyapatite can be selectively targeted from 2.7 to 11-micrometer via several laser wavelengths. Mechanistic differences in the nature of ablation and the varying surface morphology produced can be explained by the microstructure of the tissue. Suggested criteria for the choice of the optimum laser parameters for clinical use, the influence of plasma shielding and the role of exogenous water on the mechanism of ablation are discussed.

  6. Accelerating the domestication of a bioenergy crop: identifying and modelling morphological targets for sustainable yield increase in Miscanthus

    PubMed Central

    Farrar, Kerrie

    2013-01-01

    To accelerate domestication of Miscanthus, an important energy crop, 244 replicated genotypes, including two different species and their hybrids, were analysed for morphological traits and biomass yield over three growing seasons following an establishment phase of 2 years in the largest Miscanthus diversity trial described to date. Stem and leaf traits were selected that contributed both directly and indirectly to total harvested biomass yield, and there was variation in all traits measured. Morphological diversity within the population was correlated with dry matter yield (DMY) both as individual traits and in combination, in order to determine the respective contributions of the traits to biomass accumulation and to identify breeding targets for yield improvement. Predictive morphometric analysis was possible at year 3 within Miscanthus sinensis genotypes but not between M. sinensis, Miscanthus sacchariflorus, and interspecific hybrids. Yield is a complex trait, and no single simple trait explained more than 33% of DMY, which varied from 1 to 5297g among genotypes within this trial. Associating simple traits increased the power of the morphological data to predict yield to 60%. Trait variety, in combination, enabled multiple ideotypes, thereby increasing the potential diversity of the crop for multiple growth locations and end uses. Both triploids and interspecific hybrids produced the highest mature yields, indicating that there is significant heterosis to be exploited within Miscanthus that might be overlooked in early selection screens within years 1–3. The potential for optimizing biomass yield by selecting on the basis of morphology is discussed. PMID:24064927

  7. Stellar Ablation of Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Moore, Thomas E.; Horwitz, J. L.

    2007-01-01

    We review observations and theories of the solar ablation of planetary atmospheres, focusing on the terrestrial case where a large magnetosphere holds off the solar wind, so that there is little direct atmospheric impact, but also couples the solar wind electromagnetically to the auroral zones. We consider the photothermal escape flows known as the polar wind or refilling flows, the enhanced mass flux escape flows that result from localized solar wind energy dissipation in the auroral zones, and the resultant enhanced neutral atom escape flows. We term these latter two escape flows the "auroral wind." We review observations and theories of the heating and acceleration of auroral winds, including energy inputs from precipitating particles, electromagnetic energy flux at magnetohydrodynamic and plasma wave frequencies, and acceleration by parallel electric fields and by convection pickup processes also known as "centrifugal acceleration." We consider also the global circulation of ionospheric plasmas within the magnetosphere, their participation in magnetospheric disturbances as absorbers of momentum and energy, and their ultimate loss from the magnetosphere into the downstream solar wind, loading reconnection processes that occur at high altitudes near the magnetospheric boundaries. We consider the role of planetary magnetization and the accumulating evidence of stellar ablation of extrasolar planetary atmospheres. Finally, we suggest and discuss future needs for both the theory and observation of the planetary ionospheres and their role in solar wind interactions, to achieve the generality required for a predictive science of the coupling of stellar and planetary atmospheres over the full range of possible conditions.

  8. Targeted Ablation, Silencing, and Activation Establish Glycinergic Dorsal Horn Neurons as Key Components of a Spinal Gate for Pain and Itch

    PubMed Central

    Foster, Edmund; Wildner, Hendrik; Tudeau, Laetitia; Haueter, Sabine; Ralvenius, William T.; Jegen, Monika; Johannssen, Helge; Hösli, Ladina; Haenraets, Karen; Ghanem, Alexander; Conzelmann, Karl-Klaus; Bösl, Michael; Zeilhofer, Hanns Ulrich

    2015-01-01

    Summary The gate control theory of pain proposes that inhibitory neurons of the spinal dorsal horn exert critical control over the relay of nociceptive signals to higher brain areas. Here we investigated how the glycinergic subpopulation of these neurons contributes to modality-specific pain and itch processing. We generated a GlyT2::Cre transgenic mouse line suitable for virus-mediated retrograde tracing studies and for spatially precise ablation, silencing, and activation of glycinergic neurons. We found that these neurons receive sensory input mainly from myelinated primary sensory neurons and that their local toxin-mediated ablation or silencing induces localized mechanical, heat, and cold hyperalgesia; spontaneous flinching behavior; and excessive licking and biting directed toward the corresponding skin territory. Conversely, local pharmacogenetic activation of the same neurons alleviated neuropathic hyperalgesia and chloroquine- and histamine-induced itch. These results establish glycinergic neurons of the spinal dorsal horn as key elements of an inhibitory pain and itch control circuit. PMID:25789756

  9. Demonstration of a high-intensity neutron source based on a liquid-lithium target for Accelerator based Boron Neutron Capture Therapy.

    PubMed

    Halfon, S; Arenshtam, A; Kijel, D; Paul, M; Weissman, L; Berkovits, D; Eliyahu, I; Feinberg, G; Kreisel, A; Mardor, I; Shimel, G; Shor, A; Silverman, I; Tessler, M

    2015-12-01

    A free surface liquid-lithium jet target is operating routinely at Soreq Applied Research Accelerator Facility (SARAF), bombarded with a ~1.91 MeV, ~1.2 mA continuous-wave narrow proton beam. The experiments demonstrate the liquid lithium target (LiLiT) capability to constitute an intense source of epithermal neutrons, for Accelerator based Boron Neutron Capture Therapy (BNCT). The target dissipates extremely high ion beam power densities (>3 kW/cm(2), >0.5 MW/cm(3)) for long periods of time, while maintaining stable conditions and localized residual activity. LiLiT generates ~3×10(10) n/s, which is more than one order of magnitude larger than conventional (7)Li(p,n)-based near threshold neutron sources. A shield and moderator assembly for BNCT, with LiLiT irradiated with protons at 1.91 MeV, was designed based on Monte Carlo (MCNP) simulations of BNCT-doses produced in a phantom. According to these simulations it was found that a ~15 mA near threshold proton current will apply the therapeutic doses in ~1h treatment duration. According to our present results, such high current beams can be dissipated in a liquid-lithium target, hence the target design is readily applicable for accelerator-based BNCT.

  10. High power accelerator-based boron neutron capture with a liquid lithium target and new applications to treatment of infectious diseases.

    PubMed

    Halfon, S; Paul, M; Steinberg, D; Nagler, A; Arenshtam, A; Kijel, D; Polacheck, I; Srebnik, M

    2009-07-01

    A new conceptual design for an accelerator-based boron neutron capture therapy (ABNCT) facility based on the high-current low-energy proton beam driven by the linear accelerator at SARAF (Soreq Applied Research Accelerator Facility) incident on a windowless forced-flow liquid-lithium target, is described. The liquid-lithium target, currently in construction at Soreq NRC, will produce a neutron field suitable for the BNCT treatment of deep-seated tumor tissues, through the reaction (7)Li(p,n)(7)Be. The liquid-lithium target is designed to overcome the major problem of solid lithium targets, namely to sustain and dissipate the power deposited by the high-intensity proton beam. Together with diseases conventionally targeted by BNCT, we propose to study the application of our setup to a novel approach in treatment of diseases associated with bacterial infections and biofilms, e.g. inflammations on implants and prosthetic devices, cystic fibrosis, infectious kidney stones. Feasibility experiments evaluating the boron neutron capture effectiveness on bacteria annihilation are taking place at the Soreq nuclear reactor.

  11. Neutron Generation from Laser-Accelerated Ion Beams: Use of Alternative Deuteron-Rich Targets for Improved Neutron Yield and Control of Neutron Spectra

    NASA Astrophysics Data System (ADS)

    Albright, B. J.; Yin, L.; Favalli, A.

    2016-10-01

    Laser-ion-beam generation in the break-out afterburner (BOA) acceleration regime has been modeled for several deuteron-rich solid-density targets using the VPIC particle-in-cell code. Monte Carlo modeling of the transport of these beams in a beryllium converter in a pitcher-catcher neutron source configuration shows significant increases in neutron yields may be achievable through judicious choices of laser target material. Additionally, species-separation dynamics in some target materials during the BOA ion acceleration phase can be exploited to control the shapes of the neutron spectra. Work performed under the auspices of the U.S. DOE by the LANS, LLC, Los Alamos National Laboratory under Contract No. DE-AC52-06NA25396. Funding provided by the Los Alamos National Laboratory Directed Research and Development Program.

  12. Direct Pulmonary Vein Ablation with Stenosis Prevention Therapy

    PubMed Central

    DeSimone, Christopher V.; Holmes, David R.; Ebrille, Elisa; Syed, Faisal F.; Ladewig, Dorothy J.; Mikell, Susan B.; Powers, Joanne; Suddendorf, Scott H.; Gilles, Emily J.; Danielsen, Andrew J.; Hodge, David O.; Kapa, Suraj; Asirvatham, Samuel J.

    2015-01-01

    Introduction The dominant location of electrical triggers for initiating atrial fibrillation (AF) originates from the muscle sleeves inside pulmonary veins (PVs). Currently, radiofrequency ablation (RFA) is performed outside of the PVs to isolate, rather than directly ablate these tissues, due to the risk of intraluminal PV stenosis. Methods In 4 chronic canine experiments, we performed direct PV muscle sleeve RFA ± post-ablation drug-coated balloon (DCB) treatment with paclitaxel/everolimus. Of the 4 PVs, 2 PVs were ablated and treated with DCB, 1 PV was ablated without DCB treatment (positive control), and 1 PV was left as a negative control. Local electrograms were assessed in PVs for near-field signals and were targeted for ablation. After 12-14 weeks survival, PVs were interrogated for absence of near-field PV potentials, and each PV was assessed for stenosis. Results All canines survived the study period without cardiorespiratory complications, and remained ambulatory. In all canines, PVs that were ablated and treated with DCB remained without any significant intraluminal stenosis. In contrast, PVs that were ablated and not treated with DCB showed near or complete intraluminal stenosis. At terminal study, PV potentials remained undetectable. A blinded, histologic analysis demonstrated that ablated PVs without DCB treatment had extensive thrombus, fibrin, mineralization, and elastin disruption. Conclusion Our chronic canine data suggest that direct PV tissue ablation without subsequent stenosis is feasible with the use of post-ablation DCBs. PMID:26075706

  13. STRUCTURAL DESIGN CRITERIA FOR TARGET/BLANKET SYSTEM COMPONENT MATERIALS FOR THE ACCELERATOR PRODUCTION OF TRITIUM PROJECT

    SciTech Connect

    W. JOHNSON; R. RYDER; P. RITTENHOUSE

    2001-01-01

    The design of target/blanket system components for the Accelerator Production of Tritium (APT) plant is dependent on the development of materials properties data specified by the designer. These data are needed to verify that component designs are adequate. The adequacy of the data will be related to safety, performance, and economic considerations, and to other requirements that may be deemed necessary by customers and regulatory bodies. The data required may already be in existence, as in the open technical literature, or may need to be generated, as is often the case for the design of new systems operating under relatively unique conditions. The designers' starting point for design data needs is generally some form of design criteria used in conjunction with a specified set of loading conditions and associated performance requirements. Most criteria are aimed at verifying the structural adequacy of the component, and often take the form of national or international standards such as the ASME Boiler and Pressure Vessel Code (ASME B and PV Code) or the French Nuclear Structural Requirements (RCC-MR). Whether or not there are specific design data needs associated with the use of these design criteria will largely depend on the uniqueness of the conditions of operation of the component. A component designed in accordance with the ASME B and PV Code, where no unusual environmental conditions exist, will utilize well-documented, statistically-evaluated developed in conjunction with the Code, and will not be likely to have any design data needs. On the other hand, a component to be designed to operate under unique APT conditions, is likely to have significant design data needs. Such a component is also likely to require special design criteria for verification of its structural adequacy, specifically accounting for changes in materials properties which may occur during exposure in the service environment. In such a situation it is common for the design criteria and

  14. Streaked x-ray microscopy of laser-fusion targets

    SciTech Connect

    Price, R.H.; Campbell, E.M.; Rosen, M.D.; Auerbach, J.M.; Phillion, D.W.; Whitlock, R.R.; Obenshain, S.P.; McLean, E.A.; Ripin, B.H.

    1982-08-01

    An ultrafast soft x-ray streak camera has been coupled to a Wolter axisymmetric x-ray microscope. This system was used to observe the dynamics of laser fusion targets both in self emission and backlit by laser produced x-ray sources. Spatial resolution was 7 ..mu..m and temporal resolution was 20 ps. Data is presented showing the ablative acceleration of foils to velocities near 10/sup 7/ cm/sec and the collision of an accelerated foil with a second foil, observed using 3 keV streaked x-ray backlighting. Good agreement was found between hydrocode simulations, simple models of the ablative acceleration and the observed velocities of the carbon foils.

  15. Angular distribution of atoms emitted from a SrZrO{sub 3} target by laser ablation under different laser fluences and oxygen pressures

    SciTech Connect

    Konomi, I.; Motohiro, T.; Azuma, H.; Asaoka, T.; Nakazato, T.; Sato, E.; Shimizu, T.; Fujioka, S.; Sarukura, N.; Nishimura, H.

    2010-05-15

    Angular distributions of atoms emitted by laser ablation of perovskite-type oxide SrZrO{sub 3} have been investigated using electron probe microanalysis with wavelength-dispersive spectroscopy and charge-coupled device photography with an interference filter. Each constituent element has been analyzed as a two-modal distribution composed of a broad cos{sup m} {theta} distribution and a narrow cos{sup n} {theta} distribution. The exponent n characterizes the component of laser ablation while the exponent m characterizes that of thermal evaporation, where a larger n or m means a narrower angular distribution. In vacuum, O (n=6) showed a broader distribution than those of Sr (n=16) and Zr (n=17), and Sr{sup +} exhibited a spatial distribution similar to that of Sr. As the laser fluence was increased from 1.1 to 4.4 J/cm{sup 2}, the angular distribution of Sr became narrower. In the laser fluence range of 1.1-4.4 J/cm{sup 2}, broadening of the angular distribution of Sr was observed only at the fluence of 1.1 J/cm{sup 2} under the oxygen pressure of 10 Pa. Monte Carlo simulations were performed to estimate approximately the energy of emitted atoms, focusing on the broadening of the angular distribution under the oxygen pressure of 10 Pa. The energies of emitted atoms were estimated to be 1-20 eV for the laser fluence of 1.1 J/cm{sup 2}, and more than 100 eV for 2.2 and 4.4 J/cm{sup 2}.

  16. Search for Defocusing During a Single Pulse of a 2 kA Relativistic Electron Beam Due to Ions Accelerated from a Target

    SciTech Connect

    Lauer, E J; Caporaso, G J; Chambers, F W; Chen, Y-J; Falabella, S; Guethlein, G; McCarrick, J; Richardson, R; Sampayan, S; Weir, J

    2002-09-05

    The DARHT accelerator will deliver several intense relativistic electron beam pulses to an x-ray conversion target during a few microseconds. Plasma from the target can cause a partial neutralization of the vacuum self-Er field resulting in an unacceptably large beam radius at the target. The Livermore group has been developing barrier foils to block the plasma from moving upstream. Positive ions accelerated upstream from the foil in the self-Ez field during a single pulse could defocus the beam. In May, 2001 LANL used a sensitive ''two foil'' experiment to search for such effects. They measured significant time dependent effects using conducting foils (1). In January, 2002, the Livermore group repeated the experiment using the ETA II accelerator. We expected to see similar effects and planned to collect data that we could model. We saw no significant effect from conducting foils unless the beam radius was small enough to damage the foil. The reason for the different results has not been explained and is still being investigated. Possibilities have to do with the longer pulse length at LANL, (60 ns compared to 40) or with the higher energy at LANL, (20 Mev compared to 5.7) We also did some tests on dielectric targets where there is a strong effect to test our techniques.

  17. Nonequilibrium Ablation of Phenolic Impregnated Carbon Ablator

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Chen, Yih K.; Gokcen, Tahir

    2012-01-01

    In previous work, an equilibrium ablation and thermal response model for Phenolic Impregnated Carbon Ablator was developed. In general, over a wide range of test conditions, model predictions compared well with arcjet data for surface recession, surface temperature, in-depth temperature at multiple thermocouples, and char depth. In this work, additional arcjet tests were conducted at stagnation conditions down to 40 W/sq cm and 1.6 kPa. The new data suggest that nonequilibrium effects become important for ablation predictions at heat flux or pressure below about 80 W/sq cm or 10 kPa, respectively. Modifications to the ablation model to account for nonequilibrium effects are investigated. Predictions of the equilibrium and nonequilibrium models are compared with the arcjet data.

  18. Pharmacological Tests in Atrial Fibrillation Ablation

    PubMed Central

    Gourraud, Jean-Baptiste; Andrade, Jason G; Macle, Laurent

    2016-01-01

    The invasive management of atrial fibrillation (AF) has been considerably changed by the identification of major sites of AF initiation and/or maintenance within the pulmonary vein antra. Percutaneous catheter ablation of these targets has become the standard of care for sustained maintenance of sinus rhythm. Long-term failure of ablation is related to an inability to create a durable transmural lesion or to identify all of the non-pulmonary vein arrhythmia triggers. Pharmacological challenges during catheter ablation have been suggested to improve outcomes in both paroxysmal and persistent AF. Herein we review the mechanism and evidence for the use of pharmacological adjuncts during the catheter ablation of AF. PMID:28116081

  19. Pulmonary ablation: a primer.

    PubMed

    Roberton, Benjamin J; Liu, David; Power, Mark; Wan, John M C; Stuart, Sam; Klass, Darren; Yee, John

    2014-05-01

    Percutaneous image-guided thermal ablation is safe and efficacious in achieving local control and improving outcome in the treatment of both early stage non-small-cell lung cancer and pulmonary metastatic disease, in which surgical treatment is precluded by comorbidity, poor cardiorespiratory reserve, or unfavorable disease distribution. Radiofrequency ablation is the most established technology, but new thermal ablation technologies such as microwave ablation and cryoablation may offer some advantages. The use of advanced techniques, such as induced pneumothorax and the popsicle stick technique, or combining thermal ablation with radiotherapy, widens the treatment options available to the multidisciplinary team. The intent of this article is to provide the reader with a practical knowledge base of pulmonary ablation by concentrating on indications, techniques, and follow-up.

  20. Renal Ablation Update

    PubMed Central

    Khiatani, Vishal; Dixon, Robert G.

    2014-01-01

    Thermal ablative technologies have evolved considerably in the recent past and are now an important component of current clinical guidelines for the treatment of small renal masses. Both radiofrequency ablation and cryoablation have intermediate-term oncologic control that rivals surgical options, with favorable complication profiles. Studies comparing cryoablation and radiofrequency ablation show no significant difference in oncologic control or complication profile between the two modalities. Early data from small series with microwave ablation have shown similar promising results. Newer technologies including irreversible electroporation and high-intensity–focused ultrasound have theoretical advantages, but will require further research before becoming a routine part of the ablation armamentarium. The purpose of this review article is to discuss the current ablative technologies available, briefly review their mechanisms of action, discuss technical aspects of each, and provide current data supporting their use. PMID:25049445

  1. Radiofrequency Ablation of Cancer

    SciTech Connect

    Friedman, Marc; Mikityansky, Igor; Kam, Anthony; Libutti, Steven K.; Walther, McClellan M.; Neeman, Ziv; Locklin, Julia K.; Wood, Bradford J.

    2004-09-15

    Radiofrequency ablation (RFA) has been used for over 18 years for treatment of nerve-related chronic pain and cardiac arrhythmias. In the last 10 years, technical developments have increased ablation volumes in a controllable, versatile, and relatively inexpensive manner. The host of clinical applications for RFA have similarly expanded. Current RFA equipment, techniques, applications, results, complications, and research avenues for local tumor ablation are summarized.

  2. Renaissance of laser interstitial thermal ablation.

    PubMed

    Missios, Symeon; Bekelis, Kimon; Barnett, Gene H

    2015-03-01

    Laser interstitial thermal therapy (LITT) is a minimally invasive technique for treating intracranial tumors, originally introduced in 1983. Its use in neurosurgical procedures was historically limited by early technical difficulties related to the monitoring and control of the extent of thermal damage. The development of magnetic resonance thermography and its application to LITT have allowed for real-time thermal imaging and feedback control during laser energy delivery, allowing for precise and accurate provision of tissue hyperthermia. Improvements in laser probe design, surgical stereotactic targeting hardware, and computer monitoring software have accelerated acceptance and clinical utilization of LITT as a neurosurgical treatment alternative. Current commercially available LITT systems have been used for the treatment of neurosurgical soft-tissue lesions, including difficult to access brain tumors, malignant gliomas, and radiosurgery-resistant metastases, as well as for the ablation of such lesions as epileptogenic foci and radiation necrosis. In this review, the authors aim to critically analyze the literature to describe the advent of LITT as a neurosurgical, laser excision tool, including its development, use, indications, and efficacy as it relates to neurosurgical applications.

