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Sample records for high-energy plasma wakefield

  1. Magnetowave Induced Plasma Wakefield Acceleration for Ultra High Energy Cosmic Rays

    SciTech Connect

    Chang, Feng-Yin; Chen, Pisin; Lin, Guey-Lin; Noble, Robert; Sydora, Richard; /Alberta U.

    2009-10-17

    Magnetowave induced plasma wakefield acceleration (MPWA) in a relativistic astrophysical outflow has been proposed as a viable mechanism for the acceleration of cosmic particles to ultrahigh energies. Here we present simulation results that clearly demonstrate the viability of this mechanism for the first time. We invoke the high frequency and high speed whistler mode for the driving pulse. The plasma wakefield obtained in the simulations compares favorably with our newly developed relativistic theory of the MPWA. We show that, under appropriate conditions, the plasma wakefield maintains very high coherence and can sustain high-gradient acceleration over hundreds of plasma skin depths. Invoking active galactic nuclei as the site, we show that MPWA production of ultrahigh energy cosmic rays beyond ZeV (10{sup 21} eV) is possible.

  2. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe.

    PubMed

    Zhang, C J; Hua, J F; Xu, X L; Li, F; Pai, C-H; Wan, Y; Wu, Y P; Gu, Y Q; Mori, W B; Joshi, C; Lu, W

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.

  3. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    SciTech Connect

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C. -H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; Lu, W.

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. As a result, the capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.

  4. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    DOE PAGES

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; ...

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of themore » wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. As a result, the capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.« less

  5. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

    PubMed Central

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C.-H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; Lu, W.

    2016-01-01

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method. PMID:27403561

  6. High energy photon emission from wakefields

    SciTech Connect

    Farinella, D. M. Lau, C. K.; Taimourzadeh, S.; Hwang, Y.; Abazajian, K.; Canac, N.; Taborek, P.; Tajima, T.; Zhang, X. M.; Koga, J. K.; Ebisuzaki, T.

    2016-07-15

    Experimental evidence has accumulated to indicate that wakefield acceleration (WFA) accompanies intense and sometimes coherent emission of radiation such as from betatron radiation. The investigation of this issue has additional impetus nowadays because we are learning (1) there is an additional acceleration process of the ponderomotive acceleration; (2) WFA may become relevant in much higher density regimes; (3) WFA has been proposed as the mechanism for extreme high energy cosmic ray acceleration and gamma ray bursts for active galactic nuclei. These require us to closely examine the radiative mechanisms in WFA anew. We report studies of radiation from wakefield (self-injected betatron) and ponderomotive (laser field) mechanisms in scalings of the frequency and intensity of the driver, as well as the plasma density.

  7. Cosmic Plasma Wakefield Acceleration

    SciTech Connect

    Chen, P

    2004-04-26

    Recently we proposed a new cosmic acceleration mechanism which was based on the wakefields excited by the Alfven shocks in a relativistically owing plasma. In this paper we include some omitted details, and show that there exists a threshold condition for transparency below which the accelerating particle is collision-free and suffers little energy loss in the plasma medium. The stochastic encounters of the random accelerating-decelerating phases results in a power-law energy spectrum: f({epsilon}) {proportional_to} 1/{epsilon}{sup 2}. As an example, we discuss the possible production of super-GZK ultra high energy cosmic rays (UHECR) in the atmosphere of gamma ray bursts. The estimated event rate in our model agrees with that from UHECR observations.

  8. Towards Attosecond High-Energy Electron Bunches: Controlling Self-Injection in Laser-Wakefield Accelerators Through Plasma-Density Modulation

    NASA Astrophysics Data System (ADS)

    Tooley, M. P.; Ersfeld, B.; Yoffe, S. R.; Noble, A.; Brunetti, E.; Sheng, Z. M.; Islam, M. R.; Jaroszynski, D. A.

    2017-07-01

    Self-injection in a laser-plasma wakefield accelerator is usually achieved by increasing the laser intensity until the threshold for injection is exceeded. Alternatively, the velocity of the bubble accelerating structure can be controlled using plasma density ramps, reducing the electron velocity required for injection. We present a model describing self-injection in the short-bunch regime for arbitrary changes in the plasma density. We derive the threshold condition for injection due to a plasma density gradient, which is confirmed using particle-in-cell simulations that demonstrate injection of subfemtosecond bunches. It is shown that the bunch charge, bunch length, and separation of bunches in a bunch train can be controlled by tailoring the plasma density profile.

  9. Axionic suppression of plasma wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Burton, D. A.; Noble, A.; Walton, T. J.

    2016-09-01

    Contemporary attempts to explain the existence of ultra-high energy cosmic rays using plasma-based wakefield acceleration deliberately avoid non-standard model particle physics. However, such proposals exploit some of the most extreme environments in the Universe and it is conceivable that hypothetical particles outside the standard model have significant implications for the effectiveness of the acceleration process. Axions solve the strong CP problem and provide one of the most important candidates for cold dark matter, and their potential significance in the present context should not be overlooked. Our analysis of the field equations describing a plasma augmented with axions uncovers a dramatic axion-induced suppression of the energy gained by a test particle in the wakefield driven by a particle bunch, or an intense pulse of electromagnetic radiation, propagating at ultra-relativistic speeds within the strongest magnetic fields in the Universe.

  10. Results from Plasma Wakefield Experiments at FACET

    SciTech Connect

    Li, S.Z.; Clarke, C.I.; England, R.J.; Frederico, J.; Gessner, S.J.; Hogan, M.J.; Jobe, R.K.; Litos, M.D.; Walz, D.R.; Muggli, P.; An, W.; Clayton, C.E.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.; Tochitsky, S.; Adli, E.; /U. Oslo

    2011-12-13

    We report initial results of the Plasma Wakefield Acceleration (PWFA) Experiments performed at FACET - Facility for Advanced aCcelertor Experimental Tests at SLAC National Accelerator Laboratory. At FACET a 23 GeV electron beam with 1.8 x 10{sup 10} electrons is compressed to 20 {mu}m longitudinally and focused down to 10 {mu}m x 10 {mu}m transverse spot size for user driven experiments. Construction of the FACET facility completed in May 2011 with a first run of user assisted commissioning throughout the summer. The first PWFA experiments will use single electron bunches combined with a high density lithium plasma to produce accelerating gradients > 10 GeV/m benchmarking the FACET beam and the newly installed experimental hardware. Future plans for further study of plasma wakefield acceleration will be reviewed. The experimental hardware and operation of the plasma heat-pipe oven have been successfully commissioned. Plasma wakefield acceleration was not observed because the electron bunch density was insufficient to ionize the lithium vapor. The remaining commissioning time in summer 2011 will be dedicated to delivering the FACET design parameters for the experimental programs which will begin in early 2012. PWFA experiments require the shorter bunches and smaller transverse sizes to create the plasma and drive large amplitude wakefields. Low emittance and high energy will minimize head erosion which was found to be a limiting factor in acceleration distance and energy gain. We will run the PWFA experiments with the design single bunch conditions in early 2012. Future PWFA experiments at FACET are discussed in [5][6] and include drive and witness bunch production for high energy beam manipulation, ramped bunch to optimize tranformer ratio, field-ionized cesium plasma, preionized plasmas, positron acceleration, etc.. We will install a notch collimator for two-bunch operation as well as new beam diagnostics such as the X-band TCAV [7] to resolve the two bunches

  11. Wakefield Generation in Plasma Channels

    NASA Astrophysics Data System (ADS)

    Volfbeyn, P.; Leemans, W. P.; Brussaard, G. J. H.; Esarey, E.; Wurtele, J. S.

    1999-11-01

    Laser wakefield generation in plasma channels is experimentally studied. Plasma channels, produced using the ignitor-heater method [1] in hydrogen and nitrogen, have been used to guide intense (> 5 x 10^17 W/cm^2), short (<70 fs) infrared (800 nm) laser pulses. Laser pulses injected into these channels produce a plasma wake with a phase velocity close to the speed of light. The transverse density profile of the channel determines the properties of the laser mode as well as of the plasma wave mode. The longitudinally integrated properties of the channel are measured with a Mach-Zehnder interferometer using 400 nm radiation. The probe and reference beam are combined directly on a CCD camera to provide two-dimensional interferograms and also through a spectrometer to allow Fourier domain interferometry. Progress on measuring the transverse channel profile and wakefield amplitudes will be presented. [1] P. Volfbeyn, E. Esarey and W.P. Leemans, Phys. Plasmas 6, 2269 (1999).

  12. Giga-electronvolt electrons due to a transition from laser wakefield acceleration to plasma wakefield acceleration

    SciTech Connect

    Masson-Laborde, P. E. Teychenné, D.; Mo, M. Z.; Ali, A.; Fedosejevs, R.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.; Rozmus, W.

    2014-12-15

    We show through experiments that a transition from laser wakefield acceleration (LWFA) regime to a plasma wakefield acceleration (PWFA) regime can drive electrons up to energies close to the GeV level. Initially, the acceleration mechanism is dominated by the bubble created by the laser in the nonlinear regime of LWFA, leading to an injection of a large number of electrons. After propagation beyond the depletion length, leading to a depletion of the laser pulse, whose transverse ponderomotive force is not able to sustain the bubble anymore, the high energy dense bunch of electrons propagating inside bubble will drive its own wakefield by a PWFA regime. This wakefield will be able to trap and accelerate a population of electrons up to the GeV level during this second stage. Three dimensional particle-in-cell simulations support this analysis and confirm the scenario.

  13. Particle dynamics and its consequences in wakefield acceleration in a high energy collider

    SciTech Connect

    Cheshkov, S.; Tajima, T.; Horton, W.; Yokoya, K.

    1998-09-01

    The performance of a wakefield accelerator in a high energy collider application is analyzed by use of a nonlinear dynamics map built on a simple theoretical model of the wakefield generated by the laser pulse (or whatever other method) and a code based on this map. The crucial figures of merit for such a system other than the final energy include the emittance (that determines the luminosity). The more complex the system is, the more opportunities the system has to degrade the emittance (or entropy of the beam). This the map guides one to identify where the crucial elements lie that affect the emittance. If the focusing force of the wakefield is strong when there is a jitter in the position (or laser aiming) of each stage coupled with the spread in the individual particle betatron frequencies, particles experience a phase space mixing. This effect sensitively controls the emittance degradation. They investigate these effects both in a uniform plasma and in a plasma channel. They also study the effect of beam loading. Further, they briefly consider collision point physics issues for a collider expected or characteristic of such a construction based on a scenario for the multi-staged wakefield accelerators.

  14. Measurements of high-energy radiation generation from laser-wakefield accelerated electron beams

    SciTech Connect

    Schumaker, W. Vargas, M.; Zhao, Z.; Behm, K.; Chvykov, V.; Hou, B.; Maksimchuk, A.; Nees, J.; Yanovsky, V.; Thomas, A. G. R.; Krushelnick, K.; Sarri, G.; Dromey, B.; Zepf, M.

    2014-05-15

    Using high-energy (∼0.5 GeV) electron beams generated by laser wakefield acceleration (LWFA), bremsstrahlung radiation was created by interacting these beams with various solid targets. Secondary processes generate high-energy electrons, positrons, and neutrons, which can be measured shot-to-shot using magnetic spectrometers, short half-life activation, and Compton scattering. Presented here are proof-of-principle results from a high-resolution, high-energy gamma-ray spectrometer capable of single-shot operation, and high repetition rate activation diagnostics. We describe the techniques used in these measurements and their potential applications in diagnosing LWFA electron beams and measuring high-energy radiation from laser-plasma interactions.

  15. Wakefield Propagation in Plasma Channels

    NASA Astrophysics Data System (ADS)

    Geddes, Cameron; Leemans, Wim; Esarey, Eric; Shadwick, Brad; Wurtele, Johnathan

    2000-10-01

    Characteristics of laser wakefields propagating in plasma channels have been studied at the l'OASIS laser facility at LBNL. Plasma channels are formed in gas jets using the ignitor-heater method[1], allowing control of channel geometry and profile. The channels are characterized by longitudinal and transverse interferometry, giving both radial and longitudinal profiles of the channel. High intensity (>5E17 W/cm^2, 50fs) pulses at 800nm are guided in these channels and are used to create plasma wakes in the channel. Laser propagation in the channel is characterized by output mode images and energies, and the wakes are profiled by longitudinal spectral interferometry. Measurements of channel and wake profiles, and studies of wake dependence on channel parameters will be presented. [1]P.Volfbeyn, E.Esarey, W.P. Leemans, Phys Plasmas 6, 2269 (1999)

  16. A New Type of Plasma Wakefield Accelerator Driven By Magnetowaves

    SciTech Connect

    Chen, Pisin; Chang, Feng-Yin; Lin, Guey-Lin; Noble, Robert J.; Sydora, Richard; /Alberta U.

    2011-09-12

    We present a new concept for a plasma wakefield accelerator driven by magnetowaves (MPWA). This concept was originally proposed as a viable mechanism for the 'cosmic accelerator' that would accelerate cosmic particles to ultra-high energies in the astrophysical setting. Unlike the more familiar plasma wakefield accelerator (PWFA) and the laser wakefield accelerator (LWFA) where the drivers, the charged-particle beam and the laser, are independently existing entities, MPWA invokes the high-frequency and high-speed whistler mode as the driver, which is a medium wave that cannot exist outside of the plasma. Aside from the difference in drivers, the underlying mechanism that excites the plasma wakefield via the ponderomotive potential is common. Our computer simulations show that under appropriate conditions, the plasma wakefield maintains very high coherence and can sustain high-gradient acceleration over many plasma wavelengths. We suggest that in addition to its celestial application, the MPWA concept can also be of terrestrial utility. A proof-of-principle experiment on MPWA would benefit both terrestrial and celestial accelerator concepts.

  17. Plasma Wakefield Experiments at FACET

    SciTech Connect

    Hogan, M.J.; England, R.J.; Frederico, J.; Hast, C.; Li, S.Z.; Litos, M.; Walz, D.; An, W.; Clayton, C.E.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.; Tochitsky, S.; Muggli, P.; Pinkerton, S.; Shi, Y.; /Southern California U.

    2011-08-19

    FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration beginning in summer 2011. The nominal FACET parameters are 23GeV, 3nC electron bunches compressed to {approx}20{micro}m long and focused to {approx}10{micro}m wide. The intense fields of the FACET bunches will be used to field ionize neutral lithium or cesium vapor produced in a heat pipe oven. Previous experiments at the SLAC FFTB facility demonstrated 50GeV/m gradients in an 85cm field ionized lithium plasma where the interaction distance was limited by head erosion. Simulations indicate the lower ionization potential of cesium will decrease the rate of head erosion and increase single stage performance. The initial experimental program will compare the performance of lithium and cesium plasma sources with single and double bunches. Later experiments will investigate improved performance with a pre-ionized cesium plasma. The status of the experiments and expected performance are reviewed. The FACET Facility is being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The facility will begin commissioning in summer 2011 and conduct an experimental program over the coming five years to study electron and positron beam driven plasma acceleration with strong wake loading in the non-linear regime. The FACET experiments aim to demonstrate high-gradient acceleration of electron and positron beams with high efficiency and negligible emittance growth.

  18. Demonstration of the hollow channel plasma wakefield accelerator

    SciTech Connect

    Gessner, Spencer J.

    2016-09-17

    A plasma wakefield accelerator is a device that converts the energy of a relativistic particle beam into a large-amplitude wave in a plasma. The plasma wave, or wakefield, supports an enormous electricfield that is used to accelerate a trailing particle beam. The plasma wakefield accelerator can therefore be used as a transformer, transferring energy from a high-charge, low-energy particle beam into a high-energy, low-charge particle beam. This technique may lead to a new generation of ultra-compact, high-energy particle accelerators. The past decade has seen enormous progress in the field of plasma wakefield acceleration with experimental demonstrations of the acceleration of electron beams by several gigaelectron-volts. The acceleration of positron beams in plasma is more challenging, but also necessary for the creation of a high-energy electron-positron collider. Part of the challenge is that the plasma responds asymmetrically to electrons and positrons, leading to increased disruption of the positron beam. One solution to this problem, first proposed over twenty years ago, is to use a hollow channel plasma which symmetrizes the response of the plasma to beams of positive and negative charge, making it possible to accelerate positrons in plasma without disruption. In this thesis, we describe the theory relevant to our experiment and derive new results when needed. We discuss the development and implementation of special optical devices used to create long plasma channels. We demonstrate for the first time the generation of meter-scale plasma channels and the acceleration of positron beams therein.

  19. Experimental plasma wake-field acceleration project*

    NASA Astrophysics Data System (ADS)

    Militsyn, B. L.; Bechtenev, A. A.; Breizman, B. N.; Chebotaev, P. Z.; Koop, I. A.; Kudryavtsev, A. M.; Panasyuk, V. M.; Shatunov, Yu. M.; Skrinsky, A. N.

    1993-07-01

    A new experiment on plasma wake-field acceleration has been designed at the Budker Institute of Nuclear Physics in Novosibirsk. An intense modulated driving beam from the electron-positron booster (BEP), a storage ring, will be used to excite a nonlinear plasma wave in a dense plasma (n=1015 cm-3). Important advantages of this beam are its very low emittance (10-8 cmṡrad in the vertical direction), high energy (850 MeV), and high intensity (1012 particles). A new technique for modulating this beam at a submillimeter wavelength is proposed. A simple numerical code has been developed to simulate the plasma wave excitation with plasma nonlinearity and with three-dimensional effects taken into account. The code allows the calculation of the radial structure of the nonlinear wake field including the focusing force which was mostly neglected in previous studies but which is especially important for experiment. The present numerical simulations show that, in the proposed experiment, a 1 GeV/m accelerating gradient over a macroscopic distance is attainable.

  20. Energy Measurement in a Plasma Wakefield Accelerator

    SciTech Connect

    Ischebeck, R

    2007-07-06

    In the E-167 plasma wakefield acceleration experiment, electrons with an initial energy of 42GeV are accelerated in a meter-scale lithium plasma. Particles are leaving plasma with a large energy spread. To determine the spectrum of the accelerated particles, a two-plane spectrometer has been set up.

  1. A Stable High-Energy Electron Source from Laser Wakefield Acceleration

    NASA Astrophysics Data System (ADS)

    Zhang, Ping; Zhao, Baozhen; Liu, Cheng; Yan, Wenchao; Golovin, Grigory; Banerjee, Sudeep; Chen, Shouyuan; Haden, Daniel; Fruhling, Colton; Umstadter, Donald

    2016-10-01

    The stability of the electron source from laser wake-field acceleration (LWFA) is essential for applications, such as novel x-ray sources and fundamental experiments in high field physics. To obtain such a stable source, we used an optimal laser pulse and a novel gas nozzle. The high-power laser pulse on target was focused to a diffraction-limited spot by the use of adaptive wavefront correction and the pulse duration was transform limited by the use of spectral feedback control. An innovative design for the nozzle led to a stable, flat-top profile with diameters of 4 mm and 8 mm with a high Mach-number ( 6). In experiments to generate high-energy electron beams by LWFA, we were able to obtain reproducible results with beam energy of 800 MeV and charge >10 pC. Higher charge but broader energy spectrum resulted when the plasma density was increased. These developments have resulted in a laser-driven wakefield accelerator that is stable and robust. With this device, we show that narrowband high-energy x-rays beams can be generated by the inverse-Compton scattering process. This accelerator has also been used in recent experiments to study nonlinear effects in the interaction of high-energy electron beams with ultraintense laser pulses. This material is based upon work supported by NSF No. PHY-153700; US DOE, Office of Science, BES, # DE-FG02-05ER15663; AFOSR # FA9550-11-1-0157; and DHS DNDO # HSHQDC-13-C-B0036.

  2. Proton driven plasma wakefield generation in a parabolic plasma channel

    NASA Astrophysics Data System (ADS)

    Golian, Y.; Dorranian, D.

    2016-11-01

    An analytical model for the interaction of charged particle beams and plasma for a wakefield generation in a parabolic plasma channel is presented. In the suggested model, the plasma density profile has a minimum value on the propagation axis. A Gaussian proton beam is employed to excite the plasma wakefield in the channel. While previous works investigated on the simulation results and on the perturbation techniques in case of laser wakefield accelerations for a parabolic channel, we have carried out an analytical model and solved the accelerating field equation for proton beam in a parabolic plasma channel. The solution is expressed by Whittaker (hypergeometric) functions. Effects of plasma channel radius, proton bunch parameters and plasma parameters on the accelerating processes of proton driven plasma wakefield acceleration are studied. Results show that the higher accelerating fields could be generated in the PWFA scheme with modest reductions in the bunch size. Also, the modest increment in plasma channel radius is needed to obtain maximum accelerating gradient. In addition, the simulations of longitudinal and total radial wakefield in parabolic plasma channel are presented using LCODE. It is observed that the longitudinal wakefield generated by the bunch decreases with the distance behind the bunch while total radial wakefield increases with the distance behind the bunch.

  3. Staging optics considerations for a plasma wakefield acceleration linear collider

    NASA Astrophysics Data System (ADS)

    Lindstrøm, C. A.; Adli, E.; Allen, J. M.; Delahaye, J. P.; Hogan, M. J.; Joshi, C.; Muggli, P.; Raubenheimer, T. O.; Yakimenko, V.

    2016-09-01

    Plasma wakefield acceleration offers acceleration gradients of several GeV/m, ideal for a next-generation linear collider. The beam optics requirements between plasma cells include injection and extraction of drive beams, matching the main beam beta functions into the next cell, canceling dispersion as well as constraining bunch lengthening and chromaticity. To maintain a high effective acceleration gradient, this must be accomplished in the shortest distance possible. A working example is presented, using novel methods to correct chromaticity, as well as scaling laws for a high energy regime.

  4. Laser wakefield signatures: from gas plasma to nanomaterials

    NASA Astrophysics Data System (ADS)

    Farinella, Deano; Zhang, Xiaomei; Shin, Youngmin; Tajima, Toshiki

    2016-10-01

    The signatures of laser wakefields have become increasingly important in recent years due to the invention of a novel laser compression technique that may enable the creation of single cycle x-ray pulses. This x-ray driver may be able to utilize solid density targets to create acceleration gradients of up to TeV/cm. On the other hand, Laser Wakefield Acceleration (LWFA) has been identified as a potential mechanism for the generation of Extreme High Energy Cosmic Rays (EHECR) in Active Galactic Nuclei (AGN). Though these disparate density regimes may include different physics, by investigating scalings of the ratio ncr/ne we are able to survey a wide range of parameters to gain insight into particle acceleration and photon emission properties. The scaling of electron acceleration and photon radiation from wakefields as a function of the parameter ncr/ne has been studied. Further, acceleration gradient as well as other scalings were investigated in solid density channels and compared to gas plasma. Funded in part by the Norman Rostoker Fund.

  5. E-157: A Plasma Wakefield Acceleration Experiment

    SciTech Connect

    Muggli, Patrick

    2000-10-20

    The E-157 plasma wakefield experiment addresses issues relevant to a meter long plasma accelerator module. In particular, a 1.4 m long plasma source has been developed for the experiment. The transverse dynamics of the beam in the plasma is studied: multiple betatron oscillations of the beam envelope, flipping of the beam tail, stability against the hose instability, emission of synchrotron radiation by the beam in the plasma. The bending of the 28.5 GeV beam at the plasma/vapor interface is observed for the first time. The longitudinal dynamics of the beam, i.e. the energy loss and gain by the electrons in the wake, is strongly affected by the oscillation of the beam tail instability.

  6. Short-pulse, high-energy radiation generation from laser-wakefield accelerated electron beams

    NASA Astrophysics Data System (ADS)

    Schumaker, Will

    2013-10-01

    Recent experimental results of laser wakefield acceleration (LWFA) of ~GeV electrons driven by the 200TW HERCULES and the 400TW ASTRA-GEMINI laser systems and their subsequent generation of photons, positrons, and neutrons are presented. In LWFA, high-intensity (I >1019 W /cm2), ultra-short (τL < 1 / (2 πωpe)) laser pulses drive highly nonlinear plasma waves which can trap ~ nC of electrons and accelerate them to ~GeV energies over ~cm lengths. These electron beams can then be converted by a high-Z target via bremsstrahlung into low-divergence (< 20 mrad) beams of high-energy (<600 MeV) photons and subsequently into positrons via the Bethe-Heitler process. By increasing the material thickness and Z, the resulting Ne+ /Ne- ratio can approach unity, resulting in a near neutral density plasma jet. These quasi-neutral beams are presumed to retain the short-pulse (τL < 40 fs) characteristic of the electron beam, resulting in a high peak density of ne- /e+ ~ 1016 cm-3 , making the source an excellent candidate for laboratory study of astrophysical leptonic jets. Alternatively, the electron beam can be interacted with a counter-propagating, ultra-high intensity (I >1021 W /cm2) laser pulse to undergo inverse Compton scattering and emit a high-peak brightness beam of high-energy photons. Preliminary results and experimental sensitivities of the electron-laser beam overlap are presented. The high-energy photon beams can be spectrally resolved using a forward Compton scattering spectrometer. Moreover, the photon flux can be characterized by a pixelated scintillator array and by nuclear activation and (γ,n) neutron measurements from the photons interacting with a secondary solid target. Monte-Carlo simulations were performed using FLUKA to support the yield estimates. This research was supported by DOE/NSF-PHY 0810979, NSF CAREER 1054164, DARPA AXiS N66001-11-1-4208, SF/DNDO F021166, and the Leverhulme Trust ECF-2011-383.

  7. Developing high energy, stable laser wakefield accelerators: particle simulations and experiments

    NASA Astrophysics Data System (ADS)

    Geddes, Cameron

    2006-10-01

    Laser driven wakefield accelerators produce accelerating fields thousands of times those achievable in conventional radiofrequency accelerators, and recent experiments have produced high energy electron bunches with low emittance and energy spread. Challenges now include control and reproducibility of the electron beam, further improvements in energy spread, and scaling to higher energies. We present large-scale particle in cell simulations together with recent experiments towards these goals. In LBNL experiments the relativistically intense drive pulse was guided over more than 10 diffraction ranges by plasma channels. Guiding beyond the diffraction range improved efficiency by allowing use of a smaller laser spot size (and hence higher intensities) over long propagation distances. At a drive pulse power of 9 TW, electrons were trapped from the plasma and beams of percent energy spread containing > 200pC charge above 80 MeV with normalized emittance estimated at < 2 π-mm-mrad were produced. Energies have now been scaled to 1 GeV using 40 TW of laser power. Particle simulations and data showed that the high quality bunch in recent experiments was formed when beam loading turned off injection after initial self trapping, creating a bunch of electrons isolated in phase space. A narrow energy spread beam was then obtained by extracting the bunch as it outran the accelerating phase of the wake. Large scale simulations coupled with experiments are now under way to better understand the optimization of such accelerators including production of reproducible electron beams and scaling to energies beyond a GeV. Numerical resolution and two and three dimensional effects are discussed as well as diagnostics for application of the simulations to experiments. Effects including injection and beam dynamics as well as pump laser depletion and reshaping will be described, with application to design of future experiments. Supported by DOE grant DE-AC02-05CH11231 and by an INCITE

  8. Excitation of wakefields in a relativistically hot plasma created by dying non-linear plasma wakefields

    SciTech Connect

    Sahai, A. A.; Katsouleas, T. C.; Gessner, S.; Hogan, M.; Joshi, C.; Mori, W. B.

    2012-12-21

    We study the various physical processes and their timescales involved in the excitation of wakefields in relativistically hot plasma. This has relevance to the design of a high repetition-rate plasma wakefield collider in which the plasma has not had time to cool between bunches in addition to understanding the physics of cosmic jets in relativistically hot astrophysical plasmas. When the plasma is relativistically hot (plasma temperature near m{sub e}c{sup 2}), the thermal pressure competes with the restoring force of ion space charge and can reduce or even eliminate the accelerating field of a wake. We will investigate explicitly the case where the hot plasma is created by a preceding Wakefield drive bunch 10's of picoseconds to many nanoseconds ahead of the next drive bunch. The relativistically hot plasma is created when the excess energy (not coupled to the driven e{sup -} bunch) in the wake driven by the drive e{sup -} bunch is eventually converted into thermal energy on 10's of picosecond timescale. We will investigate the thermalization and diffusion processes of this non-equilibrium plasma on longer time scales, including the effects of ambi-polar diffusion of ions driven by hot electron expansion, possible Columbic explosion of ions producing higher ionization states and ionization of surrounding neutral atoms via collisions with hot electrons. Preliminary results of the transverse and longitudinal wakefields at different timescales of separation between a first and second bunch are presented and a possible experiment to study this topic at the FACET facility is described.

  9. Physics of beam self-modulation in plasma wakefield accelerators

    SciTech Connect

    Lotov, K. V.

    2015-10-15

    The self-modulation instability is a key effect that makes possible the usage of nowadays proton beams as drivers for plasma wakefield acceleration. Development of the instability in uniform plasmas and in plasmas with a small density up-step is numerically studied with the focus at nonlinear stages of beam evolution. The step parameters providing the strongest established wakefield are found, and the mechanism of stable bunch train formation is identified.

  10. High Energy Plasma Space Propulsion

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    2000-01-01

    In order to meet NASA's challenge on advanced concept activity in the propulsion area, we initiated a new program entitled "High Energy Plasma Space Propulsion Studies" within the current cooperative agreement in 1998. The goals of this work are to gain further understanding of the engine of the AIMStar spacecraft, a concept which was developed at Penn State University, and to develop a prototype concept for the engine. The AIMStar engine concept was developed at Penn State University several years ago as a hybrid between antimatter and fusion technologies. Because of limited amounts of antimatter available, and concurrently the demonstrated ability for antiprotons to efficiently ignite nuclear fusion reactions, it was felt that this was a very good match. Investigations have been made concerning the performance of the reaction trap. This is a small Penning-like electromagnetic trap, which is used to simultaneously confine antiprotons and fusion fuels. Small DHe3 or DT droplets, containing a few percent molar of a fissile material, are injected into the trap, filled with antiprotons. We have found that it is important to separate the antiprotons into two adjacent wells, to inject he droplet between them and to simultaneously bring the antiprotons to the center of the trap, surrounding the droplet. Our previous concept had the droplet falling onto one cloud of antiprotons. This proved to be inefficient, as the droplet tended to evaporate away from the cloud as it interacted on its surface.

  11. Synchrotron radiation from a curved plasma channel laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Palastro, J. P.; Kaganovich, D.; Hafizi, B.; Chen, Y.-H.; Johnson, L. A.; Peñano, J. R.; Helle, M. H.; Mamonau, A. A.

    2017-03-01

    A laser pulse guided in a curved plasma channel can excite wakefields that steer electrons along an arched trajectory. As the electrons are accelerated along the curved channel, they emit synchrotron radiation. We present simple analytical models and simulations examining laser pulse guiding, wakefield generation, electron steering, and synchrotron emission in curved plasma channels. For experimentally realizable parameters, a ˜2 GeV electron emits 0.1 photons per cm with an average photon energy of multiple keV.

  12. Theory and measurements of emittance preservation in plasma wakefield acceleration

    SciTech Connect

    Frederico, Joel

    2016-12-01

    In this dissertation, we examine the preservation and measurement of emittance in the plasma wakefield acceleration blowout regime. Plasma wakefield acceleration (PWFA) is a revolutionary approach to accelerating charged particles that has been demonstrated to have the potential for gradients orders of magnitude greater than traditional approaches. The application of PWFA to the design of a linear collider will make new high energy physics research possible, but the design parameters must first be shown to be competitive with traditional methods. Emittance preservation is necessary in the design of a linear collider in order to maximize luminosity. We examine the conditions necessary for circular symmetry in the PWFA blowout regime, and demonstrate that current proposals meet these bounds. We also present an application of beam lamentation which describes the process of beam parameter and emittance matching. We show that the emittance growth saturates as a consequence of energy spread in the beam. The initial beam parameters determine the amount of emittance growth, while the contribution of energy spread is negligible. We also present a model for ion motion in the presence of a beam that is much more dense than the plasma. By combining the model of ion motion and emittance growth, we find the emittance growth due to ion motion is minimal in the case of marginal ion motion. In addition, we present a simulation that validates the ion motion model, which is under further development to examine emittance growth of both marginal and pronounced ion motion. Finally, we present a proof-of-concept of an emittance measurement which may enable the analysis of emittance preservation in future PWFA experiments.

  13. Radial equilibrium of relativistic particle bunches in plasma wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Lotov, K. V.

    2017-02-01

    Drive particle beams in linear or weakly nonlinear regimes of the plasma wakefield accelerator quickly reach a radial equilibrium with the wakefield, which is described in detail for the first time. The equilibrium beam state and self-consistent wakefields are obtained by combining analytical relationships, numerical integration, and first-principles simulations. In the equilibrium state, the beam density is strongly peaked near the axis, the beam radius is constant along most of the beam, and longitudinal variation of the focusing strength is balanced by varying beam emittance. The transverse momentum distribution of beam particles depends on the observation radius and is neither separable nor Gaussian.

  14. Hot spots and dark current in advanced plasma wakefield accelerators

    DOE PAGES

    Manahan, G. G.; Deng, A.; Karger, O.; ...

    2016-01-29

    Dark current can spoil witness bunch beam quality and acceleration efficiency in particle beam-driven plasma wakefield accelerators. In advanced schemes, hot spots generated by the drive beam or the wakefield can release electrons from higher ionization threshold levels in the plasma media. Likewise, these electrons may be trapped inside the plasma wake and will then accumulate dark current, which is generally detrimental for a clear and unspoiled plasma acceleration process. The strategies for generating clean and robust, dark current free plasma wake cavities are devised and analyzed, and crucial aspects for experimental realization of such optimized scenarios are discussed.

  15. Hot spots and dark current in advanced plasma wakefield accelerators

    DOE PAGES

    Manahan, G.; Deng, A.; Karger, O.; ...

    2016-01-01

    Dark current can spoil witness bunch beam quality and acceleration efficiency in particle beam-driven plasma wakefield accelerators. In advanced schemes, hot spots generated by the drive beam or the wakefield can release electrons from higher ionization threshold levels in the plasma media. These electrons may be trapped inside the plasma wake and will then accumulate dark current, which is generally detrimental for a clear and unspoiled plasma acceleration process. Strategies for generating clean and robust, dark current free plasma wake cavities are devised and analyzed, and crucial aspects for experimental realization of such optimized scenarios are discussed.

  16. Excitation and Control of Plasma Wakefields by Multiple Laser Pulses

    NASA Astrophysics Data System (ADS)

    Cowley, J.; Thornton, C.; Arran, C.; Shalloo, R. J.; Corner, L.; Cheung, G.; Gregory, C. D.; Mangles, S. P. D.; Matlis, N. H.; Symes, D. R.; Walczak, R.; Hooker, S. M.

    2017-07-01

    We demonstrate experimentally the resonant excitation of plasma waves by trains of laser pulses. We also take an important first step to achieving an energy recovery plasma accelerator by showing that a plasma wave can be damped by an out-of-resonance trailing laser pulse. The measured laser wakefields are found to be in excellent agreement with analytical and numerical models of wakefield excitation in the linear regime. Our results indicate a promising direction for achieving highly controlled, GeV-scale laser-plasma accelerators operating at multikilohertz repetition rates.

  17. Modeling High Energy Density Plasmas

    NASA Astrophysics Data System (ADS)

    Albritton, J. R.; Liberman, D. A.; Wilson, B. G.

    1999-11-01

    Ultra-short-pulse lasers are being used to form plasmas at near normal/solid density, heating a target in a time shorter than that on which it can expand. Radiative signatures of the dense plasma conditions are a key diagnostic, and typically require the support of modeling for their design and interpretation. Modeling also often serves to guide the experimental program of work. Here we report on our first attempts to use the INFERNO average-atom atomic model to a construct detailed-configuration-accounting description of the plasma equation-of-state, that is, its distribution of ionization and excitation states, and further, its radiative line, edge, and continuum features.

  18. Electron trapping and acceleration by the plasma wakefield of a self-modulating proton beam

    SciTech Connect

    Lotov, K. V.; Sosedkin, A. P.; Petrenko, A. V.; Amorim, L. D.; Vieira, J.; Fonseca, R. A.; Silva, L. O.; Gschwendtner, E.; Muggli, P.

    2014-12-15

    It is shown that co-linear injection of electrons or positrons into the wakefield of the self-modulating particle beam is possible and ensures high energy gain. The witness beam must co-propagate with the tail part of the driver, since the plasma wave phase velocity there can exceed the light velocity, which is necessary for efficient acceleration. If the witness beam is many wakefield periods long, then the trapped charge is limited by beam loading effects. The initial trapping is better for positrons, but at the acceleration stage a considerable fraction of positrons is lost from the wave. For efficient trapping of electrons, the plasma boundary must be sharp, with the density transition region shorter than several centimeters. Positrons are not susceptible to the initial plasma density gradient.

  19. Emission of strong Terahertz pulses from laser wakefields in weakly coupled plasma

    NASA Astrophysics Data System (ADS)

    Singh, Divya; Malik, Hitendra K.

    2016-09-01

    The present paper discusses the laser plasma interaction for the wakefield excitation and the role of external magnetic field for the emission of Terahertz radiation in a collisional plasma. Flat top lasers are shown to be more appropriate than the conventional Gaussian lasers for the effective excitation of wakefields and hence, the generation of strong Terahertz radiation through the transverse component of wakefield.

  20. High-energy laser plasma diagnostic system

    NASA Astrophysics Data System (ADS)

    Zhao, Mingjun M.; Aye, Tin M.; Fruehauf, Norbert; Savant, Gajendra D.; Erwin, Daniel A.; Smoot, Brayton E.; Loose, Richard W.

    2000-07-01

    This paper describes the development of a non-contact diagnosis system for analyzing the plasma density profile, temperature profile, and ionic species of a high energy laser-generated plasma. The system was developed by Physical Optics Corporation in cooperation with the U.S. Army Space and Missile Defense Command, High Energy Laser Systems Test Facility at White Sands Missile Range, New Mexico. The non- contact diagnostic system consists of three subsystems: an optical fiber-based interferometer, a plasma spectrometer, and a genetic algorithm-based fringe-image processor. In the interferometer subsystem, the transmitter and the receiver are each packaged as a compact module. A narrow notch filter rejects strong plasma light, passing only the laser probing beam, which carries the plasma density information. The plasma spectrum signal is collected by an optical fiber head, which is connected to a compact spectrometer. Real- time genetic algorithm-based data processing/display permits instantaneous analysis of the plasma characteristics. The research effort included design and fabrication of a vacuum chamber, and high-energy laser plasma generation. Compactness, real-time operation, and ease of use make the laser plasma diagnosis system well suited for dual use applications such as diagnosis of electric arc and other industrial plasmas.

  1. Energy Measurements of Trapped Electrons from a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, Neil; Berry, Melissa; Blumenfeld, Ian; Decker, Franz-Josef; Hogan, Mark J.; Ischebeck, Rasmus; Iverson, Richard; Siemann, Robert H.; Walz, Dieter; Auerbach, David; Clayton, Christopher E.; Huang, Chengkun; Johnson, Devon; Joshi, Chandrashekhar; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; Zhou, Miaomiao; Katsouleas, Thomas; Muggli, Patric

    2006-11-27

    Recent electron beam driven plasma wakefield accelerator experiments carried out at SLAC indicate trapping of plasma electrons. More charge came out of than went into the plasma. Most of this extra charge had energies at or below the 10 MeV level. In addition, there were trapped electron streaks that extended from a few GeV to tens of GeV, and there were mono-energetic trapped electron bunches with tens of GeV in energy.

  2. Energy Measurements of Trapped Electrons from a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, Neal; Auerbach, David; Berry, Melissa; Blumenfeld, Ian; Clayton, Christopher E.; Decer, Franz-Josef; Hogan, Mark J.; Huang, Chengkun; Ischebeck, Rasmus; Iverson, Richard; Johnson, Devon; Joshi, Chadrashekhar; Katsouleas, Thomas; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; Muggli, Patric; Oz, Erdem; Siemann, Robert H.; Walz, Dieter; Zhou, Miaomiao; /SLAC /UCLA /Southern California U.

    2007-01-03

    Recent electron beam driven plasma wakefield accelerator experiments carried out at SLAC indicate trapping of plasma electrons. More charge came out of than went into the plasma. Most of this extra charge had energies at or below the 10 MeV level. In addition, there were trapped electron streaks that extended from a few GeV to tens of GeV, and there were mono-energetic trapped electron bunches with tens of GeV in energy.

  3. Probing plasma wakefield using femtosecond relativistic electron bunches (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Lu, Wei; Hua, Jianfei

    2017-05-01

    Light-speed moving wakefield structure in a laser plasma accelerator is directly observed and quantitatively reconstructed using an ultrashort relativistic electron probe in a single shot. The stable electron probes utilized here are directly generated through laser wakefield acceleration via ionization injection. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. From the density image of the probe, the local plasma wavelength, the wake width and the electric field in linear wakes can be accurately calculated, leading to the first observation of plasma wakes at the density as low as 1017 cm-3. Furthermore, detailed features of multiple wakes excited by a laser with the aberrated profile are observed and confirmed by 3D PIC simulations. By varying the time delay between the driving laser and the probe, time-resolved observation of the wake evolution (excitation, propagation, and damping) can be readily obtained, and this suggests that ultrafast electron probe can be a powerful new tool for the study of wakefield acceleration. The method is particularly well suited for visualizing linear wakefields that can accelerate both electrons and positrons as well as collective fields associated with shocks and instabilities in plasmas and warm dense matter.

  4. Properties of Trapped Electron Bunches in a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, Neil; /SLAC

    2009-10-30

    Plasma-based accelerators use the propagation of a drive bunch through plasma to create large electric fields. Recent plasma wakefield accelerator (PWFA) experiments, carried out at the Stanford Linear Accelerator Center (SLAC), successfully doubled the energy for some of the 42 GeV drive bunch electrons in less than a meter; this feat would have required 3 km in the SLAC linac. This dissertation covers one phenomenon associated with the PWFA, electron trapping. Recently it was shown that PWFAs, operated in the nonlinear bubble regime, can trap electrons that are released by ionization inside the plasma wake and accelerate them to high energies. These trapped electrons occupy and can degrade the accelerating portion of the plasma wake, so it is important to understand their origins and how to remove them. Here, the onset of electron trapping is connected to the drive bunch properties. Additionally, the trapped electron bunches are observed with normalized transverse emittance divided by peak current, {epsilon}{sub N,x}/I{sub t}, below the level of 0.2 {micro}m/kA. A theoretical model of the trapped electron emittance, developed here, indicates that the emittance scales inversely with the square root of the plasma density in the non-linear 'bubble' regime of the PWFA. This model and simulations indicate that the observed values of {epsilon}{sub N,x}/I{sub t} result from multi-GeV trapped electron bunches with emittances of a few {micro}m and multi-kA peak currents. These properties make the trapped electrons a possible particle source for next generation light sources. This dissertation is organized as follows. The first chapter is an overview of the PWFA, which includes a review of the accelerating and focusing fields and a survey of the remaining issues for a plasma-based particle collider. Then, the second chapter examines the physics of electron trapping in the PWFA. The third chapter uses theory and simulations to analyze the properties of the trapped electron

  5. Femtosecond Probing of Plasma Wakefields and Observation of the Plasma Wake Reversal Using a Relativistic Electron Bunch

    NASA Astrophysics Data System (ADS)

    Zhang, C. J.; Hua, J. F.; Wan, Y.; Pai, C.-H.; Guo, B.; Zhang, J.; Ma, Y.; Li, F.; Wu, Y. P.; Chu, H.-H.; Gu, Y. Q.; Xu, X. L.; Mori, W. B.; Joshi, C.; Wang, J.; Lu, W.

    2017-08-01

    We show that a high-energy electron bunch can be used to capture the instantaneous longitudinal and transverse field structures of the highly transient, microscopic, laser-excited relativistic wake with femtosecond resolution. The spatiotemporal evolution of wakefields in a plasma density up ramp is measured and the reversal of the plasma wake, where the wake wavelength at a particular point in space increases until the wake disappears completely only to reappear at a later time but propagating in the opposite direction, is observed for the first time by using this new technique.

  6. High-efficiency acceleration of an electron beam in a plasma wakefield accelerator.

    PubMed

    Litos, M; Adli, E; An, W; Clarke, C I; Clayton, C E; Corde, S; Delahaye, J P; England, R J; Fisher, A S; Frederico, J; Gessner, S; Green, S Z; Hogan, M J; Joshi, C; Lu, W; Marsh, K A; Mori, W B; Muggli, P; Vafaei-Najafabadi, N; Walz, D; White, G; Wu, Z; Yakimenko, V; Yocky, G

    2014-11-06

    High-efficiency acceleration of charged particle beams at high gradients of energy gain per unit length is necessary to achieve an affordable and compact high-energy collider. The plasma wakefield accelerator is one concept being developed for this purpose. In plasma wakefield acceleration, a charge-density wake with high accelerating fields is driven by the passage of an ultra-relativistic bunch of charged particles (the drive bunch) through a plasma. If a second bunch of relativistic electrons (the trailing bunch) with sufficient charge follows in the wake of the drive bunch at an appropriate distance, it can be efficiently accelerated to high energy. Previous experiments using just a single 42-gigaelectronvolt drive bunch have accelerated electrons with a continuous energy spectrum and a maximum energy of up to 85 gigaelectronvolts from the tail of the same bunch in less than a metre of plasma. However, the total charge of these accelerated electrons was insufficient to extract a substantial amount of energy from the wake. Here we report high-efficiency acceleration of a discrete trailing bunch of electrons that contains sufficient charge to extract a substantial amount of energy from the high-gradient, nonlinear plasma wakefield accelerator. Specifically, we show the acceleration of about 74 picocoulombs of charge contained in the core of the trailing bunch in an accelerating gradient of about 4.4 gigavolts per metre. These core particles gain about 1.6 gigaelectronvolts of energy per particle, with a final energy spread as low as 0.7 per cent (2.0 per cent on average), and an energy-transfer efficiency from the wake to the bunch that can exceed 30 per cent (17.7 per cent on average). This acceleration of a distinct bunch of electrons containing a substantial charge and having a small energy spread with both a high accelerating gradient and a high energy-transfer efficiency represents a milestone in the development of plasma wakefield acceleration into a

  7. Whittaker functions in beam driven plasma wakefield acceleration for a plasma with a parabolic density profile

    SciTech Connect

    Golian, Y.; Dorranian, D.; Aslaninejad, M.