  3. Lung Ablation: Whats New?

    PubMed

    Xiong, Lillian; Dupuy, Damian E

    2016-07-01

    Lung cancer had an estimated incidence of 221,200 in 2015, making up 13% of all cancer diagnoses. Tumor ablation is an important treatment option for nonsurgical lung cancer and pulmonary metastatic patients. Radiofrequency ablation has been used for over a decade with newer modalities, microwave ablation, cryoablation, and irreversible electroporation presenting as additional and possibly improved treatment options for patients. This minimally invasive therapy is best for small primary lesions or favorably located metastatic tumors. These technologies can offer palliation and sometimes cure of thoracic malignancies. This article discusses the current available technologies and techniques available for tumor ablation.

  4. Optically thick ablation fronts. [in interstellar medium

    NASA Technical Reports Server (NTRS)

    Konigl, A.

    1984-01-01

    The physical characteristics of optically thick ablation fronts such as interstellar clouds are analyzed. Attention is given to cold clumps in both planar and spherical geometries and modifications caused by accelerations in a gravitational field or by evaporation of the clumps when encountered hot gas. The effects of ablation on the appearance of the Rayleigh-Taylor instability are examined in both linear and nonlinear regimes. The results of the calculations are applied to the astrophysical phenomena of cold clumps immersed in a supersonic flow, optically thick jets, and ablation in stellar envelopes. Evaporation in an optically thick front is projected to be orders of magnitude larger than evaporation in electron-conduction fronts in optically thin conditions. The optically thick processes could then be useful for modeling flows from, e.g., newly formed stars and active galactic nuclei.

  5. Dynamics of Laser Ablation in Superfluid ^4{He}

    NASA Astrophysics Data System (ADS)

    Buelna, X.; Popov, E.; Eloranta, J.

    2017-02-01

    Pulsed laser ablation of metal targets immersed in superfluid ^4{He} is visualized by time-resolved shadowgraph photography and the products are analyzed by post-experiment atomic force microscopy (AFM) measurements. The expansion dynamics of the gaseous ablation half-bubble on the target surface appears underdamped and follows the predicted behavior for the thermally induced bubble growth mechanism. An inherent instability of the ablation bubble appears near its maximum radius and no tightly focused cavity collapse or rebound events are observed. During the ablation bubble retreat phase, the presence of sharp edges in the target introduces flow patterns that lead to the creation of large classical vortex rings. Furthermore, on the nanometer scale, AFM data reveal that the metal nanoparticles created by laser ablation are trapped in spherical vortex tangles and quantized vortex rings present in the non-equilibrium liquid.

  6. Development of beryllium-based neutron target system with three-layer structure for accelerator-based neutron source for boron neutron capture therapy.

    PubMed

    Kumada, Hiroaki; Kurihara, Toshikazu; Yoshioka, Masakazu; Kobayashi, Hitoshi; Matsumoto, Hiroshi; Sugano, Tomei; Sakurai, Hideyuki; Sakae, Takeji; Matsumura, Akira

    2015-12-01

    The iBNCT project team with University of Tsukuba is developing an accelerator-based neutron source. Regarding neutron target material, our project has applied beryllium. To deal with large heat load and blistering of the target system, we developed a three-layer structure for the target system that includes a blistering mitigation material between the beryllium used as the neutron generator and the copper heat sink. The three materials were bonded through diffusion bonding using a hot isostatic pressing method. Based on several verifications, our project chose palladium as the intermediate layer. A prototype of the neutron target system was produced. We will verify that sufficient neutrons for BNCT treatment are generated by the device in the near future.

  7. Ablation of carbide materials with femtosecond pulses

    NASA Astrophysics Data System (ADS)

    Dumitru, Gabriel; Romano, Valerio; Weber, Heinz P.; Sentis, Marc; Marine, Wladimir

    2003-01-01

    The response of cemented tungsten carbide and of titanium carbonitride was investigated with respect to damage and ablation properties, under interaction with ultrashort laser pulses. These carbide materials present high microhardness and are of significant interest for tribological applications. The experiments were carried out in air with a commercial Ti:sapphire laser at energy densities on the target up to 6.5 J/cm 2. The irradiated target surfaces were analyzed with optical, SEM and AFM techniques and the damage and ablation threshold values were determined using the measured spot diameters and the calculated incident energy density distributions.

  8. Ablative Thermal Protection System Fundamentals

    NASA Technical Reports Server (NTRS)

    Beck, Robin A. S.

    2013-01-01

    This is the presentation for a short course on the fundamentals of ablative thermal protection systems. It covers the definition of ablation, description of ablative materials, how they work, how to analyze them and how to model them.

  9. Nanochemical effects in femtosecond laser ablation of metals

    SciTech Connect

    Vorobyev, A. Y.; Guo, Chunlei

    2013-02-18

    We study chemical energy released from the oxidation of aluminum in multipulse femtosecond laser ablation in air and oxygen. Our study shows that the released chemical energy amounts to about 13% of the incident laser energy, and about 50% of the ablated material is oxidized. The ablated material mass per laser pulse is measured to be on the nanogram scale. Our study indicates that femtosecond laser ablation is capable of inducing nanochemical reactions since the femtosecond laser pulse can controllably produce nanoparticles, clusters, and atoms from a solid target.

  10. Modeling CO{sub 2} Laser Ablative Impulse with Polymers

    SciTech Connect

    Sinko, John E.; Phipps, Claude R.; Sasoh, Akihiro

    2010-10-08

    Laser ablation vaporization models have usually ignored the spatial dependence of the laser beam. Here, we consider effects from modeling using a Gaussian beam for both photochemical and photothermal conditions. The modeling results are compared to experimental and literature data for CO{sub 2} laser ablation of the polymer polyoxymethylene under vacuum, and discussed in terms of the ablated mass areal density and momentum coupling coefficient. Extending the scope of discussion, laser ablative impulse generation research has lacked a cohesive strategy for linking the vaporization and plasma regimes. Existing models, mostly formulated for ultraviolet laser systems or metal targets, appear to be inappropriate or impractical for applications requiring CO{sub 2} laser ablation of polymers. A recently proposed method for linking the vaporization and plasma regimes for analytical modeling is addressed here along with the implications of its use. Key control parameters are considered, along with the major propulsion parameters needed for laser ablation propulsion modeling.

  11. Laser Ablated Carbon Nanodots for Light Emission.

    PubMed

    Reyes, Delfino; Camacho, Marco; Camacho, Miguel; Mayorga, Miguel; Weathers, Duncan; Salamo, Greg; Wang, Zhiming; Neogi, Arup

    2016-12-01

    The synthesis of fluorescent carbon dots-like nanostructures (CNDs) obtained through the laser ablation of a carbon solid target in liquid environment is reported. The ablation process was induced in acetone with laser pulses of 1064, 532, and 355 nm under different irradiation times. Close-spherical amorphous CNDs with sizes between 5 and 20 nm, whose abundance strongly depends on the ablation parameters were investigated using electron microscopy and was confirmed using absorption and emission spectroscopies. The π- π* electronic transition at 3.76 eV dominates the absorption for all the CNDs species synthesized under different irradiation conditions. The light emission is most efficient due to excitation at 3.54 eV with the photoluminescence intensity centered at 3.23 eV. The light emission from the CNDs is most efficient due to ablation at 355 nm. The emission wavelength of the CNDs can be tuned from the near-UV to the green wavelength region by controlling the ablation time and modifying the ablation and excitation laser wavelength.

  12. Sprayable lightweight ablative coating

    NASA Technical Reports Server (NTRS)

    Simpson, William G. (Inventor); Sharpe, Max H. (Inventor); Hill, William E. (Inventor)

    1991-01-01

    An improved lightweight, ablative coating is disclosed that may be spray applied and cured without the development of appreciable shrinkage cracks. The ablative mixture consists essentially of phenolic microballoons, hollow glass spheres, glass fibers, ground cork, a flexibilized resin binder, and an activated colloidal clay.

  13. A Pulsed Laser-Electromagnetic Hybrid Accelerator For Space Propulsion Application

    SciTech Connect

    Shinohara, Tadaki; Horisawa, Hideyuki; Baba, Msahumi; Tei, Kazuyoku

    2010-05-06

    A fundamental study of a newly developed rectangular pulsed laser-electromagnetic hybrid thruster was conducted, in which laser-ablation plasma was induced through laser beam irradiation onto a solid target and accelerated by electrical means instead of direct acceleration only by using a laser beam. The performance of the thruster was evaluated by measuring the mass per shot and impulse bit. As results, significantly high specific impulse ranging from 5,000 approx6,000 sec were obtained at energies of 0.1 and 8.6 J, respectively. In addition, the typical thrust efficiency varied from 17% to 19% depending on the charge energy.

  14. Pulsed laser interactions with space debris: Target shape effects

    SciTech Connect

    Liedahl, D. A.; Rubenchik, A.; Libby, S. B.; Nikolaev, S.; Phipps, C. R.

    2013-05-24

    Among the approaches to the proposed mitigation and remediation of the space debris problem is the de-orbiting of objects in low Earth orbit through irradiation by ground-based high-intensity pulsed lasers. Laser ablation of a thin surface layer causes target recoil, resulting in the depletion of orbital angular momentum and accelerated atmospheric re-entry. However, both the magnitude and direction of the recoil are shape dependent, a feature of the laser-based remediation concept that has received little attention. Since the development of a predictive capability is desirable, we have investigated the dynamical response to ablation of objects comprising a variety of shapes. We derive and demonstrate a simple analytical technique for calculating the ablation-driven transfer of linear momentum, emphasizing cases for which the recoil is not exclusively parallel to the incident beam. For the purposes of comparison and contrast, we examine one case of momentum transfer in the low-intensity regime, where photon pressure is the dominant momentum transfer mechanism, showing that shape and orientation effects influence the target response in a similar, but not identical, manner. As a result, we address the related problem of target spin and, by way of a few simple examples, show how ablation can alter the spin state of a target, which often has a pronounced effect on the recoil dynamics.

  15. Pulsed laser interactions with space debris: Target shape effects

    DOE PAGES

    Liedahl, D. A.; Rubenchik, A.; Libby, S. B.; ...

    2013-05-24

    Among the approaches to the proposed mitigation and remediation of the space debris problem is the de-orbiting of objects in low Earth orbit through irradiation by ground-based high-intensity pulsed lasers. Laser ablation of a thin surface layer causes target recoil, resulting in the depletion of orbital angular momentum and accelerated atmospheric re-entry. However, both the magnitude and direction of the recoil are shape dependent, a feature of the laser-based remediation concept that has received little attention. Since the development of a predictive capability is desirable, we have investigated the dynamical response to ablation of objects comprising a variety of shapes.more » We derive and demonstrate a simple analytical technique for calculating the ablation-driven transfer of linear momentum, emphasizing cases for which the recoil is not exclusively parallel to the incident beam. For the purposes of comparison and contrast, we examine one case of momentum transfer in the low-intensity regime, where photon pressure is the dominant momentum transfer mechanism, showing that shape and orientation effects influence the target response in a similar, but not identical, manner. As a result, we address the related problem of target spin and, by way of a few simple examples, show how ablation can alter the spin state of a target, which often has a pronounced effect on the recoil dynamics.« less

  16. Arc-driven rail accelerator research

    NASA Technical Reports Server (NTRS)

    Ray, Pradosh K.

    1987-01-01

    Arc-driven rail accelerator research is analyzed by considering wall ablation and viscous drag in the plasma. Plasma characteristics are evaluated through a simple fluid-mechanical analysis considering only wall ablation. By equating the energy dissipated in the plasma with the radiation heat loss, the average properties of the plasma are determined as a function of time and rate of ablation. Locations of two simultaneously accelerating arcs were determined by optical and magnetic probes and fron streak camera photographs. All three measurements provide consistent results.

  17. Proposed double-layer target for the generation of high-quality laser-accelerated ion beams.

    PubMed

    Esirkepov, T Zh; Bulanov, S V; Nishihara, K; Tajima, T; Pegoraro, F; Khoroshkov, V S; Mima, K; Daido, H; Kato, Y; Kitagawa, Y; Nagai, K; Sakabe, S

    2002-10-21

    In order to achieve a high-quality, i.e., monoenergetic, intense ion beam, we propose the use of a double-layer target. The first layer, at the target front, consists of high-Z atoms, while the second (rear) layer is a thin coating of low-Z atoms. The generation of high-quality proton beams from the double-layer target, irradiated by an ultraintense laser pulse, is demonstrated with three-dimensional particle-in-cell simulations.

  18. Laser Navigation for Radiofrequency Ablation

    SciTech Connect

    Varro, Zoltan; Locklin, Julia K. Wood, Bradford J.

    2004-09-15

    A 45-year-old male with renal cell carcinoma secondary to von-Hippel Lindau (VHL) disease presented for radiofrequency ablation (RFA) of kidney tumors. Due to his prior history of several partial nephrectomies and limited renal reserve, RFA was chosen because of its relatively nephron-sparing nature. A laser guidance device was used to help guide probe placement in an attempt to reduce procedure time and improve targeting accuracy. The device was successful at guiding needle placement, as both tumors were located with a single pass. Follow-up CT scan confirmed accurate needle placement, showing an area of coagulation necrosis covering the previously seen tumor.

  19. Effective generation of the spread-out-Bragg peak from the laser accelerated proton beams using a carbon-proton mixed target.

    PubMed

    Yoo, Seung Hoon; Cho, Ilsung; Cho, Sungho; Song, Yongkeun; Jung, Won-Gyun; Kim, Dae-Hyun; Shin, Dongho; Lee, Se Byeong; Pae, Ki-Hong; Park, Sung Yong

    2014-12-01

    Conventional laser accelerated proton beam has broad energy spectra. It is not suitable for clinical use directly, so it is necessary for employing energy selection system. However, in the conventional laser accelerated proton system, the intensity of the proton beams in the low energy regime is higher than that in the high energy regime. Thus, to generate spread-out-Bragg peak (SOBP), stronger weighting value to the higher energy proton beams is needed and weaker weighting value to the lower energy proton beams is needed, which results in the wide range of weighting values. The purpose of this research is to investigate a method for efficient generating of the SOBP with varying magnetic field in the energy selection system using a carbon-proton mixture target. Energy spectrum of the laser accelerated proton beams was acquired using Particle-In-Cell simulations. The Geant4 Monte Carlo simulation toolkit was implemented for energy selection, particle transportation, and dosimetric property measurement. The energy selection collimator hole size of the energy selection system was changed from 1 to 5 mm in order to investigate the effect of hole size on the dosimetric properties for Bragg peak and SOBP. To generate SOBP, magnetic field in the energy selection system was changed during beam irradiation with each beam weighting factor. In this study, our results suggest that carbon-proton mixture target based laser accelerated proton beams can generate quasi-monoenergetic energy distribution and result in the efficient generation of SOBP. A further research is needed to optimize SOBP according to each range and modulated width using an optimized weighting algorithm.

  20. Tumor Ablation and Nanotechnology

    PubMed Central

    Manthe, Rachel L.; Foy, Susan P.; Krishnamurthy, Nishanth; Sharma, Blanka; Labhasetwar, Vinod

    2010-01-01

    Next to surgical resection, tumor ablation is a commonly used intervention in the treatment of solid tumors. Tumor ablation methods include thermal therapies, photodynamic therapy, and reactive oxygen species (ROS) producing agents. Thermal therapies induce tumor cell death via thermal energy and include radiofrequency, microwave, high intensity focused ultrasound, and cryoablation. Photodynamic therapy and ROS producing agents cause increased oxidative stress in tumor cells leading to apoptosis. While these therapies are safe and viable alternatives when resection of malignancies is not feasible, they do have associated limitations that prevent their widespread use in clinical applications. To improve the efficacy of these treatments, nanoparticles are being studied in combination with nonsurgical ablation regimens. In addition to better thermal effect on tumor ablation, nanoparticles can deliver anticancer therapeutics that show synergistic anti-tumor effect in the presence of heat and can also be imaged to achieve precision in therapy. Understanding the molecular mechanism of nanoparticle-mediated tumor ablation could further help engineer nanoparticles of appropriate composition and properties to synergize the ablation effect. This review aims to explore the various types of nonsurgical tumor ablation methods currently used in cancer treatment and potential improvements by nanotechnology applications. PMID:20866097

  1. Effect of plasma profile on ion acceleration in the interaction of a short laser pulse with a thin overdense target

    SciTech Connect

    Kwon, Duck-Hee; Rhee, Yong-Joo; Lee, Sungman; Cha, Hyungki

    2008-06-15

    Energetic ion generation from the interaction of a short laser pulse with a thin overdense plasma accompanied by a preplasma and a rear side plasma gradient is investigated by particle-in-cell simulations. The dynamics of ion acceleration depending on the maximum density of the preplasma in front of the overdense plasma slab with a smooth density gradient at the rear side are presented and discussed by comparing a sharp rear side boundary case.

  2. Observed transition from Richtmyer-Meshkov jet formation through feedout oscillations to Rayleigh-Taylor instability in a laser target

    SciTech Connect

    Aglitskiy, Y.; Karasik, M.; Velikovich, A. L.; Serlin, V.; Weaver, J. L.; Kessler, T. J.; Schmitt, A. J.; Obenschain, S. P.; Nikitin, S. P.; Oh, J.; Metzler, N.

    2012-10-15

    Experimental study of hydrodynamic perturbation evolution triggered by a laser-driven shock wave breakout at the free rippled rear surface of a plastic target is reported. At sub-megabar shock pressure, planar jets manifesting the development of the Richtmyer-Meshkov-type instability in a non-accelerated target are observed. As the shock pressure exceeds 1 Mbar, an oscillatory rippled expansion wave is observed, followed by the 'feedout' of the rear-surface perturbations to the ablation front and the development of the Rayleigh-Taylor instability, which breaks up the accelerated target.

  3. Recent Advances in Tumor Ablation for Hepatocellular Carcinoma.

    PubMed

    Kang, Tae Wook; Rhim, Hyunchul

    2015-09-01

    Image-guided tumor ablation for early stage hepatocellular carcinoma (HCC) is an accepted non-surgical treatment that provides excellent local tumor control and favorable survival benefit. This review summarizes the recent advances in tumor ablation for HCC. Diagnostic imaging and molecular biology of HCC has recently undergone marked improvements. Second-generation ultrasonography (US) contrast agents, new computed tomography (CT) techniques, and liver-specific contrast agents for magnetic resonance imaging (MRI) have enabled the early detection of smaller and inconspicuous HCC lesions. Various imaging-guidance tools that incorporate imaging-fusion between real-time US and CT/MRI, that are now common for percutaneous tumor ablation, have increased operator confidence in the accurate targeting of technically difficult tumors. In addition to radiofrequency ablation (RFA), various therapeutic modalities including microwave ablation, irreversible electroporation, and high-intensity focused ultrasound ablation have attracted attention as alternative energy sources for effective locoregional treatment of HCC. In addition, combined treatment with RFA and chemoembolization or molecular agents may be able to overcome the limitation of advanced or large tumors. Finally, understanding of the biological mechanisms and advances in therapy associated with tumor ablation will be important for successful tumor control. All these advances in tumor ablation for HCC will result in significant improvement in the prognosis of HCC patients. In this review, we primarily focus on recent advances in molecular tumor biology, diagnosis, imaging-guidance tools, and therapeutic modalities, and refer to the current status and future perspectives for tumor ablation for HCC.

  4. Thermal ablation for hepatocellular carcinoma.

    PubMed

    Head, Hayden W; Dodd, Gerald D

    2004-11-01

    Thermal ablation, as a form of minimally invasive therapy for hepatocellular carcinoma (HCC), has become an important treatment modality. Because of the limitations of surgery, the techniques of thermal ablation have become standard therapies for HCC in some situations. This article reviews 4 thermal ablation techniques-radiofrequency (RF) ablation, microwave ablation, laser ablation, and cryoablation. Each of these techniques may have a role in treating HCC, and the mechanisms, equipment, patient selection, results, and complications of each are considered. Furthermore, combined therapies consisting of thermal ablation and adjuvant chemotherapy also show promise for enhancing these techniques. Important areas of research into thermal ablation remain, including improving the ability of ablation to treat larger tumors, determining the indications for each thermal ablation modality, optimizing image guidance, and obtaining good outcome data on the efficacy of these techniques.

  5. Thermal tumor ablation in clinical use.

    PubMed

    Brace, C

    2011-01-01

    Although a surgical procedure is performed by visual inspection with histopathological assessment of the excised tumor and margins, percutaneous and noninvasive thermal ablation is performed strictly with the aid of imaging. Applicator guidance into the target zone, treatment monitoring and verification, and clinical follow-up rely on effective imaging. Detailed discussion of imaging is beyond the scope of this article, but the influence of imaging on the choice of thermal ablation or procedural approach will be discussed as needed. More information on imaging for interventional therapies can be found in other articles in this issue of IEEE Pulse.

  6. Invasive circuitry-based neurotherapeutics: stereotactic ablation and deep brain stimulation for OCD.

    PubMed

    Greenberg, Benjamin D; Rauch, Scott L; Haber, Suzanne N

    2010-01-01

    Psychiatric neurosurgery, specifically stereotactic ablation, has continued since the 1940s, mainly at a few centers in Europe and the US. Since the late 1990s, the resurgence of interest in this field has been remarkable; reports of both lesion procedures and the newer technique of deep brain stimulation (DBS) have increased rapidly. In early 2009, the US FDA granted limited humanitarian approval for DBS for otherwise intractable obsessive-compulsive disorder (OCD), the first such approval for a psychiatric illness. Several factors explain the emergence of DBS and continued small-scale use of refined lesion procedures. DBS and stereotactic ablation have been successful and widely used for movement disorders. There remains an unmet clinical need: current drug and behavioral treatments offer limited benefit to some seriously ill people. Understandings of the neurocircuitry underlying psychopathology and the response to treatment, while still works in progress, are much enhanced. Here, we review modern lesion procedures and DBS for OCD in the context of neurocircuitry. A key issue is that clinical benefit can be obtained after surgeries targeting different brain structures. This fits well with anatomical models, in which circuits connecting orbitofrontal cortex (OFC), medial prefrontal cortex (mPFC), basal ganglia, and thalamus are central to OCD pathophysiology and treatment response. As in movement disorders, dedicated interdisciplinary teams, here led by psychiatrists, are required to implement these procedures and maintain care for patients so treated. Available data, although limited, support the promise of stereotactic ablation or DBS in carefully selected patients. Benefit in such cases appears not to be confined to obsessions and compulsions, but includes changes in affective state. Caution is imperative, and key issues in long-term management of psychiatric neurosurgery patients deserve focused attention. DBS and contemporary ablation also present different

  7. Ablative skin resurfacing.

    PubMed

    Agrawal, Nidhi; Smith, Greg; Heffelfinger, Ryan

    2014-02-01

    Ablative laser resurfacing has evolved as a safe and effective treatment for skin rejuvenation. Although traditional lasers were associated with significant thermal damage and lengthy recovery, advances in laser technology have improved safety profiles and reduced social downtime. CO2 lasers remain the gold standard of treatment, and fractional ablative devices capable of achieving remarkable clinical improvement with fewer side effects and shorter recovery times have made it a more practical option for patients. Although ablative resurfacing has become safer, careful patient selection and choice of suitable laser parameters are essential to minimize complications and optimize outcomes. This article describes the current modalities used in ablative laser skin resurfacing and examines their efficacy, indications, and possible side effects.

  8. Moldable cork ablation material

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A successful thermal ablative material was manufactured. Moldable cork sheets were tested for density, tensile strength, tensile elongation, thermal conductivity, compression set, and specific heat. A moldable cork sheet, therefore, was established as a realistic product.

  9. Development of a non-denaturing 2D gel electrophoresis protocol for screening in vivo uranium-protein targets in Procambarus clarkii with laser ablation ICP MS followed by protein identification by HPLC-Orbitrap MS.

    PubMed

    Xu, Ming; Frelon, Sandrine; Simon, Olivier; Lobinski, Ryszard; Mounicou, Sandra

    2014-10-01

    Limited knowledge about in vivo non-covalent uranium (U)-protein complexes is largely due to the lack of appropriate analytical methodology. Here, a method for screening and identifying the molecular targets of U was developed. The approach was based on non-denaturing 1D and 2D gel electrophoresis (ND-PAGE and ND-2D-PAGE (using ND-IEF as first dimension previously described)) in conjunction with laser ablation inductively coupled plasma mass spectrometry (LA-ICP MS) for the detection of U-containing proteins. The proteins were then identified by µbore HPLC-Orbitrap MS/MS. The method was applied to the analysis of cytosol of hepatopancreas (HP) of a model U-bioaccumulating organism (Procambarus clarkii). The imaging of uranium in 2D gels revealed the presence of 11 U-containing protein spots. Six protein candidates (i.e. ferritin, glyceraldehyde-3-phosphate dehydrogenase, triosephosphate isomerase, cytosolic manganese superoxide dismutase (Mn-SOD), glutathione S transferase D1 and H3 histone family protein) were then identified by matching with the data base of crustacea Decapoda species (e.g. crayfish). Among them, ferritin was the most important one. This strategy is expected to provide an insight into U toxicology and metabolism.

  10. Catheter Ablation of Fascicular Ventricular Tachycardia

    PubMed Central

    Liu, Yaowu; Fang, Zhen; Yang, Bing; Kojodjojo, Pipin; Chen, Hongwu; Ju, Weizhu; Cao, Kejiang; Chen, Minglong

    2015-01-01

    Background— Fascicular ventricular tachycardia (FVT) is a common form of sustained idiopathic left ventricular tachycardia with an Asian preponderance. This study aimed to prospectively investigate long-term clinical outcomes of patients undergoing ablation of FVT and identify predictors of arrhythmia recurrence. Methods and Results— Consecutive patients undergoing FVT ablation at a single tertiary center were enrolled. Activation mapping was performed to identify the earliest presystolic Purkinje potential during FVT that was targeted by radiofrequency ablation. Follow-up with clinic visits, ECG, and Holter monitoring was performed at least every 6 months. A total of 120 consecutive patients (mean age, 29.3±12.7 years; 82% men; all patients with normal ejection fraction) were enrolled. FVT involved left posterior fascicle and left anterior fascicle in 118 and 2 subjects, respectively. VT was noninducible in 3 patients, and ablation was acutely successful in 117 patients. With a median follow-up of 55.7 months, VT of a similar ECG morphology recurred in 17 patients, and repeat procedure confirmed FVT recurrence involving the same fascicle. Shorter VT cycle length was the only significant predictor of FVT recurrence (P=0.03). Six other patients developed new-onset upper septal FVT that was successfully ablated. Conclusions— Ablation of FVT guided by activation mapping is associated with a single procedural success rate without the use of antiarrhythmic drugs of 80.3%. Arrhythmia recurrences after an initially successful ablation were caused by recurrent FVT involving the same fascicle in two thirds of patients or new onset of upper septal FVT in the remainder. PMID:26386017

  11. Enhanced laser-radiation-pressure-driven proton acceleration by moving focusing electric-fields in a foil-in-cone target

    SciTech Connect

    Zou, D. B.; Zhuo, H. B. Yu, T. P.; Yang, X. H.; Shao, F. Q.; Ma, Y. Y.; Yin, Y.; Ge, Z. Y.; Wu, H. C.

    2015-02-15

    A foil-in-cone target is proposed to enhance stable laser-radiation-pressure-driven proton acceleration by avoiding the beam degradation in whole stage of acceleration. Two and three-dimensional particle-in-cell simulations demonstrate that the guiding cone can substantially improve the spectral and spatial properties of the ion beam and lead to better preservation of the beam quality. This can be attributed to the focusing effect of the radial sheath electric fields formed on the inner walls of the cone, which co-move with the accelerated foil and effectively suppress the undesirable transverse explosion of the foil. It is shown that, by using a transversely Gaussian laser pulse with intensity of ∼2.74 × 10{sup 22 }W∕cm{sup 2}, a quasi-monoenergetic proton beam with a peak energy of ∼1.5 GeV/u, density ∼10n{sub c}, and transverse size ∼1λ{sub 0} can be obtained.

  12. Endometrial Ablation for Menorrhagia

    PubMed Central

    Sanders, Barry H.

    1992-01-01

    Endometrial ablation is a relatively new treatment for patients with persistent menorrhagia. The procedure can be performed by either laser photocoagulation or electrocoagulation; both have a very low risk of complication. Generally, less than 24 hours of hospitalization is required and return to normal activities, including work, is almost immediate. Endometrial ablation is likely to become a mainstay of treatment for menorrhagia as the technology and training become more readily available. PMID:21229128

  13. Recent US target-physics-related research in heavy-ion inertial fusion: simulations for tamped targets and for disk experiments in accelerator test facilities

    SciTech Connect

    Mark, J.W.K.

    1982-03-22

    Calculations suggest that experiments relating to disk heating, as well as beam deposition, focusing and transport can be performed within the context of current design proposals for accelerator test-facilities. Since the test-facilities have lower ion kinetic energy and beam pulse power as compared to reactor drivers, we achieve high-beam intensities at the focal spot by using short focal distance and properly designed beam optics. In this regard, the low beam emittance of suggested multi-beam designs are very useful. Possibly even higher focal spot brightness could be obtained by plasma lenses which involve external fields on the beam which is stripped to a higher charge state by passing through a plasma cell. Preliminary results suggest that intensities approx. 10/sup 13/ - 10/sup 14/ W/cm/sup 2/ are achievable. Given these intensities, deposition experiments with heating of disks to greater than a million degrees Kelvin (100 eV) are expected.

  14. Accelerating target discovery using pre-competitive open science—patients need faster innovation more than anyone else

    PubMed Central

    Low, Eric; Bountra, Chas; Lee, Wen Hwa

    2016-01-01

    We are experiencing a new era enabled by unencumbered access to high quality data through the emergence of open science initiatives in the historically challenging area of early stage drug discovery. At the same time, many patient-centric organisations are taking matters into their own hands by participating in, enabling and funding research. Here we present the rationale behind the innovative partnership between the Structural Genomics Consortium (SGC)—an open, pre-competitive pre-clinical research consortium and the research-focused patient organisation Myeloma UK to create a new, comprehensive platform to accelerate the discovery and development of new treatments for multiple myeloma. PMID:27594912

  15. Accelerating target discovery using pre-competitive open science-patients need faster innovation more than anyone else.

    PubMed

    Low, Eric; Bountra, Chas; Lee, Wen Hwa

    2016-01-01

    We are experiencing a new era enabled by unencumbered access to high quality data through the emergence of open science initiatives in the historically challenging area of early stage drug discovery. At the same time, many patient-centric organisations are taking matters into their own hands by participating in, enabling and funding research. Here we present the rationale behind the innovative partnership between the Structural Genomics Consortium (SGC)-an open, pre-competitive pre-clinical research consortium and the research-focused patient organisation Myeloma UK to create a new, comprehensive platform to accelerate the discovery and development of new treatments for multiple myeloma.

  16. Laser Surface Preparation of Epoxy Composites for Secondary Bonding: Optimization of Ablation Depth

    NASA Technical Reports Server (NTRS)

    Palmieri, Frank L.; Hopkins, John; Wohl, Christopher J.; Lin, Yi; Connell, John W.; Belcher, Marcus A.; Blohowiak, Kay Y.

    2015-01-01

    Surface preparation has been identified as one of the most critical aspects of attaining predictable and reliable adhesive bonds. Energetic processes such as laser ablation or plasma treatment are amenable to automation and are easily monitored and adjusted for controlled surface preparation. A laser ablation process was developed to accurately remove a targeted depth of resin, approximately 0.1 to 20 micrometers, from a carbon fiber reinforced epoxy composite surface while simultaneously changing surface chemistry and creating micro-roughness. This work demonstrates the application of this process to prepare composite surfaces for bonding without exposing or damaging fibers on the surface. Composite panels were prepared in an autoclave and had a resin layer approximately 10 micrometers thick above the fiber reinforcement. These composite panels were laser surface treated using several conditions, fabricated into bonded panels and hygrothermally aged. Bond performance of aged, experimental specimens was compared with grit blast surface treated specimens using a modified double cantilever beam test that enabled accelerated saturation of the specimen with water. Comparison of bonded specimens will be used to determine how ablation depth may affect average fracture energies and failure modes.

  17. Approximate model for laser ablation of carbon

    NASA Astrophysics Data System (ADS)

    Shusser, Michael

    2010-08-01

    The paper presents an approximate kinetic theory model of ablation of carbon by a nanosecond laser pulse. The model approximates the process as sublimation and combines conduction heat transfer in the target with the gas dynamics of the ablated plume which are coupled through the boundary conditions at the interface. The ablated mass flux and the temperature of the ablating material are obtained from the assumption that the ablation rate is restricted by the kinetic theory limitation on the maximum mass flux that can be attained in a phase-change process. To account for non-uniform distribution of the laser intensity while keeping the calculation simple the quasi-one-dimensional approximation is used in both gas and solid phases. The results are compared with the predictions of the exact axisymmetric model that uses the conservation relations at the interface derived from the momentum solution of the Boltzmann equation for arbitrary strong evaporation. It is seen that the simpler approximate model provides good accuracy.

  18. The thyroxine-containing thyroglobulin peptide (aa 2549-2560) is a target epitope in iodide-accelerated spontaneous autoimmune thyroiditis.

    PubMed

    Kolypetri, Panayota; Carayanniotis, Karen; Rahman, Shofiur; Georghiou, Paris E; Magafa, Vassiliki; Cordopatis, Paul; Carayanniotis, George

    2014-07-01

    Enhanced iodide ingestion is known to accelerate the incidence and severity of spontaneous autoimmune thyroiditis [iodide-accelerated spontaneous autoimmune thyroiditis (ISAT)] in NOD.H2(h4) mice. CD4+ cells are required for the development and maintenance of ISAT, but their target epitopes remain unknown. In this study, we show that the previously identified thyroglobulin (Tg) T cell epitope p2549-2560 containing thyroxine at position 2553 (T4p2553) induces thyroiditis as well as strong specific T and B cell responses in NOD.H2(h4) mice. In ISAT, activated CD4+ T cells specific for T4p2553 are detected before the disease onset in thyroid-draining cervical lymph nodes only in mice placed on an iodide-rich diet and not in age-matched controls. In addition, selective enrichment of CD4+ IFN-γ+ T4p2553-specific cells is observed among cervical lymph node cells and intrathyroidal lymphocytes. T4p2553 was equally detectable on dendritic cells obtained ex vivo from cervical lymph node cells of NaI-fed or control mice, suggesting that the iodide-rich diet contributes to the activation of autoreactive cells rather than the generation of the autoantigenic epitope. Furthermore, spontaneous T4p2553-specific IgG are not detectable within the strong Tg-specific autoantibody response. To our knowledge, these data identify for the first time a Tg T cell epitope as a spontaneous target in ISAT.

  19. Co-targeting Deoxyribonucleic Acid–Dependent Protein Kinase and Poly(Adenosine Diphosphate-Ribose) Polymerase-1 Promotes Accelerated Senescence of Irradiated Cancer Cells

    SciTech Connect

    Azad, Arun; Bukczynska, Patricia; Jackson, Susan; Haput, Ygal; Cullinane, Carleen; McArthur, Grant A.; Solomon, Benjamin

    2014-02-01

    Purpose: To examine the effects of combined blockade of DNA-dependent protein kinase (DNA-PK) and poly(adenosine diphosphate-ribose) polymerase-1 (PARP-1) on accelerated senescence in irradiated H460 and A549 non-small cell lung cancer cells. Methods and Materials: The effects of KU5788 and AG014699 (inhibitors of DNA-PK and PARP-1, respectively) on clonogenic survival, DNA double-strand breaks (DSBs), apoptosis, mitotic catastrophe, and accelerated senescence in irradiated cells were examined in vitro. For in vivo experiments, H460 xenografts established in athymic nude mice were treated with BEZ235 (a DNA-PK, ATM, and phosphatidylinositol 3-kinase/mammalian target of rapamycin inhibitor) and AG014699 to determine effects on proliferation, DNA DSBs, and accelerated senescence after radiation. Results: Compared with either inhibitor alone, combination treatment with KU57788 and AG014699 reduced postradiation clonogenic survival and significantly increased persistence of Gamma-H2AX (γH2AX) foci in irradiated H460 and A549 cells. Notably, these effects coincided with the induction of accelerated senescence in irradiated cells as reflected by positive β-galactosidase staining, G2-M cell-cycle arrest, enlarged and flattened cellular morphology, increased p21 expression, and senescence-associated cytokine secretion. In irradiated H460 xenografts, concurrent therapy with BEZ235 and AG014699 resulted in sustained Gamma-H2AX (γH2AX) staining and prominent β-galactosidase activity. Conclusion: Combined DNA-PK and PARP-1 blockade increased tumor cell radiosensitivity and enhanced the prosenescent properties of ionizing radiation in vitro and in vivo. These data provide a rationale for further preclinical and clinical testing of this therapeutic combination.

  20. Molecular dynamics investigation of mechanisms of femtosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Cheng, Changrui

    Laser micro-machining has been widely applied for material processing in many industries. A phenomenon called "laser ablation" is usually involved in the laser micro-machining process. Laser ablation is the process of material removal after the irradiation of a laser beam onto the material. It is commonly characterized by small temporal and spatial scales, extremely high material temperature and pressure, and strong non-equilibrium thermodynamic state. In this work, molecular dynamics (MD) simulation is conducted to study the femtosecond laser ablation of metals (nickel and copper) and dielectrics (fused silica, or glass). The laser heating and the ablation processes are numerically modeled, and the computation is accelerated by parallel processing technique. Both the pair-wise Morse potential and the many-body EAM (Embedded-Atom Method) potential are employed for metals. In the simulation of fused silica, the BKS (van Beest, Kramer and van Santen) potential is used, and the generation of free electrons, the energy transport from laser beam to free electrons and energy coupling between electrons and the lattice are considered. The main goal of this work is to illustrate the detailed processes of femtosecond laser ablation and to study its mechanisms. From the MD results, it is found that the mechanism of femtosecond laser ablation is strongly dependent on the laser fluences. For metals, low fluence laser ablation is mainly through phase explosion (homogeneous gas bubble nucleation), while spinodal decomposition is responsible for high fluence ablation. Ablation mechanism is determined by whether or not the material (liquid) temperature exceeds the critical temperature. For fused silica, the generation and existence of free electrons are found to affect ablation significantly, especially at low fluence, where Coulomb explosion is found to play an important role in material separation.

  1. Laboratory Micrometeroid/Dust Ablation Studies

    NASA Astrophysics Data System (ADS)

    Thomas, E.; Horanyi, M.; Janches, D.; Munsat, T. L.; Plane, J. M. C.; Simolka, J.; Sternovsky, Z.

    2014-12-01

    Each day, somewhere between 5-270 tonnes of meteoric material ablates in Earth's upper atmosphere. Thisenormous range is significant because the Interplanetary Dust Particle (IDP) input has implications in ourunderstanding of meteor transport in the atmosphere, the formation of layers of metal atoms and ions,nucleation of noctilucent clouds, effects on stratospheric aerosols and O3 chemistry, and dust evolution inour solar system. As the dust ablates, it produces light, as well as a plasma trail of ionized atmosphericatoms and electrons. These meteor signatures are detected by photographic means, or by radar, but thereremain uncertainties in the luminous efficiency and ionization coefficient of meteors - two parameters thatare essential to evaluate densities, masses, height distributions and fluxes. Precise measurements of theseparameters would allow for not only an understanding of the layers of metal atoms and ions and meteoricsmoke particles in the mesosphere and lower thermosphere, but also would allow for the Earth's atmosphereto be used as a dust detector to detect and characterize the dust environment in our solar system. This work discusses the preliminary results of the new dust ablation facility at the 3 MV hypervelocity dust accelerator at the Institute for Modeling Plasma, Atmospheres and Cosmic Dust (IMPACT) at the University of Colorado, which aims to characterize the ionization coefficient and luminous efficiency of ablating micrometeroids.

  2. High Current Cathodes Fabricated by KrF Laser Ablation

    SciTech Connect

    Gilgenbach, Ronald M.; Lau, Y. Y.; Jones, M. C.; Johnston, M. D.; Jordan, N. M.; Hoff, B. W.

    2010-10-08

    In this paper we review several high power laser ablation techniques that have been utilized to fabricate high current (1-80 kA) electron beam cathodes for accelerators and microwave sources: 1) Projection Ablation Lithography (PAL) cathodes, 2) Ablation Line Focus (ALF) cathodes, and 3) Metal-Oxide-Junction (MOJ) cathodes. Laser-ablative micromachining techniques (PAL and ALF) have been utilized to generate micron-scale features on metal substrates that provide electric field (beta) enhancement for Fowler-Nordheim emission and plasma cathodes. Since these laser-ablated patterns are directly, laser-written on the substrate metal they exhibit much higher thermal conductivity for higher current capability and increased damage thresholds. Metal-Oxide-Junction (MOJ) cathodes exploit the triple-point electron emission that occurs at the interface between metal, insulator and vacuum.The ablation laser is a KrF excimer laser with a pulse energy of 600 mJ and pulselength of 20 ns. Cathode experiments were performed on the MELBA-C accelerator: V = -300 kV, pulselength = 0.5 microsecond. Data will be presented for PAL, ALF and MOJ cathodes.

  3. Self-vapor cooled targets for production of I-123 at high current accelerators. [using Xe-123 production

    NASA Technical Reports Server (NTRS)

    Blue, J. W.; Scholz, K. L.; Sodd, V. J.