    2016-01-15

    A model for the interaction of charged particle beams and plasma for a linear wakefield generation in a parabolic plasma channel is presented. The density profile has the maximum on the axis. A Gaussian proton beam is employed to excite the plasma wakefield in the channel. We have built a thorough analytical model and solved the governing equations for the wakefield acceleration of a charged particle beam. The longitudinal and radial wakefields are expressed by Whittaker functions, and for certain parameters of plasma and the beam, their behaviours in longitudinal and radial directions are investigated. It is observed that the radial electric field generated by the bunch increases with the distance behind the bunch.

  8. Resonant Plasma Wakefield Experiment: Plasma Simulations and Multibunched Electron Beam Diagnostics

    NASA Astrophysics Data System (ADS)

    Kallos, Efthymios; Muggli, Patric; Katsouleas, Thomas; Yakimenko, Vitaly; Stolyarov, Daniil; Pogorelsky, Igor; Pavlishin, Igor; Kusche, Karl; Babzien, Marcus; Ben-Zvi, Ilan; Kimura, Wayne D.

    2006-11-01

    In the multibunch plasma wakefield acceleration experiment at the Brookhaven National Lab's Accelerator Test Facility a 45 MeV electron beam is initially modulated through the IFEL interaction with a CO2 laser beam at 10.6 μm into a train of short microbunches, which are spaced at the laser wavelength. It is then fed into a high-density capillary plasma with a density resonant at this spacing (1.0 × 1019cm-3). The microbunched beam can resonantly excite a plasma wakefield much larger than the wakefield excited from the non-bunched beam. Here we present plasma simulations that confirm the wakefield enhancement and the results of a series of CTR measurements performed of the multibunched electron beam.

  9. Measurement of the Decelerating Wake in a Plasma Wakefield Accelerator

    SciTech Connect

    Blumenfeld, I.; Decker, F. J.; Hogan, M. J.; Ischebeck, R.; Iverson, R. H.; Kirby, N.; Siemann, R. H.; Walz, D. R.; Clayton, C. E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W. B.; Zhou, M.; Katsouleas, T.; Muggli, P.; Oz, E.

    2009-01-22

    Recent experiments at SLAC have shown that high gradient acceleration of electrons is achievable in meter scale plasmas. Results from these experiments show that the wakefield is sensitive to parameters in the electron beam which drives it. In the experiment the bunch lengths were varied systematically at constant charge. The effort to extract a measurement of the decelerating wake from the maximum energy loss of the electron beam is discussed.

  10. Modulation of continuous electron beams in plasma wake-fields

    SciTech Connect

    Rosenzweig, J.B.

    1988-09-08

    In this paper we discuss the interaction of a continuous electron beam with wake-field generated plasma waves. Using a one-dimensional two fluid model, a fully nonlinear analytical description of the interaction is obtained. The phenomena of continuous beam modulation and wave period shortening are discussed. The relationship between these effects and the two-stream instability is also examined. 12 refs., 1 fig.

  11. Mesurement of the Decelerating Wake in a Plasma Wakefield Accelerator

    SciTech Connect

    Blumenfeld, I; Clayton, C.E.; Decker, F.J.; Hogan, M.J.; Huang, C.; Ischebeck, R.; Iverson, R.H.; Joshi, C.; Katsouleas, T.; Kirby, N.; Lu, W.; Marsh, K.A.; Mori, W.B.; Muggli, P; Oz, E.; Siemann, R.H.; Walz, D.R.; Zhou, M.; /SLAC /UCLA /USC

    2008-09-24

    Recent experiments at SLAC have shown that high gradient acceleration of electrons is achievable in meter scale plasmas. Results from these experiments show that the wakefield is sensitive to parameters in the electron beam which drives it. In the experiment the bunch lengths were varied systematically at constant charge. The effort to extract a measurement of the decelerating wake from the maximum energy loss of the electron beam is discussed.

  12. Parameter sensitivity of plasma wakefields driven by self-modulating proton beams

    SciTech Connect

    Lotov, K. V.; Minakov, V. A.; Sosedkin, A. P.

    2014-08-15

    The dependence of wakefield amplitude and phase on beam and plasma parameters is studied in the parameter area of interest for self-modulating proton beam-driven plasma wakefield acceleration. The wakefield phase is shown to be extremely sensitive to small variations of the plasma density, while sensitivity to small variations of other parameters is reasonably low. The study of large parameter variations clarifies the effects that limit the achievable accelerating field in different parts of the parameter space: nonlinear elongation of the wakefield period, insufficient charge of the drive beam, emittance-driven beam divergence, and motion of plasma ions.

  13. Summary Report of Working Group 4: Plasma Wakefield Acceleration

    SciTech Connect

    Rosenzweig, J.B.; Seryi, A.; /SLAC

    2012-06-11

    This report gives a guide to the discussions of Working Group 4 of the 2010 Advanced Accelerator Concepts Workshop, which was devoted to theory, simulation and experimental issues associated with plasma wakefield acceleration (PWFA). Sessions were organized thematically in this group, concentrating on broad issues of: exploitation of future facilities such as FACET; pushing the accelerating gradient beyond the current frontier, to over a TeV/m; use of positively charged beams to drive plasma wakes; resonant excitation of the PWFA with pulse trains; beam-plasma instabilities; and injection and capture of electron beams into PWFA systems.

  14. The status and evolution of plasma Wakefield particle accelerators.

    PubMed

    Joshi, C; Mori, W B

    2006-03-15

    The status and evolution of the electron beam-driven Plasma Wakefield Acceleration scheme is described. In particular, the effects of the radial electric field of the wake on the drive beam such as multiple envelope oscillations, hosing instability and emission of betatron radiation are described. Using ultra-short electron bunches, high-density plasmas can be produced by field ionization by the electric field of the bunch itself. Wakes excited in such plasmas have accelerated electrons in the back of the drive beam to greater that 4 G eV in just 10 cm in experiments carried out at the Stanford Linear Accelerator Centre.

  15. Optical Frequency Domain Visualization of Electron Beam Driven Plasma Wakefields

    NASA Astrophysics Data System (ADS)

    Zgadzaj, Rafal; Downer, M. C.; Muggli, Patric; Yakimenko, Vitaly; Babzien, Marcus; Kusche, Karl; Fedurin, Mikhail

    2010-11-01

    Beam-driven plasma wakefield accelerators (PWFA), such as the ``plasma afterburner,'' are a promising approach for significantly increasing the particle energies of conventional accelerators. The study and optimization of PWFA would benefit from an experimental correlation between the parameters of the drive bunch, the accelerated bunch and the corresponding, accelerating plasma wave structure. However, the plasma wave structure has not yet been observed directly in PWFA. We will report our current work on noninvasive optical Frequency Domain Interferometric (FDI) and Holographic (FDH) visualization of beam-driven plasma waves. Both techniques employ two laser pulses (probe and reference) co-propagating with the particle drive-beam and its plasma wake. The reference pulse precedes the drive bunch, while the probe overlaps the plasma wave and maps its longitudinal and transverse structure. The experiment is being developed at the BNL/ATF Linac to visualize wakes generated by two and multi-bunch drive beams.

  16. High-Brightness High-Energy Electron Beams from a Laser Wakefield Accelerator via Energy Chirp Control

    NASA Astrophysics Data System (ADS)

    Wang, W. T.; Li, W. T.; Liu, J. S.; Zhang, Z. J.; Qi, R.; Yu, C. H.; Liu, J. Q.; Fang, M.; Qin, Z. Y.; Wang, C.; Xu, Y.; Wu, F. X.; Leng, Y. X.; Li, R. X.; Xu, Z. Z.

    2016-09-01

    By designing a structured gas density profile between the dual-stage gas jets to manipulate electron seeding and energy chirp reversal for compressing the energy spread, we have experimentally produced high-brightness high-energy electron beams from a cascaded laser wakefield accelerator with peak energies in the range of 200-600 MeV, 0.4%-1.2% rms energy spread, 10-80 pC charge, and ˜0.2 mrad rms divergence. The maximum six-dimensional brightness B6 D ,n is estimated as ˜6.5 ×1 015 A /m2/0.1 % , which is very close to the typical brightness of e beams from state-of-the-art linac drivers. These high-brightness high-energy e beams may lead to the realization of compact monoenergetic gamma-ray and intense coherent x-ray radiation sources.

  17. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question.

    PubMed

    Yang, X; Brunetti, E; Gil, D Reboredo; Welsh, G H; Li, F Y; Cipiccia, S; Ersfeld, B; Grant, D W; Grant, P A; Islam, M R; Tooley, M P; Vieux, G; Wiggins, S M; Sheng, Z M; Jaroszynski, D A

    2017-03-10

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5-10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°-60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators.

  18. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question

    PubMed Central

    Yang, X.; Brunetti, E.; Gil, D. Reboredo; Welsh, G. H.; Li, F. Y.; Cipiccia, S.; Ersfeld, B.; Grant, D. W.; Grant, P. A.; Islam, M. R.; Tooley, M. P.; Vieux, G.; Wiggins, S. M.; Sheng, Z. M.; Jaroszynski, D. A.

    2017-01-01

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5–10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°–60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators. PMID:28281679

  19. Three electron beams from a laser-plasma wakefield accelerator and the energy apportioning question

    NASA Astrophysics Data System (ADS)

    Yang, X.; Brunetti, E.; Gil, D. Reboredo; Welsh, G. H.; Li, F. Y.; Cipiccia, S.; Ersfeld, B.; Grant, D. W.; Grant, P. A.; Islam, M. R.; Tooley, M. P.; Vieux, G.; Wiggins, S. M.; Sheng, Z. M.; Jaroszynski, D. A.

    2017-03-01

    Laser-wakefield accelerators are compact devices capable of delivering ultra-short electron bunches with pC-level charge and MeV-GeV energy by exploiting the ultra-high electric fields arising from the interaction of intense laser pulses with plasma. We show experimentally and through numerical simulations that a high-energy electron beam is produced simultaneously with two stable lower-energy beams that are ejected in oblique and counter-propagating directions, typically carrying off 5-10% of the initial laser energy. A MeV, 10s nC oblique beam is ejected in a 30°-60° hollow cone, which is filled with more energetic electrons determined by the injection dynamics. A nC-level, 100s keV backward-directed beam is mainly produced at the leading edge of the plasma column. We discuss the apportioning of absorbed laser energy amongst the three beams. Knowledge of the distribution of laser energy and electron beam charge, which determine the overall efficiency, is important for various applications of laser-wakefield accelerators, including the development of staged high-energy accelerators.

  20. Plasma Wakefield Acceleration of an Intense Positron Beam

    SciTech Connect

    Blue, B

    2004-04-21

    The Plasma Wakefield Accelerator (PWFA) is an advanced accelerator concept which possess a high acceleration gradient and a long interaction length for accelerating both electrons and positrons. Although electron beam-plasma interactions have been extensively studied in connection with the PWFA, very little work has been done with respect to positron beam-plasma interactions. This dissertation addresses three issues relating to a positron beam driven plasma wakefield accelerator. These issues are (a) the suitability of employing a positron drive bunch to excite a wake; (b) the transverse stability of the drive bunch; and (c) the acceleration of positrons by the plasma wake that is driven by a positron bunch. These three issues are explored first through computer simulations and then through experiments. First, a theory is developed on the impulse response of plasma to a short drive beam which is valid for small perturbations to the plasma density. This is followed up with several particle-in-cell (PIC) simulations which study the experimental parameter (bunch length, charge, radius, and plasma density) range. Next, the experimental setup is described with an emphasis on the equipment used to measure the longitudinal energy variations of the positron beam. Then, the transverse dynamics of a positron beam in a plasma are described. Special attention is given to the way focusing, defocusing, and a tilted beam would appear to be energy variations as viewed on our diagnostics. Finally, the energy dynamics imparted on a 730 {micro}m long, 40 {micro}m radius, 28.5 GeV positron beam with 1.2 x 10{sup 10} particles in a 1.4 meter long 0-2 x 10{sup 14} e{sup -}/cm{sup 3} plasma is described. First the energy loss was measured as a function of plasma density and the measurements are compared to theory. Then, an energy gain of 79 {+-} 15 MeV is shown. This is the first demonstration of energy gain of a positron beam in a plasma and it is in good agreement with the predictions

  1. Application of Plasma Waveguides to High Energy Accelerators

    SciTech Connect

    Milchberg, Howard M

    2013-03-30

    The eventual success of laser-plasma based acceleration schemes for high-energy particle physics will require the focusing and stable guiding of short intense laser pulses in reproducible plasma channels. For this goal to be realized, many scientific issues need to be addressed. These issues include an understanding of the basic physics of, and an exploration of various schemes for, plasma channel formation. In addition, the coupling of intense laser pulses to these channels and the stable propagation of pulses in the channels require study. Finally, new theoretical and computational tools need to be developed to aid in the design and analysis of experiments and future accelerators. Here we propose a 3-year renewal of our combined theoretical and experimental program on the applications of plasma waveguides to high-energy accelerators. During the past grant period we have made a number of significant advances in the science of laser-plasma based acceleration. We pioneered the development of clustered gases as a new highly efficient medium for plasma channel formation. Our contributions here include theoretical and experimental studies of the physics of cluster ionization, heating, explosion, and channel formation. We have demonstrated for the first time the generation of and guiding in a corrugated plasma waveguide. The fine structure demonstrated in these guides is only possible with cluster jet heating by lasers. The corrugated guide is a slow wave structure operable at arbitrarily high laser intensities, allowing direct laser acceleration, a process we have explored in detail with simulations. The development of these guides opens the possibility of direct laser acceleration, a true miniature analogue of the SLAC RF-based accelerator. Our theoretical studies during this period have also contributed to the further development of the simulation codes, Wake and QuickPIC, which can be used for both laser driven and beam driven plasma based acceleration schemes. We

  2. Beyond injection: Trojan horse underdense photocathode plasma wakefield acceleration

    SciTech Connect

    Hidding, B.; Rosenzweig, J. B.; Xi, Y.; O'Shea, B.; Andonian, G.; Schiller, D.; Barber, S.; Williams, O.; Pretzler, G.; Koenigstein, T.; Kleeschulte, F.; Hogan, M. J.; Litos, M.; Corde, S.; White, W. W.; Muggli, P.; Bruhwiler, D. L.; Lotov, K.

    2012-12-21

    An overview on the underlying principles of the hybrid plasma wakefield acceleration scheme dubbed 'Trojan Horse' acceleration is given. The concept is based on laser-controlled release of electrons directly into a particle-beam-driven plasma blowout, paving the way for controlled, shapeable electron bunches with ultralow emittance and ultrahigh brightness. Combining the virtues of a low-ionization-threshold underdense photocathode with the GV/m-scale electric fields of a practically dephasing-free beam-driven plasma blowout, this constitutes a 4th generation electron acceleration scheme. It is applicable as a beam brightness transformer for electron bunches from LWFA and PWFA systems alike. At FACET, the proof-of-concept experiment 'E-210: Trojan Horse Plasma Wakefield Acceleration' has recently been approved and is in preparation. At the same time, various LWFA facilities are currently considered to host experiments aiming at stabilizing and boosting the electron bunch output quality via a trojan horse afterburner stage. Since normalized emittance and brightness can be improved by many orders of magnitude, the scheme is an ideal candidate for light sources such as free-electron-lasers and those based on Thomson scattering and betatron radiation alike.

  3. Energy doubling of 42 GeV electrons in a metre-scale plasma wakefield accelerator.

    PubMed

    Blumenfeld, Ian; Clayton, Christopher E; Decker, Franz-Josef; Hogan, Mark J; Huang, Chengkun; Ischebeck, Rasmus; Iverson, Richard; Joshi, Chandrashekhar; Katsouleas, Thomas; Kirby, Neil; Lu, Wei; Marsh, Kenneth A; Mori, Warren B; Muggli, Patric; Oz, Erdem; Siemann, Robert H; Walz, Dieter; Zhou, Miaomiao

    2007-02-15

    The energy frontier of particle physics is several trillion electron volts, but colliders capable of reaching this regime (such as the Large Hadron Collider and the International Linear Collider) are costly and time-consuming to build; it is therefore important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators, a drive beam (either laser or particle) produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultrahigh accelerating fields over a substantial length to achieve a significant energy gain. Here we show that an energy gain of more than 42 GeV is achieved in a plasma wakefield accelerator of 85 cm length, driven by a 42 GeV electron beam at the Stanford Linear Accelerator Center (SLAC). The results are in excellent agreement with the predictions of three-dimensional particle-in-cell simulations. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of approximately 52 GV m(-1). This effectively doubles their energy, producing the energy gain of the 3-km-long SLAC accelerator in less than a metre for a small fraction of the electrons in the injected bunch. This is an important step towards demonstrating the viability of plasma accelerators for high-energy physics applications.

  4. Wakefield evolution and electron acceleration in interaction of frequency-chirped laser pulse with inhomogeneous plasma

    NASA Astrophysics Data System (ADS)

    Rezaei-Pandari, M.; Niknam, A. R.; Massudi, R.; Jahangiri, F.; Hassaninejad, H.; Khorashadizadeh, S. M.

    2017-02-01

    The nonlinear interaction of an ultra-short intense frequency-chirped laser pulse with an underdense plasma is studied. The effects of plasma inhomogeneity and laser parameters such as chirp, pulse duration, and intensity on plasma density and wakefield evolutions, and electron acceleration are examined. It is found that a properly chirped laser pulse could induce a stronger laser wakefield in an inhomogeneous plasma and result in higher electron acceleration energy. It is also shown that the wakefield amplitude is enhanced by increasing the slope of density in the inhomogeneous plasma.

  5. Plasma wakefield diagnostics using probe electron beam and microchannel plates

    SciTech Connect

    Fainberg, Ya.B.; Balakirev, V.A.; Berezin, A.K.

    1996-12-31

    The analytical and numerical investigations of trajectories of the probe beam electrons in the two dimensional wakefield, excited in plasma by a dense bunch of relativistic electrons with Gauss longitudinal and transverse distribution of density is carried out. On basis of calculations of probe beam deviations the diagnostic instruments is developed for parameters of experiments conducted in NSC KIPT. The diagnostic instruments consist of an electron gun forming the electron beam with energy 10KeV, current 10{mu}A and diameter 2mm which passes through the chamber of interaction and falls on collector of diameter 10mm. Collector (screen) is placed in front of the first plate of microchannel amplifier which consists of three microchannel plates (MCP) with sizes 20 - 30mm, The voltage 3kV was applied to the each plate. Total amplification of MCP amplifier is 10{sup 4} - 10{sup 5} in dependence on quantity of particles, falling on the first plate. As a result the deviations of probe beam by excited wakefield the electrons fall on first plate of amplifier and are registered by anode of amplifier, located behind the third plates. Calculated probe beam deviations and obtained amplification of MCP amplifier permit to find out and to investigate the electrical wakefields, excited by the sequence of relativistic bunches (number of particles in bunch is 2x10{sup 9}, energy is 14MeV) in plasma of density 10{sup 11} - 10{sup 13} cm{sup {minus}3}. The maximal value of the fields registered by such technique is not less 2kv/cm.

  6. Preservation of Ultra Low Emittances Using Adiabatic Matching in Future Plasma Wakefield-based Colliders

    SciTech Connect

    Gholizadeh, Reza; Muggli, Patric; Katsouleas, Tom; Mori, Warren

    2009-01-22

    The Plasma Wakefield Accelerator is a promising technique to lower the cost of the future high energy colliders by offering orders of magnitude higher gradients than the conventional accelerators. It has been shown that ion motion is an important issue to account for in the extreme regime of ultra high energies and ultra low emittances, characteristics of future high energy collider beams. In this regime, the transverse electric field of the beam is so high that in simulations, the plasma ions cannot be considered immobile at the time scale of electron plasma oscillation, thereby leading to a nonlinear focusing force. Therefore, the transverse emittance of a beam will not be preserved under these circumstances. However, we show that matched profile in case of a nonlinear focusing force still exists and can be derived from Vlasov equation. Furthermore, we introduce a plasma section that can reduce the emittance growth by adiabatically reducing the ion mass and hence increasing the nonlinear term in the focusing force. Simulation results are presented.

  7. Simulation and diagnostics of high density plasmas for multiple electron bunch wakefield generation

    NASA Astrophysics Data System (ADS)

    Kallos, Efthymios; Muggli, Patric; Katsouleas, Tom; Yakimenko, Vitaly; Stolyarov, Daniil; Pogorelsky, Igor; Pavlishin, Igor; Kusche, Karl; Babzien, Marcus; Ben-Zvi, Ilan; Kimura, Wayne

    2006-10-01

    The wakefield generated in a plasma from an electron beam can be enhanced if instead of a single bunch the beam is modulated into multiple bunches. Then the wakefields generated from the microbunches can add up in phase if the plasma density is tuned precisely at the separation between them. In the experimental setup at Brookhaven's Accelerator Test Facility the 45MeV electron beam is IFEL modulated into 150 microbunches 10.6μm apart. Here we present plasma simulations that confirm the wakefield enhancement and diagnostics we performed to tune the plasma density (Stark broadening, HeNe laser interferometry).

  8. Optical Frequency Domain Visualization of Electron Beam Driven Plasma Wakefields

    SciTech Connect

    Zgadzaj, Rafal; Downer, Michael C.; Muggli, Patric; Yakimenko, Vitaly; Kusche, Karl; Fedurin, Michhail; Babzien, Marcus

    2010-11-04

    Bunch driven plasma wakefield accelerators (PWFA), such as the 'plasma afterburner', are a promising emerging method for significantly increasing the energy output of conventional particle accelerators. The study and optimization of this method would benefit from an experimental correlation of the drive bunch parameters and the accelerated particle parameters with the corresponding plasma wave structure. However, the plasma wave structure has not been observed directly so far. We will report ongoing development of a noninvasive optical Frequency Domain Interferometric (FDI) and Holographic (FDH) diagnostics of bunch driven plasma wakes. Both FDI and FDH have been previously demonstrated in the case of laser driven wakes. These techniques employ two laser pulses co-propagating with the drive particle bunch and the trailing plasma wave. One pulse propagates ahead of the drive bunch and serves as a reference, while the second is overlapped with the plasma wave and probes its structure. The multi-shot FDI and single-shot FDH diagnostics permit direct noninvasive observation of longitudinal and transverse structure of the plasma wakes. The experiment is being developed at the 70 MeV Linac in the Accelerator Test Facility at Brookhaven National Laboratory to visualize wakes generated by two and multi-bunch drive beams.

  9. Optical Frequency Domain Visualization of Electron Beam Driven Plasma Wakefields

    NASA Astrophysics Data System (ADS)

    Zgadzaj, Rafal; Downer, Michael C.; Muggli, Patric; Yakimenko, Vitaly; Kusche, Karl; Fedurin, Michhail; Babzien, Marcus

    2010-11-01

    Bunch driven plasma wakefield accelerators (PWFA), such as the "plasma afterburner," are a promising emerging method for significantly increasing the energy output of conventional particle accelerators [1]. The study and optimization of this method would benefit from an experimental correlation of the drive bunch parameters and the accelerated particle parameters with the corresponding plasma wave structure. However, the plasma wave structure has not been observed directly so far. We will report ongoing development of a noninvasive optical Frequency Domain Interferometric (FDI) [2] and Holographic (FDH) [3] diagnostics of bunch driven plasma wakes. Both FDI and FDH have been previously demonstrated in the case of laser driven wakes. These techniques employ two laser pulses co-propagating with the drive particle bunch and the trailing plasma wave. One pulse propagates ahead of the drive bunch and serves as a reference, while the second is overlapped with the plasma wave and probes its structure. The multi-shot FDI and single-shot FDH diagnostics permit direct noninvasive observation of longitudinal and transverse structure of the plasma wakes. The experiment is being developed at the 70 MeV Linac in the Accelerator Test Facility at Brookhaven National Laboratory to visualize wakes generated by two [4] and multi-bunch [5] drive beams.

  10. Neutrino-driven wakefield plasma accelerator

    NASA Astrophysics Data System (ADS)

    Rios, L. A.; Serbeto, A.

    2003-08-01

    Processos envolvendo neutrinos são importantes em uma grande variedade de fenômenos astrofísicos, como as explosões de supernovas. Estes objetos, assim como os pulsares e as galáxias starburst, têm sido propostos como aceleradores cósmicos de partículas de altas energias. Neste trabalho, um modelo clássico de fluidos é utilizado para estudar a interação não-linear entre um feixe de neutrinos e um plasma não-colisional relativístico de pósitrons e elétrons na presença de um campo magnético. Durante a interação, uma onda híbrida superior de grande amplitude é excitada. Para parâmetros típicos de supernovas, verificamos que partículas carregadas "capturadas" por essa onda podem ser aceleradas a altas energias. Este resultado pode ser importante no estudo de mecanismos aceleradores de partículas em ambientes astrofísicos.

  11. Simulations of a meter-long plasma wakefield accelerator.

    PubMed

    Lee, S; Katsouleas, T; Hemker, R; Mori, W B

    2000-06-01

    Full-scale particle-in-cell simulations of a meter-long plasma wakefield accelerator (PWFA) are presented in two dimensions. The results support the design of a current PWFA experiment in the nonlinear blowout regime where analytic solutions are intractable. A relativistic electron bunch excites a plasma wake that accelerates trailing particles at rates of several hundred MeV/m. A comparison is made of various simulation codes, and a parallel object-oriented code OSIRIS is used to model a full meter of acceleration. Excellent agreement is obtained between the simulations and analytic expressions for the transverse betatron oscillations of the beam. The simulations are used to develop scaling laws for designing future multi-GeV accelerator experiments.

  12. High power microwave source for a plasma wakefield experiment

    NASA Astrophysics Data System (ADS)

    Shafir, G.; Shlapakovski, A.; Siman-Tov, M.; Bliokh, Yu.; Leopold, J. G.; Gleizer, S.; Gad, R.; Rostov, V. V.; Krasik, Ya. E.

    2017-01-01

    The results of the generation of a high-power microwave (˜550 MW, 0.5 ns, ˜9.6 GHz) beam and feasibility of wakefield-excitation with this beam in under-dense plasma are presented. The microwave beam is generated by a backward wave oscillator (BWO) operating in the superradiance regime. The BWO is driven by a high-current electron beam (˜250 keV, ˜1.5 kA, ˜5 ns) propagating through a slow-wave structure in a guiding magnetic field of 2.5 T. The microwave beam is focused at the desired location by a dielectric lens. Experimentally obtained parameters of the microwave beam at its waist are used for numerical simulations, the results of which demonstrate the formation of a bubble in the plasma that has almost 100% electron density modulation and longitudinal and transverse electric fields of several kV/cm.

  13. Laser-Plasma Interactions in High-Energy Density Plasmas

    SciTech Connect

    Constantin, C G; Baldis, H A; Schneider, M B; Hinkel, D E; Langdon, A B; Seka, W; Bahr, R; Depierreaux, S

    2005-08-24

    Laser-plasma interactions (LPI) have been studied experimentally in high-temperature, high-energy density plasmas. The studies have been performed using the Omega laser at the Laboratory for Laser Energetics (LLE), Rochester, NY. Up to 10 TW of power was incident upon reduced-scale hohlraums, distributed in three laser beam cones. The hot hohlraums fill quickly with plasma. Late in the laser pulse, most of the laser energy is deposited at the laser entrance hole, where most of the LPI takes place. Due to the high electron temperature, the stimulated Raman scattering (SRS) spectrum extends well beyond {omega}{sub 0}/2, due to the Bohm-Gross shift. This high-temperature, high-energy density regime provides a unique opportunity to study LPI beyond inertial confinement fusion (ICF) conditions.

  14. High-brightness, high-energy radiation generation from non-linear Thomson scattering of laser wakefield accelerated electrons

    NASA Astrophysics Data System (ADS)

    Schumaker, W.; Zhao, Z.; Thomas, A. G. R.; Krushelnick, K.; Sarri, G.; Corvan, D.; Zepf, M.; Cole, J.; Mangles, S. P. D.; Najmudin, Z.

    2014-10-01

    To date, all-optical sources of high-energy (>MeV) photons have only been reported in the linear (a0 < 1) regime of Thomson scattering using laser wakefield acceleration (LWFA). We present novel results of high-brightness, high-energy photons generated via non-linear Thomson scattering using the two-beam Astra-Gemini laser facility. With one 300 TW beam, electrons were first accelerated to 500 MeV energies inside gas cells through the process of LWFA. A second 300 TW laser pulse focused to a0 = 2 was subsequently scattered off these electrons, resulting in a highly directional, small source size, and short pulse beam of photons with >10 MeV energies. The photon beam was propagated through a low- Z converter and produced Compton-scattered electrons that were spectrally measured by magnetic deflection and correlated with the incident photons. The measured photon yield at 15 MeV was 2 ×106 photons/MeV and, when coupled with the small source size, divergence, and pulse duration, results in a record peak brightness of 2 ×1019 photons/s/mm2/mrad2/0.1%bandwidth at 15 MeV photon energy. Current Affiliation: Stanford University/SLAC National Accelerator Laboratory.

  15. Design of a plasma discharge circuit for particle wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Anania, M. P.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Ferrario, M.; Flora, F.; Gallerano, G. P.; Ghigo, A.; Marocchino, A.; Massimo, F.; Mostacci, A.; Mezi, L.; Musumeci, P.; Serio, M.

    2014-03-01

    Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV m-1), enabling acceleration of electrons to GeV energy in few centimetres. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators; radiofrequency-based accelerators, in fact, are limited in the accelerating field (10-100 MV m-1) requiring therefore kilometric distances to reach the GeV energies, but can provide very bright electron bunches. Combining high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC-LAB [1,2]. In particular, here we focus on the ionization process; we show a simplified model to study the evolution of plasma induced by discharge, very useful to design the discharge circuit able to fully ionize the gas and bring the plasma at the needed temperature and density.

  16. Experimental, Theoretical and Computational Studies of Plasma-Based Concepts for Future High Energy Accelerators

    SciTech Connect

    Joshi, Chan; Mori, W.

    2013-10-21

    This is the final report on the DOE grant number DE-FG02-92ER40727 titled, “Experimental, Theoretical and Computational Studies of Plasma-Based Concepts for Future High Energy Accelerators.” During this grant period the UCLA program on Advanced Plasma Based Accelerators, headed by Professor C. Joshi has made many key scientific advances and trained a generation of students, many of whom have stayed in this research field and even started research programs of their own. In this final report however, we will focus on the last three years of the grant and report on the scientific progress made in each of the four tasks listed under this grant. Four tasks are focused on: Plasma Wakefield Accelerator Research at FACET, SLAC National Accelerator Laboratory, In House Research at UCLA’s Neptune and 20 TW Laser Laboratories, Laser-Wakefield Acceleration (LWFA) in Self Guided Regime: Experiments at the Callisto Laser at LLNL, and Theory and Simulations. Major scientific results have been obtained in each of the four tasks described in this report. These have led to publications in the prestigious scientific journals, graduation and continued training of high quality Ph.D. level students and have kept the U.S. at the forefront of plasma-based accelerators research field.

  17. AWAKE, The Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN

    NASA Astrophysics Data System (ADS)

    Gschwendtner, E.; Adli, E.; Amorim, L.; Apsimon, R.; Assmann, R.; Bachmann, A.-M.; Batsch, F.; Bauche, J.; Berglyd Olsen, V. K.; Bernardini, M.; Bingham, R.; Biskup, B.; Bohl, T.; Bracco, C.; Burrows, P. N.; Burt, G.; Buttenschön, B.; Butterworth, A.; Caldwell, A.; Cascella, M.; Chevallay, E.; Cipiccia, S.; Damerau, H.; Deacon, L.; Dirksen, P.; Doebert, S.; Dorda, U.; Farmer, J.; Fedosseev, V.; Feldbaumer, E.; Fiorito, R.; Fonseca, R.; Friebel, F.; Gorn, A. A.; Grulke, O.; Hansen, J.; Hessler, C.; Hofle, W.; Holloway, J.; Hüther, M.; Jaroszynski, D.; Jensen, L.; Jolly, S.; Joulaei, A.; Kasim, M.; Keeble, F.; Li, Y.; Liu, S.; Lopes, N.; Lotov, K. V.; Mandry, S.; Martorelli, R.; Martyanov, M.; Mazzoni, S.; Mete, O.; Minakov, V. A.; Mitchell, J.; Moody, J.; Muggli, P.; Najmudin, Z.; Norreys, P.; Öz, E.; Pardons, A.; Pepitone, K.; Petrenko, A.; Plyushchev, G.; Pukhov, A.; Rieger, K.; Ruhl, H.; Salveter, F.; Savard, N.; Schmidt, J.; Seryi, A.; Shaposhnikova, E.; Sheng, Z. M.; Sherwood, P.; Silva, L.; Soby, L.; Sosedkin, A. P.; Spitsyn, R. I.; Trines, R.; Tuev, P. V.; Turner, M.; Verzilov, V.; Vieira, J.; Vincke, H.; Wei, Y.; Welsch, C. P.; Wing, M.; Xia, G.; Zhang, H.

    2016-09-01

    The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) aims at studying plasma wakefield generation and electron acceleration driven by proton bunches. It is a proof-of-principle R&D experiment at CERN and the world's first proton driven plasma wakefield acceleration experiment. The AWAKE experiment will be installed in the former CNGS facility and uses the 400 GeV/c proton beam bunches from the SPS. The first experiments will focus on the self-modulation instability of the long (rms 12 cm) proton bunch in the plasma. These experiments are planned for the end of 2016. Later, in 2017/2018, low energy ( 15 MeV) electrons will be externally injected into the sample wakefields and be accelerated beyond 1 GeV. The main goals of the experiment will be summarized. A summary of the AWAKE design and construction status will be presented.

  18. Proposal for a one GeV plasma wakefield acceleration experiment at SLAC

    SciTech Connect

    Assmann, R.; Chen, P.; Decker, F.J.

    1998-04-01

    A plasma-based wakefield acceleration experiment E-157 has been approved at SLAC to study acceleration of parts of an SLC bunch by up to 1 GeV/m over a length of 1 m. A single SLC bunch is used to both induce wakefields in the one meter long plasma and to witness the resulting beam acceleration. The experiment will explore and further development the techniques that are needed to apply high-gradient plasma wakefield acceleration to large scale accelerators. The one meter length of the experiment is about two orders of magnitude larger than other high gradient plasma wakefield acceleration experiments and the 1 GeV/m accelerating gradient is roughly ten times larger than that achieved with conventional metallic structures. Using existing SLAC facilities, the experiment will study high gradient acceleration at the forefront of advanced accelerator research.

  19. Coherent quantum hollow beam creation in a plasma wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Jovanović, D.; Fedele, R.; Tanjia, F.; de Nicola, S.; Belić, M.; Belić

    2013-08-01

    A theoretical investigation of the propagation of a relativistic electron (or positron) particle beam in an overdense magnetoactive plasma is carried out within a fluid plasma model, taking into account the individual quantum properties of beam particles. It is demonstrated that the collective character of the particle beam manifests mostly through the self-consistent macroscopic plasma wakefield created by the charge and the current densities of the beam. The transverse dynamics of the beam-plasma system is governed by the Schrödinger equation for a single-particle wavefunction derived under the Hartree mean field approximation, coupled with a Poisson-like equation for the wake potential. These two coupled equations are subsequently reduced to a nonlinear, non-local Schrödinger equation and solved in a strongly non-local regime. An approximate Glauber solution is found analytically in the form of a Hermite-Gauss ring soliton. Such non-stationary (`breathing' and `wiggling') coherent structure may be parametrically unstable and the corresponding growth rates are estimated analytically.

  20. Magnetically Controlled Plasma Waveguide For Laser Wakefield Acceleration

    SciTech Connect

    Froula, D H; Divol, L; Davis, P; Palastro, J; Michel, P; Leurent, V; Glenzer, S H; Pollock, B; Tynan, G

    2008-05-14

    An external magnetic field applied to a laser plasma is shown produce a plasma channel at densities relevant to creating GeV monoenergetic electrons through laser wakefield acceleration. Furthermore, the magnetic field also provides a pressure to help shape the channel to match the guiding conditions of an incident laser beam. Measured density channels suitable for guiding relativistic short-pulse laser beams are presented with a minimum density of 5 x 10{sup 17} cm{sup -3} which corresponds to a linear dephasing length of several centimeters suitable for multi-GeV electron acceleration. The experimental setup at the Jupiter Laser Facility, Lawrence Livermore National Laboratory, where a 1-ns, 150 J 1054 nm laser will produce a magnetically controlled channel to guide a < 75 fs, 10 J short-pulse laser beam through 5-cm of 5 x 10{sup 17} cm{sup -3} plasma is presented. Calculations presented show that electrons can be accelerated to 3 GeV with this system. Three-dimensional resistive magneto-hydrodynamic simulations are used to design the laser and plasma parameters and quasi-static kinetic simulations indicate that the channel will guide a 200 TW laser beam over 5-cm.

  1. Linear to non linear analysis for positron acceleration in plasma hollow channel wakefields

    NASA Astrophysics Data System (ADS)

    Amorim, Ligia Diana; An, Weiming; Mori, Warren B.; Vieira, Jorge

    2016-10-01

    Plasma wakefield accelerators are promising candidates for future generation compact accelerators. The standard regime of operation, non-linear or blowout regime, is reached when a particle bunch space charge or laser pulse ponderomotive force radially expels plasma electrons forming a bucket of ions that defocus positron bunches, thus preventing their acceleration. To avoid defocusing, hollow plasma channels have been considered. The corresponding wakefields have been examined in the linear and non-linear excitation regimes for electrons. It is therefore important to extend the theory for positron acceleration, particularly in the nonlinear regime where the wakefields strongly differ. In this work we explore the wakefield structure, examine the differences between the electron and positron beam cases, and explore positron acceleration in nonlinear regimes. We support our findings with multi-dimensional particle-in-cell simulations performed with OSIRIS and quasi-3D and QuickPIC.

  2. Laser-PlasmaWakefield Acceleration with Higher Order Laser Modes

    SciTech Connect

    Geddes, C.G.R.; Cormier-Michel, E.; Esarey, E.; Schroeder, C.B.; Mullowney, P.; Paul, K.; Cary, J.R.; Leemans, W.P.

    2010-06-01

    Laser-plasma collider designs point to staging of multiple accelerator stages at the 10 GeV level, which are to be developed on the upcoming BELLA laser, while Thomson Gamma source designs use GeV stages, both requiring efficiency and low emittance. Design and scaling of stages operating in the quasi-linear regime to address these needs are presented using simulations in the VORPAL framework. In addition to allowing symmetric acceleration of electrons and positrons, which is important for colliders, this regime has the property that the plasma wakefield is proportional to the transverse gradient of the laser intensity profile. We demonstrate use of higher order laser modes to tailor the laser pulse and hence the transverse focusing forces in the plasma. In particular, we show that by using higher order laser modes, we can reduce the focusing fields and hence increase the matched electron beam radius, which is important to increased charge and efficiency, while keeping the low bunch emittance required for applications.

  3. Plasma Wake Field Acceleration for Ultra High-Energy Cosmic Rays

    SciTech Connect

    Chen, Pisin

    2002-07-31

    A cosmic acceleration mechanism is introduced which is based on the wakefields excited by the Alfven shocks in a relativistically flowing plasma. We show that there exists a threshold condition for transparency below which the accelerating particle is collision-free and suffers little energy loss in the plasma medium. The stochastic encounters of the random accelerating-decelerating phases results in a power-law energy spectrum: f({epsilon}) {proportional_to} 1/{epsilon}{sup 2}. As an example, we discuss the possible production of super-GZK ultra high energy cosmic rays (UHECR) in the atmosphere of gamma ray bursts. The estimated event rate in our model agrees with that from UHECR observations.

  4. Plasma Focusing of High Energy Density Electron and Positron Beams

    SciTech Connect

    Ng, Johnny S.T.

    2000-10-09

    We present results from the SLAC E-150 experiment on plasma focusing of high energy density electron and, for the first time, positron beams. We also present results on plasma lens-induced synchrotron radiation, longitudinal dynamics of plasma focusing, and laser- and beam-plasma interactions.

  5. Simulations of a High-Transformer-Ratio Plasma Wakefield Accelerator Using Multiple Electron Bunches

    SciTech Connect

    Kallos, Efthymios; Muggli, Patric; Katsouleas, Thomas; Yakimenko, Vitaly; Park, Jangho

    2009-01-22

    Particle-in-cell simulations of a plasma wakefield accelerator in the linear regime are presented, consisting of four electron bunches that are fed into a high-density plasma. It is found that a high transformer ratio can be maintained over 43 cm of plasma if the charge in each bunch is increased linearly, the bunches are placed 1.5 plasma wavelengths apart and the bunch emmitances are adjusted to compensate for the nonlinear focusing forces. The generated wakefield is sampled by a test witness bunch whose energy gain after the plasma is six times the energy loss of the drive bunches.

  6. High-energy Coherent THz radiation From Laser Wakefield Accelerated Ultrashort Electron Bunches

    NASA Astrophysics Data System (ADS)

    van Tilborg, J.; Geddes, C. G. R.; Toth, C.; Esarey, E. H.; Schroeder, C. B.; Leemans, W. P.

    2003-10-01

    We report on the observation of coherent THz radiation from femtosecond laser-accelerated electron bunches [1]. These multi-nC bunches, concentrated in a length of a few plasma periods (several tens of microns) will experience a strongly reduced space charge force due to shielding by the background ions. The radiation, scaling quadratically with bunch charge, is a combination of diffraction and transition radiation by the electrons passing the plasma-vacuum boundary. If both a large collection angle as well as a large transverse plasma size are realized, theory predicts energies on the other of 0.1 mJ per THz pulse for current electron beam properties. A first improvement of the collection angle has increased the detected energy from 5 nJ to 80 nJ. Recent results on the characterization of this source (such as the spectrum) will be discussed and electron beam properties at the boundary will be addressed. (This work is performed under DOE-contract DE-AC-03-76SF0098) [1] W. P. Leemans et al., Phys. Rev. Lett., in press (2003)

  7. Enhanced betatron X-rays from axially modulated plasma wakefields

    SciTech Connect

    Palastro, J. P.; Kaganovich, D.; Gordon, D.

    2015-06-15

    In the cavitation regime of plasma-based accelerators, a population of high-energy electrons trailing the driver can undergo betatron motion. The motion results in X-ray emission, but the brilliance and photon energy are limited by the electrons' initial transverse coordinate. To overcome this, we exploit parametrically unstable betatron motion in a cavitated, axially modulated plasma. Theory and simulations are presented showing that the unstable oscillations increase both the total X-ray energy and average photon energy.

  8. HIGH ENERGY GASEOUS PLASMA CONTAINMENT DEVICE

    DOEpatents

    Josephson, V.; Hammel, J.E.

    1959-01-13

    An apparatus is presenied for producing neutrons as a result of collisions between ions in high temperature plasmas. The invention resides in the particular arrangement of ihe device whereby ihe magneiic and electric fields are made to cross at substantially right angles in several places along a torus shaped containment vessel. A plasma of deuterium gas is generated in the vessel under the electric fields and is "trapped" in any one of the "crossed field" regions to produce a release of energy.

  9. Wakefields generated by collisional neutrinos in neutral-electron-positron plasma

    SciTech Connect

    Tinakiche, Nouara

    2013-02-15

    A classical fluid description is adopted to investigate nonlinear interaction between an electron-type neutrino beam and a relativistic collisionless unmagnetized neutral-electron-positron plasma. In this work, we consider the collisions of the neutrinos with neutrals in the plasma and study their effect on the generation of wakefields in this plasma.

  10. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

    PubMed Central

    Gessner, Spencer; Adli, Erik; Allen, James M.; An, Weiming; Clarke, Christine I.; Clayton, Chris E.; Corde, Sebastien; Delahaye, J. P.; Frederico, Joel; Green, Selina Z.; Hast, Carsten; Hogan, Mark J.; Joshi, Chan; Lindstrøm, Carl A.; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; O'Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-01-01

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m−1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations. PMID:27250570

  11. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator.

    PubMed

    Gessner, Spencer; Adli, Erik; Allen, James M; An, Weiming; Clarke, Christine I; Clayton, Chris E; Corde, Sebastien; Delahaye, J P; Frederico, Joel; Green, Selina Z; Hast, Carsten; Hogan, Mark J; Joshi, Chan; Lindstrøm, Carl A; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A; Mori, Warren B; O'Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-06-02

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m(-1) is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.