    1974-01-01

    The basic elements of the vapor cooled target system are shown. This system can be operated as a heat pipe or as a conventional condenser. The choice of target fluid is based on the specific nuclear reaction chosen to produce Xe-123. The reaction using I-127 was studied and shown to have a significant yield for bombarding energies from 47 to 63 MeV. The Cs-133 reaction is also included. Xenon-123 is applied to I-123 production in a purer form for thyroid studies.

  4. A TPD and AR based comparison of accelerator neutron irradiation fields between (7)Li and W targets for BNCT.

    PubMed

    Tanaka, Kenichi; Endo, Satoru; Yonai, Shunsuke; Baba, Mamoru; Hoshi, Masaharu

    2014-06-01

    The characteristics of moderator assembly dimension was investigated for the usage of (7)Li(p,n) neutrons by 2.3-2.8MeV protons and W(p,n) neutrons by 50MeV protons. The indexes were the treatable protocol depth (TPD) and advantage depth (AD). Consequently, a configuration for W target with the Fe filter, Fluental moderator, Pb reflector showed the TPD of 5.8cm and AD of 9.3cm. Comparable indexes were found for the Li target in a geometry with the MgF2 moderator and Teflon reflector.

  5. Ultrashort-pulse laser ablation of nanocrystalline aluminum

    SciTech Connect

    Gill-Comeau, Maxime; Lewis, Laurent J.

    2011-12-01

    Molecular-dynamics simulations of the ablation of nanocrystalline Al films by ultrashort laser pulses in the low-fluence (no-ionization) regime (0-2.5 times the ablation threshold, F{sub th}) are reported. The simulations employ an embedded-atom method potential for the dynamics of the ions and a realistic two-temperature model for the electron gas (and its interactions with the ion gas), which confers different electronic properties to the monocrystalline solid, nanocrystalline solid, and liquid regions of the targets. The ablation dynamics in three nanocrystalline structures is studied: two dense targets with different crystallite sizes (d=3.1 and 6.2 nm on average) and a d=6.2 nm porous sample. The results are compared to the ablation of monocrystalline Al. Significant differences are observed, the nanocrystalline targets showing, in particular, a lower ablation threshold and a larger melting depth, and yielding pressure waves of higher amplitude than the monocrystalline targets. Furthermore, it is shown that nanocrystalline targets experience no residual stress associated with thermal expansion and lateral constraints, and that little crystal growth occurs in the solid during and after ablation. Laser-induced spallation of the back surface of the films is also investigated; we find, in particular, that the high-strain fracture resistance of nanocrystalline samples is significantly reduced in comparison to the crystalline material.

  6. Heat-Based Tumor Ablation: Role of the Immune Response.

    PubMed

    Wu, Feng

    2016-01-01

    The ideal cancer therapy not only induces the death of all localized tumor cells with less damage to surrounding normal tissue, but also activates a systemic antitumor immunity. Heat-based tumor ablation has the potential to be such a treatment as it can minimal-invasively ablate a targeted tumor below the skin surface, and may subsequently augment host antitumor immunity. This chapter primarily introduces increasing pre-clinical and clinical evidence linking antitumor immune response to thermal tumor ablation, and then discusses the potential mechanisms involved in ablation-enhanced host antitumor immunity. The seminal studies performed so far indicate that although it is not possible to make definite conclusions on the connection between thermal ablation and antitumor immune response, it is nonetheless important to conduct extensive studies on the subject in order to elucidate the processes involved.

  7. Accelerator mass spectrometry measurement of intracellular concentrations of active drug metabolites in human target cells in vivo.

    PubMed

    Chen, J; Garner, R C; Lee, L S; Seymour, M; Fuchs, E J; Hubbard, W C; Parsons, T L; Pakes, G E; Fletcher, C V; Flexner, C

    2010-12-01

    Accelerator mass spectrometry (AMS) is an ultrasensitive technique to detect radiolabeled compounds. We administered a microdose (100 µg) of (14)C-labeled zidovudine (ZDV) with or without a standard unlabeled dose (300 mg) to healthy volunteers. Intracellular ZDV-triphosphate (ZDV-TP) concentration was measured using AMS and liquid chromatography-tandem mass spectrometry (LC/MS/MS). AMS analysis yielded excellent concordance with LC/MS/MS and was 30,000-fold more sensitive. The kinetics of intracellular ZDV-TP formation changed several-fold over the dose range studied (100 µg-300 mg). AMS holds promise as a tool for quantifying intracellular drug metabolites and other biomediators in vivo.

  8. Targeted ablation of the chromogranin a (Chga) gene: normal neuroendocrine dense-core secretory granules and increased expression of other granins.

    PubMed

    Hendy, Geoffrey N; Li, Tong; Girard, Martine; Feldstein, Richard C; Mulay, Shree; Desjardins, Roxane; Day, Robert; Karaplis, Andrew C; Tremblay, Michel L; Canaff, Lucie

    2006-08-01

    Chromogranin A (CgA), originally identified in adrenal chromaffin cells, is a member of the granin family of acidic secretory glycoproteins that are expressed in endocrine cells and neurons. CgA has been proposed to play multiple roles in the secretory process. Intracellularly, CgA may control secretory granule biogenesis and target neurotransmitters and peptide hormones to granules of the regulated pathway. Extracellularly, peptides formed as a result of proteolytic processing of CgA may regulate hormone secretion. To investigate the role of CgA in the whole animal, we created a mouse mutant null for the Chga gene. These mice are viable and fertile and have no obvious developmental abnormalities, and their neural and endocrine functions are not grossly impaired. Their adrenal glands were structurally unremarkable, and morphometric analyses of chromaffin cells showed vesicle size and number to be normal. However, the excretion of epinephrine, norepinephrine, and dopamine was significantly elevated in the Chga null mutants. Adrenal medullary mRNA and protein levels of other dense-core secretory granule proteins including chromogranin B, and secretogranins II to VI were up-regulated 2- to 3-fold in the Chga null mutant mice. Hence, the increased expression of the other granin family members is likely to compensate for the Chga deficiency.

  9. A Monte Carlo investigation of low-Z target image quality generated in a linear accelerator using Varian's VirtuaLinac

    SciTech Connect

    Parsons, David; Robar, James L.; Sawkey, Daren

    2014-02-15

    Purpose: The focus of this work was the demonstration and validation of VirtuaLinac with clinical photon beams and to investigate the implementation of low-Z targets in a TrueBeam linear accelerator (Linac) using Monte Carlo modeling. Methods: VirtuaLinac, a cloud based web application utilizing Geant4 Monte Carlo code, was used to model the Linac treatment head components. Particles were propagated through the lower portion of the treatment head using BEAMnrc. Dose distributions and spectral distributions were calculated using DOSXYZnrc and BEAMdp, respectively. For validation, 6 MV flattened and flattening filter free (FFF) photon beams were generated and compared to measurement for square fields, 10 and 40 cm wide and at d{sub max} for diagonal profiles. Two low-Z targets were investigated: a 2.35 MeV carbon target and the proposed 2.50 MeV commercial imaging target for the TrueBeam platform. A 2.35 MeV carbon target was also simulated in a 2100EX Clinac using BEAMnrc. Contrast simulations were made by scoring the dose in the phosphor layer of an IDU20 aSi detector after propagating through a 4 or 20 cm thick phantom composed of water and ICRP bone. Results: Measured and modeled depth dose curves for 6 MV flattened and FFF beams agree within 1% for 98.3% of points at depths greater than 0.85 cm. Ninety three percent or greater of points analyzed for the diagonal profiles had a gamma value less than one for the criteria of 1.5 mm and 1.5%. The two low-Z target photon spectra produced in TrueBeam are harder than that from the carbon target in the Clinac. Percent dose at depth 10 cm is greater by 3.6% and 8.9%; the fraction of photons in the diagnostic energy range (25–150 keV) is lower by 10% and 28%; and contrasts are lower by factors of 1.1 and 1.4 (4 cm thick phantom) and 1.03 and 1.4 (20 cm thick phantom), for the TrueBeam 2.35 MV/carbon and commercial imaging beams, respectively. Conclusions: VirtuaLinac is a promising new tool for Monte Carlo modeling of

  10. Combining Electrolysis and Electroporation for Tissue Ablation.

    PubMed

    Phillips, Mary; Rubinsky, Liel; Meir, Arie; Raju, Narayan; Rubinsky, Boris

    2015-08-01

    Electrolytic ablation is a method that operates by delivering low magnitude direct current to the target region over long periods of time, generating electrolytic products that destroy cells. This study was designed to explore the hypothesis stating that electrolytic ablation can be made more effective when the electrolysis-producing electric charges are delivered using electric pulses with field strength typical in reversible electroporation protocols. (For brevity we will refer to tissue ablation protocols that combine electroporation and electrolysis as E(2).) The mechanistic explanation of this hypothesis is related to the idea that products of electrolysis generated by E(2) protocols can gain access to the interior of the cell through the electroporation permeabilized cell membrane and therefore cause more effective cell death than from the exterior of an intact cell. The goal of this study is to provide a first-order examination of this hypothesis by comparing the charge dosage required to cause a comparable level of damage to a rat liver, in vivo, when using either conventional electrolysis or E(2) approaches. Our results show that E(2) protocols produce tissue damage that is consistent with electrolytic ablation. Furthermore, E(2) protocols cause damage comparable to that produced by conventional electrolytic protocols while delivering orders of magnitude less charge to the target tissue over much shorter periods of time.

  11. Infrared laser bone ablation

    SciTech Connect

    Nuss, R.C.; Fabian, R.L.; Sarkar, R.; Puliafito, C.A.

    1988-01-01

    The bone ablation characteristics of five infrared lasers, including three pulsed lasers (Nd:YAG, lambda = 1064 micron; Hol:YSGG, lambda = 2.10 micron; and Erb:YAG, lambda = 2.94 micron) and two continuous-wave lasers (Nd:YAG, lambda = 1.064 micron; and CO/sub 2/, lambda = 10.6 micron), were studied. All laser ablations were performed in vitro, using moist, freshly dissected calvarium of guinea pig skulls. Quantitative etch rates of the three pulsed lasers were calculated. Light microscopy of histologic sections of ablated bone revealed a zone of tissue damage of 10 to 15 micron adjacent to the lesion edge in the case of the pulsed Nd:YAG and the Erb:YAG lasers, from 20 to 90 micron zone of tissue damage for bone ablated by the Hol:YSGG laser, and 60 to 135 micron zone of tissue damage in the case of the two continuous-wave lasers. Possible mechanisms of bone ablation and tissue damage are discussed.

  12. Wire ablation scaling in Z pinches

    NASA Astrophysics Data System (ADS)

    Yu, Edmund; Sinars, Daniel; Mehlhorn, Tom; Oliver, Bryan

    2004-11-01

    We investigate the physical processes involved in wire ablation in Z pinches, using a combination of simple 1D steady-state analytic theory (similar in approach to that described in [1]) and simulations of the Z pinch under constant current drive conditions (using the radiation-MHD code ALEGRA-MHD). Of particular interest is the dependence of mass ablation rate on wire mass and drive current. We benchmark our scaling trends against simulations of a recently conducted series of experiments on Sandia National Laboratories' Z accelerator (Albuquerque, NM), in which only the mass of the wire array was varied. [1] V.V. Aleksandrov et al., Plasma Phys. Reports 27, 89 (2001) *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockhead Martin Company for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  13. Laser ablation for the synthesis of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Holloway, Brian C. (Inventor); Eklund, Peter C. (Inventor); Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor); Shinn, Michelle (Inventor)

    2012-01-01

    Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces and output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of "side pumped", preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

  14. Laser ablation for the synthesis of carbon nanotubes

    NASA Technical Reports Server (NTRS)

    Holloway, Brian C. (Inventor); Eklund, Peter C. (Inventor); Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor); Shinn, Michelle (Inventor)

    2010-01-01

    Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces an output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of side pumped, preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

  15. Laser ablation for the synthesis of carbon nanotubes

    DOEpatents

    Holloway, Brian C.; Eklund, Peter C.; Smith, Michael W.; Jordan, Kevin C.; Shinn, Michelle

    2010-04-06

    Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces an output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of "side pumped", preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

  16. Laser ablation for the synthesis of carbon nanotubes

    DOEpatents

    Holloway, Brian C; Eklund, Peter C; Smith, Michael W; Jordan, Kevin C; Shinn, Michelle

    2012-11-27

    Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces and output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of "side pumped", preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

  17. SU-E-J-207: Assessing the Validity of 4D-CT Based Target Volumes and Free Breathing CBCT Localization in Lung Stereotactic Ablative Radiation Therapy (SABR)

    SciTech Connect

    Badkul, R; Pokhrel, D; Jiang, H; Park, J; Wang, F; Kumar, P

    2014-06-01

    Purpose: Four-dimensional-computed-tomography(4D-CT) imaging for target-volume delineation and cone-beam-tomography(CBCT) for treatment localization are widely utilized in lung-SABR.Aim of this study was to perform a quantitative-assessment and inter-comparison of Internal-targetvolumes( ITV) drawn on various phases of breathing-cycle 4D-CT-scans, Maximum-intensity-projection(MIP), average-intensity-projection(AIP)and static CT-scans of lung-motion-phantom to simulate lung-SABR patient geometry. We also analyzed and compared the ITVs drawn on freebreathing- CBCT. Materials and Methods: 4D-CT-scans were acquired on Philips big-bore 16slice CT and Bellows-respiratory monitoring-system using retrospective phase-binning method. Each respiratory cycle divided into 10-phases. Quasar-Phantom with lung-inserts and 3cm-diameter nylonball to simulate tumor and was placed on respiratory-motion-platform for 4D-CT and CBCT-acquisition. Amplitudes of motions: 0.5,1.0,2.0,3.0cm in superior-inferior direction with breathing-cycle time of 6,5,4,6sec, respectively used.4D-CTs with 10-phases(0%to90%)for each excursion-set and 3D-CT for static-phantom exported to iPlan treatment-planningsystem( TPS).Tumor-volumes delineated in all phases of 4D-CT, MIP,AIP,CBCT scans using fixed-HU-threshold(−500to1000)values automatically.For each 4D-dataset ITV obtained by unifying the tumorcontours on all phases.CBCT-ITV-volumes were drawn in Eclipse-TPS. Results: Mean volume of tumor contours for all phases compared with static 3D-CT were 0.62±0.08%, 1.67±0.26%, 4.77±0.54% and 9.27±1.23% for 0.5cm,1cm,2cm,3cm excursions respectively. Differences of mean Union-ITV with MIP-ITV were close(≤2.4%).Mean Union-ITV from expected-theoretical values differed from −4.9% to 3.8%.Union-ITV and MIP-ITV were closer within 2.3%. AIP-ITVs were underestimated from 14 to 32% compared to union-ITV for all motion datasets. Differences of −5.9% to −44% and −5% to 6.7% for CBCT-ITV from MIP-ITV and AIP

  18. Improving beam spectral and spatial quality by double-foil target in laser ion acceleration for ion-driven fast ignition

    SciTech Connect

    Huang, Chengkun; Albright, Brian J

    2010-07-16

    Mid-Z ion driven fast ignition inertial fusion requires ion beams of 100s of MeV energy and < 10% energy spread. An overdense run-scale foil target driven by a high intensity laser pulse can produce an ion beam that has attractive properties for this application. The Break Out Afterburner (BOA) is one laser-ion acceleration mechanism proposed to generate such beams, however the late stages of the BOA tend to produce too large of an energy spread. The spectral and spatial qualities of the beam quickly evolve as the ion beam and co-moving electrons continue to interact with the laser. Here we show how use of a second target foil placed behind a nm-scale foil can substantially reduce the temperature of the co-moving electrons and improve the ion beam energy spread. Particle-In-Cell simulations reveal the dynamics of the ion beam under control. Optimal conditions for improving the spectral and spatial spread of the ion beam is explored for current laser and target parameters, leading to generation of ion beams of energy 100s of MeV and 6% energy spread, a vital step for realizing ion-driven fast ignition.

  19. Accelerator mass spectrometry analysis of ultra-low-level (129)I in carrier-free AgI-AgCl sputter targets.

    PubMed

    Liu, Qi; Hou, Xiaolin; Zhou, Weijian; Fu, Yunchong

    2015-05-01

    Separation of carrier-free iodine from low-level iodine samples and accurate measurement of ultra-low-level (129)I in microgram iodine target are essential but a bottleneck in geology and environment research using naturally produced (129)I. This article presents a detection technique of accelerator mass spectrometry (AMS) for accurate determination of ultra-low-level (129)I in carrier-free AgI-AgCl sputter targets. Copper instead of aluminum was selected as the suitable sample holder material to avoid the reaction of AgI-AgCl powder with aluminum. Niobium powder was selected as thermally and electrically conductive matrix to be mixed with AgI-AgCl powder, in order to obtain and maintain a stable and high iodine ion current intensity, as well as less memory effect and low background level of (129)I. The most optimal ratio of the Nb matrix to the AgI-AgCl powder was found to be 5:1 by mass. The typical current of (127)I(5+) using AgI-AgCl targets with iodine content from 5 to 80 μg was measured to be 5 to 100 nA. Four-year AMS measurements of the (129)I/(127)I ratios in standards of low iodine content and the machine blanks showed a good repeatability and stability.

  20. Theory of laser acceleration of light-ion beams from interaction of ultrahigh-intensity lasers with layered targets.

    PubMed

    Albright, B J; Yin, L; Hegelich, B M; Bowers, Kevin J; Kwan, T J T; Fernández, J C

    2006-09-15

    Experiments at the LANL Trident facility demonstrated the production of monoenergetic ion beams from the interaction of an ultraintense laser with a target comprising a heavy ion substrate and thin layer of light ions. An analytic model is obtained that predicts how the mean energy and quality of monoenergetic ion beams and the energy of substrate ions vary with substrate material and light-ion layer composition and thickness. Dimensionless parameters controlling the dynamics are derived and the model is validated with particle-in-cell simulations and experimental data.

  1. Control of laser-ablation plasma potential with external electrodes

    SciTech Connect

    Isono, Fumika Nakajima, Mitsuo; Hasegawa, Jun; Kawamura, Tohru; Horioka, Kazuhiko

    2015-08-15

    The potential of a laser-ablation plasma was controlled stably up to +2 kV by using external ring electrodes. A stable electron sheath was formed between the plasma and the external electrodes by placing the ring electrodes away from the boundary of the drifting plasma. The plasma kept the potential for a few μs regardless of the flux change of the ablation plasma. We also found that the plasma potential changed with the expansion angle of the plasma from the target. By changing the distance between the plasma boundary and the external electrodes, we succeeded in controlling the potential of laser-ablation plasma.

  2. Shuttle subscale ablative nozzle tests

    NASA Technical Reports Server (NTRS)

    Powers, L. B.; Bailey, R. L.

    1980-01-01

    Recent subscale nozzle tests have identified new and promising carbon phenolic nozzle ablatives which utilize staple rayon, PAN, and pitch based carbon cloth. A 4-inch throat diameter submerged test nozzle designed for the 48-inch Jet Propulsion Laboratory char motor was used to evaluate five different designs incorporating 20 candidate ablatives. Test results indicate that several pitch and PAN-based carbon phenolic ablatives can provide erosion and char performance equivalent or superior to the present continuous rayon-based SRM ablative.

  3. Tracked 3D ultrasound in radio-frequency liver ablation

    NASA Astrophysics Data System (ADS)

    Boctor, Emad M.; Fichtinger, Gabor; Taylor, Russell H.; Choti, Michael A.

    2003-05-01

    Recent studies have shown that radio frequency (RF) ablation is a simple, safe and potentially effective treatment for selected patients with liver metastases. Despite all recent therapeutic advancements, however, intra-procedural target localization and precise and consistent placement of the tissue ablator device are still unsolved problems. Various imaging modalities, including ultrasound (US) and computed tomography (CT) have been tried as guidance modalities. Transcutaneous US imaging, due to its real-time nature, may be beneficial in many cases, but unfortunately, fails to adequately visualize the tumor in many cases. Intraoperative or laparoscopic US, on the other hand, provides improved visualization and target imaging. This paper describes a system for computer-assisted RF ablation of liver tumors, combining navigational tracking of a conventional imaging ultrasound probe to produce 3D ultrasound imaging with a tracked RF ablation device supported by a passive mechanical arm and spatially registered to the ultrasound volume.

  4. Laser-pump/X-ray-probe experiments with electrons ejected from a Cu(111) target: space-charge acceleration.

    PubMed

    Schiwietz, G; Kühn, D; Föhlisch, A; Holldack, K; Kachel, T; Pontius, N

    2016-09-01

    A comprehensive investigation of the emission characteristics for electrons induced by X-rays of a few hundred eV at grazing-incidence angles on an atomically clean Cu(111) sample during laser excitation is presented. Electron energy spectra due to intense infrared laser irradiation are investigated at the BESSY II slicing facility. Furthermore, the influence of the corresponding high degree of target excitation (high peak current of photoemission) on the properties of Auger and photoelectrons liberated by a probe X-ray beam is investigated in time-resolved pump and probe measurements. Strong electron energy shifts have been found and assigned to space-charge acceleration. The variation of the shift with laser power and electron energy is investigated and discussed on the basis of experimental as well as new theoretical results.

  5. Fourier-Space Nonlinear Rayleigh-Taylor Growth Measurements of 3D Laser-Imprinted Modulations in Planar Targets

    SciTech Connect

    Smalyuk, V.A.; Sadot, O.; Delettrez, J.A.; Meyerhofer, D.D.; Regan, S.P.; Sangster, T.C.

    2005-12-05

    Nonlinear growth of 3-D broadband nonuniformities was measured near saturation levels using x-ray radiography in planar foils accelerated by laser light. The initial target modulations were seeded by laser nonuniformities and later amplified during acceleration by Rayleigh-Taylor instability. The nonlinear saturation velocities are measured for the first time and are found to be in excellent agreement with Haan predictions. The measured growth of long-wavelength modes is consistent with enhanced, nonlinear, long-wavelength generation in ablatively driven targets.

  6. Epigenetic pathway targets for the treatment of disease: accelerating progress in the development of pharmacological tools: IUPHAR Review 11

    PubMed Central

    Tough, David F; Lewis, Huw D; Rioja, Inmaculada; Lindon, Matthew J; Prinjha, Rab K

    2014-01-01

    The properties of a cell are determined both genetically by the DNA sequence of its genes and epigenetically through processes that regulate the pattern, timing and magnitude of expression of its genes. While the genetic basis of disease has been a topic of intense study for decades, recent years have seen a dramatic increase in the understanding of epigenetic regulatory mechanisms and a growing appreciation that epigenetic misregulation makes a significant contribution to human disease. Several large protein families have been identified that act in different ways to control the expression of genes through epigenetic mechanisms. Many of these protein families are finally proving tractable for the development of small molecules that modulate their function and represent new target classes for drug discovery. Here, we provide an overview of some of the key epigenetic regulatory proteins and discuss progress towards the development of pharmacological tools for use in research and therapy. PMID:25060293

  7. Momentum Transfer by Laser Ablation of Irregularly Shaped Space Debris

    SciTech Connect

    Liedahl, Duane A.; Libby, Stephen B.; Rubenchik, Alexander

    2010-10-08

    Proposals for ground-based laser remediation of space debris rely on the creation of appropriately directed ablation-driven impulses to either divert the fragment or drive it into an orbit with a perigee allowing atmospheric capture. For a spherical fragment, the ablation impulse is a function of the orbital parameters and the laser engagement angle. If, however, the target is irregularly shaped and arbitrarily oriented, new impulse effects come into play. Here we present an analysis of some of these effects.

  8. Momentum Transfer by Laser Ablation of Irregularly Shaped Space Debris

    SciTech Connect

    Liedahl, D A; Libby, S B; Rubenchik, A

    2010-02-04

    Proposals for ground-based laser remediation of space debris rely on the creation of appropriately directed ablation-driven impulses to either divert the fragment or drive it into an orbit with a perigee allowing atmospheric capture. For a spherical fragment, the ablation impulse is a function of the orbital parameters and the laser engagement angle. If, however, the target is irregularly shaped and arbitrarily oriented, new impulse effects come into play. Here we present an analysis of some of these effects.

  9. First Case of Automatic His Potential Detection With a Novel Ultra High-density Electroanatomical Mapping System for AV Nodal Ablation

    PubMed Central

    Hilbert, Sebastian; Kosiuk, Jedrzej; John, Silke; Hindricks, Gerhard; Bollmann, Andreas

    2016-01-01

    A 74-year old was considered for atrioventricular (AV) nodal ablation in view of atrial fibrillation (AF) with poorly controlled ventricular rate despite being on amiodarone. Targeted AV nodal ablation was successfully performed after identifying the target site for ablation by reviewing an ultra high-density map of the His region produced by automatic electrogram annotation. PMID:25852249

  10. Salvianolic acid B accelerated ABCA1-dependent cholesterol efflux by targeting PPAR-γ and LXRα

    SciTech Connect

    Yue, Jianmei; Li, Bo; Jing, Qingping; Guan, Qingbo

    2015-07-03

    Objectives: Cholesterol efflux has been thought to be the main and basic mechanism by which free cholesterol is transferred from extra hepatic cells to the liver or intestine for excretion. Salvianolic acid B (Sal B) has been widely used for the prevention and treatment of atherosclerotic diseases. Here, we sought to investigate the effects of Sal B on the cholesterol efflux in THP-1 macrophages. Methods: After PMA-stimulated THP-1 cells were exposed to 50 mg/L of oxLDL and [{sup 3}H] cholesterol (1.0 μCi/mL) for another 24 h, the effect of Sal B on cholesterol efflux was evaluated in the presence of apoA-1, HDL{sub 2} or HDL{sub 3}. The expression of ATP binding cassette transporter A1 (ABCA1), peroxisome proliferator-activated receptor-gamma (PPAR-γ), and liver X receptor-alpha (LXRα) was detected both at protein and mRNA levels in THP-1 cells after the stimulation of Sal B. Meanwhile, specific inhibition of PPAR-γ and LXRα were performed to investigate the mechanism. Results: The results showed that Sal B significantly accelerated apoA-I- and HDL-mediated cholesterol efflux in both dose- and time-dependent manners. Meanwhile, Sal B treatment also enhanced the expression of ABCA1 at both mRNA and protein levels. Then the data demonstrated that Sal B increased the expression of PPAR-γ and LXRα. And the application of specific agonists and inhibitors of further confirmed that Sal exert the function through PPAR-γ and LXRα. Conclusion: These results demonstrate that Sal B promotes cholesterol efflux in THP-1 macrophages through ABCA1/PPAR-γ/LXRα pathway. - Highlights: • Sal B promotes the expression of ABCA1. • Sal B promotes cholesterol efflux in macrophages. • Sal B promotes the expression of ABCA1 and cholesterol efflux through PPAR-γ/LXRα signaling pathway.

  11. Plastic ablator ignition capsule design for the National Ignition Facility

    SciTech Connect

    Clark, D S; Haan, S W; Hammel, B A; Salmonson, J D; Callahan, D A; Town, R P

    2009-12-01

    The National Ignition Campaign, tasked with designing and fielding targets for fusion ignition experiments on the National Ignition Facility (NIF), has carried forward three complementary target designs for the past several years: a beryllium ablator design, a plastic ablator design, and a high-density carbon or synthetic diamond design. This paper describes current simulations and design optimization to develop the plastic ablator capsule design as a candidate for the first ignition attempt on NIF. The trade-offs in capsule scale and laser energy that must be made to achieve a comparable ignition probability to that with beryllium are emphasized. Large numbers of 1-D simulations, meant to assess the statistical behavior of the target design, as well as 2-D simulations to assess the target's susceptibility to Rayleigh-Taylor growth are presented.

  12. Plastic ablator ignition capsule design for the National Ignition Facility

    SciTech Connect

    Clark, Daniel S.; Haan, Steven W.; Hammel, Bruce A.; Salmonson, Jay D.; Callahan, Debra A.; Town, Richard P. J.

    2010-05-15

    The National Ignition Campaign, tasked with designing and fielding targets for fusion ignition experiments on the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Nucl. Fusion 44, S228 (2004)], has carried forward three complementary target designs for the past several years: a beryllium ablator design, a plastic ablator design, and a high-density carbon or synthetic diamond design. This paper describes current simulations and design optimization to develop the plastic ablator capsule design as a candidate for the first ignition attempt on NIF. The trade-offs in capsule scale and laser energy that must be made to achieve a comparable ignition probability to that with beryllium are emphasized. Large numbers of one-dimensional simulations, meant to assess the statistical behavior of the target design, as well as two-dimensional simulations to assess the target's susceptibility to Rayleigh-Taylor growth are presented.

  13. Linear Accelerators

    NASA Astrophysics Data System (ADS)

    Sidorin, Anatoly

    2010-01-01

    In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

  14. Targeted Ablation of CML Stem Cells

    DTIC Science & Technology

    2007-01-01

    the major active component in Feverfew (Tanacetum parthenium), an herbal medicine that has been used to treat migraine and rheumatoid arthritis for...glycerol for 15 minutes at room temperature. Protein/DNA complexes were resolved on a native polyacrylamide gel in 0.25 Tris-borate-EDTA (TBE...DNA complexes were resolved on a native polyacrylamide gel in 0.25X TBE. For immunoblots, cells were prepared and analyzed as previously described

  15. Targeted Ablation of CML Stem Cells

    DTIC Science & Technology

    2005-05-01

    active component in Feverfew (Tanacetum parthenium), an herbal medicine that has been used to treat migraine and rheumatoid arthritis for centuries [12...native polyacrylamide gel in 0.25X TBE. For immunoblots, cells were prepared and analyzed as previously described [6]. Blots were probed with anti

  16. Alzheimer's disease-like pathology in senescence-accelerated OXYS rats can be partially retarded with mitochondria-targeted antioxidant SkQ1.

    PubMed

    Stefanova, Natalia A; Muraleva, Natalia A; Skulachev, Vladimir P; Kolosova, Nataliya G

    2014-01-01

    We previously showed that mitochondria-targeted antioxidant SkQ1 (plastoquinonyl-decyltriphenylphosphonium) at nanomolar concentrations is capable of preventing and slowing down some cerebral dysfunctions in accelerated-senescence OXYS rats. Here we demonstrate that OXYS rats develop behavior, learning, and memory deficits against a background of neurodegeneration signs detected by magnetic resonance tomography and amyloid-β (Aβ) pathology similar to those seen in Alzheimer's disease (AD). Long-term treatment with SkQ1 (250 nmol/kg body weight daily from the age of 1.5 to 23 months) reduced the age-related alterations in behavior and spatial memory deficit in Morris water maze in OXYS and Wistar rats. Furthermore, this is the first report that SkQ1 treatment slows down pathological accumulation of AβPP, Aβ, and hyperphosphorylation of tau-protein in OXYS rats, as well as age-dependent changes in healthy Wistar rats. Our results support the possibility of using the OXYS strain as a rat model of AD-like pathology. It seems probable that the mitochondria-targeted antioxidant SkQ1 can be a good prophylactic strategy to maintain brain health and to treat AD.

  17. Microwave-accelerated surface plasmon-coupled directional luminescence 2: a platform technology for ultra fast and sensitive target DNA detection in whole blood.

    PubMed

    Aslan, Kadir; Previte, Michael J R; Zhang, Yongxia; Geddes, Chris D

    2008-02-29

    The application of Microwave-Accelerated Surface Plasmon-Coupled Luminescence (MA-SPCL) to fast and sensitive DNA hybridization assays in buffer and whole blood is presented. In this regard, a model DNA hybridization assay whereby a fluorophore-labeled target ssDNA specific to human immunodeficiency, Hepatitis C (Hep C), is probed by an anchor probe immobilized on thin gold films, is driven to completion within 1 min with microwave heating, as compared to an identical assay completed in approximately 4 h at room temperature. Finite-Difference Time-Domain calculations show that gold disks are preferentially heated around the edges creating a temperature gradient along the disks, which in turn results in the larger influx of complementary DNA towards anchor probe-modified surface. Thermal images of the assay platform during microwave heating also provide additional information on the microwave heating pattern in the microwave cavity. Finally, the effects of low power microwave heating on the ability of DNA to re-hybridize with the complimentary target on the surface gold films, which allows the multiple re-use of the gold films, is demonstrated. The MA-SPCL technique offers an alternative approach to current DNA based detection technologies, especially when speed and sensitivity are required, such as in the identification of DNA or even RNA-based diseases using whole blood samples that affect human health.

  18. Percutaneous ablation of adrenal tumors.

    PubMed

    Venkatesan, Aradhana M; Locklin, Julia; Dupuy, Damian E; Wood, Bradford J

    2010-06-01

    Adrenal tumors comprise a broad spectrum of benign and malignant neoplasms and include functional adrenal adenomas, pheochromocytomas, primary adrenocortical carcinoma, and adrenal metastases. Percutaneous ablative approaches that have been described and used in the treatment of adrenal tumors include percutaneous radiofrequency ablation, cryoablation, microwave ablation, and chemical ablation. Local tumor ablation in the adrenal gland presents unique challenges, secondary to the adrenal gland's unique anatomic and physiological features. The results of clinical series employing percutaneous ablative techniques in the treatment of adrenal tumors are reviewed in this article. Clinical and technical considerations unique to ablation in the adrenal gland are presented, including approaches commonly used in our practices, and risks and potential complications are discussed.

  19. Advances in local ablation of malignant liver lesions

    PubMed Central

    Eisele, Robert M

    2016-01-01

    Local ablation of liver tumors matured during the recent years and is now proven to be an effective tool in the treatment of malignant liver lesions. Advances focus on the improvement of local tumor control by technical innovations, individual selection of imaging modalities, more accurate needle placement and the free choice of access to the liver. Considering data found in the current literature for conventional local ablative treatment strategies, virtually no single technology is able to demonstrate an unequivocal superiority. Hints at better performance of microwave compared to radiofrequency ablation regarding local tumor control, duration of the procedure and potentially achievable larger size of ablation areas favour the comparably more recent treatment modality; image fusion enables more patients to undergo ultrasound guided local ablation; magnetic resonance guidance may improve primary success rates in selected patients; navigation and robotics accelerate the needle placement and reduces deviation of needle positions; laparoscopic thermoablation results in larger ablation areas and therefore hypothetically better local tumor control under acceptable complication rates, but seems to be limited to patients with no, mild or moderate adhesions following earlier surgical procedures. Apart from that, most techniques appear technically feasible, albeit demanding. Which technology will in the long run become accepted, is subject to future work. PMID:27099433

  20. Ablation of skeletal metastases: current status.

    PubMed

    Kurup, A Nicholas; Callstrom, Matthew R

    2010-08-01

    Image-guided percutaneous ablation of bone metastases is an effective, minimally invasive alternative to conventional therapies in the palliation of pain from metastatic disease. Ablative technologies applied in the treatment of skeletal metastases include radiofrequency ablation, cryoablation, microwave ablation, laser ablation, ethanol ablation, and, most recently, focused ultrasound. These ablative methods may be performed in combination with percutaneous cementoplasty to provide support and stabilization for metastases in weight-bearing bones at risk for pathologic fracture.

  1. Ablation-cooled material removal with ultrafast bursts of pulses

    NASA Astrophysics Data System (ADS)

    Kerse, Can; Kalaycıoğlu, Hamit; Elahi, Parviz; Çetin, Barbaros; Kesim, Denizhan K.; Akçaalan, Önder; Yavaş, Seydi; Aşık, Mehmet D.; Öktem, Bülent; Hoogland, Heinar; Holzwarth, Ronald; Ilday, Fatih Ömer

    2016-09-01

    The use of femtosecond laser pulses allows precise and thermal-damage-free removal of material (ablation) with wide-ranging scientific, medical and industrial applications. However, its potential is limited by the low speeds at which material can be removed and the complexity of the associated laser technology. The complexity of the laser design arises from the need to overcome the high pulse energy threshold for efficient ablation. However, the use of more powerful lasers to increase the ablation rate results in unwanted effects such as shielding, saturation and collateral damage from heat accumulation at higher laser powers. Here we circumvent this limitation by exploiting ablation cooling, in analogy to a technique routinely used in aerospace engineering. We apply ultrafast successions (bursts) of laser pulses to ablate the target material before the residual heat deposited by previous pulses diffuses away from the processing region. Proof-of-principle experiments on various substrates demonstrate that extremely high repetition rates, which make ablation cooling possible, reduce the laser pulse energies needed for ablation and increase the efficiency of the removal process by an order of magnitude over previously used laser parameters. We also demonstrate the removal of brain tissue at two cubic millimetres per minute and dentine at three cubic millimetres per minute without any thermal damage to the bulk.

  2. Ablation-cooled material removal with ultrafast bursts of pulses.

    PubMed

    Kerse, Can; Kalaycıoğlu, Hamit; Elahi, Parviz; Çetin, Barbaros; Kesim, Denizhan K; Akçaalan, Önder; Yavaş, Seydi; Aşık, Mehmet D; Öktem, Bülent; Hoogland, Heinar; Holzwarth, Ronald; Ilday, Fatih Ömer

    2016-09-01

    The use of femtosecond laser pulses allows precise and thermal-damage-free removal of material (ablation) with wide-ranging scientific, medical and industrial applications. However, its potential is limited by the low speeds at which material can be removed and the complexity of the associated laser technology. The complexity of the laser design arises from the need to overcome the high pulse energy threshold for efficient ablation. However, the use of more powerful lasers to increase the ablation rate results in unwanted effects such as shielding, saturation and collateral damage from heat accumulation at higher laser powers. Here we circumvent this limitation by exploiting ablation cooling, in analogy to a technique routinely used in aerospace engineering. We apply ultrafast successions (bursts) of laser pulses to ablate the target material before the residual heat deposited by previous pulses diffuses away from the processing region. Proof-of-principle experiments on various substrates demonstrate that extremely high repetition rates, which make ablation cooling possible, reduce the laser pulse energies needed for ablation and increase the efficiency of the removal process by an order of magnitude over previously used laser parameters. We also demonstrate the removal of brain tissue at two cubic millimetres per minute and dentine at three cubic millimetres per minute without any thermal damage to the bulk.

  3. Voltage-guided ablation technique for cavotricuspid isthmus-dependent atrial flutter: refining the continuous line.

    PubMed

    Jacobsen, Peter K; Klein, George J; Gula, Lorne J; Krahn, Andrew D; Yee, Raymond; Leong-Sit, Peter; Mechulan, Alexis; Skanes, Allan C

    2012-06-01

    Ablation of the cavotricuspid isthmus has become first-line therapy for "isthmus-dependent" atrial flutter. The goal of ablation is to produce bidirectional cavotricuspid isthmus block. Traditionally, this has been obtained by creation of a complete ablation line across the isthmus from the ventricular end to the inferior vena cava. This article describes an alternative method used in our laboratory. There is substantial evidence that conduction across the isthmus occurs preferentially over discrete separate bundles of tissue. Consequently, voltage-guided ablation targeting only these bundles with large amplitude atrial electrograms results in a highly efficient alternate method for the interruption of conduction across the cavotricuspid isthmus. Understanding the bundle structure of conduction over the isthmus facilitates more flexible approaches to its ablation and targeting maximum voltages in our hands has resulted in reduction of ablation time and fewer recurrences.

  4. MiR-376c down-regulation accelerates EGF-dependent migration by targeting GRB2 in the HuCCT1 human intrahepatic cholangiocarcinoma cell line.

    PubMed

    Iwaki, Jun; Kikuchi, Kunio; Mizuguchi, Yoshiaki; Kawahigashi, Yutaka; Yoshida, Hiroshi; Uchida, Eiji; Takizawa, Toshihiro

    2013-01-01

    MicroRNA miR-376c was expressed in normal intrahepatic biliary epithelial cells (HIBEpiC), but was significantly suppressed in the HuCCT1 intrahepatic cholangiocarcinoma (ICC) cell line. The biological significance of the down-regulation of miR-376c in HuCCT1 cells is unknown. We hypothesized that miR-376c could function as a tumor suppressor in these cells. To test this hypothesis, we sought the targets of miR-376c, and characterized the effect of its down-regulation on HuCCT1 cells. We performed proteomic analysis of miR-376c-overexpressing HuCCT1 cells to identify candidate targets of miR-376c, and validated these targets by 3'-UTR reporter assay. Transwell migration assays were performed to study the migratory response of HuCCT1 cells to miR-376c overexpression. Furthermore, microarrays were used to identify the signaling that were potentially involved in the miR-376c-modulated migration of HuCCT1. Finally, we assessed epigenetic changes within the potential promoter region of the miR-376c gene in these cells. Proteomic analysis and subsequent validation assays showed that growth factor receptor-bound protein 2 (GRB2) was a direct target of miR-376c. The transwell migration assay revealed that miR-376c significantly reduced epidermal growth factor (EGF)-dependent cell migration in HuCCT1 cells. DNA microarray and subsequent pathway analysis showed that interleukin 1 beta and matrix metallopeptidase 9 were possible participants in EGF-dependent migration of HuCCT1 cells. Bisulfite sequencing showed higher methylation levels of CpG sites upstream of the miR-376c gene in HuCCT1 relative to HIBEpiC cells. Combined treatment with the DNA-demethylating agent 5-aza-2'-deoxycytidine and the histone deacetylase inhibitor trichostatin A significantly upregulated the expression of miR-376c in HuCCT1 cells. We revealed that epigenetic repression of miR-376c accelerated EGF-dependent cell migration through its target GRB2 in HuCCT1 cells. These findings suggest that miR-376

  5. MiR-376c Down-Regulation Accelerates EGF-Dependent Migration by Targeting GRB2 in the HuCCT1 Human Intrahepatic Cholangiocarcinoma Cell Line

    PubMed Central

    Mizuguchi, Yoshiaki; Kawahigashi, Yutaka; Yoshida, Hiroshi; Uchida, Eiji; Takizawa, Toshihiro

    2013-01-01

    MicroRNA miR-376c was expressed in normal intrahepatic biliary epithelial cells (HIBEpiC), but was significantly suppressed in the HuCCT1 intrahepatic cholangiocarcinoma (ICC) cell line. The biological significance of the down-regulation of miR-376c in HuCCT1 cells is unknown. We hypothesized that miR-376c could function as a tumor suppressor in these cells. To test this hypothesis, we sought the targets of miR-376c, and characterized the effect of its down-regulation on HuCCT1 cells. We performed proteomic analysis of miR-376c-overexpressing HuCCT1 cells to identify candidate targets of miR-376c, and validated these targets by 3′-UTR reporter assay. Transwell migration assays were performed to study the migratory response of HuCCT1 cells to miR-376c overexpression. Furthermore, microarrays were used to identify the signaling that were potentially involved in the miR-376c-modulated migration of HuCCT1. Finally, we assessed epigenetic changes within the potential promoter region of the miR-376c gene in these cells. Proteomic analysis and subsequent validation assays showed that growth factor receptor-bound protein 2 (GRB2) was a direct target of miR-376c. The transwell migration assay revealed that miR-376c significantly reduced epidermal growth factor (EGF)-dependent cell migration in HuCCT1 cells. DNA microarray and subsequent pathway analysis showed that interleukin 1 beta and matrix metallopeptidase 9 were possible participants in EGF-dependent migration of HuCCT1 cells. Bisulfite sequencing showed higher methylation levels of CpG sites upstream of the miR-376c gene in HuCCT1 relative to HIBEpiC cells. Combined treatment with the DNA-demethylating agent 5-aza-2′-deoxycytidine and the histone deacetylase inhibitor trichostatin A significantly upregulated the expression of miR-376c in HuCCT1 cells. We revealed that epigenetic repression of miR-376c accelerated EGF-dependent cell migration through its target GRB2 in HuCCT1 cells. These findings suggest that mi

  6. Initial experimental evidence of self-collimation of target-normal-sheath-accelerated proton beam in a stack of conducting foils

    SciTech Connect

    Ni, P. A.; Bieniosek, F. M.; Logan, B. G.; Lund, S. M.; Barnard, J. J.; Bellei, C.; Cohen, R. H.; McGuffey, C.; Beg, F. N.; Kim, J.; Alexander, N.; Aurand, B.; Brabetz, C.; Neumayer, P.; Roth, M.