  12. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

    DOE PAGES

    Gessner, Spencer; Adli, Erik; Allen, James M.; ...

    2016-06-02

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. In this study, we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel ismore » created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m-1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.« less

  13. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

    SciTech Connect

    Gessner, Spencer; Adli, Erik; Allen, James M.; An, Weiming; Clarke, Christine I.; Clayton, Chris E.; Corde, Sebastien; Delahaye, J. P.; Frederico, Joel; Green, Selina Z.; Hast, Carsten; Hogan, Mark J.; Joshi, Chan; Lindstrøm, Carl A.; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; O’Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-06-02

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. In this study, we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m-1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.

  14. Plasma Density Tapering for Laser Wakefield Acceleration of Electrons and Protons

    SciTech Connect

    Ting, A.; Gordon, D.; Kaganovich, D.; Sprangle, P.; Helle, M.; Hafizi, B.

    2010-11-04

    Extended acceleration in a Laser Wakefield Accelerator can be achieved by tailoring the phase velocity of the accelerating plasma wave, either through profiling of the density of the plasma or direct manipulation of the phase velocity. Laser wakefield acceleration has also reached a maturity that proton acceleration by wakefield could be entertained provided we begin with protons that are substantially relativistic, {approx}1 GeV. Several plasma density tapering schemes are discussed. The first scheme is called ''bucket jumping'' where the plasma density is abruptly returned to the original density after a conventional tapering to move the accelerating particles to a neighboring wakefield period (bucket). The second scheme is designed to specifically accelerate low energy protons by generating a nonlinear wakefield in a plasma region with close to critical density. The third scheme creates a periodic variation in the phase velocity by beating two intense laser beams with laser frequency difference equal to the plasma frequency. Discussions and case examples with simulations are presented where substantial acceleration of electrons or protons could be obtained.

  15. Plasma Density Tapering for Laser Wakefield Acceleration of Electrons and Protons

    NASA Astrophysics Data System (ADS)

    Ting, A.; Gordon, D.; Helle, M.; Kaganovich, D.; Sprangle, P.; Hafizi, B.

    2010-11-01

    Extended acceleration in a Laser Wakefield Accelerator can be achieved by tailoring the phase velocity of the accelerating plasma wave, either through profiling of the density of the plasma or direct manipulation of the phase velocity. Laser wakefield acceleration has also reached a maturity that proton acceleration by wakefield could be entertained provided we begin with protons that are substantially relativistic, ˜1 GeV. Several plasma density tapering schemes are discussed. The first scheme is called "bucket jumping" where the plasma density is abruptly returned to the original density after a conventional tapering to move the accelerating particles to a neighboring wakefield period (bucket). The second scheme is designed to specifically accelerate low energy protons by generating a nonlinear wakefield in a plasma region with close to critical density. The third scheme creates a periodic variation in the phase velocity by beating two intense laser beams with laser frequency difference equal to the plasma frequency. Discussions and case examples with simulations are presented where substantial acceleration of electrons or protons could be obtained.

  16. Computational Simulation of High Energy Density Plasmas

    DTIC Science & Technology

    2009-10-30

    flow. NumerEx used MACH2 to simulate the flow using compressible, inviscid hydrodynamics with the SESAME equations of state . The depth of the...Figure 1 shows the liner state versus the radius of a collapsing 10 cm tall lithium liner driven by an RLC circuit model of Shiva Star. This work...the coaxial gun section, and Figure 4 shows the physical state of the plasma just prior to pinch. Figure 5 shows neutron yield reaching 1014 in this

  17. Coherent seeding of self-modulated plasma wakefield accelerators

    SciTech Connect

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Gruener, Florian; Leemans, Wim

    2013-04-30

    The growth of the beam self-modulation and hosing instabilities initiated by a seed wakefield is examined. Although the growth rates for the self-modulation and hosing instabilities are comparable, it is shown that an externally excited wakefield can be effective in selectively seeding the beam radial self-modulation, enabling the beam to fully modulate before strong beam hosing develops. Methods for coherent seeding are discussed.

  18. Coherent seeding of self-modulated plasma wakefield accelerators

    SciTech Connect

    Schroeder, C. B.; Benedetti, C.; Esarey, E.; Leemans, W. P.; Grüner, F. J.

    2013-05-15

    The growth of the beam self-modulation and hosing instabilities initiated by a seed wakefield is examined. Although the growth rates for the self-modulation and hosing instabilities are comparable, it is shown that an externally excited wakefield can be effective in selectively seeding the beam radial self-modulation, enabling the beam to fully modulate before strong beam hosing develops. Methods for coherent seeding are discussed.

  19. Simulation study of wakefield generation by two color laser pulses propagating in homogeneous plasma

    SciTech Connect

    Kumar Mishra, Rohit; Saroch, Akanksha; Jha, Pallavi

    2013-09-15

    This paper deals with a two-dimensional simulation of electric wakefields generated by two color laser pulses propagating in homogeneous plasma, using VORPAL simulation code. The laser pulses are assumed to have a frequency difference equal to the plasma frequency. Simulation studies are performed for two similarly as well as oppositely polarized laser pulses and the respective amplitudes of the generated longitudinal wakefields for the two cases are compared. Enhancement of wake amplitude for the latter case is reported. This simulation study validates the analytical results presented by Jha et al.[Phys. Plasmas 20, 053102 (2013)].

  20. Plasma based wakefield acceleration using a 46MeV multibunched electron beam

    NASA Astrophysics Data System (ADS)

    Kallos, Efthymios; Ben-Zvi, Ilan; Zhou, Feng; Kimura, Wayne

    2005-10-01

    In the multibunch plasma wakefield acceleration scheme a series of electron microbunches are fed into a high density plasma and resonantly excite a wakefield that can accelerate the beam electrons. Here we present some recent experimental results conducted at Brookhaven's Accelerator test Facility (ATF) where ˜90 microbunches at 46MeV created through the IFEL effect with a 10.6μm CO2 laser interact with a high density 10^19cm-3 12mm long plasma. Some further PIC simulations provide insight into the physics of the interaction.

  1. Meter scale plasma source for plasma wakefield experiments

    SciTech Connect

    Vafaei-Najafabadi, N.; Shaw, J. L.; Marsh, K. A.; Joshi, C.; Hogan, M. J.

    2012-12-21

    High accelerating gradients generated by a high density electron beam moving through plasma has been used to double the energy of the SLAC electron beam [1]. During that experiment, the electron current density was high enough to generate its own plasma without significant head erosion. In the newly commissioned FACET facility at SLAC, the peak current will be lower and without pre-ionization, head erosion will be a significant challenge for the planned experiments. In this work we report on our design of a meter scale plasma source for these experiments to effectively avoid the problem of head erosion. The plasma source is based on a homogeneous metal vapor gas column that is generated in a heat pipe oven [2]. A lithium oven over 30 cm long at densities over 10{sup 17} cm{sup -3} has been constructed and tested at UCLA. The plasma is then generated by coupling a 10 TW short pulse Ti:Sapphire laser into the gas column using an axicon lens setup. The Bessel profile of the axicon setup creates a region of high intensity that can stretch over the full length of the gas column with approximately constant diameter. In this region of high intensity, the alkali metal vapor is ionized through multi-photon ionization process. In this manner, a fully ionized meter scale plasma of uniform density can be formed. Methods for controlling the plasma diameter and length will also be discussed.

  2. Plasma undulator based on laser excitation of wakefields in a plasma channel.

    PubMed

    Rykovanov, S G; Schroeder, C B; Esarey, E; Geddes, C G R; Leemans, W P

    2015-04-10

    An undulator is proposed based on the plasma wakefields excited by a laser pulse in a plasma channel. Generation of the undulator fields is achieved by inducing centroid oscillations of the laser pulse in the channel. The period of such an undulator is proportional to the Rayleigh length of the laser pulse and can be submillimeter, while preserving high undulator strength. The electron trajectories in the undulator are examined, expressions for the undulator strength are presented, and the spontaneous radiation is calculated. Multimode and multicolor laser pulses are considered for greater tunability of the undulator period and strength.

  3. Electron beam manipulation, injection and acceleration in plasma wakefield accelerators by optically generated plasma density spikes

    NASA Astrophysics Data System (ADS)

    Wittig, Georg; Karger, Oliver S.; Knetsch, Alexander; Xi, Yunfeng; Deng, Aihua; Rosenzweig, James B.; Bruhwiler, David L.; Smith, Jonathan; Sheng, Zheng-Ming; Jaroszynski, Dino A.; Manahan, Grace G.; Hidding, Bernhard

    2016-09-01

    We discuss considerations regarding a novel and robust scheme for optically triggered electron bunch generation in plasma wakefield accelerators [1]. In this technique, a transversely propagating focused laser pulse ignites a quasi-stationary plasma column before the arrival of the plasma wake. This localized plasma density enhancement or optical "plasma torch" distorts the blowout during the arrival of the electron drive bunch and modifies the electron trajectories, resulting in controlled injection. By changing the gas density, and the laser pulse parameters such as beam waist and intensity, and by moving the focal point of the laser pulse, the shape of the plasma torch, and therefore the generated trailing beam, can be tuned easily. The proposed method is much more flexible and faster in generating gas density transitions when compared to hydrodynamics-based methods, and it accommodates experimentalists needs as it is a purely optical process and straightforward to implement.

  4. Wakefield effects and solitary waves of an intense short laser pulse propagation in a plasma channel

    SciTech Connect

    Hong Xueren; Xie Baisong; Zhao Xueyan; Zhang Shan; Wu Haicheng

    2011-10-15

    In the presence of relativistic and channel-coupling nonlinearity and wakefield effects, the propagation characteristics and solitary waves of an intense short laser pulse in a preformed plasma channel are investigated. The evolution equation of the laser spot size is derived by using variational technique, the initial laser and plasma parameters for propagation with constant spot size, periodic defocusing and focusing oscillations, and solitary waves are identified. For illustration, some numerical results are also presented. It is found that the laser focusing is enhanced by the wakefield effects that result in a significant reduced focusing power.

  5. Effect of beam emittance on self-modulation of long beams in plasma wakefield accelerators

    SciTech Connect

    Lotov, K. V.

    2015-12-15

    The initial beam emittance determines the maximum wakefield amplitude that can be reached as a result of beam self-modulation in the plasma. The wakefield excited by the fully self-modulated beam decreases linearly with the increase in the beam emittance. There is a value of initial emittance beyond which the self-modulation does not develop even if the instability is initiated by a strong seed perturbation. The emittance scale at which the wakefield is suppressed by a factor of two with respect to the zero-emittance case (the so called critical emittance) is determined by inability of the excited wave to confine beam particles radially and is related to beam and plasma parameters by a simple formula. The effect of beam emittance can be observed in several discussed self-modulation experiments.

  6. Modeling beam-driven and laser-driven plasma Wakefield accelerators with XOOPIC

    SciTech Connect

    Bruhwiler, David L.; Giacone, Rodolfo; Cary, John R.; Verboncoeur, John P.; Mardahl, Peter; Esarey, Eric; Leemans, Wim

    2000-06-01

    We present 2-D particle-in-cell simulations of both beam-driven and laser-driven plasma wakefield accelerators, using the object-oriented code XOOPIC, which is time explicit, fully electromagnetic, and capable of running on massively parallel supercomputers. Simulations of laser-driven wakefields with low ({approximately} 10{sup 16} W/cm{sup 2}) and high ({approximately} 10{sup 18} W/cm{sup 2}) peak intensity laser pulses are conducted in slab geometry, showing agreement with theory. Simulations of the E-157 beam wakefield experiment at the Stanford Linear Accelerator Center, in which a 30 GeV electron beam passes through 1 m of preionized lithium plasma, are conducted in cylindrical geometry, obtaining good agreement with previous work. We briefly describe some of the more significant modifications to XOOPIC required by this work, and summarize the issues relevant to modeling electron-neutral collisions in a particle-in-cell code.

  7. Laser-plasma generated very high energy electrons in radiation therapy of the prostate

    NASA Astrophysics Data System (ADS)

    DesRosiers, Colleen; Moskvin, Vadim; Cao, Minsong; Joshi, Chandrashekhar J.; Langer, Mark

    2008-02-01

    Monte Carlo simulation experiments have shown that very high energy electrons (VHEE), 150-250 MeV, have potential advantages in prostate cancer treatment over currently available electrons, photon and proton beam treatment. Small diameter VHEE beamlets can be scanned, thereby producing a finer resolution intensity modulated treatment than photon beams. VHEE beams may be delivered with greater precision and accelerators may be constructed at significantly lower cost than proton beams. A VHEE accelerator may be optimally designed using laser-plasma technology. If the accelerator is constructed to additionally produce low energy photon beams along with VHEE, real time imaging, bioprobing, and dose enhancement may be performed simultaneously. This paper describes a Monte Carlo experiment, using the parameters of the electron beam from the UCLA laser-plasma wakefield accelerator, whereby dose distributions on a human prostate are generated. The resulting dose distributions of the very high energy electrons are shown to be comparable to photon beam dose distributions. This simple experiment illustrates that the nature of the dose distribution of electrons is comparable to that of photons. However, the main advantage of electrons over photons and protons lies in the delivery and manipulation of electrons, rather than the nature of the dose distribution. This paper describes the radiation dose delivery of electrons employing technologies currently in exploration and evaluates potential benefits as compared with currently available photon and protons beams in the treatment of prostate and other cancers, commonly treated with radiation.

  8. Stable Electron Beams With Low Absolute Energy Spread From a LaserWakefield Accelerator With Plasma Density Ramp Controlled Injection

    SciTech Connect

    Geddes, Cameron G.R.; Cormier-Michel, E.; Esarey, E.; Leemans,W.P.; Nakamura, K.; Panasenko, D.; Plateau, Guillaume R.; Schroeder, CarlB.; Toth, Csaba; Cary, J.R.

    2007-06-25

    Laser wakefield accelerators produce accelerating gradientsup to hundreds of GeV/m, and recently demonstrated 1-10 MeV energy spreadat energies up to 1 GeV using electrons self-trapped from the plasma.Controlled injection and staging may further improve beam quality bycircumventing tradeoffs between energy, stability, and energyspread/emittance. We present experiments demonstrating production of astable electron beam near 1 MeV with hundred-keV level energy spread andcentral energy stability by using the plasma density profile to controlselfinjection, and supporting simulations. Simulations indicate that suchbeams can be post accelerated to high energies,potentially reducingmomentum spread in laser acceleratorsby 100-fold or more.

  9. Plasma Wakefield Acceleration and FACET - Facilities for Accelerator Science and Experimental Test Beams at SLAC

    ScienceCinema

    Andrei Seryi

    2016-07-12

    Plasma wakefield acceleration is one of the most promising approaches to advancing accelerator technology. This approach offers a potential 1,000-fold or more increase in acceleration over a given distance, compared to existing accelerators.  FACET, enabled by the Recovery Act funds, will study plasma acceleration, using short, intense pulses of electrons and positrons. In this lecture, the physics of plasma acceleration and features of FACET will be presented.  

  10. Wakefields generated by collisional neutrinos in neutral-electron-positron-ion plasma

    SciTech Connect

    Tinakiche, Nouara

    2015-12-15

    A classical fluid description is adopted to investigate nonlinear interaction between an electron-type neutrino beam and a relativistic collisionless unmagnetized neutral-electron-positron-ion plasma. In this work, we consider the collisions of the neutrinos with neutrals in the plasma and study their effect on the generation of wakefields in presence of a fraction of ions in a neutral-electron-positron plasma. The results obtained in the present work are interpreted and compared with previous studies.

  11. Scaling of the Longitudinal Electric Field and Transformer Ratio in a Nonlinear Plasma Wakefield Accelerator

    SciTech Connect

    Blumenfeld, I.; Clayton, C.E.; Decker, F.J.; Hogan, M.J.; Huang, C.; Ischebeck, R.; Iverson, R.H.; Joshi, C.; Katsouleas, T.; Kirby, N.; Lu, W.; Marsh, K.A.; Mori, W.B.; Muggli, P.; Oz, E.; Siemann, R.H.; Walz, D.R.; Zhou, M.; /UCLA

    2012-06-12

    The scaling of the two important figures of merit, the transformer ratio T and the longitudinal electric field E{sub z}, with the peak drive-bunch current I{sub p}, in a nonlinear plasma wakefield accelerator is presented for the first time. The longitudinal field scales as I{sub P}{sup 0.623{+-}0.007}, in good agreement with nonlinear wakefield theory ({approx}I{sub P}{sup 0.5}), while the unloaded transformer ratio is shown to be greater than unity and scales weakly with the bunch current. The effect of bunch head erosion on both parameters is also discussed.

  12. SU-E-T-472: Characterization of the Very High Energy Electrons, ISO - 250 MeV (VHEE) Beam Generated by ALPHA-X Laser Wakefield Accelerator Beam Line for Utilization in Monte Carlo Simulation for Biomedical Experiment Planning.

    PubMed

    Moskvin, V; Subiel, A; Desrosiers, C; Wiggins, M; Maryanski, M; Mendonca, M; Boyd, M; Sorensen, A; Cipiccia, S; Issac, R; Welsh, G; Brunetti, E; Aniculaesei, C; Jaroszynski, D A

    2012-06-01

    Progress in the development of compact high-energy pulsed laser- plasma wakefield accelerators is opening up the potential for using Very High Energy Electron (VHEEs) beams in the range of 150 - 250 MeV for biomedical studies. Initial experiments using VHEE for this purpose have been carried out using the ALPHA-X laser-plasma wakefield accelerator beam line at the University of Strathclyde, Glasgow, UK. The purpose of this investigation is to use Monte Carlo simulations to plan experiments and compare with characterization of the interaction of the VHEE beam using a dosimeter. An experiment using the VHEE beam to irradiate a muscle-equivalent BANG polymer gel dosimeter has been carried out. Simulations have been used to prepare for the experiments. These were undertaken using the expected average energy for a pulse set and an energy spread approximated by Gaussian distribution. The model was implemented in FLUKA Monte Carlo code with follow up modeling using the Geant4 toolkit. The results have been compared with 1mm̂3 voxel laser CT based measurements of the dose deposited in the BANG dosimeter and with measurement of the induced radioactivity. The results of the measured dose from induced radioactivity have been compared with data from the FLUKA simulations. The beam model based on an average energy of particles in irradiation gives an acceptable estimate of the induced radioactivity and the dose deposited in the BANG dosimeter. Comparison with the dosimeter scanned profiles shows that the structure of the spectra of VHEE beams in the experiment and secondary scattered particles in the beam line should be accounted for in any model. Such model description of the VHEE beam for the ALPHA-X beam line has been developed. Monte Carlo simulations using the FLUKA code is an efficient way to plan a VHEE experiment and analyze data from measurements. © 2012 American Association of Physicists in Medicine.

  13. A self-focusing, high transformer ratio, collinear plasma dielectric wakefield accelerator driven by a ramped bunch train

    NASA Astrophysics Data System (ADS)

    Sotnikov, Gennadij V.; Marshall, Thomas C.; Shchelkunov, Sergey V.; Hirshfield, Jay L.

    2017-03-01

    New results of studies of wakefield excitation by a ramped bunch train in a collinear, single-channel dielectriclined THz-wakefield accelerator structure that is filled with a low-temperature plasma are presented. A novel ramped train of drive bunches, together with plasma filling part of the transport channel, makes possible substantial improvement of the transformer ratio of the multimode collinear device to 6:1 while the plasma could stabilize the transverse motion of the drive and witness bunches.

  14. 3-D Simulations of Plasma Wakefield Acceleration with Non-Idealized Plasmas and Beams

    SciTech Connect

    Deng, S.; Katsouleas, T.; Lee, S.; Muggli, P.; Mori, W.B.; Hemker, R.; Ren, C.; Huang, C.; Dodd, E.; Blue, B.E.; Clayton, C.E.; Joshi, C.; Wang, S.; Decker, F.J.; Hogan, M.J.; Iverson, R.H.; O'Connell, C.; Raimondi, P.; Walz, D.; /SLAC

    2005-09-27

    3-D Particle-in-cell OSIRIS simulations of the current E-162 Plasma Wakefield Accelerator Experiment are presented in which a number of non-ideal conditions are modeled simultaneously. These include tilts on the beam in both planes, asymmetric beam emittance, beam energy spread and plasma inhomogeneities both longitudinally and transverse to the beam axis. The relative importance of the non-ideal conditions is discussed and a worst case estimate of the effect of these on energy gain is obtained. The simulation output is then propagated through the downstream optics, drift spaces and apertures leading to the experimental diagnostics to provide insight into the differences between actual beam conditions and what is measured. The work represents a milestone in the level of detail of simulation comparisons to plasma experiments.

  15. Local thermodynamic equilibrium in rapidly heated high energy density plasmas

    SciTech Connect

    Aslanyan, V.; Tallents, G. J.

    2014-06-15

    Emission spectra and the dynamics of high energy density plasmas created by optical and Free Electron Lasers (FELs) depend on the populations of atomic levels. Calculations of plasma emission and ionization may be simplified by assuming Local Thermodynamic Equilibrium (LTE), where populations are given by the Saha-Boltzmann equation. LTE can be achieved at high densities when collisional processes are much more significant than radiative processes, but may not be valid if plasma conditions change rapidly. A collisional-radiative model has been used to calculate the times taken by carbon and iron plasmas to reach LTE at varying densities and heating rates. The effect of different energy deposition methods, as well as Ionization Potential Depression are explored. This work shows regimes in rapidly changing plasmas, such as those created by optical lasers and FELs, where the use of LTE is justified, because timescales for plasma changes are significantly longer than the times needed to achieve an LTE ionization balance.

  16. Emittance and Current of Electrons Trapped in a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, N.; Blumenfeld, I.; Decker, F. J.; Hogan, M. J.; Ischebeck, R.; Iverson, R. H.; Siemann, R. H.; Walz, D. R.; Clayton, C. E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W. B.; Zhou, M.; Katsouleas, T.; Muggli, P.; Oz, E.; Martins, S.

    2009-01-22

    In recent experiments plasma electrons became trapped in a plasma wakefield accelerator (PWFA). The transverse size of these trapped electrons on a downstream diagnostic yields an upper limit measurement of transverse normalized emittance divided by peak current, {epsilon}{sub N,{sub x}}/I. The lowest upper limit for {epsilon}{sub N,{sub x}}/I measured in the experiment is 1.3{center_dot}10{sup -10} m/A.

  17. Wakefield accelerators

    SciTech Connect

    Simpson, J.D.

    1990-01-01

    The search for new methods to accelerate particle beams to high energy using high gradients has resulted in a number of candidate schemes. One of these, wakefield acceleration, has been the subject of considerable R D in recent years. This effort has resulted in successful proof of principle experiments and in increased understanding of many of the practical aspects of the technique. Some wakefield basics plus the status of existing and proposed experimental work is discussed, along with speculations on the future of wake field acceleration. 10 refs., 6 figs.

  18. Injection and acceleration of electron bunch in a plasma wakefield produced by a chirped laser pulse

    SciTech Connect

    Afhami, Saeedeh; Eslami, Esmaeil

    2014-06-15

    An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wakefield which can trap and accelerate charged particles up to GeV. One-dimensional analysis of electron injection, trapping, and acceleration by different chirped pulses propagating in plasma is investigated numerically. In this paper, we inject electron bunches in front of the chirped pulses. It is indicated that periodical chirped laser pulse can trap electrons earlier than other pulses. It is shown that periodical chirped laser pulses lead to decrease the minimum momentum necessary to trap the electrons. This is due to the fact that periodical chirped laser pulses are globally much efficient than nonchirped pulses in the wakefield generation. It is found that chirped laser pulses could lead to much larger electron energy than that of nonchirped pulses. Relative energy spread has a lower value in the case of periodical chirped laser pulses.

  19. Ion Motion Induced Emittance Growth of Matched Electron Beams in Plasma Wakefields

    DOE PAGES

    An, Weiming; Lu, Wei; Huang, Chengkun; ...

    2017-06-14

    Plasma-based acceleration is being considered as the basis for building a future linear collider. Nonlinear plasma wakefields have ideal properties for accelerating and focusing electron beams. Preservation of the emittance of nano-Coulomb beams with nanometer scale matched spot sizes in these wakefields remains a critical issue due to ion motion caused by their large space charge forces. We use fully resolved quasistatic particle-in-cell simulations of electron beams in hydrogen and lithium plasmas, including when the accelerated beam has different emittances in the two transverse planes. The projected emittance initially grows and rapidly saturates with a maximum emittance growth of lessmore » than 80% in hydrogen and 20% in lithium. The use of overfocused beams is found to dramatically reduce the emittance growth. In conclusion, the underlying physics that leads to the lower than expected emittance growth is elucidated.« less

  20. Progress Toward E-157: A 1 GeV Plasma Wakefield Accelerator

    SciTech Connect

    Assmann, R

    1999-07-07

    A plasma based wakefield acceleration (PWFA) experiment, scheduled to run this summer, will accelerate parts of a 28.5 GeV bunch from the SLAC linac by up to 1 GeV over a length of 1 meter. A single 28.5 GeV bunch will both induce the wakefields in the one meter long plasma and witness the resulting acceleration fields. The experiment will explore and further develop the techniques that are needed to apply high-gradient PWFA to large scale accelerators. This paper summarizes the goals of the first round of experiments as well as the status of the individual components: construction and diagnosis of the homogeneous lithium oven plasma source and associated ionization laser, commissioning of the electron beam, simulated performance of the electron beam energy measurement, and first PIC simulations of the full meter long experiment.

  1. Ion Motion Induced Emittance Growth of Matched Electron Beams in Plasma Wakefields

    NASA Astrophysics Data System (ADS)

    An, Weiming; Lu, Wei; Huang, Chengkun; Xu, Xinlu; Hogan, Mark J.; Joshi, Chan; Mori, Warren B.

    2017-06-01

    Plasma-based acceleration is being considered as the basis for building a future linear collider. Nonlinear plasma wakefields have ideal properties for accelerating and focusing electron beams. Preservation of the emittance of nano-Coulomb beams with nanometer scale matched spot sizes in these wakefields remains a critical issue due to ion motion caused by their large space charge forces. We use fully resolved quasistatic particle-in-cell simulations of electron beams in hydrogen and lithium plasmas, including when the accelerated beam has different emittances in the two transverse planes. The projected emittance initially grows and rapidly saturates with a maximum emittance growth of less than 80% in hydrogen and 20% in lithium. The use of overfocused beams is found to dramatically reduce the emittance growth. The underlying physics that leads to the lower than expected emittance growth is elucidated.

  2. Collective effects on the wakefield and stopping power of an ion beam pulse in plasmas

    SciTech Connect

    Zhang, Ling-yu; Zhao, Xiao-ying; Qi, Xin E-mail: duanws@nwnu.edu.cn Duan, Wen-shan E-mail: duanws@nwnu.edu.cn Xiao, Guo-qing; Yang, Lei E-mail: duanws@nwnu.edu.cn

    2015-05-15

    A two-dimensional (2D) particle-in-cell simulation is carried out to study the collective effects on the wakefield and stopping power for a hydrogen ion beam pulse propagation in hydrogen plasmas. The dependence of collective effects on the beam velocity and density is obtained and discussed. For the beam velocity, it is found that the collective effects have the strongest impact on the wakefield as well as the stopping power in the case of the intermediate beam velocities, in which the stopping power is also the largest. For the beam density, it is found that at low beam densities, the collective contribution to the stopping power increase linearly with the increase of the beam density, which corresponds well to the results calculated using the dielectric theory. However, at high beam densities, our results show that after reaching a maximum value, the collective contribution to the stopping power starts to decrease significantly with the increase of the beam density. Besides, at high beam densities, the wakefield loses typical V-shaped cone structures, and the wavelength of the oscillation wakefield increases as the beam density increases.

  3. Laser-Plasma Interactions in High-Energy-Density Plasmas

    SciTech Connect

    Baldis, H

    2006-10-17

    High temperature hohlraums (HTH) are designed to reach high radiation temperatures by coupling a maximum amount of laser energy into a small target in a short time. These 400-800 {micro}m diameter gold cylinders rapidly fill with hot plasma during irradiation with multiple beams in 1ns laser pulses. The high-Z plasmas are dense, (electron density, n{sub e}/n{sub c} {approx} 0.1-0.4), hot (electron temperature, T{sub e} {approx} 10keV) and are bathed in a high-temperature radiation field (radiation temperature, T{sub rad} {approx} 300eV). Here n{sub c}, the critical density, equals 9 x 10{sup 21}/cm{sup 3}. The laser beams heating this plasma are intense ({approx} 10{sup 15} - 10{sup 17} W/cm{sup 2}). The coupling of the laser to the plasma is a rich regime for Laser-Plasma Interaction (LPI) physics. The LPI mechanisms in this study include beam deflection and forward scattering. In order to understand the LPI mechanisms, the plasma parameters must be known. An L-band spectrometer is used to measure the and electron temperature. A ride-along experiment is to develop the x-radiation emitted by the thin back wall of the half-hohlraum into a thermal radiation source.

  4. High energy density Z-pinch plasmas using flow stabilization

    SciTech Connect

    Shumlak, U. Golingo, R. P. Nelson, B. A. Bowers, C. A. Doty, S. A. Forbes, E. G. Hughes, M. C. Kim, B. Knecht, S. D. Lambert, K. K. Lowrie, W. Ross, M. P. Weed, J. R.

    2014-12-15

    The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes – Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and

  5. Summary report of working group 1: Laser-plasma wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Gonsalves, Anthony; Pollock, Bradley; Lu, Wei

    2017-03-01

    The work presented in the laser-plasma acceleration working group at the 2016 Advanced Accelerator Concepts (AAC) Workshop is summarized. Some of the highlights include: direct visualization of the electric and magnetic fields using a LPA (laser plasma accelerator) electron probe, offering transverse snapshots of the wakefield even for very low density; first demonstration of multi-pulse LPA and wakefield cancellation with a trailing pulse (first step to energy recovery); and control over the shock front angle to optimize density transition injection, which provides stable and low-energy-spread beams that are critical for increasing the efficiency of the recently presented staged LPA. Interesting ongoing and future work discussed included LPAs driven by CO2 lasers and scaling to 10 GeV with and without optical guiding. Further details on each of these topics can be found in the respective papers in these Proceedings.

  6. Summary of Working Group 1: Laser Plasma Wakefield Accelerators

    NASA Astrophysics Data System (ADS)

    Krushelnick, Karl; Kaganovich, Dmitri; Gonsalves, Anthony

    2009-01-01

    There have been many significant experimental and theoretical advances recently with regard to the production of relativistic electron beams using laser wakefield accelerators (LWFA) driven by high power short pulse lasers. In particular, there has been an explosion of interest in this field following the discovery of methods to generate such beams with low energy spread. In recent work by many groups around the world the energy and quality of these beams has been improved and a more complete understanding of the "bubble" regime of electron acceleration has been obtained, enabling a significant improvement in the output electron beam stability. The 2008 Advanced Accelerator Concepts workshop in Santa Cruz CA brought together the leading groups engaged in this research from around the world. This paper will summarize the major results presented at the conference. Further details on the work described here can be found in the other related papers in these proceedings.

  7. Summary of Working Group 1: Laser Plasma Wakefield Accelerators

    SciTech Connect

    Krushelnick, Karl; Kaganovich, Dmitri; Gonsalves, Anthony

    2009-01-22

    There have been many significant experimental and theoretical advances recently with regard to the production of relativistic electron beams using laser wakefield accelerators (LWFA) driven by high power short pulse lasers. In particular, there has been an explosion of interest in this field following the discovery of methods to generate such beams with low energy spread. In recent work by many groups around the world the energy and quality of these beams has been improved and a more complete understanding of the 'bubble' regime of electron acceleration has been obtained, enabling a significant improvement in the output electron beam stability. The 2008 Advanced Accelerator Concepts workshop in Santa Cruz CA brought together the leading groups engaged in this research from around the world. This paper will summarize the major results presented at the conference. Further details on the work described here can be found in the other related papers in these proceedings.

  8. Two-Color Laser High-Harmonic Generation in Cavitated Plasma Wakefields

    SciTech Connect

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Leemans, Wim

    2016-10-03

    A method is proposed for producing coherent x-rays via high-harmonic generation using a laser interacting with highly-stripped ions in cavitated plasma wakefields. Two laser pulses of different colors are employed: a long-wavelength pulse for cavitation and a short-wavelength pulse for harmonic generation. This method enables efficient laser harmonic generation in the sub-nm wavelength regime.

  9. Electron Bunch Length Measurements in the E-167 Plasma Wakefield Experiment

    SciTech Connect

    Blumenfeld, Ian; Berry, Melissa; Decker, Franz-Josef; Hogan, Mark J.; Ischebeck, Rasmus; Iverson, Richard; Kirby, Neil; Siemann, Robert H.; Walz, Dieter; Zacherl, Walter; Auerbach, David; Clayton, Christopher E.; Huang, Chengkun; Johnson, Devon; Joshi, Chandrashekhar; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; Zhou, Miaomiao; Katsouleas, Thomas

    2006-11-27

    Bunch length is of prime importance to beam driven plasma wakefield acceleration experiments due to its inverse relationship to the amplitude of the accelerating wake. We present here a summary of work done by the E167 collaboration measuring the SLAC ultra-short bunches via autocorrelation of coherent transition radiation. We have studied material transmission properties and improved our autocorrelation traces using materials with better spectral characteristics.

  10. Frontiers in plasma science: a high energy density perspective

    NASA Astrophysics Data System (ADS)

    Remington, Bruce

    2015-11-01

    The potential for ground-breaking research in plasma physics in high energy density (HED) regimes is compelling. The combination of HED facilities around the world spanning microjoules to megajoules, with time scales ranging from femtoseconds to microseconds enables new regimes of plasma science to be experimentally probed. The ability to shock and ramp compress samples and simultaneously probe them allows dense, strongly coupled, Fermi degenerate plasmas relevant to planetary interiors to be studied. Shock driven hydrodynamic instabilities evolving into turbulent flows relevant to the dynamics of exploding stars are being probed. The physics and dynamics of magnetized plasmas relevant to astrophysics and inertial confinement fusion are also starting to be studied. High temperature, high velocity interacting flows are being probed for evidence of astrophysical collisionless shock formation. Turbulent, high magnetic Reynolds number flows are being experimentally generated to look for evidence of the turbulent magnetic dynamo effect. And new results from thermonuclear reactions in dense hot plasmas relevant to stellar interiors are starting to emerge. A selection of examples providing a compelling vision for frontier plasma science in the coming decade will be presented. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  11. Phase velocity and particle injection in a self-modulated proton-driven plasma wakefield accelerator.

    PubMed

    Pukhov, A; Kumar, N; Tückmantel, T; Upadhyay, A; Lotov, K; Muggli, P; Khudik, V; Siemon, C; Shvets, G

    2011-09-30

    It is demonstrated that the performance of the self-modulated proton driver plasma wakefield accelerator is strongly affected by the reduced phase velocity of the plasma wave. Using analytical theory and particle-in-cell simulations, we show that the reduction is largest during the linear stage of self-modulation. As the instability nonlinearly saturates, the phase velocity approaches that of the driver. The deleterious effects of the wake's dynamics on the maximum energy gain of accelerated electrons can be avoided using side-injections of electrons, or by controlling the wake's phase velocity by smooth plasma density gradients.

  12. Phase Velocity and Particle Injection in a Self-Modulated Proton-Driven Plasma Wakefield Accelerator

    SciTech Connect

    Pukhov, A.; Kumar, N.; Tueckmantel, T.; Upadhyay, A.; Lotov, K.; Muggli, P.; Khudik, V.; Siemon, C.; Shvets, G.

    2011-09-30

    It is demonstrated that the performance of the self-modulated proton driver plasma wakefield accelerator is strongly affected by the reduced phase velocity of the plasma wave. Using analytical theory and particle-in-cell simulations, we show that the reduction is largest during the linear stage of self-modulation. As the instability nonlinearly saturates, the phase velocity approaches that of the driver. The deleterious effects of the wake's dynamics on the maximum energy gain of accelerated electrons can be avoided using side-injections of electrons, or by controlling the wake's phase velocity by smooth plasma density gradients.

  13. DOE-HEP Final Report for 2013-2016: Studies of plasma wakefields for high repetition-rate plasma collider, and Theoretical study of laser-plasma proton and ion acceleration

    SciTech Connect

    Katsouleas, Thomas C.; Sahai, Aakash A.

    2016-08-08

    There were two goals for this funded project: 1. Studies of plasma wakefields for high repetition-rate plasma collider, and 2. Theoretical study of laser-plasma proton and ion acceleration. For goal 1, an analytical model was developed to determine the ion-motion resulting from the interaction of non-linear “blow-out” wakefields excited by beam-plasma and laser-plasma interactions. This is key to understanding the state of the plasma at timescales of 1 picosecond to a few 10s of picoseconds behind the driver-energy pulse. More information can be found in the document. For goal 2, we analytically and computationally analyzed the longitudinal instabilities of the laser-plasma interactions at the critical layer. Specifically, the process of “Doppler-shifted Ponderomotive bunching” is significant to eliminate the very high-energy spread and understand the importance of chirping the laser pulse frequency. We intend to publish the results of the mixing process in 2-D. We intend to publish Chirp-induced transparency. More information can be found in the document.

  14. High energy components and collective modes in thermonuclear plasmas

    SciTech Connect

    Coppi, B.; Cowley, S.; Detragiache, P.; Kulsrud, R.; Pegoraro, F.

    1986-02-01

    The theory of a class of collective modes of a thermonuclear magnetically confined plasma, with frequencies in the range of the ion cyclotron frequency and of its harmonics, is presented. These modes can be excited by their resonant cyclotron interaction with a plasma component of relatively high energy particles characterized by a strongly anisotropic distribution in velocity space. Normal modes that are spatially localized by the inhomogeneity of the plasma density are found. This ensures that the energy gained by their resonant interaction is not convected away. The mode spatial localization can be significantly altered by the magnetic field inhomogeneity for a given class of plasma density profiles. Special attention is devoted to the case of a spin polarized plasma, where the charged products of fusion reactions are anisotropically distributed. We show that for the mode of polarization that enhances nuclear reaction rates the tritium will be rapidly depolarized to toroidal configurations with relatively mild gradients of the confining magnetic field. 18 refs., 9 figs.

  15. Hybrid Laser Wakefield and Direct Laser Plasma Accelerator in the Plasma Bubble Regime

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Khudik, Vladimir; Pukhov, Alexander; Shvets, Gennady

    2015-11-01

    The concept of hybrid laser wakefield and direct laser plasma accelerator in plasma bubble regime was recently proposed. The advantage of this approach is two-fold: (a) electrons' energy gains from the laser and from the wake add up, and (b) dephasing is slowed down. Using 2D VLPL simulations, we will demonstrate that two conditions must be met by the electrons injected into the hybrid accelerator: (1) strong spatial overlap with the laser field, and (2) large initial transverse energy. The firstcondition is met by employing two laser pulses: one to produce a plasma bubble, and the second time-delayed pulse to interact with the injected electrons. We will show that there are two approaches to meeting the second condition: self-injection using an engineered density bump and ionization-injection. The criteria for direct laser acceleration of ionization-injected electrons will be discussed. Combinations of laser pulses with different wavelengths will also be considered. This work is supported by the US DOE grant DE-SC0007889 and the AFOSR grant FA9550-14-1-0045.

  16. Plasma wakefield acceleration studies using the quasi-static code WAKE

    SciTech Connect

    Jain, Neeraj; Palastro, John; Antonsen, T. M.; Mori, Warren B.; An, Weiming

    2015-02-15

    The quasi-static code WAKE [P. Mora and T. Antonsen, Phys. Plasmas 4, 217 (1997)] is upgraded to model the propagation of an ultra-relativistic charged particle beam through a warm background plasma in plasma wakefield acceleration. The upgraded code is benchmarked against the full particle-in-cell code OSIRIS [Hemker et al., Phys. Rev. Spec. Top. Accel. Beams 3, 061301 (2000)] and the quasi-static code QuickPIC [Huang et al., J. Comput. Phys. 217, 658 (2006)]. The effect of non-zero plasma temperature on the peak accelerating electric field is studied for a two bunch electron beam driver with parameters corresponding to the plasma wakefield acceleration experiments at Facilities for Accelerator Science and Experimental Test Beams. It is shown that plasma temperature does not affect the energy gain and spread of the accelerated particles despite suppressing the peak accelerating electric field. The role of plasma temperature in improving the numerical convergence of the electric field with the grid resolution is discussed.

  17. High-efficiency acceleration in the laser wakefield by a linearly increasing plasma density

    SciTech Connect

    Dong, Kegong; Wu, Yuchi; Zhu, Bin; Zhang, Zhimeng; Zhao, Zongqing; Zhou, Weimin; Hong, Wei; Cao, Leifeng; Gu, Yuqiu

    2014-12-15

    The acceleration length and the peak energy of the electron beam are limited by the dephasing effect in the laser wakefield acceleration with uniform plasma density. Based on 2D-3V particle in cell simulations, the effects of a linearly increasing plasma density on the electron acceleration are investigated broadly. Comparing with the uniform plasma density, because of the prolongation of the acceleration length and the gradually increasing accelerating field due to the increasing plasma density, the electron beam energy is twice higher in moderate nonlinear wakefield regime. Because of the lower plasma density, the linearly increasing plasma density can also avoid the dark current caused by additional injection. At the optimal acceleration length, the electron energy can be increased from 350 MeV (uniform) to 760 MeV (linearly increasing) with the energy spread of 1.8%, the beam duration is 5 fs and the beam waist is 1.25 μm. This linearly increasing plasma density distribution can be achieved by a capillary with special gas-filled structure, and is much more suitable for experiment.

  18. Study of Volumetrically Heated Ultra-High Energy Density Plasmas

    SciTech Connect

    Rocca, Jorge J.

    2016-10-27

    Heating dense matter to millions of degrees is important for applications, but requires complex and expensive methods. The major goal of the project was to demonstrate using a compact laser the creation of a new ultra-high energy density plasma regime characterized by simultaneous extremely high temperature and high density, and to study it combining experimental measurements and advanced simulations. We have demonstrated that trapping of intense femtosecond laser pulses deep within ordered nanowire arrays can heat near solid density matter into a new ultra hot plasma regime. Extreme electron densities, and temperatures of several tens of million degrees were achieved using laser pulses of only 0.5 J energy from a compact laser. Our x-ray spectra and simulations showed that extremely highly ionized plasma volumes several micrometers in depth are generated by irradiation of gold and Nickel nanowire arrays with femtosecond laser pulses of relativistic intensities. We obtained extraordinarily high degrees of ionization (e.g. we peeled 52 electrons from gold atoms, and up to 26 electrons from nickel atoms). In the process we generated Gigabar pressures only exceeded in the central hot spot of highly compressed thermonuclear fusion plasmas.. The plasma created after the dissolved wires expand, collide, and thermalize, is computed to have a thermal energy density of 0.3 GJ cm-3 and a pressure of 1-2 Gigabar. These are pressures only exceeded in highly compressed thermonuclear fusion plasmas. Scaling these results to higher laser intensities promises to create plasmas with temperatures and pressures exceeding those in the center of the sun.

  19. Wakefield-induced ionization injection in beam-driven plasma accelerators

    NASA Astrophysics Data System (ADS)

    Martinez de la Ossa, A.; Mehrling, T. J.; Schaper, L.; Streeter, M. J. V.; Osterhoff, J.

    2015-09-01

    We present a detailed analysis of the features and capabilities of Wakefield-Induced Ionization (WII) injection in the blowout regime of beam driven plasma accelerators. This mechanism exploits the electric wakefields to ionize electrons from a dopant gas and trap them in a well-defined region of the accelerating and focusing wake phase, leading to the formation of high-quality witness-bunches [Martinez de la Ossa et al., Phys. Rev. Lett. 111, 245003 (2013)]. The electron-beam drivers must feature high-peak currents ( Ib 0 ≳ 8.5 kA ) and a duration comparable to the plasma wavelength to excite plasma waves in the blowout regime and enable WII injection. In this regime, the disparity of the magnitude of the electric field in the driver region and the electric field in the rear of the ion cavity allows for the selective ionization and subsequent trapping from a narrow phase interval. The witness bunches generated in this manner feature a short duration and small values of the normalized transverse emittance ( k p σ z ˜ k p ɛ n ˜ 0.1 ). In addition, we show that the amount of injected charge can be adjusted by tuning the concentration of the dopant gas species, which allows for controlled beam loading and leads to a reduction of the total energy spread of the witness beams. Electron bunches, produced in this way, fulfil the requirements to drive blowout regime plasma wakes at a higher density and to trigger WII injection in a second stage. This suggests a promising new concept of self-similar staging of WII injection in steps with increasing plasma density, giving rise to the potential of producing electron beams with unprecedented energy and brilliance from plasma-wakefield accelerators.

  20. Positron acceleration in plasma bubble wakefield driven by an ultraintense laser

    SciTech Connect

    Hou, Ya-Juan; Wan, Feng; Sang, Hai-Bo Xie, Bai-Song

    2016-01-15

    The dynamics of positrons accelerating in electron-positron-ion plasma bubble fields driven by an ultraintense laser is investigated. The bubble wakefield is obtained theoretically when laser pulses are propagating in the electron-positron-ion plasma. To restrict the positrons transversely, an electron beam is injected. Acceleration regions and non-acceleration ones of positrons are obtained by the numerical simulation. It is found that the ponderomotive force causes the fluctuation of the positrons momenta, which results in the trapping of them at a lower ion density. The energy gaining of the accelerated positrons is demonstrated, which is helpful for practical applications.

  1. Generation of high-field narrowband terahertz radiation by counterpropagating plasma wakefields

    NASA Astrophysics Data System (ADS)

    Timofeev, I. V.; Annenkov, V. V.; Volchok, E. P.

    2017-10-01

    It is found that nonlinear interaction of plasma wakefields driven by counterpropagating laser or particle beams can efficiently generate high-power electromagnetic radiation at the second harmonic of the plasma frequency. Using a simple analytical theory and particle-in-cell simulations, we show that this phenomenon can be attractive for producing high-field ( ˜10 MV/cm) tunable terahertz radiation with a narrow line width. For laser drivers produced by existing petawatt-class systems, this nonlinear process opens the way to the generation of gigawatt, multi-millijoule terahertz pulses which are not presently available for any other generating schemes.

  2. Multi-GeV energy gain in a plasma-wakefield accelerator.

    PubMed

    Hogan, M J; Barnes, C D; Clayton, C E; Decker, F J; Deng, S; Emma, P; Huang, C; Iverson, R H; Johnson, D K; Joshi, C; Katsouleas, T; Krejcik, P; Lu, W; Marsh, K A; Mori, W B; Muggli, P; O'Connell, C L; Oz, E; Siemann, R H; Walz, D

    2005-07-29

    A plasma-wakefield accelerator has accelerated particles by over 2.7 GeV in a 10 cm long plasma module. A 28.5 GeV electron beam with 1.8 x 10(10) electrons is compressed to 20 microm longitudinally and focused to a transverse spot size of 10 microm at the entrance of a 10 cm long column of lithium vapor with density 2.8 x 10(17) atoms/cm3. The electron bunch fully ionizes the lithium vapor to create a plasma and then expels the plasma electrons. These electrons return one-half plasma period later driving a large amplitude plasma wake that in turn accelerates particles in the back of the bunch by more than 2.7 GeV.

  3. Electron self-injection in the proton-driven-plasma-wakefield acceleration

    SciTech Connect

    Hu, Zhang-Hu; Wang, You-Nian

    2013-12-15

    The self-injection process of plasma electrons in the proton-driven-plasma-wakefield acceleration scheme is investigated using a two-dimensional, electromagnetic particle-in-cell method. Plasma electrons are self-injected into the back of the first acceleration bucket during the initial bubble formation period, where the wake phase velocity is low enough to trap sufficient electrons. Most of the self-injected electrons are initially located within a distance of the skin depth c/ω{sub pe} to the beam axis. A decrease (or increase) in the beam radius (or length) leads to a significant reduction in the total charges of self-injected electron bunch. Compared to the uniform plasma, the energy spread, emittance and total charges of the self-injected bunch are reduced in the plasma channel case, due to a reduced injection of plasma electrons that initially located further away from the beam axis.

  4. Simulation of ionization effects for high-density positron drivers in future plasma wakefield experiments

    SciTech Connect

    Bruhwiler, D.L.; Dimitrov, D.A.; Cary, J.R.; Esarey, E.; Leemans, W.P.

    2003-05-12

    The plasma wakefield accelerator (PWFA) concept has been proposed as a potential energy doubler for present or future electron-positron colliders. Recent particle-in-cell (PIC) simulations have shown that the self-fields of the required electron beam driver can tunnel ionize neutral Li, leading to plasma wake dynamics differing significantly from that of a preionized plasma. It has also been shown, for the case of a preionized plasma, that the plasma wake of a positron driver differs strongly from that of an electron driver. We will present new PIC simulations, using the OOPIC code, showing the effects of tunneling ionization on the plasma wake generated by high-density positron drivers. The results will be compared to previous work on electron drivers with tunneling ionization and positron drivers without ionization. Parameters relevant to the energy doubler and the upcoming E-164x experiment at the Stanford Linear Accelerator Center will be considered.

  5. Plasma polymerized high energy density dielectric films for capacitors

    NASA Technical Reports Server (NTRS)

    Yamagishi, F. G.

    1983-01-01

    High energy density polymeric dielectric films were prepared by plasma polymerization of a variety of gaseous monomers. This technique gives thin, reproducible, pinhole free, conformable, adherent, and insoluble coatings and overcomes the processing problems found in the preparation of thin films with bulk polymers. Thus, devices are prepared completely in a vacuum environment. The plasma polymerized films prepared all showed dielectric strengths of greater than 1000 kV/cm and in some cases values of greater than 4000 kV/cm were observed. The dielectric loss of all films was generally less than 1% at frequencies below 10 kHz, but this value increased at higher frequencies. All films were self healing. The dielectric strength was a function of the polymerization technique, whereas the dielectric constant varied with the structure of the starting material. Because of the thin films used (thickness in the submicron range) surface smoothness of the metal electrodes was found to be critical in obtaining high dielectric strengths. High dielectric strength graft copolymers were also prepared. Plasma polymerized ethane was found to be thermally stable up to 150 C in the presence of air and 250 C in the absence of air. No glass transitions were observed for this material.

  6. X-ray Thomson scattering in high energy density plasmas

    SciTech Connect

    Glenzer, Siegfried H.; Redmer, Ronald

    2009-10-15

    Accurate x-ray scattering techniques to measure the physical properties of dense plasmas have been developed for applications in high energy density physics. This class of experiments produces short-lived hot dense states of matter with electron densities in the range of solid density and higher where powerful penetrating x-ray sources have become available for probing. Experiments have employed laser-based x-ray sources that provide sufficient photon numbers in narrow bandwidth spectral lines, allowing spectrally resolved x-ray scattering measurements from these plasmas. The backscattering spectrum accesses the noncollective Compton scattering regime which provides accurate diagnostic information on the temperature, density, and ionization state. The forward scattering spectrum has been shown to measure the collective plasmon oscillations. Besides extracting the standard plasma parameters, density and temperature, forward scattering yields new observables such as a direct measure of collisions and quantum effects. Dense matter theory relates scattering spectra with the dielectric function and structure factors that determine the physical properties of matter. Applications to radiation-heated and shock-compressed matter have demonstrated accurate measurements of compression and heating with up to picosecond temporal resolution. The ongoing development of suitable x-ray sources and facilities will enable experiments in a wide range of research areas including inertial confinement fusion, radiation hydrodynamics, material science, or laboratory astrophysics.

  7. CENTER FOR PULSED POWER DRIVEN HIGH ENERGY DENSITY PLASMA STUDIES

    SciTech Connect

    Professor Bruce R. Kusse; Professor David A. Hammer

    2007-04-18

    This annual report summarizes the activities of the Cornell Center for Pulsed-Power-Driven High-Energy-Density Plasma Studies, for the 12-month period October 1, 2005-September 30, 2006. This period corresponds to the first year of the two-year extension (awarded in October, 2005) to the original 3-year NNSA/DOE Cooperative Agreement with Cornell, DE-FC03-02NA00057. As such, the period covered in this report also corresponds to the fourth year of the (now) 5-year term of the Cooperative Agreement. The participants, in addition to Cornell University, include Imperial College, London (IC), the University of Nevada, Reno (UNR), the University of Rochester (UR), the Weizmann Institute of Science (WSI), and the P.N. Lebedev Physical Institute (LPI), Moscow. A listing of all faculty, technical staff and students, both graduate and undergraduate, who participated in Center research activities during the year in question is given in Appendix A.

  8. Laser Guiding and Wakefield Excitation in Plasma Channels.

    NASA Astrophysics Data System (ADS)

    Volfbeyn, Paul

    1998-11-01

    Laser driven plasma waves have been experimentally shown to sustain electric field gradients in excess of 10 GV/m. (For a review see E. Esarey et al., IEEE Trans. Plasma Sci. PS-24), 252 (1996). Laser diffraction limits the distance over which the high gradients are excited, thus placing a severe limit on the energy gain achievable in a laser plasma accelerating stage. To overcome the limitation on the acceleration distance due to laser beam diffraction, plasma channel guiding has been proposed in which, plasma channels with density minimum on axis can serve as optical guides. An overview is given of various techniques for plasma channel creation, relying on hydrodynamic shock expansion in laser heated plasmas (C.G. Durfee III and H. M. Milchberg, Phys. Rev. Lett., vol. 71, pp. 2409, (1993).) and capillary discharges. ( Y. Ehrlich, et al. Phys. Rev. Lett., vol.77, (no.20), p.4186-9 (1996).) Details of the dual laser pulse Ignitor - Heater scheme (P. Volfbeyn and W. P. Leemans, Phys. Rev. Lett., to be submitted.) will be presented, which allows creation of plasma channels in low atomic number gases, such as hydrogen. The current status of experiments on characterization of the plasma channel density profile and guiding of high intensity laser pulses will then be reviewed. These measurements are important since the density profile of plasma channels defines the modes of plasma oscillations and, therefore both the transverse (focusing) and longitudinal (accelerating) properties of the wake modes. Results of theoretical calculations of the wake modes for various plasma channel density profiles are presented, and their significance for the laser-plasma accelerator design is discussed.

  9. High-Energy Two-Stage Pulsed Plasma Thruster

    NASA Technical Reports Server (NTRS)

    Markusic, Tom

    2003-01-01

    A high-energy (28 kJ per pulse) two-stage pulsed plasma thruster (MSFC PPT-1) has been constructed and tested. The motivation of this project is to develop a high power (approximately 500 kW), high specific impulse (approximately 10000 s), highly efficient (greater than 50%) thruster for use as primary propulsion in a high power nuclear electric propulsion system. PPT-1 was designed to overcome four negative characteristics which have detracted from the utility of pulsed plasma thrusters: poor electrical efficiency, poor propellant utilization efficiency, electrode erosion, and reliability issues associated with the use of high speed gas valves and high current switches. Traditional PPTs have been plagued with poor efficiency because they have not been operated in a plasma regime that fully exploits the potential benefits of pulsed plasma acceleration by electromagnetic forces. PPTs have generally been used to accelerate low-density plasmas with long current pulses. Operation of thrusters in this plasma regime allows for the development of certain undesirable particle-kinetic effects, such as Hall effect-induced current sheet canting. PPT-1 was designed to propel a highly collisional, dense plasma that has more fluid-like properties and, hence, is more effectively pushed by a magnetic field. The high-density plasma loading into the second stage of the accelerator is achieved through the use of a dense plasma injector (first stage). The injector produces a thermal plasma, derived from a molten lithium propellant feed system, which is subsequently accelerated by the second stage using mega-amp level currents, which eject the plasma at a speed on the order of 100 kilometers per second. Traditional PPTs also suffer from dynamic efficiency losses associated with snowplow loading of distributed neutral propellant. The twostage scheme used in PPT-I allows the propellant to be loaded in a manner which more closely approximates the optimal slug loading. Lithium propellant

  10. High-Energy Two-Stage Pulsed Plasma Thruster

    NASA Technical Reports Server (NTRS)

    Markusic, Tom

    2003-01-01

    A high-energy (28 kJ per pulse) two-stage pulsed plasma thruster (MSFC PPT-1) has been constructed and tested. The motivation of this project is to develop a high power (approximately 500 kW), high specific impulse (approximately 10000 s), highly efficient (greater than 50%) thruster for use as primary propulsion in a high power nuclear electric propulsion system. PPT-1 was designed to overcome four negative characteristics which have detracted from the utility of pulsed plasma thrusters: poor electrical efficiency, poor propellant utilization efficiency, electrode erosion, and reliability issues associated with the use of high speed gas valves and high current switches. Traditional PPTs have been plagued with poor efficiency because they have not been operated in a plasma regime that fully exploits the potential benefits of pulsed plasma acceleration by electromagnetic forces. PPTs have generally been used to accelerate low-density plasmas with long current pulses. Operation of thrusters in this plasma regime allows for the development of certain undesirable particle-kinetic effects, such as Hall effect-induced current sheet canting. PPT-1 was designed to propel a highly collisional, dense plasma that has more fluid-like properties and, hence, is more effectively pushed by a magnetic field. The high-density plasma loading into the second stage of the accelerator is achieved through the use of a dense plasma injector (first stage). The injector produces a thermal plasma, derived from a molten lithium propellant feed system, which is subsequently accelerated by the second stage using mega-amp level currents, which eject the plasma at a speed on the order of 100 kilometers per second. Traditional PPTs also suffer from dynamic efficiency losses associated with snowplow loading of distributed neutral propellant. The twostage scheme used in PPT-I allows the propellant to be loaded in a manner which more closely approximates the optimal slug loading. Lithium propellant

  11. Generation of high quality electron beams via ionization injection in a plasma wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Vafaei-Najafabadi, Navid; Joshi, Chan; E217 SLAC Collaboration

    2016-10-01

    Ionization injection in a beam driven plasma wakefield accelerator has been used to generate electron beams with over 30 GeV of energy in a 130 cm of lithium plasma. The experiments were performed using the 3 nC, 20.35 GeV electron beam at the FACET facility of the SLAC National Accelerator Laboratory as the driver of the wakefield. The ionization of helium atoms in the up ramp of a lithium plasma were injected into the wake and over the length of acceleration maintained an emittance on the order of 30 mm-mrad, which was an order of magnitude smaller than the drive beam, albeit with an energy spread of 10-20%. The process of ionization injection occurs due to an increase in the electric field of the drive beam as it pinches through its betatron oscillations. Thus, this energy spread is attributed to the injection region encompassing multiple betatron oscillations. In this poster, we will present evidence through OSIRIS simulations of producing an injected beam with percent level energy spread and low emittance by designing the plasma parameters appropriately, such that the ionization injection occurs over a very limited distance of one betatron cycle. Work at UCLA was supported by the NSF Grant Number PHY-1415386 and DOE Grant Number DE-SC0010064. Work at SLAC was supported by DOE contract number DE-AC02-76SF00515. Simulations used the Hoffman cluster at UCLA.

  12. THE IRON OPACITY PROJECT: High-Energy-Density Plasma Opacities

    NASA Astrophysics Data System (ADS)

    Palay, E.; Orban, C.; Nahar, S.; Pradhan, A.; Pinnsonoault, M.; Bailey, J.

    2013-05-01

    Opacity governs radiation flow in plasma sources. Accurate opacities are needed to model unobservable laboratory and astrophysical conditions. High-energy-density (HED) plasma conditions prevalent in stellar interiors can now be recreated in the laboratory. The Z-pinch fusion device at the Sandia National Lab can reproduce temperatures and densities near the boundary where radiation transport changes from diffusion to convection inside the Sun. To benchmark theoretical opacities experiments are essential to resolve the outstanding discrepancy in solar abundances. The most common volatile elements C, N, O, Ne, etc. have been spectroscopically measured to be up to 50% lower than the standard abundances. This introduces conflict in the derived values of basic solar parameters such as the radiation/convection boundary, sound speed, and the primordial He abundance with precisely measured oscillations of the Sun through Helioseismology. A potential solution is increment of stellar opacities, which has inverse but complex relation with abundacnes, at least 30%. New iron opacity calculations include hitherto neglected atomic physics of fine structure and resonances which are largely treated as lines in existing opacities calculations. Preliminary results on radiative transitions in Ne Partial support: DOE,NSF.

  13. Generation of Gigabar Pressures for High-Energy-Density Plasmas

    NASA Astrophysics Data System (ADS)

    Theobald, W.; Betti, R.; Bose, A.; Seka, W.; Stoeckl, C.; Mangino, D.; Casner, A.; Beg, F. N.; Llor Aisa, E.; Ribeyre, X.; Wei, M. S.; Schoff, M. E.; Florido, R.; Mancini, R. C.

    2016-10-01

    Experiments on the OMEGA laser were performed to study gigabar pressures in small (50- μm-diam) Ti and Cu target samples for high-energy-density plasma applications. The samples were precisely placed (better than 10 μm) at the center of a spherical plastic matrix that is irradiated at incident laser intensities of 5 ×1015 W /cm2 . The laser launches a spherical shock wave that converges in the center in order to reach Gbar pressures in the sample. The shock convergence produces a short burst ( 30ps) of x-ray emission. Time-resolved and time-integrated x-ray spectroscopy provides the means to diagnose the plasma conditions in the sample. The time-resolved spectra are compared to predictions from radiation-hydrodynamic simulations to infer the material conditions at Gbar pressures. A second x-ray flash delayed by 600ps caused by the breakout of the rebounded shock through the outer surface of the compressed plastic was observed. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and by the Fusion Science Center under Grant No. DE-FC02-04ER54789.

  14. Laser-seeded modulation instability in a proton driver plasma wakefield accelerator

    SciTech Connect

    Siemon, Carl; Khudik, Vladimir; Austin Yi, S.; Shvets, Gennady; Pukhov, Alexander

    2013-10-15

    A new method for initiating the modulation instability (MI) of a proton beam in a proton driver plasma wakefield accelerator using a short laser pulse preceding the beam is presented. A diffracting laser pulse is used to produce a plasma wave that provides a seeding modulation of the proton bunch with the period equal to that of the plasma wave. Using the envelope description of the proton beam, this method of seeding the MI is analytically compared with the earlier suggested seeding technique that involves an abrupt truncation of the proton bunch. The full kinetic simulation of a realistic proton bunch is used to validate the analytic results. It is further used to demonstrate that a plasma density ramp placed in the early stages of the laser-seeded MI leads to its stabilization, resulting in sustained accelerating electric fields (of order several hundred MV/m) over long propagation distances (∼100–1000 m)

  15. Nonthermal Lorentzian wake-field effects on collision processes in complex dusty plasmas

    SciTech Connect

    Hong, Woo-Pyo; Jung, Young-Dae

    2014-10-15

    The influence of nonthermal Lorentzian wake-field on the electron-dust grain collision is investigated in complex dusty plasmas. The Eikonal method and the effective interaction potential are applied to obtain the Eikonal scattering phase shift, the differential Eikonal collision cross section, and the total Eikonal collision cross section as functions of the collision energy, the impact parameter, the Mach number, and the spectral index of Lorentzian plasma. It is found that the nonthermal effect enhances the Eikonal scattering phase shift and, however, suppresses the Eikonal collision cross section for the electron-dust grain in Lorentzian complex dusty plasmas. It is also found that the Eikonal scattering phase shift decreases with increasing Mach number and spectral index. In addition, the Eikonal collision cross section increases with an increase of the spectral index and Mach number in Lorentzian complex dusty plasmas.

  16. Laser-wakefield acceleration of monoenergetic electron beams in the first plasma-wave period.

    PubMed

    Mangles, S P D; Thomas, A G R; Kaluza, M C; Lundh, O; Lindau, F; Persson, A; Tsung, F S; Najmudin, Z; Mori, W B; Wahlström, C-G; Krushelnick, K

    2006-06-02

    Beam profile measurements of laser-wakefield accelerated electron bunches reveal that in the monoenergetic regime the electrons are injected and accelerated at the back of the first period of the plasma wave. With pulse durations ctau >or= lambda(p), we observe an elliptical beam profile with the axis of the ellipse parallel to the axis of the laser polarization. This increase in divergence in the laser polarization direction indicates that the electrons are accelerated within the laser pulse. Reducing the plasma density (decreasing ctau/lambda(p)) leads to a beam profile with less ellipticity, implying that the self-injection occurs at the rear of the first period of the plasma wave. This also demonstrates that the electron bunches are less than a plasma wavelength long, i.e., have a duration <25 fs. This interpretation is supported by 3D particle-in-cell simulations.

  17. Laser plasma wakefield acceleration gain enhancement by means of accelerating Bessel pulses

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Parola, A.; Di Trapani, P.; Jedrkiewicz, O.

    2017-06-01

    In this paper, we propose an approach to enhance the electron energy gain in standard laser-driven plasma wakefield accelerators, using accelerating Bessel pulses with tunable group velocity so to avoid electron dephasing. We use in the numerical simulations a one-dimensional theoretical model in the linear regime, taking advantage of the "diffraction-free" properties of the localized Bessel beam and thus neglecting transverse effects during the acceleration process. With a multistage tailoring approach, we show a gain enhancement of more than 100 with electron energies that may reach the GeV range over distances shorter than 1 m.

  18. Correlation of Beam Parameters to Decelerating Gradient in the E-167 Plasma Wakefield Acceleration Experiment

    SciTech Connect

    Blumenfeld, I.; Berry, M.; Decker, F.-J.; Hogan, M.J.; Ischebeck, R.; Iverson, R.; Kirby, N.; Siemann, R.; Walz, D.; Clayton, C.E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.B.; Zhou, M.; Katsouleas, T.C.; Muggli, P.; Oz, E.; /Southern California U.

    2007-06-27

    Recent experiments at SLAC have shown that high gradient acceleration of electrons is achievable in meter scale plasmas [1,2]. Results from these experiments show that the wakefield is sensitive to parameters in the electron beam which drives it. In the experiment the bunch length and beam waist location were varied systematically at constant charge. Here we investigate the correlation of peak beam current to the decelerating gradient. Limits on the transformer ratio will also be discussed. The results are compared to simulation.

  19. Challenges in plasma and laser wakefield accelerated beams diagnostic

    NASA Astrophysics Data System (ADS)

    Cianchi, A.; Anania, M. P.; Bellaveglia, M.; Castellano, M.; Chiadroni, E.; Ferrario, M.; Gatti, G.; Marchetti, B.; Mostacci, A.; Pompili, R.; Ronsivalle, C.; Rossi, A. R.; Serafini, L.

    2013-08-01

    The new frontier in the particle beam accelerator is the so called plasma acceleration. Using the strong electric field inside a plasma it is possible to achieve accelerating gradients in the order of magnitude larger with respect to the actual technologies. Different schemes have been proposed and several already tested, producing beams of energy of several GeV. Mainly two approaches are followed: either the beam is directly produced by the interaction of a TW/PW class laser with a gas jet or a preexisting particle beam is accelerated in a plasma channel. In both cases a precise determination of the emerging beam parameters is mandatory for the fine tuning of the devices. The measurement of these parameters, in particular the emittance, is not trivial, mainly due to the large energy spread and to the tight focusing of these beams or to the background noise produced in the plasma channel. We show the problems related to the diagnostic of this kind of beams and the proposed or already realized solutions.

  20. Multi-gigaelectronvolt acceleration of positrons in a self-loaded plasma wakefield

    SciTech Connect

    Corde, Sebastien; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Delahaye, J. P.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Lipkowitz, N.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Schmeltz, M.; Vafaei-Najafabadi, N.; Walz, D.; Yakimenko, V.; Yocky, G.; Clayton, C. E.

    2015-08-26

    New accelerator concepts must be developed to make future particle colliders more compact and affordable. The Plasma Wakefield Accelerator (PWFA) is one such concept, where the electric field of a plasma wake excited by a charged-particle bunch is used to accelerate a trailing bunch of particles. To apply plasma acceleration to particle colliders, it is imperative that both the electrons and their antimatter counterpart, the positrons, are efficiently accelerated at high fields using plasmas1. While substantial progress has recently been reported on high-field, high-efficiency acceleration of electrons in a PWFA powered by an electron bunch 2, such an electron-driven wake is unsuitable for the acceleration and focusing of a positron bunch. Here we demonstrate a new regime of PWFA where particles in the front of a single positron bunch transfer their energy to a substantial number of those in the rear of the same bunch by exciting a wakefield in the plasma. In the process, the accelerating field is altered – self-loaded – so that about a billion positrons gain five gigaelectronvolts (GeV) of energy with a narrow energy spread in a distance of just 1.3 meters. They extract about 30% of the wake’s energy and form a spectrally distinct bunch with as low as a 1.8% r.m.s. energy spread. This demonstrated ability of positron-driven plasma wakes to efficiently accelerate a significant number of positrons with a small energy spread may overcome the long-standing challenge of positron acceleration in plasma-based accelerators.

  1. Investigation of a Gas Jet-Produced Hollow Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, N; Blumenfeld, I.; Hogan, M.J.; Siemann, R.H.; Walz, D.R.; Davidson, A.W.; Huang, C.; /UCLA

    2009-05-21

    The effect of ion motion and the need for practical positron propagation in a plasma wakefield accelerator (PWFA) have incited interest in hollow plasma channels. These channels are typically assumed to be cylindrically symmetric; however, a different geometry might be easier to achieve. The introduction of an obstruction into the outlet of a high Mach number gas jet can produce two parallel slabs of gas separated by a density depression. Here, there is a detailed simulation study of the density depression created in such a system. This investigation reveals that the density depression is insufficient at the desired plasma density. However, insights from the simulations suggest another avenue for the creation of the hollow slab geometry.

  2. LCODE: A parallel quasistatic code for computationally heavy problems of plasma wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Sosedkin, A. P.; Lotov, K. V.

    2016-09-01

    LCODE is a freely distributed quasistatic 2D3V code for simulating plasma wakefield acceleration, mainly specialized at resource-efficient studies of long-term propagation of ultrarelativistic particle beams in plasmas. The beam is modeled with fully relativistic macro-particles in a simulation window copropagating with the light velocity; the plasma can be simulated with either kinetic or fluid model. Several techniques are used to obtain exceptional numerical stability and precision while maintaining high resource efficiency, enabling LCODE to simulate the evolution of long particle beams over long propagation distances even on a laptop. A recent upgrade enabled LCODE to perform the calculations in parallel. A pipeline of several LCODE processes communicating via MPI (Message-Passing Interface) is capable of executing multiple consecutive time steps of the simulation in a single pass. This approach can speed up the calculations by hundreds of times.

  3. Generation of high energy electron accelerated by using a tapered capillary discharge plasma

    NASA Astrophysics Data System (ADS)

    Kim, Minseok; Nam, Inhyuk; Lee, Taehee; Lee, Seungwoo; Suk, Hyyong

    2014-10-01

    The tapered plasma density in a gas-filled capillary waveguide can suppress the dephasing problem in laser wakefield acceleration (LWFA). As a result, the acceleration distance and the gained electron energy are expected to be increased. For this purpose, we developed a tapered capillary waveguide, which can produce a plasma density of ~ 1018 cm-3. Using this capillary discharge plasma, we performed the acceleration experiments with the high power laser system (20 TW/40 fs) constructed at GIST. In this presentation, the detailed electron acceleration experiments will be reported.

  4. Electron self-injection in a plasma wakefield accelerator in the strongly nonlinear regime due to inhomogeneous plasma density

    NASA Astrophysics Data System (ADS)

    Yi, S. A.; Khudik, V.; Ratliff, T. H.; Shvets, G.

    2011-10-01

    We study self-injection into a plasma wakefield accelerator (PWFA) in the blowout (or bubble) regime with an inhomogeneous background plasma density. Using an analytic model and particle-in-cell simulations, we explore an injection mechanism into a PWFA, where a growing bubble causes reduction of the electron Hamiltonian in the co-moving frame, which leads to electron trapping. In contrast to earlier work with steep density gradients, growth of the blowout region is caused by a slow decrease in plasma density along the propagation direction. To demonstrate this trapping mechanism, we generalize an analytic model for the wakefields inside the bubble, to derive expressions for the fields outside. With this extended model, we study the trapping of initially quiescent plasma electrons into the growing ultra-relativistic bubble, and show that a return current in the bubble sheath layer plays an important role in determining the trapped electron trajectories. We estimate the plasma density gradients and driver beam parameters required for self-injection, and compare our results with particle-in-cell simulations. This work is supported by the US DOE grants DE-FG02-04ER41321 and DE-FG02-07ER54945.

  5. Multi-gigaelectronvolt acceleration of positrons in a self-loaded plasma wakefield.

    PubMed

    Corde, S; Adli, E; Allen, J M; An, W; Clarke, C I; Clayton, C E; Delahaye, J P; Frederico, J; Gessner, S; Green, S Z; Hogan, M J; Joshi, C; Lipkowitz, N; Litos, M; Lu, W; Marsh, K A; Mori, W B; Schmeltz, M; Vafaei-Najafabadi, N; Walz, D; Yakimenko, V; Yocky, G

    2015-08-27

    Electrical breakdown sets a limit on the kinetic energy that particles in a conventional radio-frequency accelerator can reach. New accelerator concepts must be developed to achieve higher energies and to make future particle colliders more compact and affordable. The plasma wakefield accelerator (PWFA) embodies one such concept, in which the electric field of a plasma wake excited by a bunch of charged particles (such as electrons) is used to accelerate a trailing bunch of particles. To apply plasma acceleration to electron-positron colliders, it is imperative that both the electrons and their antimatter counterpart, the positrons, are efficiently accelerated at high fields using plasmas. Although substantial progress has recently been reported on high-field, high-efficiency acceleration of electrons in a PWFA powered by an electron bunch, such an electron-driven wake is unsuitable for the acceleration and focusing of a positron bunch. Here we demonstrate a new regime of PWFAs where particles in the front of a single positron bunch transfer their energy to a substantial number of those in the rear of the same bunch by exciting a wakefield in the plasma. In the process, the accelerating field is altered--'self-loaded'--so that about a billion positrons gain five gigaelectronvolts of energy with a narrow energy spread over a distance of just 1.3 metres. They extract about 30 per cent of the wake's energy and form a spectrally distinct bunch with a root-mean-square energy spread as low as 1.8 per cent. This ability to transfer energy efficiently from the front to the rear within a single positron bunch makes the PWFA scheme very attractive as an energy booster to an electron-positron collider.

  6. Analytic model of electron self-injection in a plasma wakefield accelerator in the strongly nonlinear bubble regime

    SciTech Connect

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

    2012-12-21

    Self-injection of background electrons in plasma wakefield accelerators in the highly nonlinear bubble regime is analyzed using particle-in-cell and semi-analytic modeling. It is shown that the return current in the bubble sheath layer is crucial for accurate determination of the trapped particle trajectories.

  7. External injection and acceleration of electron bunch in front of the plasma wakefield produced by a periodic chirped laser pulse

    NASA Astrophysics Data System (ADS)

    Eslami, Esmaeil; Afhami, Saeedeh

    2017-01-01

    Herein, we present the analytical results on the behavior of the electron bunch injected in front of the plasma wakefield produced by a chirped laser pulse. In particular, a periodic chirped pulse may produce an ultra-relativistic electron bunch with a relatively small energy spread. The electrons are trapped near the region of the first accelerating maximum of the wakefield and are compressed in both the longitudinal and transverse directions (betatron oscillation). Our results are in good agreement with the one-dimensional results recently published.

  8. Optimization of laser parameters to obtain high-energy, high-quality electron beams through laser-plasma acceleration

    SciTech Connect

    Samant, Sushil Arun; Sarkar, Deepangkar; Krishnagopal, Srinivas; Upadhyay, Ajay K.; Jha, Pallavi

    2010-10-15

    The propagation of an intense (a{sub 0}=3), short-pulse (L{approx}{lambda}{sub p}) laser through a homogeneous plasma has been investigated. Using two-dimensional simulations for a{sub 0}=3, the pulse-length and spot-size at three different plasma densities were optimized in order to get a better quality beam in laser wakefield accelerator. The study reveals that with increasing pulse-length the acceleration increases, but after a certain pulse-length (L>0.23{lambda}{sub p}) the emittance blows-up unacceptably. For spot-sizes less than that given by k{sub p0}r{sub s}=2{radical}(a{sub 0}), trapping is poor or nonexistent, and the optimal spot-size is larger. The deviation of the optimal spot-size from this formula increases as the density decreases. The efficacy of these two-dimensional simulations has been validated by running three-dimensional simulations at the highest density. It has been shown that good quality GeV-class beams can be obtained at plasma densities of {approx}10{sup 18} cm{sup -3}. The quality of the beam can be substantially improved by selecting only the high-energy peak; in this fashion an energy-spread of better than 1% and a current in tens of kA can be achieved, which are important for applications such as free-electron lasers.

  9. Colliding ionization injection in a plasma wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Wan, Y.; Zhang, C. J.; Li, F.; Wu, Y. P.; Hua, J. F.; Pai, C.-H.; Lu, W.; Gu, Y. Q.; Xu, X. L.; Joshi, C.; Mori, W. B.

    2016-03-01

    A new scheme of generating high quality electron bunches via ionization injection triggered by an counter propagating laser pulse inside a beam driven plasma wake is proposed and examined via two-dimensional particle-in-cell (PIC) simulations. This scheme has two major advantages: first, the injection distance is easily tunable by varying the launching time or the focal position of the laser pulse; second, the electrons in each injected slice are released at nearly the same time. Both factors can significantly reduce the phase space mixing during the ionization injection process (Xu et al 2014 Phys. Rev. Lett. 112 035003, Xu et al 2014 Phys. Rev. Spec. Top.: Accel. Beams 17 061301, Li et al 2013 Phys. Rev. Lett. 111 015003), leading to very small energy spreads (˜10 keV for slice,˜100 keV for the whole bunch) and very small normalized emittance (˜few nm). As an example, a 4.5 fs 0.4 pC electron bunch with normalized emittance of 3.3 nm, slice energy spread of 13 keV, absolute energy spread of 80 keV, and a brightness of 7.2× {{10}18} A m-2rad-2 is obtained under realistic conditions. This scheme may have potential applications for future compact coherent light sources.

  10. Positron Acceleration by Plasma Wakefields Driven by a Hollow Electron Beam

    NASA Astrophysics Data System (ADS)

    Jain, Neeraj; Antonsen, T. M.; Palastro, J. P.

    2015-11-01

    A scheme for positron plasma wakefield acceleration using hollow or donut-shaped electron driver beams is studied. An annular-shaped, electron-free region forms around the hollow driver beam, creating a favorable region (longitudinal field is accelerating and transverse field is focusing) for positron acceleration. For Facility for Advanced Accelerator Experimental Tests (FACET)-like parameters, the hollow beam driver produces accelerating gradients on the order of 10 GV /m . The accelerating gradient increases linearly with the total charge in the driver beam. Simulations show acceleration of a 23-GeV positron beam to 35.4 GeV with a maximum energy spread of 0.4% and very small emittance over a plasma length of 140 cm is possible.

  11. High-quality electron beam from laser wake-field acceleration in laser produced plasma plumes

    SciTech Connect

    Sanyasi Rao, Bobbili; Moorti, Anand; Rathore, Ranjana; Ali Chakera, Juzer; Anant Naik, Prasad; Dass Gupta, Parshotam

    2013-06-10

    Generation of highly collimated ({theta}{sub div}{approx}10 mrad), quasi-monoenergetic electron beam with peak energy 12 MeV and charge {approx}50 pC has been experimentally demonstrated from self-guided laser wake-field acceleration (LWFA) in a plasma plume produced by laser ablation of solid nylon (C{sub 12}H{sub 22}N{sub 2}O{sub 2}){sub n} target. A 7 TW, 45 fs Ti:sapphire laser system was used for LWFA, and the plasma plume forming pulse was derived from the Nd:YAG pump laser of the same system. The results show that a reproducible, high quality electron beam could be produced from this scheme which is simple, low cost and has the capability for high repetition rate operation.

  12. Transverse Emittance and Current of Multi-GeV Trapped Electrons in a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, N.; Blumenfeld, I.; Clayton, C.E.; Decker, F.J.; Hogan, M.J.; Huang, C.; Ischebeck, R.; Iverson, R.H.; Joshi, C.; Katsouleas, T.; Lu, W.; Marsh, K.A.; Martins, S.F.; Mori, W.B.; Muggli, P.; Oz, E.; Siemann, R.H.; Walz, D.R.; Zhou, M.; /UCLA

    2009-10-17

    Multi-GeV trapped electron bunches in a plasma wakefield accelerator (PWFA) are observed with normalized transverse emittance divided by peak current, {epsilon}{sub N,x}/I{sub t}, below the level of 0.2 {micro}m/kA. A theoretical model of the trapped electron emittance, developed here, indicates that emittance scales inversely with the square root of the plasma density in the nonlinear 'bubble' regime of the PWFA. This model and simulations indicate that the observed values of {epsilon}{sub N,x}/I{sub t} result from multi-GeV trapped electron bunches with emittances of a few {micro}m and multi-kA peak currents.

  13. Plasma wakefields in the quasi-nonlinear regime: Experiments at ATF

    NASA Astrophysics Data System (ADS)

    Rosenzweig, J. B.; Andonian, G.; Barber, S.; Ferrario, M.; Muggli, P.; O'Shea, B.; Sakai, Y.; Valloni, A.; Williams, O.; Xi, Y.; Yakimenko, V.

    2012-12-01

    In this work we present details of planned experiments to investigate certain aspects of the quasi non linear regime (QNL) of plasma wakefield acceleration (PWFA). In the QNL regime it is, in principal, possible to combine the benefits of both nonlinear and linear PWFA. That is, beams of high quality can be maintained through acceleration due to the complete ejection of plasma electrons from beam occupied region, while large energy gains can be achieved through use of transformer ratio increasing schemes, such as ramped bunch trains. With the addition of an short focal length PMQ triplet capable of focusing beams to the few micron scale and the ability to generate tunable bunch trains, the Accelerator Test Facility (ATF) at Brookhaven National Lab offers the unique capabilities to probe these characteristics of the QNL regime.

  14. Positron Acceleration by Plasma Wakefields Driven by a Hollow Electron Beam.

    PubMed

    Jain, Neeraj; Antonsen, T M; Palastro, J P

    2015-11-06

    A scheme for positron plasma wakefield acceleration using hollow or donut-shaped electron driver beams is studied. An annular-shaped, electron-free region forms around the hollow driver beam, creating a favorable region (longitudinal field is accelerating and transverse field is focusing) for positron acceleration. For Facility for Advanced Accelerator Experimental Tests (FACET)-like parameters, the hollow beam driver produces accelerating gradients on the order of 10  GV/m. The accelerating gradient increases linearly with the total charge in the driver beam. Simulations show acceleration of a 23-GeV positron beam to 35.4 GeV with a maximum energy spread of 0.4% and very small emittance over a plasma length of 140 cm is possible.

  15. Plasma density from Cerenkov radiation, betatron oscillations, and beam steering in a plasma wakefield experiment at 30 GeV

    SciTech Connect

    Catravas, P.; Chattopadhyay, S.; Esarey, E.; Leemans, W.P.; Assmann, R.; Decker, F.-J.; Hogan, M.J.; Iverson, R.; Siemann, R.H.; Walz, D.; Whittum, D.; Blue, B.; Clayton, C.; Joshi, C.; Marsh, K.; Mori, W.B.; Wang, S.; Katsouleas, T.; Lee, S.; Muggli, P.

    2001-01-01

    A method for using Cerenkov radiation near atomic spectral lines to measure plasma source properties for plasma wakefield applications has been discussed and experimentally verified. Because the radiation co-propagates with the electron beam, the radiation samples the source properties exactly along the path of interest with perfect temporal synchronization. Observation wavelengths were chosen with respect to the atomic resonances of the plasma source, where the relative change in the index of refraction strongly affects the Cerenkov cone angle, and permits flexible diagnostic design. The Cerenkov spatial profiles were systematically studied for a Lithium heat pipe oven as a function of oven temperature and observation wavelength. Neutral densities and plasma densities were extracted from the measurements.

  16. Demonstration of passive plasma lensing of a laser wakefield accelerated electron bunch

    SciTech Connect

    Kuschel, S.; Hollatz, D.; Heinemann, T.; Karger, O.; Schwab, M. B.; Ullmann, D.; Knetsch, A.; Seidel, A.; Rodel, C.; Yeung, M.; Leier, M.; Blinne, A.; Ding, H.; Kurz, T.; Corvan, D. J.; Savert, A.; Karsch, S.; Kaluza, M. C.; Hidding, B.; Zepf, M.

    2016-07-20

    We report on the first demonstration of passive all-optical plasma lensing using a two-stage setup. An intense femtosecond laser accelerates electrons in a laser wakefield accelerator (LWFA) to 100 MeV over millimeter length scales. By adding a second gas target behind the initial LWFA stage we introduce a robust and independently tunable plasma lens. We observe a density dependent reduction of the LWFA electron beam divergence from an initial value of 2.3 mrad, down to 1.4 mrad (rms), when the plasma lens is in operation. Such a plasma lens provides a simple and compact approach for divergence reduction well matched to the mm-scale length of the LWFA accelerator. The focusing forces are provided solely by the plasma and driven by the bunch itself only, making this a highly useful and conceptually new approach to electron beam focusing. Possible applications of this lens are not limited to laser plasma accelerators. Since no active driver is needed the passive plasma lens is also suited for high repetition rate focusing of electron bunches. As a result, its understanding is also required for modeling the evolution of the driving particle bunch in particle driven wake field acceleration.

  17. Demonstration of passive plasma lensing of a laser wakefield accelerated electron bunch

    DOE PAGES

    Kuschel, S.; Hollatz, D.; Heinemann, T.; ...

    2016-07-20

    We report on the first demonstration of passive all-optical plasma lensing using a two-stage setup. An intense femtosecond laser accelerates electrons in a laser wakefield accelerator (LWFA) to 100 MeV over millimeter length scales. By adding a second gas target behind the initial LWFA stage we introduce a robust and independently tunable plasma lens. We observe a density dependent reduction of the LWFA electron beam divergence from an initial value of 2.3 mrad, down to 1.4 mrad (rms), when the plasma lens is in operation. Such a plasma lens provides a simple and compact approach for divergence reduction well matchedmore » to the mm-scale length of the LWFA accelerator. The focusing forces are provided solely by the plasma and driven by the bunch itself only, making this a highly useful and conceptually new approach to electron beam focusing. Possible applications of this lens are not limited to laser plasma accelerators. Since no active driver is needed the passive plasma lens is also suited for high repetition rate focusing of electron bunches. As a result, its understanding is also required for modeling the evolution of the driving particle bunch in particle driven wake field acceleration.« less

  18. Synergistic Direct/Wakefield Acceleration of Plasma Electrons In the Plasma Bubble Regime Using Tailored Laser Pulses

    NASA Astrophysics Data System (ADS)

    Shvets, Gennady

    2016-10-01

    The integration of direct laser acceleration (DLA) and laser wakefield acceleration (LWFA) is a new approach to plasma-based acceleration that confers several benefits over both schemes taken separately. Such integration requires a significant portion of the laser energy (e.g., a separate laser pulse) to trail the main bubble-producing laser pulse, and resonantly interact with the trapped accelerated electrons undergoing betatron motion inside the plasma bubble. I will demonstrate how electron dephasing from the accelerating wakefield, which is one of the key limitations of LWFA, is reduced by their growing undulating motion. Moreover, the distinct energy gains from wake and the laser pulse are compounding, thereby increasing the total energy gain. Even more significant increases of the overall acceleration can be obtained by moving away from single-frequency laser format toward combining mid-infrared laser pulses for plasma bubble generation with short-wavelength trailing pulses for DLA. Various injection mechanisms, such as ionization injection, external injection, self-injection, and their advantages will also be discussed. Translating these new concepts into specific experiments will take advantage of recent technological advances in synchronizing laser and electron beams, and using multiple beamlines for producing sophisticated laser pulse formats.

  19. Accelerating Particles with Plasma

    SciTech Connect

    Litos, Michael; Hogan, Mark

    2014-11-05

    Researchers at SLAC explain how they use plasma wakefields to accelerate bunches of electrons to very high energies over only a short distance. Their experiments offer a possible path for the future of particle accelerators.

  20. Accelerating Particles with Plasma

    ScienceCinema

    Litos, Michael; Hogan, Mark

    2016-07-12

    Researchers at SLAC explain how they use plasma wakefields to accelerate bunches of electrons to very high energies over only a short distance. Their experiments offer a possible path for the future of particle accelerators.

  1. Kilohertz laser wakefield accelerator using near critical density plasmas and millijoule-level drive pulses

    NASA Astrophysics Data System (ADS)

    Goers, Andy

    2016-10-01

    Laser wakefield accelerators operating in the so-called bubble or blowout regime are typically driven by Joule-class femtosecond laser systems driving plasma waves in highly underdense plasmas (1017 -1019cm-3). While these accelerators are very promising for accelerating GeV scale, low emittance electron beams, the large energy requirements of the laser systems have so far limited them to repetition rates below 10 Hz. However, there are a variety of applications, such as ultrafast electron diffraction or high repetition rate gamma ray sources for materials characterization or medical radiography, which would benefit from lower energy (1-10 MeV) but higher repetition rate ( 1 kHz) sources of relativistic electrons. This talk will describe relativistic wakefield acceleration of electron bunches in the range 1-10 MeV, driven by a 1 kHz, 30 fs, 1-12 mJ laser system. Our results are made possible by the use of very high density cryogenic H2 and He gas jet targets yielding electron densities >1021cm-3 in thin 100 μm gas flows. At these high densities the critical power for relativistic self-focusing and the plasma wave phase velocity are greatly reduced, leading to pulse collapse and self-injection even with 1 mJ drive laser pulses. Applications of this source to ultrafast electron diffraction and gamma ray radiography will be discussed. This research supported by the U.S. Department of Energy, National Science Foundation, and Air Force Office of Scientific Research.

  2. Measurements of radiation near an atomic spectral line in a 30 GeV plasma wakefield experiment, E157.

    NASA Astrophysics Data System (ADS)

    Catravas, P.; Chattopadhyay, S.; Esarey, E. H.; Leemans, W. P.; Assmann, R.; Decker, F.-J.; Iverson, R.; Hogan, M. J.; Siemann, R. H.; Walz, D.; Whittum, D.; Blue, B.; Clayton, C.; Joshi, C.; Marsh, K. A.; Mori, W. B.; Wang, S.; Katsouleas, T.; Lee, S.; Muggli, P.