    2013-08-15

    Phenomena consistent with self-collimation (or weak self-focusing) of laser target-normal-sheath-accelerated protons was experimentally observed for the first time, in a specially engineered structure (“lens”) consisting of a stack of 300 thin aluminum foils separated by 50 μm vacuum gaps. The experiments were carried out in a “passive environment,” i.e., no external fields applied, neutralization plasma or injection of secondary charged particles was imposed. Experiments were performed at the petawatt “PHELIX” laser user facility (E = 100 J, Δt = 400 fs, λ = 1062 nm) at the “Helmholtzzentrum für Schwerionenforschung–GSI” in Darmstadt, Germany. The observed rms beam spot reduction depends inversely on energy, with a focusing degree decreasing monotonically from 2 at 5.4 MeV to 1.5 at 18.7 MeV. The physics inside the lens is complex, resulting in a number of different mechanisms that can potentially affect the particle dynamics within the structure. We present a plausible simple interpretation of the experiment in which the combination of magnetic self-pinch forces generated by the beam current together with the simultaneous reduction of the repulsive electrostatic forces due to the foils are the dominant mechanisms responsible for the observed focusing/collimation. This focusing technique could be applied to a wide variety of space-charge dominated proton and heavy ion beams and impact fields and applications, such as HEDP science, inertial confinement fusion in both fast ignition and heavy ion fusion approaches, compact laser-driven injectors for a Linear Accelerator (LINAC) or synchrotron, medical therapy, materials processing, etc.

  7. Initial experimental evidence of self-collimation of target-normal-sheath-accelerated proton beam in a stack of conducting foils

    NASA Astrophysics Data System (ADS)

    Ni, P. A.; Lund, S. M.; McGuffey, C.; Alexander, N.; Aurand, B.; Barnard, J. J.; Beg, F. N.; Bellei, C.; Bieniosek, F. M.; Brabetz, C.; Cohen, R. H.; Kim, J.; Neumayer, P.; Roth, M.; Logan, B. G.

    2013-08-01

    Phenomena consistent with self-collimation (or weak self-focusing) of laser target-normal-sheath-accelerated protons was experimentally observed for the first time, in a specially engineered structure ("lens") consisting of a stack of 300 thin aluminum foils separated by 50 μm vacuum gaps. The experiments were carried out in a "passive environment," i.e., no external fields applied, neutralization plasma or injection of secondary charged particles was imposed. Experiments were performed at the petawatt "PHELIX" laser user facility (E = 100 J, Δt = 400 fs, λ = 1062 nm) at the "Helmholtzzentrum für Schwerionenforschung-GSI" in Darmstadt, Germany. The observed rms beam spot reduction depends inversely on energy, with a focusing degree decreasing monotonically from 2 at 5.4 MeV to 1.5 at 18.7 MeV. The physics inside the lens is complex, resulting in a number of different mechanisms that can potentially affect the particle dynamics within the structure. We present a plausible simple interpretation of the experiment in which the combination of magnetic self-pinch forces generated by the beam current together with the simultaneous reduction of the repulsive electrostatic forces due to the foils are the dominant mechanisms responsible for the observed focusing/collimation. This focusing technique could be applied to a wide variety of space-charge dominated proton and heavy ion beams and impact fields and applications, such as HEDP science, inertial confinement fusion in both fast ignition and heavy ion fusion approaches, compact laser-driven injectors for a Linear Accelerator (LINAC) or synchrotron, medical therapy, materials processing, etc.

  8. Investigation of laser-induced ablation of ceramic materials for spaceborne applications

    NASA Astrophysics Data System (ADS)

    Schroeder, H.; Hippler, M.; Allenspacher, P.; Riede, W.; Ciapponi, A.; Mateo, A. B.; Ivanov, T.; Alves, J.; Piris, J.; Heese, C.; Wernham, D.

    2016-12-01

    In this work tests for determination of ablation thresholds of various ceramic materials for pulsed laser irradiations at wavelengths of 355 nm and 1064 nm in vacuum are presented. For comparison tests with copper and aluminium are also reported. The ablation process was monitored insitu by long-distance microscopy. The morphology of ablation spots was exsitu inspected by scanning electron microscopy. Furthermore, the redeposition of potentially released particles on optics in the vicinity to the target was examined.

  9. Laser ablation sample transfer for mass spectrometry imaging.

    PubMed

    Park, Sung-Gun; Murray, Kermit K

    2015-01-01

    Infrared laser ablation sample transfer (IR-LAST) is a novel ambient sampling technique for mass spectrometry. In this technique, a pulsed mid-IR laser is used to ablate materials that are collected for mass spectrometry analysis; the material can be a solid sample or deposited on a sample target. After collection, the sample can be further separated or analyzed directly by mass spectrometry. For IR-LAST sample transfer tissue imaging using MALDI mass spectrometry, a tissue section is placed on a sample slide and material transferred to a target slide by scanning the tissue sample under a focused laser beam using transmission-mode (back side) IR laser ablation. After transfer, the target slide is analyzed using MALDI imaging. The spatial resolution is approximately 400 μm and limited by the spread of the laser desorption plume. IR-LAST for MALDI imaging provides several new capabilities including ambient sampling, area to spot concentration of ablated material, multiple ablation and analysis from a single section, and direct deposition on matrix-free nanostructured targets.

  10. [Ablative and fractional lasers].

    PubMed

    Beylot, C; Grognard, C; Michaud, T

    2009-10-01

    The use of pulsed or scanning Carbon Dioxide, and pulsed Erbium-YAG lasers allows the programmable and reproducible photocoagulation of thin layers of the epidermis and superficial dermis. Thermal damage depends on the type of laser and is greater with CO(2) lasers. The degree of neocollagenesis is proportional to the thermal damage and is better with CO(2) lasers. Their main indication is the correction of photoaged facial skin but they can also be used for corrective dermatology, e.g. for scars and genodermatosis. Results are highly satisfactory but the technique is invasive and the patient experiences a social hindrance of around two weeks. Fractionated techniques treat 25% of the defective skin area at each session in noncontiguous microzones; four sessions are therefore necessary to treat the entire cutaneous surface. The treatment is given under topical anesthesia and is much less invasive, particularly with nonablative fractional laser treatment in which photothermolysis does not penetrate below the epidermis and/or the effects are slight, with no or very little social isolation. However, the results are much less satisfactory than the results of ablative laser and there is no firming effect. Other zones than the face can be treated. With the fractional CO(2) and Erbium ablative lasers, which have multiplied over the past 2 years, the much wider impacts cause perforation of the epidermis and there is a zone of ablation by laser photovaporization, with a zone of thermal damage below. The results are better in correcting photoaging of the face, without, however, achieving the efficacy of ablative lasers, which remain the reference technique. However, the effects are not insignificant, requiring at least 5 days of social isolation.

  11. Recent Advances in Tumor Ablation for Hepatocellular Carcinoma

    PubMed Central

    Kang, Tae Wook; Rhim, Hyunchul

    2015-01-01

    Image-guided tumor ablation for early stage hepatocellular carcinoma (HCC) is an accepted non-surgical treatment that provides excellent local tumor control and favorable survival benefit. This review summarizes the recent advances in tumor ablation for HCC. Diagnostic imaging and molecular biology of HCC has recently undergone marked improvements. Second-generation ultrasonography (US) contrast agents, new computed tomography (CT) techniques, and liver-specific contrast agents for magnetic resonance imaging (MRI) have enabled the early detection of smaller and inconspicuous HCC lesions. Various imaging-guidance tools that incorporate imaging-fusion between real-time US and CT/MRI, that are now common for percutaneous tumor ablation, have increased operator confidence in the accurate targeting of technically difficult tumors. In addition to radiofrequency ablation (RFA), various therapeutic modalities including microwave ablation, irreversible electroporation, and high-intensity focused ultrasound ablation have attracted attention as alternative energy sources for effective locoregional treatment of HCC. In addition, combined treatment with RFA and chemoembolization or molecular agents may be able to overcome the limitation of advanced or large tumors. Finally, understanding of the biological mechanisms and advances in therapy associated with tumor ablation will be important for successful tumor control. All these advances in tumor ablation for HCC will result in significant improvement in the prognosis of HCC patients. In this review, we primarily focus on recent advances in molecular tumor biology, diagnosis, imaging-guidance tools, and therapeutic modalities, and refer to the current status and future perspectives for tumor ablation for HCC. PMID:26674766

  12. Can Accelerators Accelerate Learning?

    NASA Astrophysics Data System (ADS)

    Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

    2009-03-01

    The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ) [1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

  13. PARTICLE ACCELERATOR

    DOEpatents

    Teng, L.C.

    1960-01-19

    ABS>A combination of two accelerators, a cyclotron and a ring-shaped accelerator which has a portion disposed tangentially to the cyclotron, is described. Means are provided to transfer particles from the cyclotron to the ring accelerator including a magnetic deflector within the cyclotron, a magnetic shield between the ring accelerator and the cyclotron, and a magnetic inflector within the ring accelerator.

  14. Dependence of the ion energy on the parameters of the laser pulse and target in the radiation-pressure-dominated regime of acceleration

    SciTech Connect

    Echkina, E. Yu.; Inovenkov, I. N.; Esirkepov, T. Zh.; Pegoraro, F.; Borghesi, M.; Bulanov, S. V.

    2010-01-15

    When the dominant mechanism for ion acceleration is the laser radiation pressure, the conversion efficiency of the laser energy into the energy of relativistic ions may be very high. Stability analysis of a thin plasma layer accelerated by the radiation pressure shows that Raleigh-Taylor instability may enhance plasma inhomogeneity. In the linear stage of instability, the plasma layer decays into separate bunches, which are accelerated by the radiation pressure similarly to clusters accelerated under the action of an electromagnetic wave. The energy and luminosity of an ion beam accelerated in the radiation-pressure-dominated regime are calculated.

  15. Experimental scaling law for mass ablation rate from a Sn plasma generated by a 1064 nm laser

    SciTech Connect

    Burdt, Russell A.; Yuspeh, Sam; Najmabadi, Farrokh; Sequoia, Kevin L.; Tao Yezheng; Tillack, Mark S.

    2009-08-01

    The ablation depth in planar Sn targets irradiated with a pulsed 1064 nm laser was investigated over laser intensities from 3x10{sup 11} to 2x10{sup 12} W/cm{sup 2}. The ablation depth was measured by irradiating a thin layer of Sn evaporated onto a Si wafer, and looking for signatures of Si ions in the expanding plasma with spectroscopic and particle diagnostics. It was found that ablation depth scales with laser intensity to the (5/9)th power, which is consistent with analytical models of steady-state laser ablation, as well as empirical formulae from previous studies of mass ablation rate in overlapping parameter space. In addition, the scaling of mass ablation rate with atomic number of the target as given by empirical formulae in previous studies using targets such as C and Al, are shown to remain valid for the higher atomic number of the target (Z=50) used in these experiments.

  16. The shape effect of space debris on recoil impulse by pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Wang, Chenglin; Zhang, Yan; Wang, Kunpeng

    2016-10-01

    Removing space debris by high-energy pulsed laser may be the most effective way to mitigate the threat posed by the increasing space debris. Laser ablation of a thin surface layer causes recoil impulse, which will lower the orbit perigee of space debris and accelerate the atmospheric capture. When the laser beam vertically irradiates a flat debris, it requires a certain laser fluence to reach the optimal impulse coupling, and the recoil impulse is parallel to the laser beam. However, the incident laser fluence varies in different parts of a non-flat surface. We have taken the shape effect into account to propose a numerical method of calculating the recoil impulse. Taking cylinder debris as the target, we have compared the recoil impulse in different laser fluences through simulation experiments, which implies that a higher laser fluence than the optimal one is needed to obtain a larger recoil impulse for irregularly shaped space debris.

  17. Automatic Tracking Algorithm in Coaxial Near-Infrared Laser Ablation Endoscope for Fetus Surgery

    NASA Astrophysics Data System (ADS)

    Hu, Yan; Yamanaka, Noriaki; Masamune, Ken

    2014-07-01

    This article reports a stable vessel object tracking method for the treatment of twin-to-twin transfusion syndrome based on our previous 2 DOF endoscope. During the treatment of laser coagulation, it is necessary to focus on the exact position of the target object, however it moves by the mother's respiratory motion and still remains a challenge to obtain and track the position precisely. In this article, an algorithm which uses features from accelerated segment test (FAST) to extract the features and optical flow as the object tracking method, is proposed to deal with above problem. Further, we experimentally simulate the movement due to the mother's respiration, and the results of position errors and similarity verify the effectiveness of the proposed tracking algorithm for laser ablation endoscopy in-vitro and under water considering two influential factors. At average, the errors are about 10 pixels and the similarity over 0.92 are obtained in the experiments.

  18. OCDR guided laser ablation device

    DOEpatents

    Dasilva, Luiz B.; Colston, Jr., Bill W.; James, Dale L.

    2002-01-01

    A guided laser ablation device. The device includes a mulitmode laser ablation fiber that is surrounded by one or more single mode optical fibers that are used to image in the vicinity of the laser ablation area to prevent tissue damage. The laser ablation device is combined with an optical coherence domain reflectometry (OCDR) unit and with a control unit which initializes the OCDR unit and a high power laser of the ablation device. Data from the OCDR unit is analyzed by the control unit and used to control the high power laser. The OCDR images up to about 3 mm ahead of the ablation surface to enable a user to see sensitive tissue such as a nerve or artery before damaging it by the laser.

  19. Catheter Ablation for Ventricular Arrhythmias

    PubMed Central

    Nof, Eyal; Stevenson, William G; John, Roy M

    2013-01-01

    Catheter ablation has emerged as an important and effective treatment option for many recurrent ventricular arrhythmias. The approach to ablation and the risks and outcomes are largely determined by the nature of the severity and type of underlying heart disease. In patients with structural heart disease, catheter ablation can effectively reduce ventricular tachycardia (VT) episodes and implantable cardioverter defibrillator (ICD) shocks. For VT and symptomatic premature ventricular beats that occur in the absence of structural heart disease, catheter ablation is often effective as the sole therapy. Advances in catheter technology, imaging and mapping techniques have improved success rates for ablation. This review discusses current approaches to mapping and ablation for ventricular arrhythmias. PMID:26835040

  20. The effects of fat layer on temperature distribution during microwave atrial fibrillation catheter ablation.

    PubMed

    Zhai, Fei; Nan, Qun; Guo, Xuemei

    2016-01-01

    To investigate the effects of fat layer on the temperature distribution during microwave atrial fibrillation catheter ablation in the conditions of different ablation time; 3D finite element models (fat layer and no fat layer) were built, and temperature distribution was obtained based on coupled electromagnetic-thermal analysis at 2.45 GHz and 30 W of microwave power. Results shown: in the endocardial ablation, the existence of the fat layer did not affect the shape of the 50 °C contour before 30 s. The increase speed of depth became quite slowly in the model with fat layer after 30 s. When ablation depth needed fixed, there are no significant effect on effectively ablation depth whether fat layer over or not. However, the existence of fat layer makes the temperature lower in the myocardium, and maximum temperature point closer to the myocardium surface. What is more, in the model with fat layer, effective ablation reach lower maximum temperature and the shallower depth of 50 °C contour. But there are larger ablation axial length and transverse width. In this case, doctor should ensure safety of normal cardiac tissue around the target tissue. In the epicardial ablation, the existence of fat layer seriously affects result of the microwave ablation. The epicardial ablation needs more heating time to create lesion. But epicardial ablation can be better controlled in the shape of effective ablation area because of the slowly increase of target variables after the appearing of 50 °C contour. Doctor can choose endocardial or epicardial ablation in different case of clinic requirement.

  1. Laser Ion Acceleration Control

    NASA Astrophysics Data System (ADS)

    Kawata, Shigeo; Nagashima, T.; Izumiyama, T.; Sato, D.; Takano, M.; Barada, D.; Ma, Y. Y.; Gu, Y. J.; Kong, Q.; Wang, P. X.; Wang, W. M.

    2013-10-01

    An intense femtosecond pulsed laser is employed to accelerate ions. The issues in the laser ion accelerator include the energy efficiency from the laser to the ions, the ion beam collimation, the ion energy spectrum control, the ion beam bunching, the ion particle energy control, etc. In the study particle computer simulations were performed to solve the issues, and each component was designed to control the ion beam quality. When an intense laser illuminates a target, electrons in the target are accelerated and leave from the target; temporarily a strong electric field is formed between the high-energy electrons and the target ions, and the target ions are accelerated. The energy efficiency from the laser to ions was improved by using a solid target with a fine sub-wavelength structure or by a near critical density gas plasma. The ion beam collimation was realized by holes behind the solid target. The control of the ion energy spectrum and the ion particle energy, and the ion beam bunching were successfully realized by a multi-stage laser-target interaction. The present study proposed a novel concept for a future compact laser ion accelerator, based on each component study required to control the ion beam quality and parameters. Partly supported by JSPS, MEXT, CORE, Japan/US Cooperation program, ASHULA and ILE/Osaka University.

  2. Radiofrequency Ablation for Liver Cancer.

    PubMed

    Jacobs, Amy

    2015-01-01

    Interventional ablative technologies aided by imaging techniques such as ultrasonography, computed tomography, and magnetic resonance imaging have been crucial in managing patients with primary liver cancer and liver metastases over the past 20 years. Several ablative technologies have been used to treat liver cancer; however, radiofrequency ablation (RFA) has emerged as the most common ablative therapy for hepatic lesions, both in the United States and globally. RFA is the treatment of choice for patients who cannot have surgical resection of the liver. This article focuses on the role of imaging in RFA treatment of primary and metastatic hepatic lesions.

  3. Role of debris cover to control specific ablation of adjoining Batal and Sutri Dhaka glaciers in Chandra Basin (Himachal Pradesh) during peak ablation season

    NASA Astrophysics Data System (ADS)

    Sharma, Parmanand; Patel, Lavkush K.; Ravindra, Rasik; Singh, Ajit; K, Mahalinganathan; Thamban, Meloth

    2016-04-01

    As part of the on-going annual mass balance measurements on Batal and Sutri Dhaka glaciers, observations were made during peak ablation (August-September) season in 2013 to understand the response of debris covered and clean-ice (debris free) glacier surface to melting processes. Though, both the Batal and Sutri Dhaka glaciers have almost similar geographical disposition, Batal shows extensive debris cover (90% of the ablation area), while the latter is free from debris (only 5% of the ablation area). The thickness of debris in Batal glacier is inversely proportional to altitude, whereas Sutri Dhaka mostly experienced debris-free zone except snout area. Observation revealed that the vertical gradient of ablation rate in ablation area is contrastingly opposite in these two glaciers, reflecting significant control of debris thickness and their distribution over glacier surface on the ablation rates. While different thickness (2-100 cm) of debris have attenuated melting rates up to 70% of total melting, debris cover of <2 cm thickness has accelerated melting up to 10% of the total melting. Estimated melt ratio reveals that about 90% of the ablation area has experienced inhibited melting in Batal glacier, whereas only less than 5% ablation area of Sutri Dhaka has undergone inhibited melting. Comparison of topographical maps of 1962 with successive satellite images of the area demonstrates a terminus retreat of 373 ± 33.5 m and 579 ± 33.5 m for Batal and Sutri Dhaka glaciers for the period 1962-2013, respectively.