    2000-10-01

    Cerenkov radiation from a 30 GeV electron beam propagating through a Li plasma column ( ~ 10^15 cm-3, >1 meter) has been utilized to extract the column neutral and UV-laser photoionized plasma density in a plasma wakefield experiment. Narrow bandwidth cones near the 670.8 nm atomic spectral line of Lithium neutrals were studied as a function of oven temperature, observation wavelength, and timing between laser and electron beam. Neutral and plasma densities obtained with the technique are roughly in agreement with accompanying betatron oscillations and UV absorption measurements. Large increases in the number of intercepted photons were observed near strong spectral lines of Lithium neutrals and ions and were found to depend on the relative timing of the electron beam and ionizing laser. We speculate that these emissions are due to increased recombination radiation from wakefield energy dissipation through excitation and ionization of the component species.

  3. Efficient modeling of plasma wakefield acceleration in quasi-non-linear-regimes with the hybrid code Architect

    NASA Astrophysics Data System (ADS)

    Marocchino, A.; Massimo, F.; Rossi, A. R.; Chiadroni, E.; Ferrario, M.

    2016-09-01

    In this paper we present a hybrid approach aiming to assess feasible plasma wakefield acceleration working points with reduced computation resources. The growing interest for plasma wakefield acceleration and especially the need to control with increasing precision the quality of the accelerated bunch demands for more accurate and faster simulations. Particle in cell codes are the state of the art technique to simulate the underlying physics, however the run-time represents the major drawback. Architect is a hybrid code that treats the bunch kinetically and the background electron plasma as a fluid, initialising bunches in vacuum so to take into account for the transition from vacuum to plasma. Architect solves directly the Maxwell's equations on a Yee lattice. Such an approach allows us to drastically reduce run time without loss of generality or accuracy up to the weakly non linear regime.

  4. Analytic model for electromagnetic fields in the bubble regime of plasma wakefield in non-uniform plasmas

    NASA Astrophysics Data System (ADS)

    Golovanov, A. A.; Kostyukov, I. Yu.; Thomas, J.; Pukhov, A.

    2017-10-01

    Based on a model of plasma wakefield in the strongly nonlinear (bubble) regime, we develop a lowest-order perturbation theory for the components of electromagnetic fields inside and outside the bubble using the assumption of small thickness of the electron sheath on the boundary of the bubble. Unlike previous models, we derive simple explicit expressions for the components of electromagnetic fields not only in the vicinity of the center of the bubble, but in the whole volume of the bubble (including the areas of driving or accelerated bunches) as well as outside it. Moreover, we apply the results to the case of radially non-uniform plasma and, in particular, to plasma with a hollow channel. The obtained results are verified with 3D particle-in-cell simulations which show a good correspondence to our model.

  5. Optimizing density down-ramp injection for beam-driven plasma wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Martinez de la Ossa, A.; Hu, Z.; Streeter, M. J. V.; Mehrling, T. J.; Kononenko, O.; Sheeran, B.; Osterhoff, J.

    2017-09-01

    Density down-ramp (DDR) injection is a promising concept in beam-driven plasma wakefield accelerators for the generation of high-quality witness beams. We review and complement the theoretical principles of the method and employ particle-in-cell (PIC) simulations in order to determine constrains on the geometry of the density ramp and the current of the drive beam, regarding the applicability of DDR injection. Furthermore, PIC simulations are utilized to find optimized conditions for the production of high-quality beams. We find and explain the intriguing result that the injection of an increased charge by means of a steepened ramp favors the generation of beams with lower emittance. Exploiting this fact enables the production of beams with high charge (˜140 pC ), low normalized emittance (˜200 nm ) and low uncorrelated energy spread (0.3%) in sufficiently steep ramps even for drive beams with moderate peak current (˜2.5 kA ).

  6. Time-resolved measurements with streaked diffraction patterns from electrons generated in laser plasma wakefield

    NASA Astrophysics Data System (ADS)

    He, Zhaohan; Nees, John; Hou, Bixue; Krushelnick, Karl; Thomas, Alec; Beaurepaire, Benoît; Malka, Victor; Faure, Jérôme

    2013-10-01

    Femtosecond bunches of electrons with relativistic to ultra-relativistic energies can be robustly produced in laser plasma wakefield accelerators (LWFA). Scaling the electron energy down to sub-relativistic and MeV level using a millijoule laser system will make such electron source a promising candidate for ultrafast electron diffraction (UED) applications due to the intrinsic short bunch duration and perfect synchronization with the optical pump. Recent results of electron diffraction from a single crystal gold foil, using LWFA electrons driven by 8-mJ, 35-fs laser pulses at 500 Hz, will be presented. The accelerated electrons were collimated with a solenoid magnetic lens. By applying a small-angle tilt to the magnetic lens, the diffraction pattern can be streaked such that the temporal evolution is separated spatially on the detector screen after propagation. The observable time window and achievable temporal resolution are studied in pump-probe measurements of photo-induced heating on the gold foil.

  7. Efficient numerical modelling of the emittance evolution of beams with finite energy spread in plasma wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Mehrling, T. J.; Robson, R. E.; Erbe, J.-H.; Osterhoff, J.

    2016-09-01

    This paper introduces a semi-analytic numerical approach (SANA) for the rapid computation of the transverse emittance of beams with finite energy spread in plasma wakefield accelerators in the blowout regime. The SANA method is used to model the beam emittance evolution when injected into and extracted from realistic plasma profiles. Results are compared to particle-in-cell simulations, establishing the accuracy and efficiency of the procedure. In addition, it is demonstrated that the tapering of vacuum-to-plasma and plasma-to-vacuum transitions is a viable method for the mitigation of emittance growth of beams during their injection and extraction from and into plasma cells.

  8. Wakefield in a waveguide

    NASA Astrophysics Data System (ADS)

    Bliokh, Y. P.; Leopold, J. G.; Shafir, G.; Shlapakovski, A.; Krasik, Ya. E.

    2017-06-01

    The feasibility of an experiment which is being set up in our plasma laboratory to study the effect of a wakefield formed by an ultra-short (≤10-9 s) high-power (˜1 GW) microwave (10 GHz) pulse propagating in a cylindrical waveguide filled with an under-dense [(2-5) × 1010 cm-3] plasma is modeled theoretically and simulated by a particle in cell code. It is shown that the radial ponderomotive force plays a circular key role in the wakefield formation by the TM mode waveguide. The model and the simulations show that powerful microwave pulses produce a wakefield at lower plasma density and electric field gradients but larger space and time scales compared to the laser produced wakefield in plasmas, thus providing a more accessible platform for the experimental study.

  9. Exploration of Plasma Jets Approach to High Energy Density Physics. Final report

    SciTech Connect

    Chen, Chiping

    2013-08-26

    High-energy-density laboratory plasma (HEDLP) physics is an emerging, important area of research in plasma physics, nuclear physics, astrophysics, and particle acceleration. While the HEDLP regime occurs at extreme conditions which are often found naturally in space but not on the earth, it may be accessible by colliding high intensity plasmas such as high-energy-density plasma jets, plasmoids or compact toroids from plasma guns. The physics of plasma jets is investigated in the context of high energy density laboratory plasma research. This report summarizes results of theoretical and computational investigation of a plasma jet undergoing adiabatic compression and adiabatic expansion. A root-mean-squared (rms) envelope theory of plasma jets is developed. Comparison between theory and experiment is made. Good agreement between theory and experiment is found.

  10. Fluid simulation of relativistic electron beam driven wakefield in a cold plasma

    SciTech Connect

    Bera, Ratan Kumar; Sengupta, Sudip; Das, Amita

    2015-07-15

    Excitation of wakefield in a cold homogeneous plasma, driven by an ultra-relativistic electron beam is studied in one dimension using fluid simulation techniques. For a homogeneous rigid beam having density (n{sub b}) less than or equal to half the plasma density (n{sub 0}), simulation results are found to be in good agreement with the analytical work of Rosenzweig [Phys. Rev. Lett. 58, 555 (1987)]. Here, Rosenzweig's work has been analytically extended to regimes where the ratio of beam density to plasma density is greater than half and results have been verified using simulation. Further in contrast to Rosenzweig's work, if the beam is allowed to evolve in a self-consistent manner, several interesting features are observed in simulation viz. splitting of the beam into beam-lets (for l{sub b} > λ{sub p}) and compression of the beam (for l{sub b} < λ{sub p}), l{sub b} and λ{sub p}, respectively, being the initial beam length and plasma wavelength.

  11. An accurate Rb density measurement method for a plasma wakefield accelerator experiment using a novel Rb reservoir

    NASA Astrophysics Data System (ADS)

    Öz, E.; Batsch, F.; Muggli, P.

    2016-09-01

    A method to accurately measure the density of Rb vapor is described. We plan on using this method for the Advanced Wakefield (AWAKE) (Assmann et al., 2014 [1]) project at CERN , which will be the world's first proton driven plasma wakefield experiment. The method is similar to the hook (Marlow, 1967 [2]) method and has been described in great detail in the work by Hill et al. (1986) [3]. In this method a cosine fit is applied to the interferogram to obtain a relative accuracy on the order of 1% for the vapor density-length product. A single-mode, fiber-based, Mach-Zenhder interferometer will be built and used near the ends of the 10 meter-long AWAKE plasma source to be able to make accurate relative density measurement between these two locations. This can then be used to infer the vapor density gradient along the AWAKE plasma source and also change it to the value desired for the plasma wakefield experiment. Here we describe the plan in detail and show preliminary results obtained using a prototype 8 cm long novel Rb vapor cell.

  12. The AWAKE Proton-driven Plasma Wakefield Acceleration Experiment at CERN

    NASA Astrophysics Data System (ADS)

    Muggli, Patric

    2012-10-01

    We are planning an experiment at CERN to accelerate externally injected electrons e^- on the wake driven by a long, self-modulated proton p^+ bunch. In the plan the 12cm-long bunch from the SPS with 10^11 p^+ experiences a two-stream transverse instability that modulates the bunch radius at the plasma wake period. The bunch is focused to 200μm into a plasma with density in the 10^14-10^15cm-3 range. The modulation instability is seeded by co-propagating with the p^+ bunch a short laser pulse that ionizes a gas or vapor. The modulation resonantly drives wakefields to large amplitude. The low energy e^- ( 5-20MeV) produced by a rf-photoinjector gun are injected after the instability has saturated, 3-5m into the plasma and is accelerated to the GeV energy range. The e^- energy spectrum is measured by a large energy acceptance magnetic spectrometer. Bunch modulation diagnostics such as time resolved OTR and electro-optic measurements are also included. The general plans for the experiment as well as the latest developments will be presented.

  13. Application of Plasma Waveguides to High Energy Accelerators

    SciTech Connect

    Milchberg, Howard

    2016-07-01

    This grant supported basic experimental, theoretical and computer simulation research into developing a compact, high pulse repetition rate laser accelerator using the direct laser acceleration mechanism in plasma-based slow wave structures.

  14. Development of high energy pulsed plasma simulator for plasma-lithium trench experiment

    NASA Astrophysics Data System (ADS)

    Jung, Soonwook

    To simulate detrimental events in a tokamak and provide a test-stand for a liquid lithium infused trench (LiMIT) device, a pulsed plasma source utilizing a theta pinch in conjunction with a coaxial plasma accelerator has been developed. An overall objective of the project is to develop a compact device that can produce 100 MW/m2 to 1 GW/m2 of plasma heat flux (a typical heat flux level in a major fusion device) in ~ 100 mus (≤ 0.1 MJ/m2) for a liquid lithium plasma facing component research. The existing theta pinch device, DEVeX, was built and operated for study on lithium vapor shielding effect. However, a typical plasma energy of 3 - 4 kJ/m2 is too low to study an interaction of plasma and plasma facing components in fusion devices. No or little preionized plasma, ringing of magnetic field, collisions of high energy particles with background gas have been reported as the main issues. Therefore, DEVeX is reconfigured to mitigate these issues. The new device is mainly composed of a plasma gun for a preionization source, a theta pinch for heating, and guiding magnets for a better plasma transportation. Each component will be driven by capacitor banks and controlled by high voltage / current switches. Several diagnostics including triple Langmuir probe, calorimeter, optical emission measurement, Rogowski coil, flux loop, and fast ionization gauge are used to characterize the new device. A coaxial plasma gun is manufactured and installed in the previous theta pinch chamber. The plasma gun is equipped with 500 uF capacitor and a gas puff valve. The increase of the plasma velocity with the plasma gun capacitor voltage is consistent with the theoretical predictions and the velocity is located between the snowplow model and the weak - coupling limit. Plasma energies measured with the calorimeter ranges from 0.02 - 0.065 MJ/m2 and increases with the voltage at the capacitor bank. A cross-check between the plasma energy measured with the calorimeter and the triple probe

  15. Plasma wakefields driven by an incoherent combination of laser pulses: A path towards high-average power laser-plasma accelerators

    SciTech Connect

    Benedetti, C.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2014-05-15

    The wakefield generated in a plasma by incoherently combining a large number of low energy laser pulses (i.e., without constraining the pulse phases) is studied analytically and by means of fully self-consistent particle-in-cell simulations. The structure of the wakefield has been characterized and its amplitude compared with the amplitude of the wake generated by a single (coherent) laser pulse. We show that, in spite of the incoherent nature of the wakefield within the volume occupied by the laser pulses, behind this region, the structure of the wakefield can be regular with an amplitude comparable or equal to that obtained from a single pulse with the same energy. Wake generation requires that the incoherent structures in the laser energy density produced by the combined pulses exist on a time scale short compared to the plasma period. Incoherent combination of multiple laser pulses may enable a technologically simpler path to high-repetition rate, high-average power laser-plasma accelerators, and associated applications.

  16. Plasma wakefields driven by an incoherent combination of laser pulses: a path towards high-average power laser-plasma accelerators

    SciTech Connect

    Benedetti, C.; Schroeder, C.B.; Esarey, E.; Leemans, W.P.

    2014-05-01

    he wakefield generated in a plasma by incoherently combining a large number of low energy laser pulses (i.e.,without constraining the pulse phases) is studied analytically and by means of fully-self-consistent particle-in-cell simulations. The structure of the wakefield has been characterized and its amplitude compared with the amplitude of the wake generated by a single (coherent) laser pulse. We show that, in spite of the incoherent nature of the wakefield within the volume occupied by the laser pulses, behind this region the structure of the wakefield can be regular with an amplitude comparable or equal to that obtained from a single pulse with the same energy. Wake generation requires that the incoherent structure in the laser energy density produced by the combined pulses exists on a time scale short compared to the plasma period. Incoherent combination of multiple laser pulses may enable a technologically simpler path to high-repetition rate, high-average power laser-plasma accelerators and associated applications.

  17. High-quality electron beams from a laser wakefield accelerator using plasma-channel guiding.

    PubMed

    Geddes, C G R; Toth, C S; Van Tilborg, J; Esarey, E; Schroeder, C B; Bruhwiler, D; Nieter, C; Cary, J; Leemans, W P

    2004-09-30

    Laser-driven accelerators, in which particles are accelerated by the electric field of a plasma wave (the wakefield) driven by an intense laser, have demonstrated accelerating electric fields of hundreds of GV m(-1) (refs 1-3). These fields are thousands of times greater than those achievable in conventional radio-frequency accelerators, spurring interest in laser accelerators as compact next-generation sources of energetic electrons and radiation. To date, however, acceleration distances have been severely limited by the lack of a controllable method for extending the propagation distance of the focused laser pulse. The ensuing short acceleration distance results in low-energy beams with 100 per cent electron energy spread, which limits potential applications. Here we demonstrate a laser accelerator that produces electron beams with an energy spread of a few per cent, low emittance and increased energy (more than 10(9) electrons above 80 MeV). Our technique involves the use of a preformed plasma density channel to guide a relativistically intense laser, resulting in a longer propagation distance. The results open the way for compact and tunable high-brightness sources of electrons and radiation.

  18. 9 GeV energy gain in a beam-driven plasma wakefield accelerator

    SciTech Connect

    Litos, M.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Corde, S.; Clayton, C. E.; Frederico, J.; Gessner, S. J.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W. B.; Schmeltz, M.; Vafaei-Najafabadi, N.; Yakimenko, V.

    2016-02-15

    An electron beam has gained a maximum energy of 9 GeV per particle in a 1.3 m-long electron beam-driven plasma wakefield accelerator. The amount of charge accelerated in the spectral peak was 28.3 pC, and the root-mean-square energy spread was 5.0%. The mean accelerated charge and energy gain per particle of the 215 shot data set was 115 pC and 5.3 GeV, respectively, corresponding to an acceleration gradient of 4.0 GeV m-1 at the spectral peak. Moreover, the mean energy spread of the data set was 5.1%. Our results are consistent with the extrapolation of the previously reported energy gain results using a shorter, 36 cm-long plasma source to within 10%, evincing a non-evolving wake structure that can propagate distances of over a meter in length. Wake-loading effects were evident in the data through strong dependencies observed between various spectral properties and the amount of accelerated charge.

  19. 9 GeV energy gain in a beam-driven plasma wakefield accelerator

    DOE PAGES

    Litos, M.; Adli, E.; Allen, J. M.; ...

    2016-02-15

    An electron beam has gained a maximum energy of 9 GeV per particle in a 1.3 m-long electron beam-driven plasma wakefield accelerator. The amount of charge accelerated in the spectral peak was 28.3 pC, and the root-mean-square energy spread was 5.0%. The mean accelerated charge and energy gain per particle of the 215 shot data set was 115 pC and 5.3 GeV, respectively, corresponding to an acceleration gradient of 4.0 GeV m-1 at the spectral peak. Moreover, the mean energy spread of the data set was 5.1%. Our results are consistent with the extrapolation of the previously reported energy gainmore » results using a shorter, 36 cm-long plasma source to within 10%, evincing a non-evolving wake structure that can propagate distances of over a meter in length. Wake-loading effects were evident in the data through strong dependencies observed between various spectral properties and the amount of accelerated charge.« less

  20. Controlled laser plasma wakefield acceleration of electrons via colliding pulse injection in non-collinear geometry

    NASA Astrophysics Data System (ADS)

    Toth, Csaba; Nakamura, Kei; Geddes, Cameron; Panasenko, Dmitriy; Plateau, Guillaume; Matlis, Nicholas; Schroeder, Carl; Esarey, Eric; Leemans, Wim

    2007-11-01

    Colliding laser pulses [1] have been proposed as a method for controlling injection of electrons into a laser wakefield accelerator (LWFA) and hence producing high quality electron beams with energy spread below 1% and normalized emittances < 1 micron. The. One pulse excites a plasma wake, and a collinear pulse following behind it collides with a counterpropagating pulse forming a beat pattern that boosts background electrons into accelerating phase. A variation of the original method uses only two laser pulses [2] which may be non-collinear. The first pulse drives the wake, and beating of the trailing edge of this pulse with the colliding pulse injects electrons. Non-collinear injection avoids optical elements on the electron beam path (avoiding emittance growth). We report on progress of non-collinear experiments at LBNL, using the Ti:Sapphire laser at the LOASIS facility of LBNL. New results indicate that the electron beam properties are affected by the presence of the second beam. [1] E. Esarey, et al, Phys. Rev. Lett 79, 2682 (1997) [2] G. Fubiani, Phys. Rev. E 70, 016402 (2004)

  1. Betatron radiation based diagnostics for plasma wakefield accelerated electron beams at the SPARC_LAB test facility

    NASA Astrophysics Data System (ADS)

    Shpakov, V.; Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Curcio, A.; Dabagov, S.; Ferrario, M.; Filippi, F.; Marocchino, A.; Paroli, B.; Pompili, R.; Rossi, A. R.; Zigler, A.

    2016-09-01

    Recent progress with wake-field acceleration has shown a great potential in providing high gradient acceleration fields, while the quality of the beams remains relatively poor. Precise knowledge of the beam size at the exit from the plasma and matching conditions for the externally injected beams are the key for improvement of beam quality. Betatron radiation emitted by the beam during acceleration in the plasma is a powerful tool for the transverse beam size measurement, being also non-intercepting. In this work we report on the technical solutions chosen at SPARC_LAB for such diagnostics tool, along with expected parameters of betatron radiation.

  2. Counter-facing plasma focus system as a repetitive and/or long-pulse high energy density plasma source

    SciTech Connect

    Aoyama, Yutaka; Nakajima, Mitsuo; Horioka, Kazuhiko

    2009-11-15

    A plasma focus system composed of a pair of counter-facing coaxial plasma guns is proposed as a long-pulse and/or repetitive high energy density plasma source. A proof-of-concept experiment demonstrated that with an assist of breakdown and outer electrode connections, current sheets evolved into a configuration for stable plasma confinement at the center of the electrodes. The current sheets could successively compress and confine the high energy density plasma every half period of the discharge current, enabling highly repetitive light emissions in extreme ultraviolet region with time durations in at least ten microseconds.

  3. Counter-facing plasma focus system as a repetitive and/or long-pulse high energy density plasma source

    NASA Astrophysics Data System (ADS)

    Aoyama, Yutaka; Nakajima, Mitsuo; Horioka, Kazuhiko

    2009-11-01

    A plasma focus system composed of a pair of counter-facing coaxial plasma guns is proposed as a long-pulse and/or repetitive high energy density plasma source. A proof-of-concept experiment demonstrated that with an assist of breakdown and outer electrode connections, current sheets evolved into a configuration for stable plasma confinement at the center of the electrodes. The current sheets could successively compress and confine the high energy density plasma every half period of the discharge current, enabling highly repetitive light emissions in extreme ultraviolet region with time durations in at least ten microseconds.

  4. Phase-contrast imaging using radiation sources based on laser-plasma wakefield accelerators: state of the art and future development

    NASA Astrophysics Data System (ADS)

    Reboredo., D.; Cipiccia, S.; Grant, P. A.; Welsh, G. H.; Grant, D. W.; McKendrick, G.; Subiel, A.; Maneuski, D.; Wiggins, S. M.; Jaroszynski, D. A.

    2015-03-01

    Both the laser-plasma wakefield accelerator (LWFA) and X-ray phase-contrast imaging (XPCi) are promising technologies that are attracting the attention of the scientific community. Conventional X-ray absorption imaging cannot be used as a means of imaging biological material because of low contrast. XPCi overcomes this limitation by exploiting the variation of the refraction index of materials. The contrast obtained is higher than for conventional absorption imaging and requires a lower dose. The LWFA is a new concept of acceleration where electrons are accelerated to very high energy (~150 MeV) in very short distances (mm scale) by surfing plasma waves excited by the passage of an ultra-intense laser pulse (~1018 Wcm-2) through plasma. Electrons in the LWFA can undergo transverse oscillation and emit synchrotron-like (betatron) radiation in a narrow cone around the propagation axis. The properties of the betatron radiation produced by LWFA, such as source size and spectrum, make it an excellent candidate for XPCi. In this work we present the characterization of betatron radiation produced by the LWFA in the ALPHA-X laboratory (University of Strathclyde). We show how phase contrast images can be obtained using the betatron radiation in a free-space propagation configuration and we discuss the potential and limitation of the LWFA driven XPCi.

  5. High energy density micro plasma bunch from multiple laser interaction with thin target

    SciTech Connect

    Xu, Han; Yu, Wei; Luan, S. X.; Xu, Z. Z.; Yu, M. Y.; Cai, H. B.; Zhou, C. T.; Yang, X. H.; Yin, Y.; Zhuo, H. B.; Wang, J. W.; Murakami, M.

    2014-01-13

    Three-dimensional particle-in-cell simulation is used to investigate radiation-pressure driven acceleration and compression of small solid-density plasma by intense laser pulses. It is found that multiple impacts by presently available short-pulse lasers on a small hemispheric shell target can create a long-living tiny quasineutral monoenergetic plasma bunch of very high energy density.

  6. Plasma simulations of emission line regions in high energy environments

    NASA Astrophysics Data System (ADS)

    Richardson, Chris T.

    This dissertation focuses on understanding two different, but in each case extreme, astrophysical environments: the Crab Nebula and emission line galaxies. These relatively local objects are well constrained by observations and are test cases of phenomena seen at high-z where detailed observations are rare. The tool used to study these objects is the plasma simulation code known as Cloudy. The introduction provides a brief summary of relevant physical concepts in nebular astrophysics and presents the basic features and assumptions of Cloudy. The first object investigated with Cloudy, the Crab Nebula, is a nearby supernova remnant that previously has been subject to photoionization modeling to reproduce the ionized emission seen in the nebula's filamentary structure. However, there are still several unanswered questions: (1) What excites the H2 emitting gas? (2) How much mass is in the molecular component? (3) How did the H2 form? (4) What is nature of the dust grains? A large suite of observations including long slit optical and NIR spectra over ionized, neutral and molecular gas in addition to HST and NIR ground based images constrain a particularly bright region of H2 emission, Knot 51, which exhibits a high excitation temperature of ˜3000 K. Simulations of K51 revealed that only a trace amount of H2 is needed to reproduce the observed emission and that H2 forms through an uncommon nebular process known as associative detachment. The final chapters of this dissertation focus on interpreting the narrow line region (NLR) in low-z emission line galaxies selected by a novel technique known as mean field independent component analysis (MFICA). A mixture of starlight and radiation from an AGN excites the gas present in galaxies. MFICA separates galaxies over a wide range of ionization into subsets of pure AGN and pure star forming galaxies allowing simulations to reveal the properties responsible for their observed variation in ionization. Emission line ratios can

  7. Atomic physics calculations in support of studies for high energy density plasmas

    SciTech Connect

    Wang, P.; MacFarlane, J.J.; Moses, G.A.; Mehlhorn, T.A.

    1995-12-31

    The studies of high energy density plasmas require basic atomic data, equations of state, opacities, and stopping power. Unfortunately, the related experimental data are very limited. To obtain these data for a wide domain of plasma conditions, one must rely on theoretical calculations. The authors have developed an atomic physics calculation package which can provide high quality atomic data for numerical simulations of high energy density plasmas. In this paper, they give detailed descriptions of physics models used in the package. Particular emphasis will be on a hybrid model for equations of state, a self-consistent field model for ion stopping power, and opacity calculations.

  8. Generation of wakefields by whistlers in spin quantum magnetoplasmas

    SciTech Connect

    Misra, A. P.; Brodin, G.; Marklund, M.; Shukla, P. K.

    2010-12-15

    The excitation of electrostatic wakefields in a magnetized spin quantum plasma by the classical and the spin-induced ponderomotive force (CPF and SPF, respectively) due to whistler waves is reported. The nonlinear dynamics of the whistlers and the wakefields is shown to be governed by a coupled set of nonlinear Schroedinger and driven Boussinesq-like equations. It is found that the quantum force associated with the Bohm potential introduces two characteristic length scales, which lead to the excitation of multiple wakefields in a strongly magnetized dense plasma (with a typical magnetic field strength B{sub 0} or approx. 10{sup 9} T and particle density n{sub 0} > or approx. 10{sup 36} m{sup -3}), where the SPF strongly dominates over the CPF. In other regimes, namely, B{sub 0} < or approx. 10{sup 8} T and n{sub 0} < or approx. 10{sup 35} m{sup -3}, where the SPF is comparable to the CPF, a plasma wakefield can also be excited self-consistently with one characteristic length scale. Numerical results reveal that the wakefield amplitude is enhanced by the quantum tunneling effect; however, it is lowered by the external magnetic field. Under appropriate conditions, the wakefields can maintain high coherence over multiple plasma wavelengths and thereby accelerate electrons to extremely high energies. The results could be useful for particle acceleration at short scales, i.e., at nanometer and micrometer scales, in magnetized dense plasmas where the driver is the whistler wave instead of a laser or a particle beam.

  9. High-quality electron beams from beam-driven plasma accelerators by wakefield-induced ionization injection.

    PubMed

    Martinez de la Ossa, A; Grebenyuk, J; Mehrling, T; Schaper, L; Osterhoff, J

    2013-12-13

    We propose a new and simple strategy for controlled ionization-induced trapping of electrons in a beam-driven plasma accelerator. The presented method directly exploits electric wakefields to ionize electrons from a dopant gas and capture them into a well-defined volume of the accelerating and focusing wake phase, leading to high-quality witness bunches. This injection principle is explained by example of three-dimensional particle-in-cell calculations using the code OSIRIS. In these simulations a high-current-density electron-beam driver excites plasma waves in the blowout regime inside a fully ionized hydrogen plasma of density 5×10(17)cm-3. Within an embedded 100  μm long plasma column contaminated with neutral helium gas, the wakefields trigger ionization, trapping of a defined fraction of the released electrons, and subsequent acceleration. The hereby generated electron beam features a 1.5 kA peak current, 1.5  μm transverse normalized emittance, an uncorrelated energy spread of 0.3% on a GeV-energy scale, and few femtosecond bunch length.

  10. Shielding effect and wakefield pattern of a moving test charge in a non-Maxwellian dusty plasma

    NASA Astrophysics Data System (ADS)

    Ali, S.; Khan, S.

    2013-07-01

    By using the Vlasov-Poisson equations, we calculate an expression for the electrostatic potential caused by a test charge in an unmagnetized non-Maxwellian dusty plasma, whose constituents are the superthermal hot-electrons, the mobile cold-electrons with a neutralizing background of cold ions, and charge fluctuating isolated dust grains. The superthermality effects due to hot electrons not only modify the dielectric constant of the electron-acoustic waves but also significantly affect the electrostatic potential. The latter can be decomposed into the Debye-Hückel and oscillatory wake potentials. Analytical and numerical results reveal that the Debye-Hückel and wakefield potentials converge to the Maxwellian case for large values of superthermality parameter. Furthermore, the plasma parameters play a vital role in the formation of shielding and wakefield pattern in a two-electron temperature plasma. The present results should be important for laboratory and space dusty plasmas, where hot-electrons can be assumed to follow the non-Maxwellian distribution function.

  11. Shielding effect and wakefield pattern of a moving test charge in a non-Maxwellian dusty plasma

    SciTech Connect

    Ali, S.; Khan, S.

    2013-07-15

    By using the Vlasov-Poisson equations, we calculate an expression for the electrostatic potential caused by a test charge in an unmagnetized non-Maxwellian dusty plasma, whose constituents are the superthermal hot-electrons, the mobile cold-electrons with a neutralizing background of cold ions, and charge fluctuating isolated dust grains. The superthermality effects due to hot electrons not only modify the dielectric constant of the electron-acoustic waves but also significantly affect the electrostatic potential. The latter can be decomposed into the Debye-Hückel and oscillatory wake potentials. Analytical and numerical results reveal that the Debye-Hückel and wakefield potentials converge to the Maxwellian case for large values of superthermality parameter. Furthermore, the plasma parameters play a vital role in the formation of shielding and wakefield pattern in a two-electron temperature plasma. The present results should be important for laboratory and space dusty plasmas, where hot-electrons can be assumed to follow the non-Maxwellian distribution function.

  12. Analytic model of electron self-injection in a plasma wakefield accelerator in the strongly nonlinear bubble regime

    NASA Astrophysics Data System (ADS)

    Yi, Sunghwan; Khudik, Vladimir; Shvets, Gennady

    2012-10-01

    We study self-injection into a plasma wakefield accelerator in the blowout (or bubble) regime, where the bubble evolves due to background density inhomogeneities. To explore trapping, we generalize an analytic model for the wakefields inside the bubble [1] to derive expressions for the fields outside. With this extended model, we show that a return current in the bubble sheath layer plays an important role in determining the trapped electron trajectories. We explore an injection mechanism where bubble growth due to a background density downramp causes reduction of the electron Hamiltonian in the co-moving frame, trapping the particle in the dynamically deepening potential well [2]. Model calculations agree quantitatively with PIC simulations on the bubble expansion rate required for trapping, as well as the range of impact parameters for which electrons are trapped. This is an improvement over our previous work [3] using a simplified spherical bubble model, which ignored the fields outside of the bubble and hence overestimated the expansion rate required for trapping. [4pt] [1] W. Lu et al., Phys. Plasmas 13, 056709 (2006).[0pt] [2] S. Kalmykov et al., Phys. Rev. Lett 103, 135004 (2009).[0pt] [3] S.A. Yi et al., Plasma Phys. Contr. Fus. 53, 014012 (2011).

  13. Colliding pulse injection experiments in non-collinear geometry for controlled laser plasma wakefield acceleration of electrons

    NASA Astrophysics Data System (ADS)

    Toth, Csaba; Nakamura, K.; Geddes, C.; Michel, P.; Schroeder, C.; Esarey, E.; Leemans, W.

    2006-10-01

    A method for controlled injection of electrons into a plasma wakefield relying on colliding laser pulses [1] has been proposed a decade ago to produce high quality relativistic electron beams with energy spread below 1% and normalized emittances < 1 micron from a laser wakefield accelerator (LWFA). The original idea uses three pulses in which one pulse excites the plasma wake and a trailing laser pulse collides with a counterpropagating one to form a beat pattern that boosts background electrons to catch the plasma wave. Another, two-beam off-axis injection method [2] with crossing angles varying from 180 to 90 degrees avoids having optical elements on the path of the electron beam and has been studied at the LOASIS facility of LBNL as a viable method for laser triggered injection. It allows low dark current operation with controllable final beam energy and low energy spread. Here, we report on progress of electron optical injection via the two-beam non-collinear colliding pulse scheme using multi-terawatt Ti:Sapphire laser beams (45 fs, 100s of mJ) focused onto a Hydrogen gas plume. Experimental results indicate that electron beam properties are affected by the second beam. *This work is supported by DoE under contract DE-AC02-05CH11231. [1] E. Esarey, et al, Phys. Rev. Lett 79, 2682 (1997) [2] G. Fubiani, Phys. Rev. E 70, 016402 (2004)

  14. Analysis of radial and longitudinal force of plasma wakefield generated by a chirped pulse laser

    SciTech Connect

    Ghasemi, Leila; Afhami, Saeedeh; Eslami, Esmaeil

    2015-08-15

    In present paper, the chirp effect of an electromagnetic pulse via an analytical model of wakefield generation is studied. Different types of chirps are employed in this study. Our results show that by the use of nonlinear chirped pulse the longitudinal wakefield and focusing force is stronger than that of linear chirped pulse. It is indicated that quadratic nonlinear chirped pulses are globally much efficient than periodic nonlinear chirped pulses. Our calculations also predict that in nonlinear chirped pulse case, the overlap of focusing and accelerating regions is broader than that achieved in linear chirped pulse.

  15. Limitation on the accelerating gradient of a wakefield excited by an ultrarelativistic electron beam in rubidium plasma

    NASA Astrophysics Data System (ADS)

    Vafaei-Najafabadi, N.; Marsh, K. A.; Clayton, C. E.; An, W.; Mori, W. B.; Joshi, C.; Lu, W.; Adli, E.; Corde, S.; Clarke, C. I.; Litos, M.; Green, S. Z.; Gessner, S.; Frederico, J.; Fisher, A. S.; Wu, Z.; Walz, D.; Hogan, M. J.

    2016-10-01

    We have investigated the viability of using plasmas formed by ionization of high Z, low ionization potential element rubidium (Rb) for beam-driven plasma wakefield acceleration. The Rb vapor column confined by argon (Ar) buffer gas was used to reduce the expected limitation on the beam propagation length due to head erosion that was observed previously when a lower Z but higher ionization potential lithium vapor was used. However, injection of electrons into the wakefield due to ionization of Ar buffer gas and nonuniform ionization of Rb1 + to Rb2 + was a possible concern. In this paper we describe experimental results and the supporting simulations which indicate that such ionization of Ar and Rb1 + in the presence of combined fields of the beam and the wakefield inside the wake does indeed occur. Some of this charge accumulates in the accelerating region of the wake leading to the reduction of the electric field—an effect known as beam loading. The beam-loading effect is quantified by determining the average transformer ratio ⟨R ⟩ which is the maximum energy gained divided by the maximum energy lost by the electrons in the bunch used to produce the wake. ⟨R ⟩ is shown to depend on the propagation length and the quantity of the accumulated charge, indicating that the distributed injection of secondary Rb electrons is the main cause of beam loading in this experiment. The average transformer ratio is reduced from 1.5 to less than 1 as the excess charge from secondary ionization increased from 100 to 700 pC. The simulations show that while the decelerating field remains constant, the accelerating field is reduced from its unloaded value of 82 to 46 GeV /m due to this distributed injection of dark current into the wake.

  16. Laser wakefield acceleration of polarized electron beams

    NASA Astrophysics Data System (ADS)

    Pugacheva, D. V.; Andreev, N. E.; Cros, B.

    2016-11-01

    The acceleration of highly polarized electron beams are widely used in state-of-the-art high-energy physics experiments. In this work, a model for investigation of polarization dynamics of electron beams in the laser-plasma accelerator depending on the initial energy of electrons was developed and tested. To obtain the evolution of the trajectory and momentum of the electron for modeling its acceleration the wakefield structure was determined. The spin precession of the beam electron was described by Thomas-Bargman-Michel-Telegdi equations. The evolution of the electron beam polarization was investigated for zero-emittance beams with zero-energy spread.

  17. Dense Plasma Focus - From Alternative Fusion Source to Versatile High Energy Density Plasma Source for Plasma Nanotechnology

    NASA Astrophysics Data System (ADS)

    Rawat, R. S.

    2015-03-01

    The dense plasma focus (DPF), a coaxial plasma gun, utilizes pulsed high current electrical discharge to heat and compress the plasma to very high density and temperature with energy densities in the range of 1-10 × 1010 J/m3. The DPF device has always been in the company of several alternative magnetic fusion devices as it produces intense fusion neutrons. Several experiments conducted on many different DPF devices ranging over several order of storage energy have demonstrated that at higher storage energy the neutron production does not follow I4 scaling laws and deteriorate significantly raising concern about the device's capability and relevance for fusion energy. On the other hand, the high energy density pinch plasma in DPF device makes it a multiple radiation source of ions, electron, soft and hard x-rays, and neutrons, making it useful for several applications in many different fields such as lithography, radiography, imaging, activation analysis, radioisotopes production etc. Being a source of hot dense plasma, strong shockwave, intense energetic beams and radiation, etc, the DPF device, additionally, shows tremendous potential for applications in plasma nanoscience and plasma nanotechnology. In the present paper, the key features of plasma focus device are critically discussed to understand the novelties and opportunities that this device offers in processing and synthesis of nanophase materials using, both, the top-down and bottom-up approach. The results of recent key experimental investigations performed on (i) the processing and modification of bulk target substrates for phase change, surface reconstruction and nanostructurization, (ii) the nanostructurization of PLD grown magnetic thin films, and (iii) direct synthesis of nanostructured (nanowire, nanosheets and nanoflowers) materials using anode target material ablation, ablated plasma and background reactive gas based synthesis and purely gas phase synthesis of various different types of

  18. Electron self-injection due to a plasma density downramp and gas ionization in a plasma wakefield accelerator in the blowout regime

    NASA Astrophysics Data System (ADS)

    Yi, S. A.; D'Avignon, E. C.; Khudik, V.; Shvets, G.

    2010-11-01

    We study self-injection into a plasma wakefield accelerator (PWFA) in the blowout regime analytically and through particle-in-cell (PIC) simulations. We propose a new injection mechanism into a plasma wakefield accelerator, where growth of the blowout region is enabled through a slow decrease in background plasma density along the direction of propagation. Deepening of the potential well due to this growth causes a reduction of electron Hamiltonian in the co-moving frame. This reduction depends on the shape of the blowout region, its growth rate, and impact parameter of the electron. When the reduction is greater than mc^2 [1,2], the electron becomes trapped inside the bubble. We demonstrate this effect using analytic expressions for the bubble potentials [3], and estimate plasma density gradients, and beam charge and size required for injection. We also apply the injection criterion to electron trapping through gas ionization. This work is supported by the US DOE grants DE-FG02-04ER41321 and DE-FG02-07ER54945. [1] S. Kalmykov, S.A. Yi, V. Khudik, and G. Shvets, Phys. Rev. Lett. 103, 135004 (2009). [2] S.A. Yi, V. Khudik, S. Kalmykov, and G. Shvets, Plasma Phys. Contr. Fus., in press. [3] W. Lu, C. Huang, M. Zhou, M. Tzoufras et al., Phys. Plasmas 13, 056709 (2006).

  19. Filamentation in Laser Wakefields

    NASA Astrophysics Data System (ADS)

    Los, Eva; Trines, Raoul; Silva, Luis; Bingham, Robert

    2016-10-01

    Laser filamentation instability is observed in plasma wakefields with sub-critical densities, and in high density inertial fusion plasmas. This leads to non-uniform acceleration or compression respectively. Here, we present simulation results on laser filamentation in plasma wakefields. The 2-D simulations are carried out using the particle-in-cell code Osiris. The filament intensity was found to increase exponentially before saturating. The maximum amplitude to which the highest intensity filament grew for a specific set of parameters was also recorded, and plotted against a corresponding parameter value. Clear, positively correlated linear trends were established between plasma density, transverse wavenumber k, laser pulse amplitude and maximum filament amplitude. Plasma density and maximum filament amplitude also showed a positive correlation, which saturated after a certain plasma density. Pulse duration and interaction length did not affect either filament intensity or transverse k value in a predictable manner. There was no discernible trend between pulse amplitude and filament width.

  20. Direct laser acceleration of electrons in plasma bubbles or ion channels with and without a longitudinal wakefield

    NASA Astrophysics Data System (ADS)

    Khudik, Vladimir; Zhang, Xi; Arefiev, Alexey; Shvets, Gennady

    2017-03-01

    We investigate the motion of electrons in a plasma bubble (or an ion channel) under combined action of an oscillating laser field, quasistatic transverse wakefield, and longitudinal electric field. The longitudinal field E∥ significantly influences the broadband resonance between betatron oscillations of electrons and oscillations of the laser wave, which results in the profoundly different electron dynamics at different signs and magnitudes of the longitudinal force -eE∥. Specifically, we make a contrast between three representative cases: when this force is absent (-eE∥ = 0), when it accelerates electrons (-eE∥ > 0), and when it decelerates them (-eE∥ < 0). We estimate the electron energy gain at given laser-plasma parameters.

  1. Enhancing Understanding of High Energy Density Plasmas Using Fluid Modeling with Kinetic Closures

    NASA Astrophysics Data System (ADS)

    Hansen, David; Held, Eric; Srinivasan, Bhuvana; Masti, Robert; King, Jake

    2016-10-01

    This work seeks to understand possible stabilization mechanisms of the early-time electrothermal instability in the evolution of the Rayleigh-Taylor instability in MagLIF (Magnetized Liner Inertial Fusion) experiments. Such mechanisms may include electron thermal conduction, viscosity, and large magnetic fields. Experiments have shown that the high-energy density plasmas from wire-array implosions require physics modelling that goes well beyond simple models such as ideal MHD. The plan is to develop a multi-fluid extended-MHD model that includes kinetic closures for thermal conductivity, resistivity, and viscosity using codes that are easily available to the wider research community. Such an effort would provide the community with a well-benchmarked tool capable of advanced modeling of high-energy-density plasmas.

  2. Shock waves in a Z-pinch and the formation of high energy density plasma

    SciTech Connect

    Rahman, H. U.; Wessel, F. J.; Ney, P.; Presura, R.; Ellahi, Rahmat; Shukla, P. K.

    2012-12-15

    A Z-pinch liner, imploding onto a target plasma, evolves in a step-wise manner, producing a stable, magneto-inertial, high-energy-density plasma compression. The typical configuration is a cylindrical, high-atomic-number liner imploding onto a low-atomic-number target. The parameters for a terawatt-class machine (e.g., Zebra at the University of Nevada, Reno, Nevada Terawatt Facility) have been simulated. The 2-1/2 D MHD code, MACH2, was used to study this configuration. The requirements are for an initial radius of a few mm for stable implosion; the material densities properly distributed, so that the target is effectively heated initially by shock heating and finally by adiabatic compression; and the liner's thickness adjusted to promote radial current transport and subsequent current amplification in the target. Since the shock velocity is smaller in the liner, than in the target, a stable-shock forms at the interface, allowing the central load to accelerate magnetically and inertially, producing a magneto-inertial implosion and high-energy density plasma. Comparing the implosion dynamics of a low-Z target with those of a high-Z target demonstrates the role of shock waves in terms of compression and heating. In the case of a high-Z target, the shock wave does not play a significant heating role. The shock waves carry current and transport the magnetic field, producing a high density on-axis, at relatively low temperature. Whereas, in the case of a low-Z target, the fast moving shock wave preheats the target during the initial implosion phase, and the later adiabatic compression further heats the target to very high energy density. As a result, the compression ratio required for heating the low-Z plasma to very high energy densities is greatly reduced.

  3. Simulation of high-energy proton production by fast magnetosonic shock waves in pinched plasma discharges

    NASA Astrophysics Data System (ADS)

    Mizuguchi, Yusuke; Sakai, Jun-Ichi; Yousefi, Hamid Reza; Haruki, Takayuki; Masugata, Katsumi

    2007-03-01

    High-energy particles of a few hundred keV for electrons and up to MeV for ions were observed in a plasma focus device. Haruki et al. [Phys. Plasmas 13, 082106-1 (2006)] studied the mechanism of high-energy particle production in pinched plasma discharges by use of a 3D relativistic and fully electromagnetic particle-in-cell code. It was found that the pinched current is unstable against a sausage instability, and then becomes unstable against a kink instability. As a result high-energy electrons were observed, but protons with MeV energies were not observed. In this paper the same pinch dynamics as Haruki and co-workers is investigated, focusing on the shock formation and the shock acceleration during the pinched current. It is found that a fast magnetosonic shock wave is produced during the pinching phase which, after the maximum pinch occurs, is strongly enhanced and propagates outwards. Some protons trapped in the electrostatic potential produced near the shock front can be accelerated to a few MeV by the surfatron acceleration mechanism. It is also found that the protons accelerated along the pinched axis have a ring-shaped angular distribution that is observed from numerous experiments.

  4. High-energy ions from near-critical density plasmas via magnetic vortex acceleration.

    PubMed

    Nakamura, Tatsufumi; Bulanov, Sergei V; Esirkepov, Timur Zh; Kando, Masaki

    2010-09-24

    Ultraintense laser pulses propagating in near-critical density plasmas generate magnetic dipole vortex structures. In the region of decreasing plasma density, the vortex expands both in forward and lateral directions. The magnetic field pressure pushes electrons and ions to form a density jump along the vortex axis and induces a longitudinal electric field. This structure moves together with the expanding dipole vortex. The background ions located ahead of the electric field are accelerated to high energies. The energy scaling of ions generated by this magnetic vortex acceleration mechanism is derived and corroborated using particle-in-cell simulations.

  5. High-Energy Ions from Near-Critical Density Plasmas via Magnetic Vortex Acceleration

    SciTech Connect

    Nakamura, Tatsufumi; Bulanov, Sergei V.; Esirkepov, Timur Zh.; Kando, Masaki

    2010-09-24

    Ultraintense laser pulses propagating in near-critical density plasmas generate magnetic dipole vortex structures. In the region of decreasing plasma density, the vortex expands both in forward and lateral directions. The magnetic field pressure pushes electrons and ions to form a density jump along the vortex axis and induces a longitudinal electric field. This structure moves together with the expanding dipole vortex. The background ions located ahead of the electric field are accelerated to high energies. The energy scaling of ions generated by this magnetic vortex acceleration mechanism is derived and corroborated using particle-in-cell simulations.

  6. Numerical simulation of inducing characteristics of high energy electron beam plasma for aerodynamics applications

    NASA Astrophysics Data System (ADS)

    Yongfeng, DENG; Jian, JIANG; Xianwei, HAN; Chang, TAN; Jianguo, WEI

    2017-04-01

    The problem of flow active control by low temperature plasma is considered to be one of the most flourishing fields of aerodynamics due to its practical advantages. Compared with other means, the electron beam plasma is a potential flow control method for large scale flow. In this paper, a computational fluid dynamics model coupled with a multi-fluid plasma model is established to investigate the aerodynamic characteristics induced by electron beam plasma. The results demonstrate that the electron beam strongly influences the flow properties, not only in the boundary layers, but also in the main flow. A weak shockwave is induced at the electron beam injection position and develops to the other side of the wind tunnel behind the beam. It brings additional energy into air, and the inducing characteristics are closely related to the beam power and increase nonlinearly with it. The injection angles also influence the flow properties to some extent. Based on this research, we demonstrate that the high energy electron beam air plasma has three attractive advantages in aerodynamic applications, i.e. the high energy density, wide action range and excellent action effect. Due to the rapid development of near space hypersonic vehicles and atmospheric fighters, by optimizing the parameters, the electron beam can be used as an alternative means in aerodynamic steering in these applications.

  7. Numerical simulation of inducing characteristics of high energy electron beam plasma for aerodynamics applications

    NASA Astrophysics Data System (ADS)

    Deng, Yongfeng; Jiang, Jian; Han, Xianwei; Tan, Chang; Wei, Jianguo

    2017-04-01

    The problem of flow active control by low temperature plasma is considered to be one of the most flourishing fields of aerodynamics due to its practical advantages. Compared with other means, the electron beam plasma is a potential flow control method for large scale flow. In this paper, a computational fluid dynamics model coupled with a multi-fluid plasma model is established to investigate the aerodynamic characteristics induced by electron beam plasma. The results demonstrate that the electron beam strongly influences the flow properties, not only in the boundary layers, but also in the main flow. A weak shockwave is induced at the electron beam injection position and develops to the other side of the wind tunnel behind the beam. It brings additional energy into air, and the inducing characteristics are closely related to the beam power and increase nonlinearly with it. The injection angles also influence the flow properties to some extent. Based on this research, we demonstrate that the high energy electron beam air plasma has three attractive advantages in aerodynamic applications, i.e. the high energy density, wide action range and excellent action effect. Due to the rapid development of near space hypersonic vehicles and atmospheric fighters, by optimizing the parameters, the electron beam can be used as an alternative means in aerodynamic steering in these applications.

  8. High-Energy Ion Acceleration Mechanisms in a Dense Plasma Focus Z-Pinch

    NASA Astrophysics Data System (ADS)

    Higginson, D. P.; Link, A.; Schmidt, A.; Welch, D.

    2016-10-01

    The compression of a Z-pinch plasma, specifically in a dense plasma focus (DPF), is known to accelerate high-energy electrons, ions and, if using fusion-reactant ions (e.g. D, T), neutrons. The acceleration of particles is known to coincide with the peak constriction of the pinch, however, the exact physical mechanism responsible for the acceleration remains an area of debate and uncertainty. Recent work has suggested that this acceleration is linked to the growth of an m =0 (sausage) instability that evacuates a region of low-density, highly-magnetized plasma and creates a strong (>MV/cm) electric field. Using the fully kinetic particle-in-cell code LSP in 2D-3V, we simulate the compression of a 2 MA, 35 kV DPF plasma and investigate in detail the formation of the electric field. The electric field is found to be predominantly in the axial direction and driven via charge-separation effects related to the resistivity of the kinetic plasma. The strong electric and magnetic fields are shown to induce non-Maxwellian distributions in both the ions and electrons and lead to the acceleration of high-energy tails. We compare the results in the kinetic simulations to assumptions of magnetohydrodynamics (MHD). Prepared by LLNL under Contract DE-AC52-07NA27344.

  9. High energy electron fluxes in dc-augmented capacitively coupled plasmas I. Fundamental characteristics

    SciTech Connect

    Wang Mingmei; Kushner, Mark J.

    2010-01-15

    Power deposition from electrons in capacitively coupled plasmas (CCPs) has components from stochastic heating, Joule heating, and from the acceleration of secondary electrons through sheaths produced by ion, electron, or photon bombardment of electrodes. The sheath accelerated electrons can produce high energy beams which, in addition to producing excitation and ionization in the gas can penetrate through the plasma and be incident on the opposite electrode. In the use of CCPs for microelectronics fabrication, there may be an advantage to having these high energy electrons interact with the wafer. To control the energy and increase the flux of the high energy electrons, a dc bias can be externally imposed on the electrode opposite the wafer, thereby producing a dc-augmented CCP (dc-CCP). In this paper, the characteristics of dc-CCPs will be discussed using results from a computational study. We found that for a given rf bias power, beams of high energy electrons having a narrow angular spread (<1 deg. ) can be produced incident on the wafer. The maximum energy in the high energy electron flux scales as {epsilon}{sub max}=-V{sub dc}+V{sub rf}+V{sub rf0}, for a voltage on the dc electrode of V{sub dc}, rf voltage of V{sub rf}, and dc bias on the rf electrode of V{sub rf0}. The dc current from the biased electrode must return to ground through surfaces other than the rf electrode and so seeks out a ground plane, typically the side walls. If the side wall is coated with a poorly conducting polymer, the surface will charge to drive the dc current through.

  10. Simulation of electron post-acceleration in a two-stage laser Wakefield accelerator

    SciTech Connect

    Reitsma, A.J.W.; Leemans, W.P.; Esarey, E.; Kamp, L.P.J.; Schep, T.J.

    2002-04-01

    Electron bunches produced in self-modulated laser wakefield experiments usually have a broad energy spectrum, with most electrons at low energy (1-3 MeV) and only a small fraction at high energy. We propose and investigate further acceleration of such bunches in a channel-guided resonant laser wakefield accelerator. Two-dimensional simulations with and without the effects of self-consistent beam loading are performed and compared. These results indicate that it is possible to trap about 40 percent of the injected bunch charge and accelerate this fraction to an average energy of about 50 MeV in a plasma channel of a few mn.

  11. Phase-space moment-equation model of highly relativistic electron-beams in plasma-wakefield accelerators

    SciTech Connect

    Robson, R.E.; Mehrling, T.; Osterhoff, J.

    2015-05-15

    We formulate a new procedure for modelling the transverse dynamics of relativistic electron beams with significant energy spread when injected into plasma-based accelerators operated in the blow-out regime. Quantities of physical interest, such as the emittance, are furnished directly from solution of phase space moment equations formed from the relativistic Vlasov equation. The moment equations are closed by an Ansatz, and solved analytically for prescribed wakefields. The accuracy of the analytic formulas is established by benchmarking against the results of a semi-analytic/numerical procedure which is described within the scope of this work, and results from a simulation with the 3D quasi-static PIC code HiPACE.

  12. Comparisons of time explicit hybrid kinetic-fluid code Architect for Plasma Wakefield Acceleration with a full PIC code

    SciTech Connect

    Massimo, F.; Atzeni, S.; Marocchino, A.

    2016-12-15

    Architect, a time explicit hybrid code designed to perform quick simulations for electron driven plasma wakefield acceleration, is described. In order to obtain beam quality acceptable for applications, control of the beam-plasma-dynamics is necessary. Particle in Cell (PIC) codes represent the state-of-the-art technique to investigate the underlying physics and possible experimental scenarios; however PIC codes demand the necessity of heavy computational resources. Architect code substantially reduces the need for computational resources by using a hybrid approach: relativistic electron bunches are treated kinetically as in a PIC code and the background plasma as a fluid. Cylindrical symmetry is assumed for the solution of the electromagnetic fields and fluid equations. In this paper both the underlying algorithms as well as a comparison with a fully three dimensional particle in cell code are reported. The comparison highlights the good agreement between the two models up to the weakly non-linear regimes. In highly non-linear regimes the two models only disagree in a localized region, where the plasma electrons expelled by the bunch close up at the end of the first plasma oscillation.

  13. Comparisons of time explicit hybrid kinetic-fluid code Architect for Plasma Wakefield Acceleration with a full PIC code

    NASA Astrophysics Data System (ADS)

    Massimo, F.; Atzeni, S.; Marocchino, A.

    2016-12-01

    Architect, a time explicit hybrid code designed to perform quick simulations for electron driven plasma wakefield acceleration, is described. In order to obtain beam quality acceptable for applications, control of the beam-plasma-dynamics is necessary. Particle in Cell (PIC) codes represent the state-of-the-art technique to investigate the underlying physics and possible experimental scenarios; however PIC codes demand the necessity of heavy computational resources. Architect code substantially reduces the need for computational resources by using a hybrid approach: relativistic electron bunches are treated kinetically as in a PIC code and the background plasma as a fluid. Cylindrical symmetry is assumed for the solution of the electromagnetic fields and fluid equations. In this paper both the underlying algorithms as well as a comparison with a fully three dimensional particle in cell code are reported. The comparison highlights the good agreement between the two models up to the weakly non-linear regimes. In highly non-linear regimes the two models only disagree in a localized region, where the plasma electrons expelled by the bunch close up at the end of the first plasma oscillation.

  14. Experimental investigation of opacity models for stellar interior, inertial fusion, and high energy density plasmas

    SciTech Connect

    Bailey, J. E.; Rochau, G. A.; Mancini, R. C.; Iglesias, C. A.; MacFarlane, J. J.; Golovkin, I. E.; Blancard, C.; Cosse, Ph.; Faussurier, G.

    2009-05-15

    Theoretical opacities are required for calculating energy transport in plasmas. In particular, understanding stellar interiors, inertial fusion, and Z pinches depends on the opacities of mid-atomic-number elements over a wide range of temperatures. The 150-300 eV temperature range is particularly interesting. The opacity models are complex and experimental validation is crucial. For example, solar models presently disagree with helioseismology and one possible explanation is inadequate theoretical opacities. Testing these opacities requires well-characterized plasmas at temperatures high enough to produce the ion charge states that exist in the sun. Typical opacity experiments heat a sample using x rays and measure the spectrally resolved transmission with a backlight. The difficulty grows as the temperature increases because the heating x-ray source must supply more energy and the backlight must be bright enough to overwhelm the plasma self-emission. These problems can be overcome with the new generation of high energy density (HED) facilities. For example, recent experiments at Sandia's Z facility [M. K. Matzen et al., Phys. Plasmas 12, 055503 (2005)] measured the transmission of a mixed Mg and Fe plasma heated to 156{+-}6 eV. This capability will also advance opacity science for other HED plasmas. This tutorial reviews experimental methods for testing opacity models, including experiment design, transmission measurement methods, accuracy evaluation, and plasma diagnostics. The solar interior serves as a focal problem and Z facility experiments illustrate the techniques.

  15. Particle-in-cell simulation of x-ray wakefield acceleration and betatron radiation in nanotubes

    SciTech Connect

    Zhang, Xiaomei; Tajima, Toshiki; Farinella, Deano; Shin, Youngmin; Mourou, Gerard; Wheeler, Jonathan; Taborek, Peter; Chen, Pisin; Dollar, Franklin; Shen, Baifei

    2016-10-18

    Though wakefield acceleration in crystal channels has been previously proposed, x-ray wakefield acceleration has only recently become a realistic possibility since the invention of the single-cycled optical laser compression technique. We investigate the acceleration due to a wakefield induced by a coherent, ultrashort x-ray pulse guided by a nanoscale channel inside a solid material. By two-dimensional particle-in-cell computer simulations, we show that an acceleration gradient of TeV/cm is attainable. This is about 3 orders of magnitude stronger than that of the conventional plasma-based wakefield accelerations, which implies the possibility of an extremely compact scheme to attain ultrahigh energies. In addition to particle acceleration, this scheme can also induce the emission of high energy photons at ~O(10–100) MeV. Here, our simulations confirm such high energy photon emissions, which is in contrast with that induced by the optical laser driven wakefield scheme. In addition to this, the significantly improved emittance of the energetic electrons has been discussed.

  16. Particle-in-cell simulation of x-ray wakefield acceleration and betatron radiation in nanotubes

    DOE PAGES

    Zhang, Xiaomei; Tajima, Toshiki; Farinella, Deano; ...

    2016-10-18

    Though wakefield acceleration in crystal channels has been previously proposed, x-ray wakefield acceleration has only recently become a realistic possibility since the invention of the single-cycled optical laser compression technique. We investigate the acceleration due to a wakefield induced by a coherent, ultrashort x-ray pulse guided by a nanoscale channel inside a solid material. By two-dimensional particle-in-cell computer simulations, we show that an acceleration gradient of TeV/cm is attainable. This is about 3 orders of magnitude stronger than that of the conventional plasma-based wakefield accelerations, which implies the possibility of an extremely compact scheme to attain ultrahigh energies. In additionmore » to particle acceleration, this scheme can also induce the emission of high energy photons at ~O(10–100) MeV. Here, our simulations confirm such high energy photon emissions, which is in contrast with that induced by the optical laser driven wakefield scheme. In addition to this, the significantly improved emittance of the energetic electrons has been discussed.« less

  17. Particle-in-cell simulation of x-ray wakefield acceleration and betatron radiation in nanotubes

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaomei; Tajima, Toshiki; Farinella, Deano; Shin, Youngmin; Mourou, Gerard; Wheeler, Jonathan; Taborek, Peter; Chen, Pisin; Dollar, Franklin; Shen, Baifei

    2016-10-01

    Though wakefield acceleration in crystal channels has been previously proposed, x-ray wakefield acceleration has only recently become a realistic possibility since the invention of the single-cycled optical laser compression technique. We investigate the acceleration due to a wakefield induced by a coherent, ultrashort x-ray pulse guided by a nanoscale channel inside a solid material. By two-dimensional particle-in-cell computer simulations, we show that an acceleration gradient of TeV /cm is attainable. This is about 3 orders of magnitude stronger than that of the conventional plasma-based wakefield accelerations, which implies the possibility of an extremely compact scheme to attain ultrahigh energies. In addition to particle acceleration, this scheme can also induce the emission of high energy photons at ˜O (10 - 100 ) MeV . Our simulations confirm such high energy photon emissions, which is in contrast with that induced by the optical laser driven wakefield scheme. In addition to this, the significantly improved emittance of the energetic electrons has been discussed.

  18. The formation of reverse shocks in magnetized high energy density supersonic plasma flows

    SciTech Connect

    Lebedev, S. V. E-mail: l.suttle10@imperial.ac.uk; Suttle, L.; Swadling, G. F.; Bennett, M.; Bland, S. N.; Burdiak, G. C.; Chittenden, J. P.; Grouchy, P. de; Hall, G. N.; Hare, J. D.; Kalmoni, N.; Niasse, N.; Patankar, S.; Smith, R. A.; Suzuki-Vidal, F.; Burgess, D.; Clemens, A.; Ciardi, A.; Sheng, L.; Yuan, J.; and others

    2014-05-15

    A new experimental platform was developed, based on the use of supersonic plasma flow from the ablation stage of an inverse wire array z-pinch, for studies of shocks in magnetized high energy density physics plasmas in a well-defined and diagnosable 1-D interaction geometry. The mechanism of flow generation ensures that the plasma flow (Re{sub M} ∼ 50, M{sub S} ∼ 5, M{sub A} ∼ 8, V{sub flow} ≈ 100 km/s) has a frozen-in magnetic field at a level sufficient to affect shocks formed by its interaction with obstacles. It is found that in addition to the expected accumulation of stagnated plasma in a thin layer at the surface of a planar obstacle, the presence of the magnetic field leads to the formation of an additional detached density jump in the upstream plasma, at a distance of ∼c/ω{sub pi} from the obstacle. Analysis of the data obtained with Thomson scattering, interferometry, and local magnetic probes suggests that the sub-shock develops due to the pile-up of the magnetic flux advected by the plasma flow.

  19. Fully-kinetic simulations of the Rayleigh-Taylor instability in high-energy-density plasmas

    NASA Astrophysics Data System (ADS)

    Alves, E. Paulo; Mori, Warren B.; Fiuza, Frederico

    2016-10-01

    The Rayleigh-Taylor instability (RTI) in high-energy-density (HED) plasmas is a central problem in a wide range of scenarios. It dictates, for instance, the dynamics of supernovae in astrophysical plasmas, and is also recognized as a critical challenge to achieving ignition in inertial confinement fusion. In some of these conditions the Larmor radius or Coulomb mean free path (m.f.p.) is finite, allowing kinetic effects to become important, and it is not fully clear how the development of the RTI deviates from standard hydrodynamic behavior. In order to obtain an accurate description of the RTI in these HED conditions it is essential to capture the self-consistent interplay between collisional and collisionless plasma processes, and the role of self-generated electric and magnetic fields. We have explored the dynamics of the RTI in HED plasma conditions using first-principles particle-in-cell simulations combined with Monte Carlo binary collisions. Our simulations capture the role of kinetic diffusion as well as the self-generated electric (e.g. space-charge) and magnetic (e.g. Biermann battery) fields on the growth rate and nonlinear evolution of the RTI for different plasma conditions. We will discuss how different collisional m.f.p. relative to the collisionless plasma skin depth affect the RTI development. This work was supported by the DOE Office of Science, Fusion Energy Science (FWP 100182).

  20. Design of a High-Energy, Two-Stage Pulsed Plasma Thruster

    NASA Technical Reports Server (NTRS)

    Markusic, T. E.; Thio, Y. C. F.; Cassibry, J. T.; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    Design details of a proposed high-energy (approx. 50 kJ/pulse), two-stage pulsed plasma thruster are presented. The long-term goal of this project is to develop a high-power (approx. 500 kW), high specific impulse (approx. 7500 s), highly efficient (approx. 50%),and mechanically simple thruster for use as primary propulsion in a high-power nuclear electric propulsion system. The proposed thruster (PRC-PPT1) utilizes a valveless, liquid lithium-fed thermal plasma injector (first stage) followed by a high-energy pulsed electromagnetic accelerator (second stage). A numerical circuit model coupled with one-dimensional current sheet dynamics, as well as a numerical MHD simulation, are used to qualitatively predict the thermal plasma injection and current sheet dynamics, as well as to estimate the projected performance of the thruster. A set of further modelling efforts, and the experimental testing of a prototype thruster, is suggested to determine the feasibility of demonstrating a full scale high-power thruster.

  1. Numerical Modeling and Testing of an Inductively-Driven and High-Energy Pulsed Plasma Thrusters

    NASA Technical Reports Server (NTRS)

    Parma, Brian

    2004-01-01

    Pulsed Plasma Thrusters (PPTs) are advanced electric space propulsion devices that are characterized by simplicity and robustness. They suffer, however, from low thrust efficiencies. This summer, two approaches to improve the thrust efficiency of PPTs will be investigated through both numerical modeling and experimental testing. The first approach, an inductively-driven PPT, uses a double-ignition circuit to fire two PPTs in succession. This effectively changes the PPTs configuration from an LRC circuit to an LR circuit. The LR circuit is expected to provide better impedance matching and improving the efficiency of the energy transfer to the plasma. An added benefit of the LR circuit is an exponential decay of the current, whereas a traditional PPT s under damped LRC circuit experiences the characteristic "ringing" of its current. The exponential decay may provide improved lifetime and sustained electromagnetic acceleration. The second approach, a high-energy PPT, is a traditional PPT with a variable size capacitor bank. This PPT will be simulated and tested at energy levels between 100 and 450 joules in order to investigate the relationship between efficiency and energy level. Arbitrary Coordinate Hydromagnetic (MACH2) code is used. The MACH2 code, designed by the Center for Plasma Theory and Computation at the Air Force Research Laboratory, has been used to gain insight into a variety of plasma problems, including electric plasma thrusters. The goals for this summer include numerical predictions of performance for both the inductively-driven PPT and high-energy PFT, experimental validation of the numerical models, and numerical optimization of the designs. These goals will be met through numerical and experimental investigation of the PPTs current waveforms, mass loss (or ablation), and impulse bit characteristics.

  2. Numerical Modeling and Testing of an Inductively-Driven and High-Energy Pulsed Plasma Thrusters

    NASA Technical Reports Server (NTRS)

    Parma, Brian

    2004-01-01

    Pulsed Plasma Thrusters (PPTs) are advanced electric space propulsion devices that are characterized by simplicity and robustness. They suffer, however, from low thrust efficiencies. This summer, two approaches to improve the thrust efficiency of PPTs will be investigated through both numerical modeling and experimental testing. The first approach, an inductively-driven PPT, uses a double-ignition circuit to fire two PPTs in succession. This effectively changes the PPTs configuration from an LRC circuit to an LR circuit. The LR circuit is expected to provide better impedance matching and improving the efficiency of the energy transfer to the plasma. An added benefit of the LR circuit is an exponential decay of the current, whereas a traditional PPT s under damped LRC circuit experiences the characteristic "ringing" of its current. The exponential decay may provide improved lifetime and sustained electromagnetic acceleration. The second approach, a high-energy PPT, is a traditional PPT with a variable size capacitor bank. This PPT will be simulated and tested at energy levels between 100 and 450 joules in order to investigate the relationship between efficiency and energy level. Arbitrary Coordinate Hydromagnetic (MACH2) code is used. The MACH2 code, designed by the Center for Plasma Theory and Computation at the Air Force Research Laboratory, has been used to gain insight into a variety of plasma problems, including electric plasma thrusters. The goals for this summer include numerical predictions of performance for both the inductively-driven PPT and high-energy PFT, experimental validation of the numerical models, and numerical optimization of the designs. These goals will be met through numerical and experimental investigation of the PPTs current waveforms, mass loss (or ablation), and impulse bit characteristics.

  3. Spheromaks and how plasmas may explain the ultra high energy cosmic ray mystery

    DOE PAGES

    Fowler, T. Kenneth; Li, Hui

    2016-10-10

    In recent papers, we show how accretion disks around massive black holes could act as dynamos producing magnetic jets similar to the jets that create spheromaks in the laboratory. In this paper, we discuss how these magnetic astrophysical jets might naturally produce runaway ion beams accelerated tomore » $$10^{20}$$ eV or more, finally ejected as ultra high energy cosmic rays (UHECRs) long regarded as one of the mysteries of astrophysics. The acceleration is mainly due to the drift cyclotron loss cone kinetic instability known from plasma research. Finally, experiments and simulations are suggested to verify the acceleration process.« less

  4. Solar High-energy Astrophysical Plasmas Explorer (SHAPE). Volume 1: Proposed concept, statement of work and cost plan

    NASA Technical Reports Server (NTRS)

    Dennis, Brian R.; Martin, Franklin D.; Prince, T.; Lin, R.; Bruner, M.; Culhane, L.; Ramaty, R.; Doschek, G.; Emslie, G.; Lingenfelter, R.

    1986-01-01

    The concept of the Solar High-Energy Astrophysical Plasmas Explorer (SHAPE) is studied. The primary goal is to understand the impulsive release of energy, efficient acceleration of particles to high energies, and rapid transport of energy. Solar flare studies are the centerpieces of the investigation because in flares these high energy processes can be studied in unmatched detail at most wavelenth regions of the electromagnetic spectrum as well as in energetic charged particles and neutrons.

  5. Pressure-driven, resistive magnetohydrodynamic interchange instabilities in laser-produced high-energy-density plasmas

    SciTech Connect

    Li, C. K.; Frenje, J. A.; Petrasso, R. D.; Seguin, F. H.; Amendt, P. A.; Landen, O. L.; Town, R. P. J.; Betti, R.; Knauer, J. P.; Meyerhofer, D. D.; Soures, J. M.

    2009-07-15

    Recent experiments using proton backlighting of laser-foil interactions provide unique opportunities for studying magnetized plasma instabilities in laser-produced high-energy-density plasmas. Time-gated proton radiograph images indicate that the outer structure of a magnetic field entrained in a hemispherical plasma bubble becomes distinctly asymmetric after the laser turns off. It is shown that this asymmetry is a consequence of pressure-driven, resistive magnetohydrodynamic (MHD) interchange instabilities. In contrast to the predictions made by ideal MHD theory, the increasing plasma resistivity after laser turn-off allows for greater low-mode destabilization (m>1) from reduced stabilization by field-line bending. For laser-generated plasmas presented herein, a mode-number cutoff for stabilization of perturbations with m>{approx}[8{pi}{beta}(1+D{sub m}k{sub perpendicular}{sup 2}{gamma}{sub max}{sup -1})]{sup 1/2} is found in the linear growth regime. The growth is measured and is found to be in reasonable agreement with model predictions.

  6. The impact of Hall physics on magnetized high energy density plasma jets

    SciTech Connect

    Gourdain, P.-A.; Seyler, C. E.; Atoyan, L.; Greenly, J. B.; Hammer, D. A.; Kusse, B. R.; Pikuz, S. A.; Potter, W. M.; Schrafel, P. C.; Shelkovenko, T. A.

    2014-05-15

    Hall physics is often neglected in high energy density plasma jets due to the relatively high electron density of such jets (n{sub e} ∼ 10{sup 19} cm{sup −3}). However, the vacuum region surrounding the jet has much lower densities and is dominated by Hall electric field. This electric field redirects plasma flows towards or away from the axis, depending on the radial current direction. A resulting change in the jet density has been observed experimentally. Furthermore, if an axial field is applied on the jet, the Hall effect is enhanced and ignoring it leads to serious discrepancies between experimental results and numerical simulations. By combining high currents (∼1 MA) and magnetic field helicity (15° angle) in a pulsed power generator such as COBRA, plasma jets can be magnetized with a 10 T axial field. The resulting field enhances the impact of the Hall effect by altering the density profile of current-free plasma jets and the stability of current-carrying plasma jets (e.g., Z-pinches)

  7. Pressure-driven, resistive magnetohydrodynamic interchange instabilities in laser-produced high-energy-density plasmas.

    PubMed

    Li, C K; Frenje, J A; Petrasso, R D; Séguin, F H; Amendt, P A; Landen, O L; Town, R P J; Betti, R; Knauer, J P; Meyerhofer, D D; Soures, J M

    2009-07-01

    Recent experiments using proton backlighting of laser-foil interactions provide unique opportunities for studying magnetized plasma instabilities in laser-produced high-energy-density plasmas. Time-gated proton radiograph images indicate that the outer structure of a magnetic field entrained in a hemispherical plasma bubble becomes distinctly asymmetric after the laser turns off. It is shown that this asymmetry is a consequence of pressure-driven, resistive magnetohydrodynamic (MHD) interchange instabilities. In contrast to the predictions made by ideal MHD theory, the increasing plasma resistivity after laser turn-off allows for greater low-mode destabilization (m>1) from reduced stabilization by field-line bending. For laser-generated plasmas presented herein, a mode-number cutoff for stabilization of perturbations with m> approximately [8pibeta(1+D_{m}k_{ perpendicular};{2}gamma_{max};{-1})];{1/2} is found in the linear growth regime. The growth is measured and is found to be in reasonable agreement with model predictions.

  8. Two-stage acceleration of interstellar ions driven by high-energy lepton plasma flows

    NASA Astrophysics Data System (ADS)

    Cui, YunQian; Sheng, ZhengMing; Lu, QuanMing; Li, YuTong; Zhang, Jie

    2015-10-01

    We present the particle-in-cell (PIC) simulation results of the interaction of a high-energy lepton plasma flow with background electron-proton plasma and focus on the acceleration processes of the protons. It is found that the acceleration follows a two-stage process. In the first stage, protons are significantly accelerated transversely (perpendicular to the lepton flow) by the turbulent magnetic field "islands" generated via the strong Weibel-type instabilities. The accelerated protons shows a perfect inverse-power energy spectrum. As the interaction continues, a shockwave structure forms and the protons in front of the shockwave are reflected at twice of the shock speed, resulting in a quasi-monoenergetic peak located near 200 MeV under the simulation parameters. The presented scenario of ion acceleration may be relevant to cosmic-ray generation in some astrophysical environments.

  9. Reduced entropic model for studies of multidimensional nonlocal transport in high-energy-density plasmas

    NASA Astrophysics Data System (ADS)

    Del Sorbo, D.; Feugeas, J.-L.; Nicolaï, Ph.; Olazabal-Loumé, M.; Dubroca, B.; Guisset, S.; Touati, M.; Tikhonchuk, V.

    2015-08-01

    Hydrodynamic simulations of high-energy-density plasmas require a detailed description of energy fluxes. For low and intermediate atomic number materials, the leading mechanism is the electron transport, which may be a nonlocal phenomenon requiring a kinetic modeling. In this paper, we present and test the results of a nonlocal model based on the first angular moments of a simplified Fokker-Planck equation. This multidimensional model is closed thanks to an entropic relation (the Boltzman H-theorem). It provides a better description of the electron distribution function, thus enabling studies of small scale kinetic effects within the hydrodynamic framework. Examples of instabilities of electron plasma and ion-acoustic waves, driven by the heat flux, are presented and compared with the classical formula.

  10. Reduced entropic model for studies of multidimensional nonlocal transport in high-energy-density plasmas

    SciTech Connect

    Del Sorbo, D.; Feugeas, J.-L.; Nicolaï, Ph.; Olazabal-Loumé, M.; Dubroca, B.; Guisset, S.; Touati, M.; Tikhonchuk, V.

    2015-08-15

    Hydrodynamic simulations of high-energy-density plasmas require a detailed description of energy fluxes. For low and intermediate atomic number materials, the leading mechanism is the electron transport, which may be a nonlocal phenomenon requiring a kinetic modeling. In this paper, we present and test the results of a nonlocal model based on the first angular moments of a simplified Fokker-Planck equation. This multidimensional model is closed thanks to an entropic relation (the Boltzman H-theorem). It provides a better description of the electron distribution function, thus enabling studies of small scale kinetic effects within the hydrodynamic framework. Examples of instabilities of electron plasma and ion-acoustic waves, driven by the heat flux, are presented and compared with the classical formula.

  11. Dense Plasma Focus With High Energy Helium Beams for Radiological Source Replacement

    NASA Astrophysics Data System (ADS)

    Schmidt, Andrea; Ellsworth, Jennifer; Falabella, Steve; Link, Anthony; Rusnak, Brian; Sears, Jason; Tang, Vincent

    2014-10-01

    A dense plasma focus (DPF) is a compact accelerator that can produce intense high energy ion beams (multiple MeV). It could be used in place of americium-beryllium (AmBe) neutron sources in applications such as oil well logging if optimized to produce high energy helium beams. AmBe sources produce neutrons when 5.5 MeV alphas emitted from the Am interact with the Be. However, due to the very small alpha-Be cross section for alphas <2 MeV, an AmBe source replacement would have to accelerate ~0.15 μC of He to 2 + MeV in order to produce 107 neutrons per pulse. We are using our particle in cell (PIC) model in LSP of a 4 kJ dense plasma focus discharge to guide the optimization of a compact DPF for the production of high-energy helium beam. This model is fluid for the run-down phase, and then transitions to fully kinetic prior to the pinch in order to include kinetic effects such as ion beam formation and anomalous resistivity. An external pulsed-power driver circuit is used at the anode-cathode boundary. Simulations will be benchmarked to He beam measurements using filtered and time-of-flight Faraday cup diagnostics. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work supported by US DOE/NA-22 Office of Non-proliferation Research and Development. Computing support for this work came from the LLNL Institutional Computing Grand Challenge program.

  12. Magnetohydrodynamics of laser-produced high-energy-density plasma in a strong external magnetic field.

    PubMed

    Matsuo, Kazuki; Nagatomo, Hideo; Zhang, Zhe; Nicolai, Philippe; Sano, Takayoshi; Sakata, Shohei; Kojima, Sadaoki; Lee, Seung Ho; Law, King Fai Farley; Arikawa, Yasunobu; Sakawa, Youichi; Morita, Taichi; Kuramitsu, Yasuhiro; Fujioka, Shinsuke; Azechi, Hiroshi

    2017-05-01

    Recent progress in the generation in the laboratory of a strong (>100-T) magnetic field enables us to investigate experimentally unexplored magnetohydrodynamics phenomena of a high-energy-density plasma, which an external magnetic field of 200-300 T notably affects due to anisotropic thermal conduction, even when the magnetic field pressure is much lower than the plasma pressure. The external magnetic field reduces electron thermal conduction across the external magnetic field lines because the Larmor radius of the thermal electrons in the external magnetic field is much shorter than the mean free path of the thermal electrons. The velocity of a thin polystyrene foil driven by intense laser beams in the strong external magnetic field is faster than that in the absence of the external magnetic field. Growth of sinusoidal corrugation imposed initially on the laser-driven polystyrene surface is enhanced by the external magnetic field because the plasma pressure distribution becomes nonuniform due to the external magnetic-field structure modulated by the perturbed plasma flow ablated from the corrugated surface.

  13. Magnetohydrodynamics of laser-produced high-energy-density plasma in a strong external magnetic field

    NASA Astrophysics Data System (ADS)

    Matsuo, Kazuki; Nagatomo, Hideo; Zhang, Zhe; Nicolai, Philippe; Sano, Takayoshi; Sakata, Shohei; Kojima, Sadaoki; Lee, Seung Ho; Law, King Fai Farley; Arikawa, Yasunobu; Sakawa, Youichi; Morita, Taichi; Kuramitsu, Yasuhiro; Fujioka, Shinsuke; Azechi, Hiroshi

    2017-05-01

    Recent progress in the generation in the laboratory of a strong (>100 -T) magnetic field enables us to investigate experimentally unexplored magnetohydrodynamics phenomena of a high-energy-density plasma, which an external magnetic field of 200-300 T notably affects due to anisotropic thermal conduction, even when the magnetic field pressure is much lower than the plasma pressure. The external magnetic field reduces electron thermal conduction across the external magnetic field lines because the Larmor radius of the thermal electrons in the external magnetic field is much shorter than the mean free path of the thermal electrons. The velocity of a thin polystyrene foil driven by intense laser beams in the strong external magnetic field is faster than that in the absence of the external magnetic field. Growth of sinusoidal corrugation imposed initially on the laser-driven polystyrene surface is enhanced by the external magnetic field because the plasma pressure distribution becomes nonuniform due to the external magnetic-field structure modulated by the perturbed plasma flow ablated from the corrugated surface.

  14. Controlled electron injection using nanoparticles in laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Cho, Myung Hoon; Pathak, Vishwa Bandhu; Kim, Hyung Taek; Nakajima, Kazuhisa; Nam, Chang Hee; CenterRelativistic Laser Science Team

    2016-10-01

    Laser wakefield acceleration is one of compact electron acceleration schemes due to its high accelerating gradient. Despite of the great progress of several GeV electron beams with high power lasers, the electron injection to the wakefield is still a critical issue for a very low density plasma 1017 electrons/cc. In this talk a novel method to control the injection using nanoparticles is proposed. We investigate the electron injection by analyzing the interaction of electrons with the two potentials - one created by a nanoparticle and the other by the wakefield. The nanoparticle creates a localized electric potential and this nanoparticle potential just slips the present wake potential. To confirm the Hamiltonian description of the interaction, a test particle calculation is performed by controlling the bubble and the nanoparticle potentials. A multi-dimensional particle-in-cell simulations are also presented as a proof-of-principle. Comparing theoretical estimates and PIC simulation, we suggest nanoparticle parameters of size and electron density depending on the background plasma density. Our scheme can be applicable for low plasma density to break though the limitation of self-injection toward extremely high energy electron energy.

  15. Experimental investigation of opacity models for stellar interiors, inertial fusion, and high energy density plasmas

    NASA Astrophysics Data System (ADS)

    Bailey, James

    2008-11-01

    Theoretical opacities are required for calculating energy transport in plasmas. In particular, understanding stellar interiors, inertial fusion, and Z-pinches depends on the opacities of mid-atomic-number elements in the 150-300 eV temperature range. These models are complex and experimental validation is crucial. For example, solar models presently disagree with helioseismology and one possible explanation is inadequate opacities. Testing these opacities requires a uniform plasma at temperatures high enough to produce the ion charge states that exist in the sun. Typical opacity experiments heat a sample using x-rays and measure the spectrally resolved transmission with a backlight. The difficulty grows as the temperature increases because the heating x-ray source must supply more energy and the backlighter source must be bright enough to overwhelm the plasma self emission. These problems were overcome using the dynamic hohlraum x-ray source at Sandia's Z facility to measure the transmission of a mixed Mg-Fe plasma heated above 150 eV. This capability will also advance opacity science for other high energy density plasmas. This tutorial describes opacity experiment challenges including accurate transmission measurements, plasma diagnostics, and quantitative model comparisons. The solar interior serves as a focal problem and Z facility experiments are used to illustrate the techniques. **In collaboration with C. Iglesias (LLNL), R. Mancini (U. Nevada), J.MacFarlane, I. Golovkin and P. Wang (Prism), C. Blancard, Ph. Cosse, G. Faussurier, F. Gilleron, and J.C. Pain (CEA), J. Abdallah Jr. (LANL), and G.A. Rochau and P.W. Lake (Sandia). ++Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.

  16. Modeling Nuclear Fusion in High Energy Density Plasmas Using a Strongly Magnetized Non-neutral Plasma

    NASA Astrophysics Data System (ADS)

    Dubin, D. H. E.

    2005-10-01

    In the hot dense interiors of stars and giant planets, nuclear reactions are predicted to occur at rates that are greatly enhanced compared to those at low densities. The enhancement is caused by plasma screening of the reacting pairs, increasing the probability of close collisions. However, strongly enhanced nuclear reaction rates have never been observed in the laboratory. This poster discusses a method for observing the enhancement using an analogy between nuclear energy and cyclotron energy in a non-neutral plasma in a strong magnetic field. In such a plasma, cyclotron energy is an adiabatic invariant, and is released only through close collisions that break this invariant. It is shown that the rate of release of cyclotron energy is enhanced by precisely the same factor as that for the release of nuclear energy, because both processes rely on close collisions that are enhanced by plasma screening.ootnotetextD. Dubin, Phys. Rev. Lett. 94, 025002 (2005). Simulations measuring the screening enhancement will be presented, and the possibility of exciting and studying burn fronts will be discussed.ootnotetextSee also adjacent poster by J. Bollinger.

  17. Experimental and Computational Studies of High Energy Density Plasma Streams Ablated from Fine Wires

    SciTech Connect

    Greenly, John B.; Seyler, Charles

    2014-03-30

    Experimental and computational studies of high energy density plasma streams ablated from fine wires. Laboratory of Plasma Studies, School of Electrical and Computer Engineering, Cornell University. Principal Investigators: Dr. John B. Greenly and Dr. Charles E. Seyler. This report summarizes progress during the final year of this project to study the physics of high energy density (HED) plasma streams of 10^17-10^20/cm3 density and high velocity (~100-500 km/s). Such streams are produced from 5-250 micrometer diameter wires heated and ionized by a 1 MA, 250 ns current pulse on the COBRA pulsed power facility at Cornell University. Plasma is ablated from the wires and is driven away to high velocity by unbalanced JxB force. A wire, or an array of wires, can persist as an essentially stationary, continuous source of this streaming plasma for >200 ns, even with driving magnetic fields of many Tesla and peak current densities in the plasma of many MA/cm2. At the heart of the ablation stream generation is the continuous transport of mass from the relatively cold, near-solid-density wire "core" into current-carrying plasma within 1 mm of the wire, followed by the magnetic acceleration of that plasma and its trapped flux to form a directed stream. In the first two years of this program, an advancing understanding of ablation physics led to the discovery of several novel wire ablation experimental regimes. In the final year, one of these new HED plasma regimes has been studied in quantitative detail. This regime studies highly reproducible magnetic reconnection in strongly radiating plasma with supersonic and superalfvenic flow, and shock structures in the outflow. The key discovery is that very heavy wires, e.g. 250 micrometer diameter Al or 150 micrometer Cu, behave in a qualitatively different way than the lighter wires typically used in wire-array Z-pinches. Such wires can be configured to produce a static magnetic X-point null geometry that stores magnetic and

  18. Observations of subsonic and supersonic shear flows in laser driven high-energy-density plasmas

    NASA Astrophysics Data System (ADS)

    Harding, E. C.

    2009-11-01

    Shear layers containing strong velocity gradients appear in many high-energy-density (HED) systems and play important roles in mixing and the transition to turbulence. Yet few laboratory experiments have been carried out to study their detailed evolution in this extreme environment where plasmas are compressible, actively ionizing, often involve strong shock waves and have complex material properties. Many shear flows produce the Kelvin-Helmholtz (KH) instability, which initiates the mixing at a fluid interface. We present results from two dedicated shear flow experiments that produced overall subsonic and supersonic flows using novel target designs. In the subsonic case, the Omega laser was used to drive a blast wave along a rippled interface between plastic and foam, shocking both the materials to produce two fluids separated by a sharp shear layer. The interface subsequently rolled-upped into large KH vortices that were accompanied by bubble-like structures of unknown origin. This was the first time the evolution of a well-resolved KH instability was observed in a HED plasma in the laboratory. We have analyzed the properties and dynamics of the plasma based on the data and fundamental models, without resorting to simulated values. In the second, supersonic experiment the Nike laser was used to drive a supersonic flow of Al plasma along a rippled, low-density foam surface. Here again the flowing plasma drove a shock into the second material, so that two fluids were separated by a shear layer. In contrast to the subsonic case, the flow developed shocks around the ripples in response to the supersonic flow of Al. Collaborators: R.P. Drake, O.A. Hurricane, J.F. Hansen, Y. Aglitskiy, T. Plewa, B.A. Remington, H.F. Robey, J.L. Weaver, A.L. Velikovich, R.S. Gillespie, M.J. Bono, M.J. Grosskopf, C.C. Kuranz, A. Visco.

  19. Measurements of Ion Stopping around the Bragg Peak in High-Energy-Density Plasmas

    NASA Astrophysics Data System (ADS)

    Frenje, Johan

    2015-11-01

    Over the last few decades, ion stopping in weakly- to strongly-coupled High-Energy-Density (HED) plasmas has been subject to extensive analytical and numerical studies, but only a limited set of experimental data exists to check the validity of these theories. Most of these experiments also did not probe the detailed characteristics of the Bragg peak (peak ion stopping) where the ion velocity is similar to the average thermal electron velocity. To the best of our knowledge, only one exploratory attempt to do this was conducted by Hicks et al., who were able to describe qualitatively the behavior of the Bragg peak for one plasma condition. The work described in this presentation makes significant advances over previous experimental efforts by quantitatively assessing the characteristics of the ion stopping, ranging from low-velocity stopping, through the Bragg peak, to high-velocity stopping for different HED plasma conditions. This was achieved by measuring the energy loss of DD-tritons, D3He-alphas, DD-protons and D3He-protons, with distinctly different velocities, and the results indicate that the stopping power varies strongly with Te and ne. This effort represents the first experimental test of state-of-art plasma-stopping-power theories around the Bragg peak, which is an important first step in our efforts of getting a fundamental understanding of DT-alpha stopping in HED plasmas, a prerequisite for understanding ignition margins in various implosion designs with varying hot spot areal density at the National Ignition Facility. The work described here was performed in part at the LLE National Laser User's Facility (NLUF), and was supported in part by US DOE (Grant No. DE-FG03- 03SF22691), LLNL (subcontract Grant No. B504974) and LLE (subcontract Grant No. 412160-001G).