  4. Mechanisms of Carbon Nanotube Production by Laser Ablation Process

    NASA Technical Reports Server (NTRS)

    Scott, Carl D.; Arepalli, Sivaram; Nikolaev, Pavel; Smalley, Richard E.; Nocholson, Leonard S. (Technical Monitor)

    2000-01-01

    We will present possible mechanisms for nanotube production by laser oven process. Spectral emission of excited species during laser ablation of a composite graphite target is compared with that of laser irradiated C60 vapor. The similarities in the transient and spectral data suggest that fullerenes are intermediate precursors for nanotube formation. The confinement of the ablation products by means of a 25-mm diameter tube placed upstream of the target seems to improve the production and purity of nanotubes. Repeated laser pulses vaporize the amorphous/graphitic carbon and possibly catalyst particles, and dissociate fullerenes yielding additional feedstock for SWNT growth.

  5. Plastic ablator ignition capsule design for the National Ignition Facility

    SciTech Connect

    Clark, D S; Haan, S W; Hammel, B A; Salmonson, J D; Callahan, D A; Town, R J

    2009-10-06

    This paper describes current efforts to develop a plastic ablator capsule design for the first ignition attempt on the National Ignition Facility. The trade-offs in capsule scale and laser energy that must be made to achieve ignition probabilities comparable to those with other candidate ablators, beryllium and high-density carbon, are emphasized. Large numbers of 1-D simulations, meant to assess the statistical behavior of the target design, as well as 2-D simulations to assess the target's susceptibility to Rayleigh-Taylor growth are discussed.

  6. Evaluation of a Thermoprotective Gel for Hydrodissection During Percutaneous Microwave Ablation: In Vivo Results

    SciTech Connect

    Moreland, Anna J. Lubner, Meghan G. Ziemlewicz, Timothy J. Kitchin, Douglas R. Hinshaw, J. Louis Johnson, Alexander D. Lee, Fred T. Brace, Christopher L.

    2015-06-15

    PurposeTo evaluate whether thermoreversible poloxamer 407 15.4 % in water (P407) can protect non-target tissues adjacent to microwave (MW) ablation zones in a porcine model.Materials and MethodsMW ablation antennas were placed percutaneously into peripheral liver, spleen, or kidney (target tissues) under US and CT guidance in five swine such that the expected ablation zones would extend into adjacent diaphragm, body wall, or bowel (non-target tissues). For experimental ablations, P407 (a hydrogel that transitions from liquid at room temperature to semi-solid at body temperature) was injected into the potential space between target and non-target tissues, and the presence of a gel barrier was verified on CT. No barrier was used for controls. MW ablation was performed at 65 W for 5 min. Thermal damage to target and non-target tissues was evaluated at dissection.ResultsAntennas were placed 7 ± 3 mm from the organ surface for both control and gel-protected ablations (p = 0.95). The volume of gel deployed was 49 ± 27 mL, resulting in a barrier thickness of 0.8 ± 0.5 cm. Ablations extended into non-target tissues in 12/14 control ablations (mean surface area = 3.8 cm{sup 2}) but only 4/14 gel-protected ablations (mean surface area = 0.2 cm{sup 2}; p = 0.0005). The gel barrier remained stable at the injection site throughout power delivery.ConclusionWhen used as a hydrodissection material, P407 protected non-targeted tissues and was successfully maintained at the injection site for the duration of power application. Continued investigations to aid clinical translation appear warranted.

  7. WE-G-BRE-09: Targeted Radiotherapy Enhancement During Accelerated Partial Breast Irradiation (ABPI) Using Controlled Release of Gold Nanoparticles (GNPs)

    SciTech Connect

    Cifter, G; Ngwa, W; Chin, J; Cifter, F; Sajo, E; Sinha, N; Bellon, J

    2014-06-15

    Purpose: Several studies have demonstrated low rates of local recurrence with brachytherapy-based accelerated partial breast irradiation (APBI). However, long-term outcomes on toxicity (e.g. telangiectasia), and cosmesis remain a major concern. The purpose of this study is to investigate the dosimetric feasibility of using targeted non-toxic radiosensitizing gold nanoparticles (GNPs) for localized dose enhancement to the planning target volume (PTV) during APBI while reducing dose to normal tissue. Methods: Two approaches for administering the GNPs were considered. In one approach, GNPs are assumed to be incorporated in a micrometer-thick polymer film on the surface of routinely used mammosite balloon applicators, for sustained controlled in-situ release, and subsequent treatment using 50-kVp Xoft devices. In case two, GNPs are administered directly into the lumpectomy cavity e.g. via injection or using fiducials coated with the GNP-loaded polymer film. Recent studies have validated the use of fiducials for reducing the PTV margin during APBI with 6 MV beams. An experimentally determined diffusion coefficient was used to determine space-time customizable distribution of GNPs for feasible in-vivo concentrations of 43 mg/g. An analytic calculational approach from previously published work was employed to estimate the dose enhancement due to GNPs (2 and 10 nm) as a function of distance up to 1 cm from lumpectomy cavity. Results: Dose enhancement due to GNP was found to be about 130% for 50-kVp x-rays, and 110% for 6-MV external beam radiotherapy, 1 cm away from the lumpectomy cavity wall. Higher customizable dose enhancement could be achieved at other distances as a function of nanoparticle size. Conclusion: Our preliminary results suggest that significant dose enhancement can be achieved to residual tumor cells targeted with GNPs during APBI with electronic brachytherapy or external beam therapy. The findings provide a useful basis for developing nanoparticle

  8. Time Resolved Shadowgraph Images of Silicon during Laser Ablation:Shockwaves and Particle Generation

    SciTech Connect

    Liu, C.Y.; Mao, X.L.; Greif, R.; Russo, R.E.

    2006-05-06

    Time resolved shadowgraph images were recorded of shockwaves and particle ejection from silicon during laser ablation. Particle ejection and expansion were correlated to an internal shockwave resonating between the shockwave front and the target surface. The number of particles ablated increased with laser energy and was related to the crater volume.

  9. Plasma-mediated ablation: An optical tool for submicrometer surgery on neuronal and vascular systems

    PubMed Central

    Tsai, Philbert S.; Blinder, Pablo; Migliori, Benjamin J.; Neev, Joseph; Jin, Yishi; Squier, Jeffrey A.; Kleinfeld, David

    2009-01-01

    Plasma-mediated ablation makes use of high energy laser pulses to ionize molecules within the first few femtoseconds of the pulse. This process leads to a submicrometer-sized bubble of plasma that can ablate tissue with negligible heat transfer and collateral damage to neighboring tissue. We review the physics of plasma-mediated ablation and its use as a tool to generate targeted insults at the subcellular level to neurons and blood vessels deep within nervous tissue. Illustrative examples from axon regeneration and microvascular research illustrate the utility of this tool. We further discuss the use of ablation as an integral part of automated histology. PMID:19269159

  10. Computational simulation of (nat)UO2, (232)ThO2 and U3O8-Al pills to estimate (p,fission) (99)Mo yield in the modeled targets irradiated by CYCLONE30 accelerator.

    PubMed

    Jozvaziri, Atieh; Gholamzadeh, Zohreh; Yousefi, Kamran; Mirvakili, Seyed Mohammad; Alizadeh, Masoomeh; Aboudzadeh, Mohammadreza

    2017-03-01

    (99)Mo is important for both therapy and imaging purposes. Accelerator and reactor-based procedures are applied to produce it. Newly proton-fission method has been taken in attention by some research centers. In the present work, computationally investigation of the (99)Mo yield in different fissionable targets irradiated by proton was aimed. The results showed UO2 pill target could be efficiently used to produce 11.12Ci/g-U saturation yield of (99)Mo using 25MeV proton irradiation of the optimized-dimension target with 70µA current.

  11. Role of Wavelength and Pulse Structure in the Ablation of Tissue and Gelatin

    NASA Astrophysics Data System (ADS)

    Tribble, Jerri Ann

    The goal of these measurements has been to investigate the wavelength dependence of infrared laser induced tissue ablation. Fourier transform infrared spectroscopy of tissues guided the selection of wavelengths to which the Vanderbilt Free-Electron Laser (FEL) was tuned in order to study ablation rates and residual thermal damage in tissues including neural, ocular and dermal. Targeting FEL radiation to the amide II mode of proteins leads to tissue ablation characterized by minimal collateral damage while maintaining a substantial ablation rate. To account for these observations, a novel ablation mechanism has been proposed based on compromising tissue through resonant denaturation of structural proteins, which was tested using dynamic measurements on mechanical (ns) time scales of ablation of gelatin by FEL radiation. Simultaneous measurements of ejected material using a continuous HeNe probe beam tangential to the gelatin surface and the concomitant stress wave in the bulk of the sample provide an intriguing dynamical picture of the ablation event generated by infrared radiation of different wavelengths and different macropulse durations. By varying the macropulse duration from 60 to 200 ns with a broadband infrared Pockels cell, it is evident in both ejecta data and the stress transient data that the bulk of the ablation occurs after the end of the laser pulse. The most significant difference between ablation induced by different laser wavelengths, however, appears during the laser pulse, at the onset of ablation.

  12. Multidiagnostic analysis of ultrafast laser ablation of metals with pulse pair irradiation

    NASA Astrophysics Data System (ADS)

    Amoruso, S.; Bruzzese, R.; Wang, X.; O'Connell, G.; Lunney, J. G.

    2010-12-01

    Copper targets are irradiated in the ablation regime by pairs of equal, time-delayed collinear laser pulses separated on a timescale going from ≈2 ps to ≈2 ns. The ablation plume is characterized by ion probe diagnostic, fast imaging, and temporally and spatially resolved optical emission spectroscopy. The variation in the ablation efficiency with the delay between the pulses is analyzed by measuring the ablation crater profile with a contact profilometer. The second laser pulse modifies the characteristics of the plasma plume produced by the first pulse and the ablation efficiency. The different mechanisms involved in double pulse ultrafast laser ablation are identified and discussed. The experimental findings are interpreted in the frame of a simple model of the interaction of the second pulse with the nascent ablation plume produced by the first pulse. This model yields consistent and quantitative agreement with the experimental findings predicting the observed experimental trends of the ablation depth reduction and ion yield increase with the delay between the pulses, as well as the characteristic timescale of the observed changes. The possibility of controlling the characteristics of the plumes produced during ultrafast laser ablation via an efficient coupling of the energy of the second pulse to the various ablation components produced by the first pulse is of particular interest in ultrafast pulsed laser deposition and microprobe analyses of materials.

  13. Epicardial ablation guidance using coronary arterial models and live fluoroscopic overlay registrations

    NASA Astrophysics Data System (ADS)

    Manzke, R.; Thiagalingam, A.; Movassaghi, B.; d'Avila, A.; Reddy, V. Y.; Chan, R. C.

    2008-03-01

    Knowledge of patient-specific cardiac anatomy is required for catheter-based ablation in epicardial ablation procedures such as ventricular tachycardia (VT) ablation interventions. In particular, knowledge of critical structures such as the coronary arteries is essential to avoid collateral damage. In such ablation procedures, ablation catheters are brought in via minimally-invasive subxiphoid access. The catheter is then steered to ablation target sites on the left ventricle (LV). During the ablation and catheter navigation it is of vital importance to avoid damage of coronary structures. Contrast-enhanced rotational X-ray angiography of the coronary arteries delivers a 3D impression of the anatomy during the time of intervention. Vessel modeling techniques have been shown to be able to deliver accurate 3D anatomical models of the coronary arteries. To simplify epicardial navigation and ablation, we propose to overlay coronary arterial models, derived from rotational X-ray angiography and vessel modeling, onto real-time X-ray fluoroscopy. In a preclinical animal study, we show that overlay of intra-operatively acquired 3D arterial models onto X-ray helps to place ablation lesions at a safe distance from coronary structures. Example ablation lesions have been placed based on the model overlay at reasonable distances between key arterial vessels and on top of marginal branches.

  14. Molecular dynamic simulation of tungsten ablation under transient high heat flux

    NASA Astrophysics Data System (ADS)

    Yan, Sha; Zhu, Yizhou; Xue, Jianming; Zhang, Jie; Qu, Miao; Le, Xiaoyun

    2015-08-01

    Molecular dynamic (MD) method is used to simulation the tungsten ablation under transient high heat flux generated by energetic ions. A model including 363,600 W atoms was built based on Finnis-Sinclair potential. The results show that the ablation threshold is much lower than the one of boiling. So the ablation effects might be underestimated if using energy threshold of boiling instead of that of ablation. Particle size distribution of ablation products follows a power decay law with an exponent around -2.5, which does not affect by the incident heat flux. The transverse velocities of particles obey normal distribution, and a stream speed is added to the random movement for the longitudinal velocity. As the ablation start up, the recoiled impulse can induce shock wave in remained target, which is supported by experimental pressure wave measurements.

  15. Numerical study of the thermal ablation of wet solids by ultrashort laser pulses

    SciTech Connect

    Perez, Danny; Beland, Laurent Karim; Deryng, Delphine; Lewis, Laurent J.; Meunier, Michel

    2008-01-01

    The ablation by ultrashort laser pulses at relatively low fluences (i.e., in the thermal regime) of solids wetted by a thin liquid film is studied using a generic numerical model. In comparison with dry targets, the liquid is found to significantly affect ablation by confining the solid and slowing down the expansion of the laser-heated material. These factors affect the relative efficiency of the various ablation mechanisms, leading, in particular, to the complete inhibition of phase explosion at lower fluences, a reduced ablation yield, and significant changes in the composition of the plume. As a consequence, at fluences above the ablation threshold, the size of the ejected nanoclusters is lower in presence of the liquid. Our results provide a qualitative understanding of the effect of wetting layers on the ablation process.

  16. High temperature ablative foam

    NASA Technical Reports Server (NTRS)

    Liu, Matthew T. (Inventor)

    1992-01-01

    An ablative foam composition is formed of approximately 150 to 250 parts by weight polymeric isocyanate having an isocyanate functionality of 2.6 to 3.2; approximately 15 to 30 parts by weight reactive flame retardant having a hydroxyl number range from 200-260; approximately 10 to 40 parts by weight non-reactive flame retardant; approximately 10 to 40 parts by weight nonhydrolyzable silicone copolymer having a hydroxyl number range from 75-205; and approximately 3 to 16 parts by weight amine initiated polyether resin having an isocyanate functionality greater than or equal to 3.0 and a hydroxyl number range from 400-800.

  17. Matricectomy and nail ablation.

    PubMed

    Baran, Robert; Haneke, Eckart

    2002-11-01

    Matricectomy refers to the complete extirpation of the nail matrix, resulting in permanent nail loss. Usually however, matricectomy is only partial, restricted to one or both lateral horns of the matrix. Nail ablation is the definitive removal of the entire nail organ. The most important common denominator in the successful matricectomy is the total removal or destruction of the matrix tissue. Matricectomy may be indicated for the management of onychauxis, onychogryphosis, congenital nail dystrophies, and chronic painful nail, such as recalcitrant ingrown toenail or split within the medial or lateral one-third of the nail.

  18. Plasma-mediated ablation for the management of obstructive sleep apnea

    NASA Astrophysics Data System (ADS)

    Puchalski, Robert; Shah, Udayan K.

    2000-05-01

    Plasma-mediated ablation (PMA) removes tissue by developing an electrically induced plasma layer between the instrument and target tissue. Charged particles within the plasma field then accelerate toward the tissue, breaking the molecular bonds within the top layer of tissue. Thermal damage to collateral tissue is minimal, resulting in the moniker, 'cold' ablation, for this method. Recently, instrumentation has been developed to permit application for soft tissue resection in Otolaryngology. Presentation of the theory, as well as the benefits and disadvantages associated with CoblationTM technology will be followed by examples of its use. A brief videotape will demonstrate the application of PMA for UPPP, tonsillectomy and nasal turbinate reduction. Preliminary experience from our institution, including eighteen children treated with tonsillectomy and followed for at least one month post-operatively, has provided an initial cohort for comparing the risks and benefits of the approach. The advantage of CoblationTM technology identified thus far, that of less thermal damage, is balanced against a decreased level of hemostasis (compared to MES) and an increased cost.

  19. Similarities and differences in ablative and non-ablative iron oxide nanoparticle hyperthermia cancer treatment

    NASA Astrophysics Data System (ADS)

    Petryk, Alicia A.; Misra, Adwiteeya; Kastner, Elliot J.; Mazur, Courtney M.; Petryk, James D.; Hoopes, P. Jack

    2015-03-01

    The use of hyperthermia to treat cancer is well studied and has utilized numerous delivery techniques, including microwaves, radio frequency, focused ultrasound, induction heating, infrared radiation, warmed perfusion liquids (combined with chemotherapy), and recently, metallic nanoparticles (NP) activated by near infrared radiation (NIR) and alternating magnetic field (AMF) based platforms. It has been demonstrated by many research groups that ablative temperatures and cytotoxicity can be produced with locally NP-based hyperthermia. Such ablative NP techniques have demonstrated the potential for success. Much attention has also been given to the fact that NP may be administered systemically, resulting in a broader cancer therapy approach, a lower level of tumor NP content and a different type of NP cancer therapy (most likely in the adjuvant setting). To use NP based hyperthermia successfully as a cancer treatment, the technique and its goal must be understood and utilized in the appropriate clinical context. The parameters include, but are not limited to, NP access to the tumor (large vs. small quantity), cancer cell-specific targeting, drug carrying capacity, potential as an ionizing radiation sensitizer, and the material properties (magnetic characteristics, size and charge). In addition to their potential for cytotoxicity, the material properties of the NP must also be optimized for imaging, detection and direction. In this paper we will discuss the differences between, and potential applications for, ablative and non-ablative magnetic nanoparticle hyperthermia.

  20. Thermal melting and ablation of silicon by femtosecond laser radiation

    SciTech Connect

    Ionin, A. A.; Kudryashov, S. I. Seleznev, L. V.; Sinitsyn, D. V.; Bunkin, A. F.; Lednev, V. N.; Pershin, S. M.

    2013-03-15

    The space-time dynamics of thermal melting, subsurface cavitation, spallative ablation, and fragmentation ablation of the silicon surface excited by single IR femtosecond laser pulses is studied by timeresolved optical reflection microscopy. This dynamics is revealed by monitoring picosecond and (sub)nanosecond oscillations of probe pulse reflection, which is modulated by picosecond acoustic reverberations in the dynamically growing surface melt subjected to ablation and having another acoustic impedance, and by optical interference between the probe pulse replicas reflected by the spalled layer surface and the layer retained on the target surface. The acoustic reverberation periods change during the growth and ablation of the surface melt film, which makes it possible to quantitatively estimate the contributions of these processes to the thermal dynamics of the material surface. The results on the thermal dynamics of laser excitation are supported by dynamic measurements of the ablation parameters using noncontact ultrasonic diagnostics, scanning electron microscopy, atomic force microscopy, and optical interference microscopy of the modified regions appearing on the silicon surface after ablation.

  1. Laser ablation in analytical chemistry.

    PubMed

    Russo, Richard E; Mao, Xianglei; Gonzalez, Jhanis J; Zorba, Vassilia; Yoo, Jong

    2013-07-02

    In 2002, we wrote an Analytical Chemistry feature article describing the Physics of Laser Ablation in Microchemical Analysis. In line with the theme of the 2002 article, this manuscript discusses current issues in fundamental research, applications based on detecting photons at the ablation site (LIBS and LAMIS) and by collecting particles for excitation in a secondary source (ICP), and directions for the technology.

  2. Infrared laser ablation sample transfer for MALDI imaging.

    PubMed

    Park, Sung-Gun; Murray, Kermit K

    2012-04-03

    An infrared laser was used to ablate material from tissue sections under ambient conditions for direct collection on a matrix assisted laser desorption ionization (MALDI) target. A 10 μm thick tissue sample was placed on a microscope slide and was mounted tissue-side down between 70 and 450 μm from a second microscope slide. The two slides were mounted on a translation stage, and the tissue was scanned in two dimensions under a focused mid-infrared (IR) laser beam to transfer material to the target slide via ablation. After the material was transferred to the target slide, it was analyzed using MALDI imaging using a tandem time-of-flight mass spectrometer. Images were obtained from peptide standards for initial optimization of the system and from mouse brain tissue sections using deposition either onto a matrix precoated target or with matrix addition after sample transfer and compared with those from standard MALDI mass spectrometry imaging. The spatial resolution of the transferred material is approximately 400 μm. Laser ablation sample transfer provides several new capabilities not possible with conventional MALDI imaging including (1) ambient sampling for MALDI imaging, (2) area to spot concentration of ablated material, (3) collection of material for multiple imaging analyses, and (4) direct collection onto nanostructure assisted laser desorption ionization (NALDI) targets without blotting or ultrathin sections.