  20. Talbot-Lau x-ray interferometry for high energy density plasma diagnostic

    SciTech Connect

    Stutman, D.; Finkenthal, M.

    2011-11-15

    High resolution density diagnostics are difficult in high energy density laboratory plasmas (HEDLP) experiments due to the scarcity of probes that can penetrate above solid density plasmas. Hard x-rays are one possible probe for such dense plasmas. We study the possibility of applying an x-ray method recently developed for medical imaging, differential phase-contrast with Talbot-Lau interferometers, for the diagnostic of electron density and small-scale hydrodynamic instabilities in HEDLP experiments. The Talbot method uses micro-periodic gratings to measure the refraction and ultra-small angle scatter of x-rays through an object and is attractive for HEDLP diagnostic due to its capability to work with incoherent and polychromatic x-ray sources such as the laser driven backlighters used for HEDLP radiography. Our paper studies the potential of the Talbot method for HEDLP diagnostic, its adaptation to the HEDLP environment, and its extension of high x-ray energy using micro-periodic mirrors. The analysis is illustrated with experimental results obtained using a laboratory Talbot interferometer.

  1. Talbot-Lau x-ray interferometry for high energy density plasma diagnostic.

    PubMed

    Stutman, D; Finkenthal, M

    2011-11-01

    High resolution density diagnostics are difficult in high energy density laboratory plasmas (HEDLP) experiments due to the scarcity of probes that can penetrate above solid density plasmas. Hard x-rays are one possible probe for such dense plasmas. We study the possibility of applying an x-ray method recently developed for medical imaging, differential phase-contrast with Talbot-Lau interferometers, for the diagnostic of electron density and small-scale hydrodynamic instabilities in HEDLP experiments. The Talbot method uses micro-periodic gratings to measure the refraction and ultra-small angle scatter of x-rays through an object and is attractive for HEDLP diagnostic due to its capability to work with incoherent and polychromatic x-ray sources such as the laser driven backlighters used for HEDLP radiography. Our paper studies the potential of the Talbot method for HEDLP diagnostic, its adaptation to the HEDLP environment, and its extension of high x-ray energy using micro-periodic mirrors. The analysis is illustrated with experimental results obtained using a laboratory Talbot interferometer. © 2011 American Institute of Physics

  2. Megagauss field generation for high-energy-density plasma science experiments.

    SciTech Connect

    Rovang, Dean Curtis; Struve, Kenneth William; Porter, John Larry Jr.

    2008-10-01

    There is a need to generate magnetic fields both above and below 1 megagauss (100 T) with compact generators for laser-plasma experiments in the Beamlet and Petawatt test chambers for focused research on fundamental properties of high energy density magnetic plasmas. Some of the important topics that could be addressed with such a capability are magnetic field diffusion, particle confinement, plasma instabilities, spectroscopic diagnostic development, material properties, flux compression, and alternate confinement schemes, all of which could directly support experiments on Z. This report summarizes a two-month study to develop preliminary designs of magnetic field generators for three design regimes. These are, (1) a design for a relatively low-field (10 to 50 T), compact generator for modest volumes (1 to 10 cm3), (2) a high-field (50 to 200 T) design for smaller volumes (10 to 100 mm3), and (3) an extreme field (greater than 600 T) design that uses flux compression. These designs rely on existing Sandia pulsed-power expertise and equipment, and address issues of magnetic field scaling with capacitor bank design and field inductance, vacuum interface, and trade-offs between inductance and coil designs.

  3. Note: Experimental platform for magnetized high-energy-density plasma studies at the omega laser facility.

    PubMed

    Fiksel, G; Agliata, A; Barnak, D; Brent, G; Chang, P-Y; Folnsbee, L; Gates, G; Hasset, D; Lonobile, D; Magoon, J; Mastrosimone, D; Shoup, M J; Betti, R

    2015-01-01

    An upgrade of the pulsed magnetic field generator magneto-inertial fusion electrical discharge system [O. Gotchev et al., Rev. Sci. Instrum. 80, 043504 (2009)] is described. The device is used to study magnetized high-energy-density plasma and is capable of producing a pulsed magnetic field of tens of tesla in a volume of a few cubic centimeters. The magnetic field is created by discharging a high-voltage capacitor through a small wire-wound coil. The coil current pulse has a duration of about 1 μs and a peak value of 40 kA. Compared to the original, the updated version has a larger energy storage and improved switching system. In addition, magnetic coils are fabricated using 3-D printing technology which allows for a greater variety of the magnetic field topology.

  4. Note: Experimental platform for magnetized high-energy-density plasma studies at the omega laser facility

    NASA Astrophysics Data System (ADS)

    Fiksel, G.; Agliata, A.; Barnak, D.; Brent, G.; Chang, P.-Y.; Folnsbee, L.; Gates, G.; Hasset, D.; Lonobile, D.; Magoon, J.; Mastrosimone, D.; Shoup, M. J.; Betti, R.

    2015-01-01

    An upgrade of the pulsed magnetic field generator magneto-inertial fusion electrical discharge system [O. Gotchev et al., Rev. Sci. Instrum. 80, 043504 (2009)] is described. The device is used to study magnetized high-energy-density plasma and is capable of producing a pulsed magnetic field of tens of tesla in a volume of a few cubic centimeters. The magnetic field is created by discharging a high-voltage capacitor through a small wire-wound coil. The coil current pulse has a duration of about 1 μs and a peak value of 40 kA. Compared to the original, the updated version has a larger energy storage and improved switching system. In addition, magnetic coils are fabricated using 3-D printing technology which allows for a greater variety of the magnetic field topology.

  5. Measurements of ion stopping around the Bragg peak in high-energy-density plasmas

    SciTech Connect

    Frenje, J. A.; Grabowski, P. E.; Li, C. K.; Seguin, F. H.; Zylstra, A. B.; Gatu Johnson, M.; Petrasso, R. D.; Glebov, V. Yu; Sangster, T. C.

    2015-11-09

    For the first time, quantitative measurements of ion stopping at energies about the Bragg peak (or peak ion stopping, which occurs at an ion velocity comparable to the average thermal electron velocity), and its dependence on electron temperature (Te) and electron number density (ne) in the range of 0.5 – 4.0 keV and 3 × 1022 – 3 × 1023 cm-3 have been conducted, respectively. It is experimentally demonstrated that the position and amplitude of the Bragg peak varies strongly with Te with ne. As a result, the importance of including quantum diffraction is also demonstrated in the stopping-power modeling of High-Energy-Density Plasmas.

  6. Spheromaks and how plasmas may explain the ultra high energy cosmic ray mystery

    SciTech Connect

    Fowler, T. Kenneth; Li, Hui

    2016-10-10

    In recent papers, we show how accretion disks around massive black holes could act as dynamos producing magnetic jets similar to the jets that create spheromaks in the laboratory. In this paper, we discuss how these magnetic astrophysical jets might naturally produce runaway ion beams accelerated to$10^{20}$ eV or more, finally ejected as ultra high energy cosmic rays (UHECRs) long regarded as one of the mysteries of astrophysics. The acceleration is mainly due to the drift cyclotron loss cone kinetic instability known from plasma research. Finally, experiments and simulations are suggested to verify the acceleration process.

  7. Measurements of ion stopping around the Bragg peak in high-energy-density plasmas

    DOE PAGES

    Frenje, J. A.; Grabowski, P. E.; Li, C. K.; ...

    2015-11-09

    For the first time, quantitative measurements of ion stopping at energies about the Bragg peak (or peak ion stopping, which occurs at an ion velocity comparable to the average thermal electron velocity), and its dependence on electron temperature (Te) and electron number density (ne) in the range of 0.5 – 4.0 keV and 3 × 1022 – 3 × 1023 cm-3 have been conducted, respectively. It is experimentally demonstrated that the position and amplitude of the Bragg peak varies strongly with Te with ne. As a result, the importance of including quantum diffraction is also demonstrated in the stopping-power modelingmore » of High-Energy-Density Plasmas.« less

  8. Nuclear science research with dynamic high energy density plasmas at NIF

    NASA Astrophysics Data System (ADS)

    Shaughnessy, D. A.; Gharibyan, N.; Moody, K. J.; Despotopulos, J. D.; Grant, P. M.; Yeamans, C. B.; Berzak Hopkins, L.; Cerjan, C. J.; Schneider, D. H. G.; Faye, S.

    2016-05-01

    Nuclear reaction measurements are performed at the National Ignition Facility in a high energy density plasma environment by adding target materials to the outside of the hohlraum thermo-mechanical package on an indirect-drive exploding pusher shot. Materials are activated with 14.1-MeV neutrons and the post-shot debris is collected via the Solid Radiochemistry diagnostic, which consists of metal discs fielded 50 cm from target chamber center. The discs are removed post-shot and analyzed via radiation counting and mass spectrometry. Results from a shot using Nd and Tm foils as targets are presented, which indicate enhanced collection of the debris in the line of sight of a given collector. The capsule performance was not diminished due to the extra material. This provides a platform for future measurements of nuclear reaction data through the use of experimental packages mounted external to the hohlraum.

  9. Large Enhancement in High-Energy Photoionization of Fe XVII and Missing Continuum Plasma Opacity.

    PubMed

    Nahar, Sultana N; Pradhan, Anil K

    2016-06-10

    Aimed at solving the outstanding problem of solar opacity, and radiation transport plasma models in general, we report substantial photoabsorption in the high-energy regime due to atomic core photoexcitations not heretofore considered. In extensive R-matrix calculations of unprecedented complexity for an important iron ion Fe xvii (Fe^{16+}), with a wave function expansion of 99 Fe xviii (Fe^{17+}) LS core states from n≤4 complexes (equivalent to 218 fine structure levels), we find (i) up to orders of magnitude enhancement in background photoionization cross sections, in addition to strongly peaked photo-excitation-of-core resonances not considered in current opacity models, and ii) demonstrate convergence with respect to successive core excitations. The resulting increase in the monochromatic continuum, and 35% in the Rosseland mean opacity, are compared with the "higher-than-predicted" iron opacity measured at the Sandia Z-pinch fusion device at solar interior conditions.

  10. Large Enhancement in High-Energy Photoionization of Fe XVII and Missing Continuum Plasma Opacity

    NASA Astrophysics Data System (ADS)

    Nahar, Sultana N.; Pradhan, Anil K.

    2016-06-01

    Aimed at solving the outstanding problem of solar opacity, and radiation transport plasma models in general, we report substantial photoabsorption in the high-energy regime due to atomic core photoexcitations not heretofore considered. In extensive R -matrix calculations of unprecedented complexity for an important iron ion Fe xvii (Fe16 + ), with a wave function expansion of 99 Fe xviii (Fe17 + ) LS core states from n ≤4 complexes (equivalent to 218 fine structure levels), we find (i) up to orders of magnitude enhancement in background photoionization cross sections, in addition to strongly peaked photo-excitation-of-core resonances not considered in current opacity models, and ii) demonstrate convergence with respect to successive core excitations. The resulting increase in the monochromatic continuum, and 35% in the Rosseland mean opacity, are compared with the "higher-than-predicted" iron opacity measured at the Sandia Z -pinch fusion device at solar interior conditions.

  11. Note: Experimental platform for magnetized high-energy-density plasma studies at the omega laser facility

    SciTech Connect

    Fiksel, G.; Agliata, A.; Barnak, D.; Brent, G.; Chang, P. -Y.; Folnsbee, L.; Gates, G.; Hasset, D.; Lonobile, D.; Magoon, J.; Mastrosimone, D.; Shoup, III, M. J.; Betti, R.

    2015-01-12

    Here, an upgrade of the pulsed magnetic field generator magneto-inertial fusion electrical discharge system [O. Gotchev et al., Rev. Sci. Instrum. 80, 043504 (2009)] is described. The device is used to study magnetized high-energy-density plasma and is capable of producing a pulsed magnetic field of tens of tesla in a volume of a few cubic centimeters. The magnetic field is created by discharging a high-voltage capacitor through a small wire-wound coil. The coil current pulse has a duration of about 1 μs and a peak value of 40 kA. Compared to the original, the updated version has a larger energy storage and improved switching system. In addition, magnetic coils are fabricated using 3-D printing technology which allows for a greater variety of the magnetic field topology.

  12. Note: Experimental platform for magnetized high-energy-density plasma studies at the omega laser facility

    DOE PAGES

    Fiksel, G.; Agliata, A.; Barnak, D.; ...

    2015-01-12

    Here, an upgrade of the pulsed magnetic field generator magneto-inertial fusion electrical discharge system [O. Gotchev et al., Rev. Sci. Instrum. 80, 043504 (2009)] is described. The device is used to study magnetized high-energy-density plasma and is capable of producing a pulsed magnetic field of tens of tesla in a volume of a few cubic centimeters. The magnetic field is created by discharging a high-voltage capacitor through a small wire-wound coil. The coil current pulse has a duration of about 1 μs and a peak value of 40 kA. Compared to the original, the updated version has a larger energymore » storage and improved switching system. In addition, magnetic coils are fabricated using 3-D printing technology which allows for a greater variety of the magnetic field topology.« less

  13. Measurements of Ion Stopping Around the Bragg Peak in High-Energy-Density Plasmas.

    PubMed

    Frenje, J A; Grabowski, P E; Li, C K; Séguin, F H; Zylstra, A B; Gatu Johnson, M; Petrasso, R D; Glebov, V Yu; Sangster, T C

    2015-11-13

    For the first time, quantitative measurements of ion stopping at energies around the Bragg peak (or peak ion stopping, which occurs at an ion velocity comparable to the average thermal electron velocity), and its dependence on electron temperature (T(e)) and electron number density (n(e)) in the range of 0.5-4.0 keV and 3×10(22) to 3×10(23) cm(-3) have been conducted, respectively. It is experimentally demonstrated that the position and amplitude of the Bragg peak varies strongly with T(e) with n(e). The importance of including quantum diffraction is also demonstrated in the stopping-power modeling of high-energy-density plasmas.

  14. Progress Towards Plasma Pulse Compression of High Energy, Long Pulse Laser Beams

    SciTech Connect

    Kirkwood, R K; Ping, Y; Rygg, R; Wilks, S; Meezan, N; Niemann, C; Landen, O; Fisch, N; Malkin, V; Valeo, E; Wurtele, J

    2008-06-19

    Compression of laser pulses to < {approx} 1-10 ps duration using stimulated Raman scattering (SRS) in a plasma promises to provide unprecedented power and intensity for a variety of applications, by avoiding the limits to fluence and intensity that are needed to avoid damage to the solid state optics that are used in conventional approaches. In particular, the ability to compress pump beam pulses of {approx} ns duration will allow present facilities with 10's kJ to over a MJ of energy to produce ultra short pulses efficiently, advancing applications in; fusion by fast ignition, x-ray production of high energy density experiments, as well as laser driven particle accelerators. We will discuss a series of experiments to demonstrate the needed beam amplification rate, and focal spot quality in a < 3mm plasma with the properties needed for compression of these pulses (n{sub e} {approx} 10{sup 19}/cm{sup 3}, T{sub e} 200 to 300 eV) when the plasma is extended. The experiments use He plasmas produced with a 300 J, 1 ns, beam at the Jupiter Laser facility to amplify a counter-propagating, ultra-short pulse (USP) seed by a factor of 10x to 37x and study the dependence of the amplification, the associated non-linear wave response, and the resulting beam quality and energy, on the intensity of both seed and pump beam. In particular, a regime in which amplification of USP beams is achieved while maintaining a low angular divergence of the beam consistent with good focal spot quality will be discussed.

  15. Observation of laser chirp dependency on electron yield in laser wakefield accelerators.

    NASA Astrophysics Data System (ADS)

    Leemans, W. P.; Catravas, P. E.; Esarey, E.; Geddes, C. G. R.; Shadwick, B. A.; Toth, C.; van Tilborg, J.; Trines, R.; Cary, J. R.; Giacone, R.

    2001-10-01

    The effect of laser chirp on laser wakefield acceleration of electrons has been studied experimentally and theoretically. The experiments operated in the self-modulated laser wakefield acceleration regime and used a high density (1-5 × 10^19 cm-3) laser ionized plasma and a Ti:Al_2O3 laser producing up to 10 TW peak power in 45-55 fs duration laser pulses [1]. For the same peak power, positively chirped laser pulse are found to result in significantly higher amounts of charge per bunch than negatively chirped pulses. Simulations using PIC codes indicate that larger amplitude fast phase velocity plasma waves are generated for positively chirped pulses as well as larger amounts of stimulated Raman backscattering (SRS-B). The enhanced SRS-B in turn leads to larger amounts of trapped, high energy electrons, consistent with the experiments. [1] W.P. Leemans et al., Phys. Plasmas 8, 2510(2001)

  16. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Mechanism of high-energy electron production in a laser plasma

    NASA Astrophysics Data System (ADS)

    Belyaev, V. S.

    2004-01-01

    A mechanism of high-energy electron production in the interaction of high-intensity short laser pulses with a solid target is proposed and analysed. The theoretical dependences of fast-electron kinetic energy on the parameters of laser radiation and target material are given. The effect of ionisation of the target material is considered. The generation of ultrastrong magnetic fields in the laser plasma is shown to play the key part in the formation, transfer, and acceleration of electron beams. This results in the production of vortex electric fields accelerating electrons. The theoretical dependences yield well-proved limits for the electron energy and are in good agreement with the results of experiments performed on high-intensity laser setups, including the results obtained with participation of the author.

  17. Development of optics for x-ray phase-contrast imaging of high energy density plasmas

    SciTech Connect

    Stutman, D.; Finkenthal, M.; Moldovan, N.

    2010-10-15

    Phase-contrast or refraction-enhanced x-ray radiography can be useful for the diagnostic of low-Z high energy density plasmas, such as imploding inertial confinement fusion (ICF) pellets, due to its sensitivity to density gradients. To separate and quantify the absorption and refraction contributions to x-ray images, methods based on microperiodic optics, such as shearing interferometry, can be used. To enable applying such methods with the energetic x rays needed for ICF radiography, we investigate a new type of optics consisting of grazing incidence microperiodic mirrors. Using such mirrors, efficient phase-contrast imaging systems could be built for energies up to {approx}100 keV. In addition, a simple lithographic method is proposed for the production of the microperiodic x-ray mirrors based on the difference in the total reflection between a low-Z substrate and a high-Z film. Prototype mirrors fabricated with this method show promising characteristics in laboratory tests.

  18. Jet Tomography of Quark Gluon Plasmas in High Energy Nuclear Collisions

    NASA Astrophysics Data System (ADS)

    Gyulassy, Miklos

    2015-04-01

    The attenuation pattern of high energy jet fragments in ultra-relativistic nuclear collisions provides information on the space-time evolution and dynamical properties of the Quark Gluon Plasma (QGP) phase of matter discovered at the Relativistic Heavy Ion Collider (RHIC) and observed at higher densities at the Large Hadron Collider (LHC). First I review our jet tomography theory of quark and gluon energy loss in a weakly coupled picture of the QGP. While the average attenuation pattern of light and heavy quark jets were well accounted for in that picture, the predicted azimuthal elliptic asymmetry of jets was underestimated when realistic bulk collective flow effects were taken into account. I then show that the elliptic asymmetry of jet fragments can also be quantitatively understood when nonperturbative lattice QCD constraints on the suppression of color electric fluctuations and the enhancement of color magnetic fluctuations near the critical QCD confinement temperature, Tc ~ 160 MeV, are incorporated into the theory. Our analysis provides a novel quantitative connection between the jet transport properties controlling the hard jet quenching observables and the bulk viscous transport properties controlling the remarkable ``perfect fluidity'' of QGP observed at RHIC and LHC.

  19. Machine learning applied to proton radiography of high-energy-density plasmas

    NASA Astrophysics Data System (ADS)

    Chen, Nicholas F. Y.; Kasim, Muhammad Firmansyah; Ceurvorst, Luke; Ratan, Naren; Sadler, James; Levy, Matthew C.; Trines, Raoul; Bingham, Robert; Norreys, Peter

    2017-04-01

    Proton radiography is a technique extensively used to resolve magnetic field structures in high-energy-density plasmas, revealing a whole variety of interesting phenomena such as magnetic reconnection and collisionless shocks found in astrophysical systems. Existing methods of analyzing proton radiographs give mostly qualitative results or specific quantitative parameters, such as magnetic field strength, and recent work showed that the line-integrated transverse magnetic field can be reconstructed in specific regimes where many simplifying assumptions were needed. Using artificial neural networks, we demonstrate for the first time 3D reconstruction of magnetic fields in the nonlinear regime, an improvement over existing methods, which reconstruct only in 2D and in the linear regime. A proof of concept is presented here, with mean reconstruction errors of less than 5% even after introducing noise. We demonstrate that over the long term, this approach is more computationally efficient compared to other techniques. We also highlight the need for proton tomography because (i) certain field structures cannot be reconstructed from a single radiograph and (ii) errors can be further reduced when reconstruction is performed on radiographs generated by proton beams fired in different directions.

  20. Machine learning applied to proton radiography of high-energy-density plasmas.

    PubMed

    Chen, Nicholas F Y; Kasim, Muhammad Firmansyah; Ceurvorst, Luke; Ratan, Naren; Sadler, James; Levy, Matthew C; Trines, Raoul; Bingham, Robert; Norreys, Peter

    2017-04-01

    Proton radiography is a technique extensively used to resolve magnetic field structures in high-energy-density plasmas, revealing a whole variety of interesting phenomena such as magnetic reconnection and collisionless shocks found in astrophysical systems. Existing methods of analyzing proton radiographs give mostly qualitative results or specific quantitative parameters, such as magnetic field strength, and recent work showed that the line-integrated transverse magnetic field can be reconstructed in specific regimes where many simplifying assumptions were needed. Using artificial neural networks, we demonstrate for the first time 3D reconstruction of magnetic fields in the nonlinear regime, an improvement over existing methods, which reconstruct only in 2D and in the linear regime. A proof of concept is presented here, with mean reconstruction errors of less than 5% even after introducing noise. We demonstrate that over the long term, this approach is more computationally efficient compared to other techniques. We also highlight the need for proton tomography because (i) certain field structures cannot be reconstructed from a single radiograph and (ii) errors can be further reduced when reconstruction is performed on radiographs generated by proton beams fired in different directions.

  1. Development of optics for x-ray phase-contrast imaging of high energy density plasmas.

    PubMed

    Stutman, D; Finkenthal, M; Moldovan, N

    2010-10-01

    Phase-contrast or refraction-enhanced x-ray radiography can be useful for the diagnostic of low-Z high energy density plasmas, such as imploding inertial confinement fusion (ICF) pellets, due to its sensitivity to density gradients. To separate and quantify the absorption and refraction contributions to x-ray images, methods based on microperiodic optics, such as shearing interferometry, can be used. To enable applying such methods with the energetic x rays needed for ICF radiography, we investigate a new type of optics consisting of grazing incidence microperiodic mirrors. Using such mirrors, efficient phase-contrast imaging systems could be built for energies up to ∼100 keV. In addition, a simple lithographic method is proposed for the production of the microperiodic x-ray mirrors based on the difference in the total reflection between a low-Z substrate and a high-Z film. Prototype mirrors fabricated with this method show promising characteristics in laboratory tests.

  2. Magnetohydrodynamics of high-energy-density-plasma in strong magnetic field

    NASA Astrophysics Data System (ADS)

    Matsuo, Kazuki; Nagatomo, Hideo; Sano, Takayoshi; Zhang, Zhe; Sakawa, Youichi; Hara, Yukiko; Shimogawara, Hiroshi; Airikawa, Yasunobu; Sakata, Shouhei; Law, Kingfaifarley; Lee, Seungho; Kojima, Sadaoki; Katou, Hiroki; Shigemori, Keisuke; Fujioka, Shinsuke; Azechi, Hiroshi

    2016-10-01

    The magneto-hydrodynamics (MHD) of a high-energy-density-plasma (HEDP) in a strong external magnetic field contains a lot of fundamental and essential physics related to astro- and solar- physics and B-assisted inertial confinement fusion energy development. Especially, hydrodynamic instability in a strong magnetic field is a key physics for success of B-assisted inertial confinement fusion. Hydrodynamic instability growth is affected by strong magnetic field as a result of non-uniform heat flow. Experiments were conducted with a corrugated plastic target that is set between a pair of capacitor-coil. A pair of capacitor-coil targets was used to generate spatially uniform magnetic field. The plastic targets were irradiated by an intense laser pulse having 1013 W/cm2 of intensity. Temporal evolution of perturbation growth was observed with x-ray backlight technique. Enhancement of the perturbation growth in strong magnetic field was observed experimentally, and the result was consistent with hydrodynamic simulation.

  3. Argonne Wakefield Accelerator facility upgrade.

    SciTech Connect

    Conde, M.E.; Gai, W.; Konecny, R.; Power, J.G.; Schoessow, P.; Sun, X.

    2001-07-11

    The Argonne Wakefield Accelerator has been successfully used for conducting wakefield experiments in dielectric loaded structures and plasmas. Although the initial wakefield experiments were successful, higher drive beam quality would substantially improve the wakefield accelerating gradients. For this reason they have built a new 1-1/2 cell L-band photocathode RF gun. This gun is expected to produce 10-100 nC bunches with 2-5 ps rms pulse length and normalized emittance less than 100 mm mrad. The gun will initially have a copper photocathode, which will soon be replaced by a high quantum efficiency cesium telluride one, allowing the generation of a train of high charge bunches. the beam energy at the exit of the gun cavity will be in the range 7.5-10 MeV. A standing-wave linac structure operating at the same frequency (1.3 GHz) will increase the beam energy to about 15 MeV. This beam will be used in high-gradient wakefield acceleration experiments and other high intensity electron beam applications. Traveling-wave dielectric loaded structures, operating at 7.8 and 15.6 GHz, will be excited by the propagation of single bunches or by trains of up to 32 electron bunches, reaching gradients in excess of 100 MV/m over distances of the order of 1 meter.

  4. Controlled electron injection in laser wakefield accelerators using axially tailored plasmas

    NASA Astrophysics Data System (ADS)

    Gonsalves, Anthony

    2009-11-01

    Controlling injection of electrons in laser plasma accelerators (LPA's) is crucial for improving the beam quality and enabling applications such as free electron lasers (FEL's). In addition, techniques are needed to control the amount of charge, energy and energy spread. To date, LPA's have typically operated in a highly nonlinear regime in which electrons are self-injected into a laser-excited plasma density wave. Although percent level energy spread beams have been demonstrated experimentally [1-4], production of lower energy spread beams will require accurate control of the injection process. In order to avoid self-trapping, an LPA would have to operate with lower wake amplitude, whether linear or non-linear. This also necessitates the use of a laser guiding structure to overcome diffraction of the laser beam. Such guiding structures have been obtained by transversely shaping the plasma density profile and they have successfully been used in experiments using laser-produced [2] or capillary-based channels [4]. In this talk, experimental results are presented that demonstrate the use of a longitudinally tailored plasma density profile in a capillary discharge waveguide to control trapping, significantly improving LPA performance. A gas jet was embedded in the capillary to locally alter the plasma density. It was found that electrons can be trapped and accelerated to hundreds of MeV using plasma densities in the capillary lower than in previous experiments, where no stable self-trapped electron beams were obtained in previous experiments [5]. It is found that using a longitudinally tailored density profile improves and increases control over electron beam properties. [4pt] [1] Mangles et al., Nature 431, 535 (2004)[0pt] [2] Geddes et al., Nature 431, 538 (2004)[0pt] [3] Faure et al., Nature 431, 541 (2004)[0pt] [4] Leemans et al., Nat. Phys. 2, 696 (2006)[0pt] [5] Nakamura et al., Phys. Plasmas 14, 056708 (2007)

  5. Interaction of high-energy trapped particles with ballooning modes in a tokamak with a high-. beta. plasma

    SciTech Connect

    Mikhailovskii, A. B.; Novakovaskii, S. V.; Smolyakov, A. I.

    1988-12-01

    A theory is derived for the interaction of high-energy trapped particleswith ballooning modes in a tokamak with a high-..beta.. plasma. A dispersionrelation is derived to describe the ballooning modes in the presence ofsuch particles; the effects of the high plasma ..beta.. are taken into account.The stability boundary for ballooning modes with zero and finite frequenciesis studied. The effects of finite bananas on the stability of ballooningmodes with zero frequencies are determined.

  6. Observation of a Kelvin-helmholtz instability in a high-energy-density plasma on the omega laser.

    PubMed

    Harding, E C; Hansen, J F; Hurricane, O A; Drake, R P; Robey, H F; Kuranz, C C; Remington, B A; Bono, M J; Grosskopf, M J; Gillespie, R S

    2009-07-24

    A laser initiated experiment is described in which an unstable plasma shear layer is produced by driving a blast wave along a plastic surface with sinusoidal perturbations. In response to the vorticity deposited and the shear flow established by the blast wave, the interface rolls up into large vortices characteristic of the Kelvin-Helmholtz instability. The experiment used x-ray radiography to capture the first well-resolved images of Kelvin-Helmholtz vortices in a high-energy-density plasma.

  7. Laser wakefield acceleration research by using a tapered capillary waveguide at GIST

    NASA Astrophysics Data System (ADS)

    Kim, Minseok; Jang, Donggyu; Nam, Inhyuk; Lee, Taehee; Suk, Hyyong

    2012-10-01

    The tapered plasma density in a gas-filled capillary waveguide can suppress the dephasing problem in laser wakefield acceleration (LWFA). As a result, the acceleration distance and the gained electron energy are expected to be increased significantly. For this purpose, we recently developed a tapered capillary waveguide, which can produce a plasma density of 10^18 cm-3. This capillary plasma waveguide will be used for high-energy electron generation experiment together with a 20 TW/35 fs Ti:sapphire laser system that will be completed by this summer. In this presentation, the ongoing experiments will be reported.

  8. High-energy tail formation in an ion energy distribution function in the cylindrical Hall thruster plasma

    NASA Astrophysics Data System (ADS)

    Lim, Youbong; Kim, Holak; Park, Jaesun; Seon, Jongho; Choe, Wonho

    2014-10-01

    Ion energy distribution functions (IEDFs) of individual ion species having different charge states (i.e. Xe+, Xe2+, Xe3+, etc.) in the Hall thruster plasma are obtained from the measured E × B probe spectrum by a novel inversion technique using the iterative Tikhonov regularization method. The obtained IEDFs show the existence of a high-energy tail in the cylindrical Hall thruster plasmas that is mainly due to Xe+ ions despite the presence of Xe2+ and Xe3+ ions with a large fraction. Ion dynamics inside the plasma was numerically investigated to demonstrate that the high-energy tail is due to nonlinear ion acceleration in the plasma oscillating at typically 100 to 500 kHz. We found that this oscillation driven by transit-time instability is responsible for the shift of the IEDF of the Xe+ ions toward the high-energy side, showing the formation of high-energy tail in the overall IEDF. It was also found that the Xe flow rate raised from 4 to 10 sccm increases the oscillation strength at the same frequency of 360 kHz, which can be applied to control of the shape of the IEDF.

  9. Laser beam coupling with capillary discharge plasma for laser wakefield acceleration applications

    NASA Astrophysics Data System (ADS)

    Bagdasarov, G. A.; Sasorov, P. V.; Gasilov, V. A.; Boldarev, A. S.; Olkhovskaya, O. G.; Benedetti, C.; Bulanov, S. S.; Gonsalves, A.; Mao, H.-S.; Schroeder, C. B.; van Tilborg, J.; Esarey, E.; Leemans, W. P.; Levato, T.; Margarone, D.; Korn, G.

    2017-08-01

    One of the most robust methods, demonstrated to date, of accelerating electron beams by laser-plasma sources is the utilization of plasma channels generated by the capillary discharges. Although the spatial structure of the installation is simple in principle, there may be some important effects caused by the open ends of the capillary, by the supplying channels etc., which require a detailed 3D modeling of the processes. In the present work, such simulations are performed using the code MARPLE. First, the process of capillary filling with cold hydrogen before the discharge is fired, through the side supply channels is simulated. Second, the simulation of the capillary discharge is performed with the goal to obtain a time-dependent spatial distribution of the electron density near the open ends of the capillary as well as inside the capillary. Finally, to evaluate the effectiveness of the beam coupling with the channeling plasma wave guide and of the electron acceleration, modeling of the laser-plasma interaction was performed with the code INF&RNO.

  10. Kinetic Modeling of Radiative Turbulence in Relativistic Astrophysical Plasmas: Particle Acceleration and High-Energy Flares

    NASA Astrophysics Data System (ADS)

    Uzdensky, Dmitri

    Relativistic astrophysical plasma environments routinely produce intense high-energy emission, which is often observed to be nonthermal and rapidly flaring. The recently discovered gamma-ray (> 100 MeV) flares in Crab Pulsar Wind Nebula (PWN) provide a quintessential illustration of this, but other notable examples include relativistic active galactic nuclei (AGN) jets, including blazars, and Gamma-ray Bursts (GRBs). Understanding the processes responsible for the very efficient and rapid relativistic particle acceleration and subsequent emission that occurs in these sources poses a strong challenge to modern high-energy astrophysics, especially in light of the necessity to overcome radiation reaction during the acceleration process. Magnetic reconnection and collisionless shocks have been invoked as possible mechanisms. However, the inferred extreme particle acceleration requires the presence of coherent electric-field structures. How such large-scale accelerating structures (such as reconnecting current sheets) can spontaneously arise in turbulent astrophysical environments still remains a mystery. The proposed project will conduct a first-principles computational and theoretical study of kinetic turbulence in relativistic collisionless plasmas with a special focus on nonthermal particle acceleration and radiation emission. The main computational tool employed in this study will be the relativistic radiative particle-in-cell (PIC) code Zeltron, developed by the team members at the Univ. of Colorado. This code has a unique capability to self-consistently include the synchrotron and inverse-Compton radiation reaction force on the relativistic particles, while simultaneously computing the resulting observable radiative signatures. This proposal envisions performing massively parallel, large-scale three-dimensional simulations of driven and decaying kinetic turbulence in physical regimes relevant to real astrophysical systems (such as the Crab PWN), including the

  11. Studies of a hybrid Trojan Horse wakefield accelerator with high transformer ratio

    NASA Astrophysics Data System (ADS)

    Cook, Nathan; Bruhwiler, David; Hidding, Bernhard; Vay, Jean-Luc; Webb, Stephen

    2015-11-01

    Plasma wakefield acceleration uses relativistic high-charge electron bunches to generate a plasma blowout supporting intense electric fields for trapping and acceleration. Dramatic improvements in emittance, peak current and brightness are achievable through laser-controlled ionization in the plasma blowout, which is the premise of the Trojan Horse approach. The hybrid Trojan Horse concept extends this approach to use the output beam from a laser plasma accelerator to drive a Trojan Horse, resulting in a compact system that can produce higher brightness bunches with order-of-magnitude lower energy spread. We are exploring the use of multiple, shaped laser pulses to resonantly inject a shaped electron drive bunch. The resulting output bunch could generate wakes in PWFA or beam-driven dielectric structures with transformer ratios of 5 to 10 or larger. Hence, a hybrid Trojan Horse accelerator with bunch shaping may provide a compact source of nC bunches that can drive a variety of systems for studying high-gradient wakefields and lepton acceleration. Initial work will use previously simulated electron bunches from a laser plasma accelerator to drive the plasma wakefield stage. We present preliminary results from simulations using the parallel, particle-in-cell framework Warp. Work supported by the U.S. Department of Energy, Office of High Energy Physics, under Award Number DE-SC0013855.

  12. High field terahertz emission from relativistic laser-driven plasma wakefields

    SciTech Connect

    Chen, Zi-Yu; Pukhov, Alexander

    2015-10-15

    We propose a method to generate high field terahertz (THz) radiation with peak strength of GV/cm level in the THz frequency gap range of 1–10 THz using a relativistic laser interaction with a gaseous plasma target. Due to the effect of local pump depletion, an initially Gaussian laser pulse undergoes leading edge erosion and eventually evolves to a state with leading edge being step function. Interacting with such a pulse, electrons gain transverse residual momentum and excite net transverse currents modulated by the relativistic plasma frequency. These currents give rise to the low frequency THz emission. We demonstrate this process with one and two dimensional particle-in-cell simulations.

  13. Laser-driven plasma wakefield electron acceleration and coherent femtosecond pulse generation in X-ray and gamma ranges

    NASA Astrophysics Data System (ADS)

    Trunov, V. I.; Lotov, K. V.; Gubin, K. V.; Pestryakov, E. V.; Bagayev, S. N.; Logachev, P. V.

    2017-01-01

    The laser wakefield acceleration (LWFA) of electrons in capillaries and gas jets followed by inverse Compton scattering of high intensity femtosecond laser pulses is discussed. The drive and scattered pulses will be produced by the two-channel multi-terawatt laser system developed in ILP SB RAS.

  14. Compact disposal of high-energy electron beams using passive or laser-driven plasma decelerating stage

    SciTech Connect

    Bonatto, A.; Schroeder, C. B.; Vay, J. -L.; Geddes, C. R.; Benedetti, C.; Esarey and, E.; Leemans, W. P.

    2014-07-13

    A plasma decelerating stage is investigated as a compact alternative for the disposal of high-energy beams (beam dumps). This could benefit the design of laser-driven plasma accelerator (LPA) applications that require transportability and or high-repetition-rate operation regimes. Passive and laser-driven (active) plasma-based beam dumps are studied analytically and with particle-in-cell (PIC) simulations in a 1D geometry. Analytical estimates for the beam energy loss are compared to and extended by the PIC simulations, showing that with the proposed schemes a beam can be efficiently decelerated in a centimeter-scale distance.

  15. Compact disposal of high-energy electron beams using passive or laser-driven plasma decelerating stage

    SciTech Connect

    Bonatto, A.; Schroeder, C. B.; Vay, J. -L.; Geddes, C. R.; Benedetti, C.; Esarey and, E.; Leemans, W. P.

    2014-07-13

    A plasma decelerating stage is investigated as a compact alternative for the disposal of high-energy beams (beam dumps). This could benefit the design of laser-driven plasma accelerator (LPA) applications that require transportability and or high-repetition-rate operation regimes. Passive and laser-driven (active) plasma-based beam dumps are studied analytically and with particle-in-cell (PIC) simulations in a 1D geometry. Analytical estimates for the beam energy loss are compared to and extended by the PIC simulations, showing that with the proposed schemes a beam can be efficiently decelerated in a centimeter-scale distance.

  16. Theory of laser chirp effects on instabilities in laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Schroeder, C.; Esarey, E.; van Tilborg, J.; Leemans, W. P.; Shadwick, B. A.; Trines, R.; Cary, J. R.; Giacone, R.

    2001-10-01

    Experimentally, laser chirp is found to be an important parameter affecting electron output from self-modulated laser wakefield accelerators (SMLWFAs). In SMLWFAs, electrons are accelerated to high energies by plasma wakefields generated by the self-modulation instability and forward Raman scattering, whereas the initial trapping and heating of the electrons is strongly affected by backward and sideways Raman scattering. The effect of laser frequency chirp on self-modulation and Raman instabilities is analyzed theoretically. Expressions for chirp-modified growth rates are presented. Theoretical results are compared to results from various simulation models, including time-averaged quasi-static envelope fluid codes, full fluid codes, and particle-in-cell codes. In addition, comparison is made to recent experimental results obtained at LBNL.(W.P. Leemans et al., Phys. Plasmas 8), 2510 (2001).

  17. Computational studies and optimization of wakefield accelerators

    SciTech Connect

    Tsung, Frank S.; Bruhwiler, David L.; Cary, John R.; Esarey, Eric H.; Mori, Warren B.; Vay, Jean-Luc; Martins, Samuel F.; Katsouleas, Tom; Cormier-Michel, Estelle; Fawley, William M.; Huang, Chengkun; Wang, Xiadong; Cowan, Ben; Decyk, Victor K.; Fonseca, Ricardo A.; Lu, Wei; Messmer, Peter; Mullowney, Paul; Nakamura, Kei; Paul, Kevin; Plateau, Guillaume R.; Schroeder, Carl B.; Silva, Luis O.; Toth, Csaba; Geddes, C.G.R.; Tzoufras, Michael; Antonsen, Tom; Vieira, Jorge; Leemans, Wim P.

    2008-06-16

    Laser- and particle beam-driven plasma wakefield accelerators produce accelerating fields thousands of times higher than radio-frequency accelerators, offering compactness and ultrafast bunches to extend the frontiers of high energy physics and to enable laboratory-scale radiation sources. Large-scale kinetic simulations provide essential understanding of accelerator physics to advance beam performance and stability and show and predict the physics behind recent demonstration of narrow energy spread bunches. Benchmarking between codes is establishing validity of the models used and, by testing new reduced models, is extending the reach of simulations to cover upcoming meter-scale multi-GeV experiments. This includes new models that exploit Lorentz boosted simulation frames to speed calculations. Simulations of experiments showed that recently demonstrated plasma gradient injection of electrons can be used as an injector to increase beam quality by orders of magnitude. Simulations are now also modeling accelerator stages of tens of GeV, staging of modules, and new positron sources to design next-generation experiments and to use in applications in high energy physics and light sources.

  18. Dependence of electron trapping on bubble geometry in laser-plasma wakefield acceleration

    SciTech Connect

    Li, X. F.; Yu, Q.; Huang, S.; Zhang, F.; Kong, Q.; Gu, Y. J.; Kawata, S.

    2014-07-15

    The effect of bubble shape in laser-plasma electron acceleration was investigated. We showed the general existence of an ellipsoid bubble. The electromagnetic field in this bubble and its dependence on bubble shape were determined through theory. The electron-trapping cross-section for different bubble aspect ratios was studied in detail. When the shape of the bubble was close to spherical, the trapping cross-section reached to the maximum. When the bubble deviated from a spherical shape, the cross-section decreased until electron injection no longer occurred. These results were confirmed by particle-in-cell simulation.

  19. 26Al Production in the Early Solar Nebula by Neutral High-Energy Plasma Winds

    NASA Astrophysics Data System (ADS)

    Spergel, M. S.

    1995-09-01

    In the light of recent observations, I believe that the sources for the presence of ^26Al within the solar nebula must be reconsidered [2,3]. Recent low observational estimates of the probability of encounters between mass-losing evolved stars and molecular clouds [4] for the production of ^26Al and the observed low production [5] of 26 Al from AGB (Asymptotic Giant Branch stars) along with the predicted low abundance of cosmic ray induced local production [6] in the early solar nebula all support continued investigation for additional sources of the solar nebula ^26Al presence. It is suggested based on the presences of new cross section data [7], that an important source of this ^26Al presence might be from enhanced interactions from the collisions of the local "T. Tauri" like plasma winds with the atomic and molecular Early Solar Nebula (ESN). Interactions like ^26Mg (p,n) ^26Al in this "neutral" electrical setting may provide the needed selective production. The ESN provides an environment where plasma winds can lead to such nucleosynthesis. Stellar winds of 300-700 km/s (about 3x10^7 K) are seen to T. Tauri like stars, presumed precursor to solar like stars, and also within the Solar heliosphere [8.9]. These winds provide the source of Solar High Energy Particles which can interact with such in situ targets such as ^26Mg to produce the ^26Al. The presence of the atomic and molecular environments, will enhance [10] nucleosynthesis over that seen in scattering of protons off bare nuclei. Such enhancement has been recently observed in low energy scattering on electrically shield targets [7]. There it was also suggested that in stellar convective zones, electron clouds of the plasma shield may also shield bare target nuclei. Measured values of low energy proton scattered on atomic and molecular targets indicated [7] that fusion cross sections are enlarged and elastic cross sections are reduced, therefore simple extrapolation of accelerator data can lead to an

  20. Interaction of the high energy deuterons with the graphite target in the plasma focus devices based on Lee model

    SciTech Connect

    Akel, M. Alsheikh Salo, S.; Ismael, Sh.; Saw, S. H.; Lee, S.

    2014-07-15

    Numerical experiments are systematically carried out using the Lee model code extended to compute the ion beams on various plasma focus devices operated with Deuterium gas. The deuteron beam properties of the plasma focus are studied for low and high energy plasma focus device. The energy spectral distribution for deuteron ions ejected from the pinch plasma is calculated and the ion numbers with energy around 1 MeV is then determined. The deuteron–graphite target interaction is studied for different conditions. The yield of the reaction {sup 12}C(d,n){sup 13}N and the induced radioactivity for one and multi shots plasma focus devices in the graphite solid target is investigated. Our results present the optimized high energy repetitive plasma focus devices as an alternative to accelerators for the production of {sup 13}N short lived radioisotopes. However, technical challenges await solutions on two fronts: (a) operation of plasma focus machines at high rep rates for a sufficient period of time (b) design of durable targets that can take the thermal load.

  1. Analysis of radial and longitudinal field of plasma wakefield generated by a Laguerre-Gauss laser pulse

    SciTech Connect

    Firouzjaei, Ali Shekari; Shokri, Babak

    2016-06-15

    In the present paper, we study the wakes known as the donut wake which is generated by Laguerre-Gauss (LG) laser pulses. Effects of the special spatial profile of a LG pulse on the radial and longitudinal wakefields are presented via an analytical model in a weakly non-linear regime in two dimensions. Different aspects of the donut-shaped wakefields have been analyzed and compared with Gaussian-driven wakes. There is also some discussion about the accelerating-focusing phase of the donut wake. Variations of longitudinal and radial wakes with laser amplitude, pulse length, and pulse spot size have been presented and discussed. Finally, we present the optimum pulse duration for such wakes.