  3. Dynamics of multiple plumes in laser ablation: Modeling of the shielding effect

    NASA Astrophysics Data System (ADS)

    Zinovik, Igor; Povitsky, Alex

    2006-07-01

    The scattering and absorption of laser radiation by previously ablated plumes in laser ablation (known as the shielding effect) dramatically affect the efficiency of laser ablation process. The ablated plumes consisting of water vapor, droplets, and particles are modeled as a gas-particle equilibrium mixture by solution of the Euler equations combined with the transport equation for the ratio of heat capacities. Shielding effect on the overall ablated mass by multiple plumes is studied for a wide range of concentration of particles in vaporized plumes, various laser repetition rates, scattering, and absorption of laser energy. The shielding phenomenon is studied for short sequences of discrete plumes to focus on the shielding effect of individual plumes. The results of numerical modeling were compared to experimental results of laser-induced water explosive vaporization. Ablation rate was calculated for a single ablated plume and for the sequence of six laser pulses at the repetition rates of 0.33 and 1MHz at which gas dynamics interactions between plumes are strong but plumes have not yet form a continuous jet. A single ablated plume has an initial semispherical shape which transforms into mushroomlike cloud with a thin stem and a ring vortex as it was observed in experiments with water and cornea ablation. For the plume with a given ablated mass, the longer ejection of plume with smaller density produces the plume with smaller shielding capacity. For multiple laser pulses, the velocity of ejected mixture increases from the center of the target to its periphery because of the shielding effect. The ablated mass of the current plume depends on the attenuation of the incident laser beam energy caused by the propagation of laser beam through previously ablated plumes. In the case of laser energy absorption, the ablation rate per pulse exceeds 2-2.5 times the rate obtained for the laser energy scattering.

  4. Retrograde Inversion Stripping as a Complication of the Clarivein® Mechanochemical Venous Ablation Procedure

    PubMed Central

    Moore, HM; Franklin, IJ; Davies, AH

    2015-01-01

    The endovenous revolution has accelerated the development of new techniques and devices for the treatment of varicose veins. The ClariVein® mechanochemical ablation device offers tumescentless treatment with a rotating ablation tip that can theoretically become stuck in tissue. We present the first report of retrograde stripping of the small saphenous vein without anaesthesia following attempted use of the ClariVein® device, without adverse sequelae. PMID:25723675

  5. Prediction of back-scatter radiations to a beam monitor chamber of medical linear accelerators by use of the digitized target-current-pulse analysis method.

    PubMed

    Suzuki, Yusuke; Hayashi, Naoki; Kato, Hideki; Fukuma, Hiroshi; Hirose, Yasujiro; Kawano, Makoto; Nishii, Yoshio; Nakamura, Masaru; Mukouyama, Takashi

    2013-01-01

    In small-field irradiation, the back-scattered radiation (BSR) affects the counts measured with a beam monitor chamber (BMC). In general, the effect of the BSR depends on the opened-jaw size. The effect is significantly large in small-field irradiation. Our purpose in this study was to predict the effect of BSR on LINAC output accurately with an improved target-current-pulse (TCP) technique. The pulse signals were measured with a system consisting of a personal computer and a digitizer. The pulse signals were analyzed with in-house software. The measured parameters were the number of pulses, the change in the waveform and the integrated signal values of the TCPs. The TCPs were measured for various field sizes with four linear accelerators. For comparison, Yu's method in which a universal counter was used was re-examined. The results showed that the variance of the measurements by the new method was reduced to approximately 1/10 of the variance by the previous method. There was no significant variation in the number of pulses due to a change in the field size in the Varian Clinac series. However, a change in the integrated signal value was observed. This tendency was different from the result of other investigations in the past. Our prediction method is able to define the cutoff voltage for the TCP acquired by digitizer. This functionality provides the capability of clearly classifying TCPs into signals and noise. In conclusion, our TCP analysis method can predict the effect of BSR on the BMC even for small-field irradiations.

  6. Targeted Gene Deletion Using DNA-Free RNA-Guided Cas9 Nuclease Accelerates Adaptation of CHO Cells to Suspension Culture.

    PubMed

    Lee, Namil; Shin, JongOh; Park, Jin Hyoung; Lee, Gyun Min; Cho, Suhyung; Cho, Byung-Kwan

    2016-11-18

    Chinese hamster ovary (CHO) cells are the preferred host for the production of a wide array of biopharmaceuticals. Thus, efficient and rational CHO cell line engineering methods have been in high demand to improve quality and productivity. Here, we provide a novel genome engineering platform for increasing desirable phenotypes of CHO cells based upon the integrative protocol of high-throughput RNA sequencing and DNA-free RNA-guided Cas9 (CRISPR associated protein9) nuclease-based genome editing. For commercial production of therapeutic proteins, CHO cells have been adapted for suspension culture in serum-free media, which is highly beneficial with respect to productivity and economics. To engineer CHO cells for rapid adaptation to a suspension culture, we exploited strand-specific RNA-seq to identify genes differentially expressed according to their adaptation trajectory in serum-free media. More than 180 million sequencing reads were generated and mapped to the currently available 109,152 scaffolds of the CHO-K1 genome. We identified significantly downregulated genes according to the adaptation trajectory and then verified their effects using the genome editing method. Growth-based screening and targeted amplicon sequencing revealed that the functional deletions of Igfbp4 and AqpI gene accelerate suspension adaptation of CHO-K1 cells. The availability of this strand-specific transcriptome sequencing and DNA-free RNA-guided Cas9 nuclease mediated genome editing facilitates the rational design of the CHO cell genome for efficient production of high quality therapeutic proteins.

  7. Calcified lesion modeling for excimer laser ablation

    NASA Astrophysics Data System (ADS)

    Scott, Holly A.; Archuleta, Andrew; Splinter, Robert

    2009-06-01

    Objective: Develop a representative calcium target model to evaluate penetration of calcified plaque lesions during atherectomy procedures using 308 nm Excimer laser ablation. Materials and Methods: An in-vitro model representing human calcified plaque was analyzed using Plaster-of-Paris and cement based composite materials as well as a fibrinogen model. The materials were tested for mechanical consistency. The most likely candidate(s) resulting from initial mechanical and chemical screening was submitted for ablation testing. The penetration rate of specific multi-fiber catheter designs and a single fiber probe was obtained and compared to that in human cadaver calcified plaque. The effects of lasing parameters and catheter tip design on penetration speed in a representative calcified model were verified against the results in human cadaver specimens. Results: In Plaster of Paris, the best penetration was obtained using the single fiber tip configuration operating at 100 Fluence, 120 Hz. Calcified human lesions are twice as hard, twice as elastic as and much more complex than Plaster of Paris. Penetration of human calcified specimens was highly inconsistent and varied significantly from specimen to specimen and within individual specimens. Conclusions: Although Plaster of Paris demonstrated predictable increases in penetration with higher energy density and repetition rate, it can not be considered a totally representative laser ablation model for calcified lesions. This is in part due to the more heterogeneous nature and higher density composition of cadaver intravascular human calcified occlusions. Further testing will require a more representative model of human calcified lesions.

  8. Status of the Ablative Laser Propulsion Studies

    NASA Technical Reports Server (NTRS)

    Herren, Kenneth A.; Lin, Jun; Cohen, Tinothy; Pakhomov, Andrew V.; Thompson, M. Shane

    2004-01-01

    We present a short review of our laser-propulsion research as well as some of the current results of the Ablative Laser Propulsion (ALP) studies currently underway at the University of Alabama in Huntsville. It has been shown that direct surface ablation of a solid material produces high specific impulse (Isp) at relatively high energy conversion efficiency (20 - 40%). We detail measurements of specific impulse, thrust and coupling coefficients for elemental target materials both with single and with double pulse laser shots. We also present measurements taken using three independent methods for determination of Isp. The three methods produce consistent values from ion time-of-flight technique, impulse measurements and imaging of the expansion front of plasma plume. We present a demonstration of our ALP lightcraft, a small free-flying micro-vehicle that is propelled by ablation. For ALP lightcraft we use a subscale thin shell of nickel replicated over a diamond turned mandrel that produces a highly polished self-focusing, truncated at the focus parabolic mirror. The mass of the lightcraft is 54 mg and it is driven by 100-ps wide, 35-mJ laser pulses at 532 nm wavelength. This is an ongoing research. We also present the latest work on laserdriven micro-thrusters and detail some the near term goals of our program.

  9. Simulation of Pellet Ablation

    NASA Astrophysics Data System (ADS)

    Parks, P. B.; Ishizaki, Ryuichi

    2000-10-01

    In order to clarify the structure of the ablation flow, 2D simulation is carried out with a fluid code solving temporal evolution of MHD equations. The code includes electrostatic sheath effect at the cloud interface.(P.B. Parks et al.), Plasma Phys. Contr. Fusion 38, 571 (1996). An Eulerian cylindrical coordinate system (r,z) is used with z in a spherical pellet. The code uses the Cubic-Interpolated Psudoparticle (CIP) method(H. Takewaki and T. Yabe, J. Comput. Phys. 70), 355 (1987). that divides the fluid equations into non-advection and advection phases. The most essential element of the CIP method is in calculation of the advection phase. In this phase, a cubic interpolated spatial profile is shifted in space according to the total derivative equations, similarly to a particle scheme. Since the profile is interpolated by using the value and the spatial derivative value at each grid point, there is no numerical oscillation in space, that often appears in conventional spline interpolation. A free boundary condition is used in the code. The possibility of a stationary shock will also be shown in the presentation because the supersonic ablation flow across the magnetic field is impeded.

  10. Effects of Liquid Medium and Ablation Wavelength on the Properties of Cadmium Sulfide Nanoparticles Formed by Pulsed-Laser Ablation.

    PubMed

    García Guillén, Grisel; Zuñiga Ibarra, Veronica Anahi; Mendivil Palma, Maria Isabel; Krishnan, Bindu; Avellaneda Avellaneda, David; Shaji, Sadasivan

    2016-11-03

    Pulsed-laser ablation in liquid (PLAL) is a green synthesis technique to obtain semiconductor nanomaterials in colloidal form. Herein, cadmium sulfide (CdS) nanoparticles were synthesized by the pulsed-laser ablation of a CdS target in different liquid media by using λ=532 and 1064 nm outputs from a pulsed (10 ns, 10 Hz) Nd:YAG laser at different ablation fluence values. The morphology, structure, crystalline phase, elemental composition, optical, and luminescent properties of CdS nanomaterials were analyzed by using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV/Vis absorption spectroscopy, and fluorescence spectroscopy. By changing the liquid medium and ablation wavelength, CdS nanoparticles with different morphology and size were formed, as demonstrated by using TEM analysis. The crystallinity and chemical states of the ablation products were confirmed by using XRD and XPS analyses. The optical bandgap of the CdS nanoparticles was dependent on the ablation wavelength and the fluence. These nanocolloids presented different green emissions, which implied the presence of several emission centers. CdS nanocolloids in distilled water catalyzed the photocatalytic decay of methylene blue dye under light irradiation from a solar simulator.

  11. Aerospace Laser Ignition/Ablation Variable High Precision Thruster

    NASA Technical Reports Server (NTRS)

    Campbell, Jonathan W. (Inventor); Edwards, David L. (Inventor); Campbell, Jason J. (Inventor)

    2015-01-01

    A laser ignition/ablation propulsion system that captures the advantages of both liquid and solid propulsion. A reel system is used to move a propellant tape containing a plurality of propellant material targets through an ignition chamber. When a propellant target is in the ignition chamber, a laser beam from a laser positioned above the ignition chamber strikes the propellant target, igniting the propellant material and resulting in a thrust impulse. The propellant tape is advanced, carrying another propellant target into the ignition chamber. The propellant tape and ignition chamber are designed to ensure that each ignition event is isolated from the remaining propellant targets. Thrust and specific impulse may by precisely controlled by varying the synchronized propellant tape/laser speed. The laser ignition/ablation propulsion system may be scaled for use in small and large applications.

  12. High-power electron beam tests of a liquid-lithium target and characterization study of (7)Li(p,n) near-threshold neutrons for accelerator-based boron neutron capture therapy.

    PubMed

    Halfon, S; Paul, M; Arenshtam, A; Berkovits, D; Cohen, D; Eliyahu, I; Kijel, D; Mardor, I; Silverman, I

    2014-06-01

    A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center (SNRC). The target is intended to demonstrate liquid-lithium target capabilities to constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals. The lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power >5kW generated by high-intensity proton beams, necessary for sufficient therapeutic neutron flux. In preliminary experiments liquid lithium was flown through the target loop and generated a stable jet on the concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power densities of more than 4kW/cm(2) and volumetric power density around 2MW/cm(3) at a lithium flow of ~4m/s, while maintaining stable temperature and vacuum conditions. These power densities correspond to a narrow (σ=~2mm) 1.91MeV, 3mA proton beam. A high-intensity proton beam irradiation (1.91-2.5MeV, 2mA) is being commissioned at the SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator. In order to determine the conditions of LiLiT proton irradiation for BNCT and to tailor the neutron energy spectrum, a characterization of near threshold (~1.91MeV) (7)Li(p,n) neutrons is in progress based on Monte-Carlo (MCNP and Geant4) simulation and on low-intensity experiments with solid LiF targets. In-phantom dosimetry measurements are performed using special designed dosimeters based on CR-39 track detectors.

  13. Thermal response and ablation characteristics of light weight ceramic ablators

    NASA Technical Reports Server (NTRS)

    Tran, Huy K.; Rasky, Daniel J.; Esfahani, Lili

    1993-01-01

    An account is given of the thermal performance and ablation characteristics of the NASA-Ames Lightweight Ceramic Ablators (LCAs) in supersonic, high-enthalpy convective environments, which use low density ceramic or carbon fiber matrices as substrates for main structural support, with organic resin fillers. LCA densities are in the 0.224-1.282 g/cu cm range. In-depth temperature data have been obtained to determine thermal penetration depths and conductivity. The addition of SiC and PPMA is noted to significantly improve the ablation performance of LCAs with silica substrates. Carbon-based LCAs are the most mass-efficient at high flux levels.

  14. Dopant Distribution in NIF Beryllium Ablator Capsules

    NASA Astrophysics Data System (ADS)

    Huang, H.; Xu, H. W.; Youngblood, K. P.; Wall, D. R.; Stephens, R. B.; Moreno, K. A.; Nikroo, A.; Salmonson, J. D.; Haan, S. W.; Wu, K. J.; Wang, Y. M.; Hamza, A. V.

    2012-10-01

    Good implosion performance requires capsule ablator material with spherically uniform x-ray opacity, which is controlled by one of several dopants (Cu, Si, Al, etc.) in the Be shell. During production, the dopant concentration is radially stepped. However, the various Be-dopant interactions result in vastly different dopant distribution patterns, some quite inhomogeneous. We have characterized these structures and established the phenomenological basis and the magnitudes of the inhomogeneity both in spatial length scales and in atomic percent. We will discuss the case of inhomogeneous Cu diffusion in detail, followed by discussions of other dopants and the estimate of the impact of these structures on target implosion.

  15. Dynamical modeling of laser ablation processes

    SciTech Connect

    Leboeuf, J.N.; Chen, K.R.; Donato, J.M.; Geohegan, D.B.; Liu, C.L.; Puretzky, A.A.; Wood, R.F.

    1995-09-01

    Several physics and computational approaches have been developed to globally characterize phenomena important for film growth by pulsed laser deposition of materials. These include thermal models of laser-solid target interactions that initiate the vapor plume; plume ionization and heating through laser absorption beyond local thermodynamic equilibrium mechanisms; gas dynamic, hydrodynamic, and collisional descriptions of plume transport; and molecular dynamics models of the interaction of plume particles with the deposition substrate. The complexity of the phenomena involved in the laser ablation process is matched by the diversity of the modeling task, which combines materials science, atomic physics, and plasma physics.

  16. Antibacterial effects of laser ablated Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Shamaila, S.; Wali, H.; Sharif, R.; Nazir, J.; Zafar, N.; Rafique, M. S.

    2013-10-01

    The interaction of nickel nanoparticles with Escherichia coli (E. coli) bacteria has been studied. The nickel nanoparticles have been fabricated by continuous wave laser ablation of nickel target and their properties are studied using different characterization techniques. The antibacterial activity of nickel nanoparticles was checked against E. coli bacteria. Escherichia coli were cultured in nutrients broth and different concentrations of nickel nanoparticles were added to bacterial culture solution to investigate the interaction of nickel nanoparticles with bacteria and to check toxicity of the nickel nanoparticles against E. coli. The fabricated Ni nanoparticles have exhibited considerable antimicrobial activity against E. coli.

  17. PLANS FOR WARM DENSE MATTER EXPERIMENTS AND IFE TARGET EXPERIMENTS ON NDCX-II

    SciTech Connect

    Waldron, W.L.; Barnard, J.J.; Bieniosek, F.M.; Friedman, A.; Henestroza, E.; Leitner, M.; Logan, B.G.; Ni, P.A.; Roy, P.K.; Seidl, P.A.; Sharp, W.M.

    2008-09-22

    The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) is currently developing design concepts for NDCX-II, the second phase of the Neutralized Drift Compression Experiment, which will use ion beams to explore Warm Dense Matter (WDM) and Inertial Fusion Energy (IFE) target hydrodynamics. The ion induction accelerator will consist of a new short pulse injector and induction cells from the decommissioned Advanced Test Accelerator (ATA) at Lawrence Livermore National Laboratory (LLNL). To fit within an existing building and to meet the energy and temporal requirements of various target experiments, an aggressive beam compression and acceleration schedule is planned. WDM physics and ion-driven direct drive hydrodynamics will initially be explored with 30 nC of lithium ions in experiments involving ion deposition, ablation, acceleration and stability of planar targets. Other ion sources which may deliver higher charge per bunch will be explored. A test stand has been built at Lawrence Berkeley National Laboratory (LBNL) to test refurbished ATA induction cells and pulsed power hardware for voltage holding and ability to produce various compression and acceleration waveforms. Another test stand is being used to develop and characterize lithium-doped aluminosilicate ion sources. The first experiments will include heating metallic targets to 10,000 K and hydrodynamics studies with cryogenic hydrogen targets.

  18. Pulsed laser ablation of pepsin on an inorganic substrate

    NASA Astrophysics Data System (ADS)

    Cicco, N.; Lopizzo, T.; Marotta, V.; Morone, A.; Verrastro, M.; Viggiano, V.

    2009-03-01

    Pressed pepsin pellets used as targets were ablated with the pulses of the Nd-YAG laser. The activity of the pepsin thin layer, deposited on a glass substrate, was successfully detected by analyzing the proteolytic degradation areas on the polyacrylamide gel (PA-gel) copolymerized with albumin from the hen egg white (ovalbumin), used as an enzymatic substrate.

  19. Infrared Laser Ablation Sample Transfer for MALDI and Electrospray

    NASA Astrophysics Data System (ADS)

    Park, Sung-Gun; Murray, Kermit King

    2011-08-01

    We have used an infrared laser to ablate materials under ambient conditions that were captured in solvent droplets. The droplets were either deposited on a MALDI target for off-line analysis by MALDI time-of-flight mass spectrometry or flow-injected into a nanoelectrospray source of an ion trap mass spectrometer. An infrared optical parametric oscillator (OPO) laser system at 2.94 μm wavelength and approximately 1 mJ pulse energy was focused onto samples for ablation at atmospheric pressure. The ablated material was captured in a solvent droplet 1-2 mm in diameter that was suspended from a silica capillary a few millimeters above the sample target. Once the sample was transferred to the droplet by ablation, the droplet was deposited on a MALDI target. A saturated matrix solution was added to the deposited sample, or in some cases, the suspended capture droplet contained the matrix. Peptide and protein standards were used to assess the effects of the number of IR laser ablation shots, sample to droplet distance, capture droplet size, droplet solvent, and laser pulse energy. Droplet collected samples were also injected into a nanoelectrospray source of an ion trap mass spectrometer with a 500 nL injection loop. It is estimated that pmol quantities of material were transferred to the droplet with an efficiency of approximately 1%. The direct analysis of biological fluids for off-line MALDI and electrospray was demonstrated with blood, milk, and egg. The implications of this IR ablation sample transfer approach for ambient imaging are discussed.

  20. [New techniques of tumor ablation (microwaves, electroporation)].

    PubMed

    de Baere, T

    2011-09-01

    Since the introduction of radiofrequency tumor ablation of liver tumors in the late 1990s, local destructive therapies have been applied to lung, renal and bone lesions. In addition, new techniques have been introduced to compensate for the limitations of radiofrequency ablation, namely the reduced rate of complete ablation for tumors larger than 3 cm and tumors near vessels larger than 3 mm. Microwave ablation is currently evolving rapidly. While it is a technique based on thermal ablation similar to radiofrequency ablation, there are significant differences between both techniques. Electroporation, of interest because of the non-thermal nature of the ablation process, also is under evaluation.