  2. Increasing energy coupling into plasma waves by tailoring the laser radial focal spot distribution in a laser wakefield accelerator

    SciTech Connect

    Genoud, G.; Burza, M.; Persson, A.; Svensson, K.; Wahlström, C.-G.; Bloom, M. S.; Najmudin, Z.; Mangles, S. P. D.; Vieira, J.; Silva, L. O.

    2013-06-15

    By controlling the focal spot quality with a deformable mirror, we are able to show that increasing the fraction of pulse energy contained within the central part of the focal spot, while keeping the total energy and central spot size constant, significantly increases the amount of energy transferred to the wakefield: Our measurements show that the laser loses significantly more laser energy and undergoes greater redshifting and that more charge is produced in the accelerated beam. Three dimensional particle in cell simulations performed with accurate representations of the measured focal spot intensity distribution confirm that energy in the wings of the focal spot is effectively wasted. Even though self-focusing occurs, energy in the wings of the focal spot distribution is not coupled into the wakefield, emphasising the vital importance of high quality focal spot profiles in experiments.

  3. Probing the K-edge of a laser heated aluminum plasma using X-rays from betatron oscillations in a laser wakefield accelerator with femtosecond resolution

    NASA Astrophysics Data System (ADS)

    Behm, Keegan; Hussein, Amina; Zhao, Tony; Hill, Edward; Maksimchuk, Anatoly; Nees, John; Yanovsky, Victor; Mangles, Stuart; Krushelnick, Karl; Thomas, Alexander; CenterUltrafast Optical Science Team; Plasmas Group Team

    2016-10-01

    Presented here are data from a two-beam pump-probe experiment. We used synchrotron-like X-rays created by betatron oscillations to probe a thin metal foil that is pumped by the secondary laser beam. The Hercules Ti:Sapphire laser facility was operated with a pulse duration of 34 fs and a power of 80 TW split. A 75-25 beam splitter was used to drive a laser wakefield accelerator and heat the secondary target. We observed opacity changes around the K-edge of thin aluminum foil as it was heated by an ultrafast pump laser. To understand how the opacity is changing with heating and expansion of the plasma, the delay between the two laser paths was adjusted on a femtosecond time scale from 50 to 400 fs. Experimental data for aluminum shows variation in opacity around the K-edge with changes in the probe delay. The transmitted synchrotron-like spectrum was measured using single photon counting on an X-ray CCD camera and was available on a shot-by-shot basis. The success of this work demonstrates a practical application for X-rays produced from betatron oscillations in a wakefield accelerator. U.S. Department of Energy and the National Nuclear Security Administration.

  4. Femtosecond probing around the K-edge of a laser heated plasma using X-rays from betatron oscillations in a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Behm, Keegan; Zhao, Tony; Maksimchuk, Anatoly; Yanovsky, Victor; Nees, John; Mangles, Stuart; Krushelnick, Karl; Thomas, Alexander; CenterUltrafast Optical Science Team; Plasmas Group Team

    2015-11-01

    Presented here are data from a two-beam pump-probe experiment. We used synchrotron-like X-rays created by betatron oscillations to probe a thin metal foil that is pumped by the secondary laser beam. The Hercules Ti:Sapph laser facility was operated with a pulse duration of 34 fs and a power of 65 TW split to drive a laser wakefield accelerator and heat the secondary target. We observed opacity changes around the K-edge of thin foils as they were heated by an ultrafast pump laser. To understand how the opacity is changing with heating and expansion of the plasma, the delay between the two laser paths was adjusted on a fs and ps time scale. Experimental data for polyvinylidene chloride (PVDC) and aluminum show variations in opacity around the Cl and Al K-edges with changes in the probe delay. The transmitted synchrotron-like spectrum was measured using single photon counting on an X-ray CCD camera and was available on a shot-by-shot basis. The success of this work demonstrates a practical application for X-rays produced from betatron oscillations in a wakefield accelerator. The compact size of these ``table-top'' accelerators and the ultrashort nature of the generated X-ray pulses allows pump-probe experiments that can probe events that occur on the femtosecond time scale.

  5. Tomographic reconstruction of high-energy-density plasmas with picosecond temporal resolution.

    PubMed

    Baker, K L

    2006-03-15

    Three-dimensional reconstruction of the electron density in a plasma can be obtained by passing multiple beams at different field angles simultaneously through a plasma and performing a tomographic reconstruction of the measured field-dependent phase profiles. A relatively simple experimental setup is proposed and simulations are carried out to verify the technique. The plasma distribution is modeled as a discrete number of phase screens, and a Zernike polynomial representation of the phase screens is used to reconstruct the plasma profile.

  6. Applications of laser wakefield accelerator-based light sources

    DOE PAGES

    Albert, Felicie; Thomas, Alec G. R.

    2016-10-01

    Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons inmore » the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. Here, we first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.« less

  7. Applications of laser wakefield accelerator-based light sources

    SciTech Connect

    Albert, Felicie; Thomas, Alec G. R.

    2016-10-01

    Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons in the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. Here, we first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.

  8. Applications of laser wakefield accelerator-based light sources

    NASA Astrophysics Data System (ADS)

    Albert, Félicie; Thomas, Alec G. R.

    2016-11-01

    Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons in the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. We first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.

  9. Applications of laser wakefield accelerator-based light sources

    SciTech Connect

    Albert, Felicie; Thomas, Alec G. R.

    2016-10-01

    Laser-wakefield accelerators (LWFAs) were proposed more than three decades ago, and while they promise to deliver compact, high energy particle accelerators, they will also provide the scientific community with novel light sources. In a LWFA, where an intense laser pulse focused onto a plasma forms an electromagnetic wave in its wake, electrons can be trapped and are now routinely accelerated to GeV energies. From terahertz radiation to gamma-rays, this article reviews light sources from relativistic electrons produced by LWFAs, and discusses their potential applications. Betatron motion, Compton scattering and undulators respectively produce x-rays or gamma-rays by oscillating relativistic electrons in the wakefield behind the laser pulse, a counter-propagating laser field, or a magnetic undulator. Other LWFA-based light sources include bremsstrahlung and terahertz radiation. Here, we first evaluate the performance of each of these light sources, and compare them with more conventional approaches, including radio frequency accelerators or other laser-driven sources. We have then identified applications, which we discuss in details, in a broad range of fields: medical and biological applications, military, defense and industrial applications, and condensed matter and high energy density science.

  10. Hosing Instability of the Drive Electron Beam in the E157 Plasma-Wakefield Acceleration Experiment at the Stanford Linear Accelerator

    SciTech Connect

    Blue, Brent Edward; /SLAC /UCLA

    2005-10-10

    In the plasma-wakefield experiment at SLAC, known as E157, an ultra-relativistic electron beam is used to both excite and witness a plasma wave for advanced accelerator applications. If the beam is tilted, then it will undergo transverse oscillations inside of the plasma. These oscillations can grow exponentially via an instability know as the electron hose instability. The linear theory of electron-hose instability in a uniform ion column predicts that for the parameters of the E157 experiment (beam charge, bunch length, and plasma density) a growth of the centroid offset should occur. Analysis of the E157 data has provided four critical results. The first was that the incoming beam did have a tilt. The tilt was much smaller than the radius and was measured to be 5.3 {micro}m/{delta}{sub z} at the entrance of the plasma (IP1.) The second was the beam centroid oscillates in the ion channel at half the frequency of the beam radius (betatron beam oscillations), and these oscillations can be predicted by the envelope equation. Third, up to the maximum operating plasma density of E157 ({approx}2 x 10{sup 14} cm{sup -3}), no growth of the centroid offset was measured. Finally, time-resolved data of the beam shows that up to this density, no significant growth of the tail of the beam (up to 8ps from the centroid) occurred even though the beam had an initial tilt.

  11. Tomographic reconstruction of high energy density plasmas with picosecond temporal resolution

    SciTech Connect

    Baker, K L

    2005-09-20

    Three-dimensional reconstruction of the electron density in a plasma can be obtained by passing multiple beams at different field angles simultaneously through a plasma and performing a tomographic reconstruction of the measured field-dependent phase profiles. In this letter, a relatively simple experimental setup is proposed and simulations are carried out to verify the technique. The plasma distribution is modeled as a discreet number of phase screens and a Zernike polynomial representation of the phase screens is used to reconstruct the plasma profile. Using a subpicosecond laser, the complete three-dimensional electron density of the plasma can be obtained with a time resolution limited only by the transit time of the probe through the plasma.

  12. Plasma Diagnostic Calibration and Characterizations with High Energy X-rays

    SciTech Connect

    Zaheer Ali

    2009-06-05

    National Security Technologies’ High Energy X-ray (HEX) Facility is unique in the U.S. Department of Energy complex. The HEX provides fluorescent X-rays of 5 keV to 100 keV with fluence of 10^5–10^6 photons/cm^2/second at the desired line energy. Low energy lines can be filtered, and both filters and fluorescers can be changed rapidly. We present results of calibrating image plates (sensitivity and modulation transfer function), a Bremsstrahlung spectrometer (stacked filters and image plates), and the National Ignition Facility’s Filter- Fluorescer Experiment (FFLEX) high energy X-ray spectrometer. We also show results of a scintillator light yield and alignment study for a neutron imaging system.

  13. Spark plasma sintered Sm(2)Co(17)-FeCo nanocomposite permanent magnets synthesized by high energy ball milling.

    PubMed

    Sreenivasulu, G; Gopalan, R; Chandrasekaran, V; Markandeyulu, G; Suresh, K G; Murty, B S

    2008-08-20

    Nanocomposite Sm(2)Co(17)-5 wt% FeCo magnets were synthesized by high energy ball milling followed by consolidation into bulk shape by the spark plasma sintering technique. The evolution of magnetic properties was systematically investigated in milled powders as well as in spark plasma sintered samples. A high energy product of 10.2 MGOe and the other magnetic properties of M(s) = 107 emu g(-1), M(r) = 59 emu g(-1), M(r)/M(s) = 0.55 and H(c) = 6.4 kOe were achieved in a 5 h milled and spark plasma sintered Sm(2)Co(17)-5 wt% FeCo nanocomposite magnet. The spark plasma sintering was carried out at 700 °C for 5 min with a pressure of 70 MPa. The nanocomposite showed a higher Curie temperature of 955 °C for the Sm(2)Co(17) phase in comparison to its bulk Curie temperature for the Sm(2)Co(17) phase (920 °C). This higher Curie temperature can improve the performance of the magnet at higher temperatures.

  14. X-ray phase contrast imaging of biological specimens with femtosecond pulses of betatron radiation from a compact laser plasma wakefield accelerator

    SciTech Connect

    Kneip, S.; McGuffey, C.; Dollar, F.; Chvykov, V.; Kalintchenko, G.; Krushelnick, K.; Maksimchuk, A.; Mangles, S. P. D.; Matsuoka, T.; Schumaker, W.; Thomas, A. G. R.; Yanovsky, V.; Bloom, M. S.; Najmudin, Z.; Palmer, C. A. J.; Schreiber, J.

    2011-08-29

    We show that x-rays from a recently demonstrated table top source of bright, ultrafast, coherent synchrotron radiation [Kneip et al., Nat. Phys. 6, 980 (2010)] can be applied to phase contrast imaging of biological specimens. Our scheme is based on focusing a high power short pulse laser in a tenuous gas jet, setting up a plasma wakefield accelerator that accelerates and wiggles electrons analogously to a conventional synchrotron, but on the centimeter rather than tens of meter scale. We use the scheme to record absorption and phase contrast images of a tetra fish, damselfly and yellow jacket, in particular highlighting the contrast enhancement achievable with the simple propagation technique of phase contrast imaging. Coherence and ultrafast pulse duration will allow for the study of various aspects of biomechanics.

  15. Negative-permittivity plasma generation in negative-permeability space with high-energy metamaterials

    NASA Astrophysics Data System (ADS)

    Sakai, Osamu; Nakamura, Yoshihiro; Iwai, Akinori; Iio, Satoshi

    2016-10-01

    Plasma generation by electromagnetic waves in negative-permeability space is analyzed using experimental results and theoretical models. Installation of negative-permeability metamaterials triggers drastic changes to the propagation of electromagnetic waves. Unlike usual cases in which permeability is  +1, negative permeability induces evanescent modes in a space without plasma. However, if permittivity becomes negative due to high-electron-density or overdense plasma, electromagnetic waves can propagate because negative-refractive-index states emerge. In this study, reviewing our previous experimental data, we study the underlying physical processes in plasma generation in terms of wave propagation and parameters of wave media. We confirm nonlinear (transition) processes in the phase of density evolution up to the negative permittivity state and negative-refractive-index states in the quasi-steady phase. We also note that such energetic metamaterials are built up when we use plasma, unlike conventional metamaterials composed of solid-state materials.

  16. Impact of the Hall effect on high-energy-density plasma jets.

    PubMed

    Gourdain, P-A; Seyler, C E

    2013-01-04

    Using a 1-MA, 100 ns-rise-time pulsed power generator, radial foil configurations can produce strongly collimated plasma jets. The resulting jets have electron densities on the order of 10(20) cm(-3), temperatures above 50 eV and plasma velocities on the order of 100 km/s, giving Reynolds numbers of the order of 10(3), magnetic Reynolds and Péclet numbers on the order of 1. While Hall physics does not dominate jet dynamics due to the large particle density and flow inside, it strongly impacts flows in the jet periphery where plasma density is low. As a result, Hall physics affects indirectly the geometrical shape of the jet and its density profile. The comparison between experiments and numerical simulations demonstrates that the Hall term enhances the jet density when the plasma current flows away from the jet compared to the case where the plasma current flows towards it.

  17. A nonlinear particle dynamics map of wakefield acceleration in a linear collider

    SciTech Connect

    Tajima, T.; Cheshkov, S.; Horton, W.; Yokoya, K.

    1998-08-01

    The performance of a wakefield accelerator in a high energy collider application is analyzed. In order to carry out this task, it is necessary to construct a strawman design system (no matter how preliminary) and build a code of the systems approach. A nonlinear dynamics map built on a simple theoretical model of the wakefield generated by the laser pulse (or whatever other method) is obtained and they employ this as a base for building a system with multi-stages (and components) as a high energy collider. The crucial figures of merit for such a system other than the final energy include the emittance (that determines the luminosity). The more complex the system is, the more opportunities the system has to degrade the emittance (or entropy of the beam). Thus the map gu ides one to identify where the crucial elements lie that affect the emittance. They find that a strong focusing force of the wakefield coupled with a possible jitter of the axis (or laser aiming) of each stage and a spread in the betatron frequencies arising from different phase space positions for individual particles leads to a phase space mixing. This sensitively controls the emittance degradation. They show that in the case of a uniform plasma the effect of emittance growth is large and may cause serious problems. They discuss possibilities to avoid it and control the situation.

  18. Generation of Quasi-monoenergetic High-energy Electron Beam by Plasma Wave

    SciTech Connect

    Koyama, K.; Saito, N.; Ogata, A.; Masuda, S.; Tanimoto, M.; Miura, E.; Kato, S.; Adachi, M

    2004-12-07

    We have demonstrated an acceleration of a quasi-monoenergetic electron beam by trapping electrons in a plasma wave. Experiments were performed by focusing 2-TW (50 fs) laser pulses on supersonic gas jet targets. An intensity was 5 x 1018W/cm2(a0 = 1.5). An electron density was estimated to be 1.3 x 1020cm-3. The quasi-monoenergetic electron beam at 7 MeV was observed with a peak to foot ratio of 10. An appearance of a Stokes Raman satellite in the forward scattering well correlated with the quasi-monoenergetic electron beam. A frequency shift of the satellite coincided with a plasma frequency at the measured plasma density. Appearance of the Raman satellite coincided with appearances of a fishbone structure in a side-scattering image. Supposing the fishbone structure originated from the plasma wave, an acceleration length was estimated to be 200 to 500 microns.

  19. Novel high-energy physics studies using intense lasers and plasmas

    SciTech Connect

    Leemans, Wim P.; Bulanov, Stepan; Esarey, Eric; Schroeder, Carl

    2015-06-29

    In the framework of the project “Novel high-energy physics studies using intense lasers and plasmas” we conducted the study of ion acceleration and “flying mirrors” with high intensity lasers in order to develop sources of ion beams and high frequency radiation for different applications. Since some schemes of laser ion acceleration are also considered a good source of “flying mirrors”, we proposed to investigate the mechanisms of “mirror” formation. As a result we were able to study the laser ion acceleration from thin foils and near critical density targets. We identified several fundamental factors limiting the acceleration in the RPA regime and proposed the target design to compensate these limitations. In the case of near critical density targets, we developed a concept for the laser driven ion source for the hadron therapy. Also we studied the mechanism of “flying mirror” generation during the intense laser interaction with thin solid density targets. As for the laser-based positron creation and capture we initially proposed to study different regimes of positron beam generation and positron beam cooling. Since the for some of these schemes a good quality electron beam is required, we studied the generation of ultra-low emittance electron beams. In order to understand the fundamental physics of high energy electron beam interaction with high intensity laser pulses, which may affect the efficient generation of positron beams, we studied the radiation reaction effects.

  20. High Energy Plasmas, General Relativity and Collective Modes in the Vicinity of Black Holes*

    NASA Astrophysics Data System (ADS)

    Coppi, B.

    2009-05-01

    Plasmas around black holes can take different equilibrium configurations^1 from those known from fluid theory as the vertical Lorentz compression due to plasma currents can overtake that of the gravitational force. In a disk with a ``seed'' magnetic field, axisymmetric modes as well as tri-dimensional spirals can be excited by the combined effects of the radial gradient of the plasma rotation frequency and of the plasma pressure gradient^2. The spirals' properties depend strongly on their vertical structure^3. Axisymmetric modes can produce vertical counter-flows of thermal energy and particles and be candidates for the origin of the winds emanating from disks in Active Galactic Nuclei (AGN's)^2. The excitation of radially localized density spirals corotating with the plasma near a black hole can provide an explanation for^4 the observed Quasi Periodic Oscillations (QPO's) of the X-ray emission from compact objects. Convective spiral modes^3 that are purely oscillatory in time and not localized radially can acquire their amplitudes from coupling to unstable modes and provide transport^3 of angular momentum toward the outer region of the disk structure.*Sponsored in part by the U.S. DOE. ^1B. Coppi and F. Rousseau, Ap. J., 641, 458 (2006). ^2B. Coppi, Europhys. Letters 82, 19001 (2008). ^3B. Coppi, MIT/LNS Report 08/08, submitted to A&A (2008). ^4B. Coppi and P. Rebusco, Paper P5.154, E.P.S. Conf. Pl. Phys. (Crete, 2008).

  1. Spectroscopic Study of a Pulsed High-Energy Plasma Deflagration Accelerator

    NASA Astrophysics Data System (ADS)

    Loebner, Keith; Underwood, Thomas; Mouratidis, Theodore; Cappelli, Mark

    2015-11-01

    Observations of broadened Balmer lines emitted by a highly-ionized transient plasma jet are presented. A gated CCD camera coupled to a high-resolution spectrometer is used to obtain chord-averaged broadening data for a complete cross section of the plasma jet, and the data is Abel inverted to derive the radial plasma density distribution. This measurement is performed over narrow gate widths and at multiple axial positions to provide high spatial and temporal resolution. A streak camera coupled to a spectrometer is used to obtain continuous-time broadening data over the entire duration of the discharge event (10-50 microseconds). Analyses of discharge characteristics and comparisons with previous work are discussed. This work is supported by the U.S. Department of Energy Stewardship Science Academic Program, as well as the National Defense Science Engineering Graduate Fellowship.

  2. High-energy ion generation in interaction. of short laser pulse with high-density plasma

    NASA Astrophysics Data System (ADS)

    Sentoku, Y.; Bychenkov, V. Y.; Flippo, K.; Maksimchuk, A.; Mima, K.; Mourou, G.; Sheng, Z. M.; Umstadter, D.

    2002-03-01

    Multi-MeV ion production from the interaction of a short laser pulse with a high-density plasma, accompanied by an underdense preplasma, has been studied with a particle-in-cell simulation and good agreement is found with experiment. The mechanism primarily responsible for the acceleration of ions is identified. Comparison with experiments sheds light on the ion-energy dependence on laser intensity, preplasma scale length, and relative ion energies for a multi-species plasma. Two regimes of maximum ion-energy dependence on laser intensity, I, have been identified: subrelativistic, ∝I; and relativistic, ∝. Simulations show that the energy of the accelerated ions versus the preplasma scale length increases linearly and then saturates. In contrast, the ion energy decreases with the thickness of the solid-density plasma.

  3. A Method for Determining the High Energy Photon Spectrum of a Pulsed Plasma Source.

    DTIC Science & Technology

    1984-03-01

    SCHOOL OF ENOX .. UNCLRSSIF[ED C N DERSON MAR 84 AFIT/GNE/PH/84M- 1 F/0 18/4 EEEEohmhmhhEEE sfffffflllllflm|hh|h|hE|hEEK I EE|hh|h|hE|hh I...fllfllfllfllfllfll|f EEEEEE|h|hhhhE 4! S \\/ 1111 1 ’ 2.8 12.5 lil 1.0 l 112. 11111125 DI .. 111. -. ~~~~~~- T9 u.-~ ~ - j - - T -eOF S F -- F. (-,-’ OCDI 18 p...E ECT r OCT 1 I986 -.. Approved for public release; distributed unlimited. ., AFIT/GNE/PH/84M- 1 A METHOD FOR DETERMI4lIN THE HIGH ENERGY PHOTON

  4. Demonstration of x-ray fluorescence imaging of a high-energy-density plasma.

    PubMed

    MacDonald, M J; Keiter, P A; Montgomery, D S; Biener, M M; Fein, J R; Fournier, K B; Gamboa, E J; Klein, S R; Kuranz, C C; LeFevre, H J; Manuel, M J-E; Streit, J; Wan, W C; Drake, R P

    2014-11-01

    Experiments at the Trident Laser Facility have successfully demonstrated the use of x-ray fluorescence imaging (XRFI) to diagnose shocked carbonized resorcinol formaldehyde (CRF) foams doped with Ti. One laser beam created a shock wave in the doped foam. A second laser beam produced a flux of vanadium He-α x-rays, which in turn induced Ti K-shell fluorescence within the foam. Spectrally resolved 1D imaging of the x-ray fluorescence provided shock location and compression measurements. Additionally, experiments using a collimator demonstrated that one can probe specific regions within a target. These results show that XRFI is a capable alternative to path-integrated measurements for diagnosing hydrodynamic experiments at high energy density.

  5. Demonstration of x-ray fluorescence imaging of a high-energy-density plasma

    SciTech Connect

    MacDonald, M. J. Gamboa, E. J.; Keiter, P. A.; Fein, J. R.; Klein, S. R.; Kuranz, C. C.; LeFevre, H. J.; Manuel, M. J.-E.; Wan, W. C.; Drake, R. P.; Montgomery, D. S.; Biener, M. M.; Fournier, K. B.; Streit, J.

    2014-11-15

    Experiments at the Trident Laser Facility have successfully demonstrated the use of x-ray fluorescence imaging (XRFI) to diagnose shocked carbonized resorcinol formaldehyde (CRF) foams doped with Ti. One laser beam created a shock wave in the doped foam. A second laser beam produced a flux of vanadium He-α x-rays, which in turn induced Ti K-shell fluorescence within the foam. Spectrally resolved 1D imaging of the x-ray fluorescence provided shock location and compression measurements. Additionally, experiments using a collimator demonstrated that one can probe specific regions within a target. These results show that XRFI is a capable alternative to path-integrated measurements for diagnosing hydrodynamic experiments at high energy density.

  6. Argonne's new Wakefield Test Facility

    SciTech Connect

    Simpson, J.D.

    1992-07-20

    The first phase of a high current, short bunch length electron beam research facility, the AWA, is near completion at Argonne. At the heart of the facility is a photocathode based electron gun and accelerating sections designed to deliver 20 MeV pulses with up to 100 nC per pulse and with pulse lengths of approximately 15 ps (fw). Using a technique similar to that originated at Argonne's AATF facility, a separate weak probe pulse can be generated and used to diagnose wake effects produced by the intense pulses. Initial planned experiments include studies of plasma wakefields and dielectric wakefield devices, and expect to demonstrate large, useful accelerating gradients (> 100 MeV/m). Later phases of the facility will increase the drive bunch energy to more than 100 MeV to enable acceleration experiments up to the GeV range. Specifications, design details, and commissioning progress are presented.

  7. Fabrication of lanthanum-doped thorium dioxide by high-energy ball milling and spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Scott, Spencer M.; Yao, Tiankai; Lu, Fengyuan; Xin, Guoqing; Zhu, Weiguang; Lian, Jie

    2017-03-01

    High-energy ball milling was used to synthesize Th1-xLaxO2-0.5x (x = 0.09, 0.23) solid solutions, as well as improve the sinterability of ThO2 powders. Dense La-doped ThO2 pellets with theoretical density above 94% were consolidated by spark plasma sintering at temperatures above 1400 °C for 20 min, and the densification behavior and the non-equilibrium effects on phase and structure were investigated. A lattice contraction of the SPS-densified pellets occurred with increasing ball milling duration, and a secondary phase with increased La-content was observed in La-doped pellets. A dependence on the La-content and sintering duration for the onset of localized phase segregation has been proposed. The effects of high-energy ball milling, La-content, and phase formation on the thermal diffusivity were also studied for La-doped ThO2 pellets by laser flash measurement. Increasing La-content and high energy ball milling time decreases thermal diffusivity; while the sintering peak temperature and holding time beyond 1600 °C dramatically altered the temperature dependence of the thermal diffusivity beyond 600 °C.

  8. Measurement of continuous x-radiation and determination of the energy distribution function of high-energy electrons from an ECR plasma

    SciTech Connect

    Bernhardi, Karl

    1980-02-12

    Investigations were made on the x-radiation emitted by a plasma. The methods applied here represent a further development of experimental and numerical methods used hitherto for determining the bremsstrahlung emitted by a plasma, and makes possible a more precise determination of the high-energy electron component of a plasma.

  9. Wakefield generation via two color laser pulses

    SciTech Connect

    Jha, Pallavi; Saroch, Akanksha; Kumar Verma, Nirmal

    2013-05-15

    The analytical study for the evolution of longitudinal as well as transverse electric wakefields, generated via passage of two color laser pulses through uniform plasma, has been presented in the mildly relativistic regime. The frequency difference between the two laser pulses is assumed to be equal to the plasma frequency, in the present analysis. The relative angle between the directions of polarization of the two laser pulses is varied and the wakefield amplitudes are compared. Further, the amplitude of the excited wakes by two color pulses are compared with those generated by a single laser pulse.

  10. Ringing After a High-Energy Collision: Ambipolar Oscillations During Impact Plasma Expansion

    NASA Technical Reports Server (NTRS)

    Zimmerman, M. I.; Farrell, W. M.; Stubbs, T. J.

    2012-01-01

    High-velocity impacts on the Moon and other airless bodies deliver energy and material to the lunar surface and exosphere. The target and i mpactor material may become vaporized and ionized to form a collision al plasma that expands outward and eventually becomes collisionless. In the present work, kinetic simulations of the later collision less stage of impact plasma expansion are performed. Attention is paid to characterizing "ambipolar oscillations" in which thermodynamic distur bances propagate outward to generate "ringing" within the expanding e lectron cloud, which could radiate an electromagnetic signature of lo cal plasma conditions. The process is not unlike a beam-plasma intera ction, with the perturbing electron population in the present case ac ting as a highly thermal "beam" that resonates along the expanding de nsity gradient. Understanding the electromagnetic aspects of impact p lasma expansion could provide insight into the lasting effects of nat ural, impact-generated currents on airless surfaces and charging haza rds to human exploration infrastructure and instrumentation.

  11. Experimental characterization of railgun-driven supersonic plasma jets motivated by high energy density physics applications

    SciTech Connect

    Hsu, S. C.; Moser, A. L.; Awe, T. J.; Davis, J. S.; Dunn, J. P.; Merritt, E. C.; Adams, C. S.; Brockington, S. J. E.; Case, A.; Messer, S. J.; Witherspoon, F. D.; Cassibry, J. T.; Gilmore, M. A.; Lynn, A. G.

    2012-12-15

    We report experimental results on the parameters, structure, and evolution of high-Mach-number (M) argon plasma jets formed and launched by a pulsed-power-driven railgun. The nominal initial average jet parameters in the data set analyzed are density Almost-Equal-To 2 Multiplication-Sign 10{sup 16} cm{sup -3}, electron temperature Almost-Equal-To 1.4 eV, velocity Almost-Equal-To 30 km/s, M Almost-Equal-To 14, ionization fraction Almost-Equal-To 0.96, diameter Almost-Equal-To 5 cm, and length Almost-Equal-To 20 cm. These values approach the range needed by the Plasma Liner Experiment, which is designed to use merging plasma jets to form imploding spherical plasma liners that can reach peak pressures of 0.1-1 Mbar at stagnation. As these jets propagate a distance of approximately 40 cm, the average density drops by one order of magnitude, which is at the very low end of the 8-160 times drop predicted by ideal hydrodynamic theory of a constant-M jet.

  12. High Energy Electron Acceleration from Underdense Plasma Channeling Using the OMEGA EP Laser

    NASA Astrophysics Data System (ADS)

    Batson, Thomas; Raymond, Anthony; Hussein, Amina; Krushelnick, Karl; Willingale, Louise; Nilson, Phil; Froula, Dustin; Harberberger, Dan; Davies, Andrew; Theobald, Wolfgang; Williams, Jackson; Chen, Hui; Arefiev, Alexey

    2016-10-01

    For intense, ps scale lasers, propagation through underdense plasmas results in forces which expel electrons from along the laser axis, resulting in the formation of channels. Electrons can then be injected from the channel walls into the laser path, which results in the direct laser acceleration (DLA) of these electrons and the occurrence of an electron beam of 100's of MeV. Experiments performed at the OMEGA EP laser studied the formation of a laser channel in an underdense CH plasma, as well as the spatial properties and energy of an electron beam created via DLA mechanisms. The 4 omega optical probe diagnostic was used to characterize the density of the plasma plume, while proton radiography was used to observe the electromagnetic fields of the channel formation. These electric fields as well as the spectra of the accelerated electrons have been studied across different plasma density profiles. The channel behavior and electron spectra are compared to 2D particle-in-cell simulations.

  13. Final Report for Statistical Nonlinear Optics of High Energy Density Plasmas: The Physics of Multiple Crossing Laser Beams

    SciTech Connect

    Afeyan, Bedros; Hueller, Stefan; Montgomery, David S.; Hammer, James H.; Meezan, Nathan B.; Heebner, John E.

    2016-10-24

    The various implementations of the STUD pulse program (spike trains of uneven duration and delay) for LPI (laser-plasma instability) control were studied in depth, and novel regimes were found. How to generate STUD pulses with large time-bandwidth products, how to measure their optical scattering signatures, and how to experimentally demonstrate their usefulness were explored. Theoretical and numerical studies were conducted on Stimulated Brillouin Scattering (SBS) and Crossed Beam Energy Transfer (CBET) including statistical models. We established how LPI can be tamed and gain democratized in space and time. Implementing STUD pulses on NIF was also studied. Future high rep rate lasers and fast diagnostics will aid in the adoption of the whole STUD pulse program for LPI control in High Energy Density Plasmas (HEDP).

  14. Talbot-Lau X-ray Deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments

    DOE PAGES

    Valdivia, M. P.; Stutman, D.; Stoeckl, C.; ...

    2016-04-21

    Talbot-Lau X-ray Deflectometry has been developed as an electron density diagnostic for High Energy Density plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping was demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moire pattern formation and grating survival was also observed using a copper x-pinch driven at 400 kA, ~1 kA/ns. Lastly, these results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

  15. Talbot-Lau X-ray Deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments

    SciTech Connect

    Valdivia, M. P.; Stutman, D.; Stoeckl, C.; Mileham, C.; Begishev, I.; Theobald, W.; Bromage, J.; Regan, S. P.; Klein, S. R.; Munoz-Cordoves, G.; Vescovi, M.; Valenzuela-Villaseca, V.; Veloso, F.

    2016-04-21

    Talbot-Lau X-ray Deflectometry has been developed as an electron density diagnostic for High Energy Density plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping was demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moire pattern formation and grating survival was also observed using a copper x-pinch driven at 400 kA, ~1 kA/ns. Lastly, these results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

  16. The extremely high-energy plasma/particle sensor for electron (XEP-e) of the ERG satellite

    NASA Astrophysics Data System (ADS)

    Higashio, N.; Matsumoto, H.

    2015-12-01

    It is well known that satellites are always in danger in space and especially high-energy radiation damages them. One of the sources that cause them is the radiation belt (the Van Allen belt). It was thought to be static, but in the 1990s it rediscovered the radiation belt fluctuates greatly. There are some reasons to occur this phenomenon, but we have not understood a clear reason of this yet. On the other hand, it is well known that the energetic particle flux vary during geomagnetic disturbances and the relativistic electrons in the other radiation belt change with solar wind speed. Now we are trying to develop the satellite (ERG) to reveal this mechanism. ERG (Energization and Radiation in Geospace) satellite is the small space science platform for rapid investigation and test satellite of JAXA/ISAS. This satellite will be lanched in 2016. Our group is developing the instrument (the XEP-e) to measure high-energy electrons (400keV~20MeV), that is one of many ERG satellite instruments. The XEP-e (eXtremely high Energy Plasma/ particle sensor for electron) is consists of the 5 SSDs (Solid-State Silicon Detectors) and a GSO single crystal scintillator. It has one-way conic sight and an electric part is unified with a part of sensor that is covered with aluminum to protect from contaminationand and an anti-scintillator to detect it. The front part of the SSDs discriminate a radiation enters into the sensor and the back part of the plastic scintillator get the value of its energy. We can get the data of high-energy electron by using this sensor and it will be useful to reveal the detail of the radiation belt's fluctuation.

  17. Enhancement of wave growth for warm plasmas with a high-energy tail distribution

    NASA Technical Reports Server (NTRS)

    Thorne, Richard M.; Summers, Danny

    1991-01-01

    The classical linear theory of electromagnetic wave growth in a warm plasma is considered for waves propagating parallel to a uniform ambient magnetic field. Wave-growth rates are calculated for ion-driven right-hand mode waves for Kappa and Maxwellian particle distribution functions and for various values of the spectral index, the temperature anisotropy, and the ratio of plasma pressure to magnetic pressure appropriate to the solar wind. When the anisotropy is low the wave growth is limited to frequencies below the proton gyrofrequency and the growth rate increases dramatically as the spectral index is reduced. The growth rate for any Kappa distribution greatly exceeds that for a Maxwellian with the same bulk properties. For large thermal anisotropy the growth rate from either distribution is greatly enhanced. The growth rates from a Kappa distribution are generally larger than for a Maxwellian distribution, and significant wave growth occurs over a broader range of frequencies.

  18. Surface protection from high energy electrons and X-ray radiation analysis in tokamak plasma.

    PubMed

    Salar Elahi, A; Ghoranneviss, M

    2017-05-24

    Plasma cooling due to hard x-ray radiation from the Runaway electrons is an important issue in tokamaks. Thus, developing effective methods to reduce the Runaway electrons and the emitted hard x-ray is also important for optimal tokamak plasma operation. In this study, we investigated the effects of external fields on hard x-ray intensity and the Magnetohydrodynamic (MHD) activity. In other words, we presented the effects of positive biased limiter and Resonant Helical Field (RHF) on the MHD fluctuations and hard x-ray emission from the Runaway electrons. MHD activity and hard x-ray intensity were analyzed using Wavelet transform in the presence of external fields and without them. The experimental results showed that the MHD activity and therefore the hard x-ray intensity could be controlled by the external electric and magnetic fields.

  19. Enhancement of wave growth for warm plasmas with a high-energy tail distribution

    NASA Technical Reports Server (NTRS)

    Thorne, Richard M.; Summers, Danny

    1991-01-01

    The classical linear theory of electromagnetic wave growth in a warm plasma is considered for waves propagating parallel to a uniform ambient magnetic field. Wave-growth rates are calculated for ion-driven right-hand mode waves for Kappa and Maxwellian particle distribution functions and for various values of the spectral index, the temperature anisotropy, and the ratio of plasma pressure to magnetic pressure appropriate to the solar wind. When the anisotropy is low the wave growth is limited to frequencies below the proton gyrofrequency and the growth rate increases dramatically as the spectral index is reduced. The growth rate for any Kappa distribution greatly exceeds that for a Maxwellian with the same bulk properties. For large thermal anisotropy the growth rate from either distribution is greatly enhanced. The growth rates from a Kappa distribution are generally larger than for a Maxwellian distribution, and significant wave growth occurs over a broader range of frequencies.

  20. Development of a Hybrid Model for Non-Equilibrium High-Energy Plasmas

    DTIC Science & Technology

    2007-11-02

    performance electric propulsion systems , high-power conditioning, novel diagnostics methods, material fabrication, etc. The plasma conditions in these new...velocity distribution function (DF) that describes the system and its dynamics, i.e. solving the Boltzmann equation: )’,( ffCRfaff t vx =∇⋅+∇⋅+ ∂ ∂ ρρρρ...effects. However, a complete knowledge of the system DF is not possible given the current and even foreseeable computing capabilities, due to the

  1. Hybrid Kinetic-Fluid Electromagnetic Simulations of Imploding High Energy Density Plasmas for IFE

    NASA Astrophysics Data System (ADS)

    Welch, Dale; Rose, Dave; Thoma, Carsten; Genoni, Thomas; Bruner, Nichelle; Clark, Robert; Stygar, William; Leeper, Ramon

    2011-10-01

    A new simulation technique is being developed to study high current and moderate density-radius product (ρR) z-pinch plasmas relevant to Inertial Fusion Energy (IFE). Fully kinetic, collisional, and electromagnetic simulations of the time evolution of up to 40-MA current (deuterium and DT) z-pinches, but with relatively low ρR, have yielded new insights into the mechanisms of neutron production. At fusion relevant conditions (ρR > 0.01 gm/cm2) , however, this technique requires a prohibitively large number of cells and particles. A new hybrid implicit technique has been developed that accurately describes high-density and magnetized imploding plasmas. The technique adapts a recently published algorithm, that enables accurate descriptions of highly magnetized particle orbits, to high density plasmas and also makes use of an improved kinetic particle remap technique. We will discuss the new technique, stable range of operation, and application to an IFE relevant z-pinch design at 60 MA. Work supported by Sandia National Laboratories.

  2. Macroscopic plasma oscillation bursts (fishbones) resulting from high-energy populations

    SciTech Connect

    Coppi, B.; Migliuolo, S.; Porcelli, F.

    1988-06-01

    Oscillation bursts (fishbones) of magnetically confined plasmas are associated with the excitation of an m/sup 0/ = 1 mode when the ideal magnetohydrodynamic (MHD) threshold for the instability of this mode is reached. Near this threshold and in the absence of an effective ''viscous'' dissipative process, this mode remains marginally stable as a result of finite ion Larmor radius effects and has a real frequency of oscillation near the ion diamagnetic frequency. The release of the mode excitation energy related to the gradient of the plasma pressure, in the case of perpendicular neutral beam injection, is allowed by the resonant interaction of the mode with fast trapped ions that precess around the torus as a result of the curvature and the gradient of the confining magnetic field. This process plays the role of an effective viscosity. A consequence of the presented interpretation is that fishbone oscillations may also be excited in the case of parallel beam injection. In fact, for relatively low values of the beam transverse pressure, the basic mode frequency is related to the parameters of the target plasma and does not depend on the magnetic drift frequency of the beam particles that are injected nor on their velocity distribution.

  3. High-energy-density electron beam generation in ultra intense laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Liu, Jianxun; Ma, Yanyun; Yang, Xiaohu; Zhao, Jun; Yu, Tongpu; Shao, Fuqiu; Zhuo, Hongbin; Gan, Longfei; Zhang, Guobo; Zhao, Yuan; Yang, Jingkang

    2017-01-01

    By using a two-dimensional particle-in-cell simulation, we demonstrate a scheme for high-energy-density electron beam generation by irradiating an ultra intense laser pulse onto an aluminum (Al) target. With the laser having a peak intensity of 4 × 1023 W cm‑2, a high quality electron beam with a maximum density of 117nc and a kinetic energy density up to 8.79 × 1018 J m‑3 is generated. The temperature of the electron beam can be 416 MeV, and the beam divergence is only 7.25°. As the laser peak intensity increases (e.g., 1024 W cm‑2), both the beam energy density (3.56 × 1019 J m‑3) and the temperature (545 MeV) are increased, and the beam collimation is well controlled. The maximum density of the electron beam can even reach 180nc. Such beams should have potential applications in the areas of antiparticle generation, laboratory astrophysics, etc. This work is financially supported by the National Natural Science Foundation of China (Nos. 11475260, 11305264, 11622547, 91230205, and 11474360), the National Basic Research Program of China (No. 2013CBA01504), and the Research Project of NUDT (No. JC14-02-02).

  4. Radiation from Ag high energy density Z-pinch plasmas and applications to lasing

    SciTech Connect

    Weller, M. E. Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Shrestha, I.; Stafford, A.; Keim, S. F.; Shlyaptseva, V. V.; Osborne, G. C.; Petkov, E. E.; Apruzese, J. P.; Giuliani, J. L.; Chuvatin, A. S.

    2014-03-15

    Silver (Ag) wire arrays were recently introduced as efficient x-ray radiators and have been shown to create L-shell plasmas that have the highest electron temperature (>1.8 keV) observed on the Zebra generator so far and upwards of 30 kJ of energy output. In this paper, results of single planar wire arrays and double planar wire arrays of Ag and mixed Ag and Al that were tested on the UNR Zebra generator are presented and compared. To further understand how L-shell Ag plasma evolves in time, a time-gated x-ray spectrometer was designed and fielded, which has a spectral range of approximately 3.5–5.0 Å. With this, L-shell Ag as well as cold L{sub α} and L{sub β} Ag lines was captured and analyzed along with photoconducting diode (PCD) signals (>0.8 keV). Along with PCD signals, other signals, such as filtered XRD (>0.2 keV) and Si-diodes (SiD) (>9 keV), are analyzed covering a broad range of energies from a few eV to greater than 53 keV. The observation and analysis of cold L{sub α} and L{sub β} lines show possible correlations with electron beams and SiD signals. Recently, an interesting issue regarding these Ag plasmas is whether lasing occurs in the Ne-like soft x-ray range, and if so, at what gains? To help answer this question, a non-local thermodynamic equilibrium (LTE) kinetic model was utilized to calculate theoretical lasing gains. It is shown that the Ag L-shell plasma conditions produced on the Zebra generator at 1.7 maximum current may be adequate to produce gains as high as 6 cm{sup −1} for various 3p → 3s transitions. Other potential lasing transitions, including higher Rydberg states, are also included in detail. The overall importance of Ag wire arrays and plasmas is discussed.

  5. A non-LTE analysis of high energy density Kr plasmas on Z and NIF

    DOE PAGES

    Dasgupta, A.; Clark, R. W.; Ouart, N.; ...

    2016-10-20

    We report that multi-keV X-ray radiation sources have a wide range of applications, from biomedical studies and research on thermonuclear fusion to materials science and astrophysics. The refurbished Z pulsed power machine at the Sandia National Laboratories produces intense multi-keV X-rays from argon Z-pinches, but for a krypton Z-pinch, the yield decreases much faster with atomic number ZA than similar sources on the National Ignition Facility (NIF) laser at the Lawrence Livermore National Laboratory. To investigate whether fundamental energy deposition differences between pulsed power and lasers could account for the yield differences, we consider the Kr plasma on the twomore » machines. The analysis assumes the plasma not in local thermodynamic equilibrium, with a detailed coupling between the hydrodynamics, the radiation field, and the ionization physics. While for the plasma parameters of interest the details of krypton’s M-shell are not crucial, both the L-shell and the K-shell must be modeled in reasonable detail, including the state-specific dielectronic recombination processes that significantly affect Kr’s ionization balance and the resulting X-ray spectrum. We present a detailed description of the atomic model, provide synthetic K- and L-shell spectra, and compare these with the available experimental data from the Z-machine and from NIF to show that the K-shell yield behavior versus ZA is indeed related to the energy input characteristics. In conclusion, this work aims at understanding the probable causes that might explain the differences in the X-ray conversion efficiencies of several radiation sources on Z and« less

  6. A non-LTE analysis of high energy density Kr plasmas on Z and NIF

    NASA Astrophysics Data System (ADS)

    Dasgupta, A.; Clark, R. W.; Ouart, N.; Giuliani, J.; Velikovich, A.; Ampleford, D. J.; Hansen, S. B.; Jennings, C.; Harvey-Thompson, A. J.; Jones, B.; Flanagan, T. M.; Bell, K. S.; Apruzese, J. P.; Fournier, K. B.; Scott, H. A.; May, M. J.; Barrios, M. A.; Colvin, J. D.; Kemp, G. E.

    2016-10-01

    Multi-keV X-ray radiation sources have a wide range of applications, from biomedical studies and research on thermonuclear fusion to materials science and astrophysics. The refurbished Z pulsed power machine at the Sandia National Laboratories produces intense multi-keV X-rays from argon Z-pinches, but for a krypton Z-pinch, the yield decreases much faster with atomic number ZA than similar sources on the National Ignition Facility (NIF) laser at the Lawrence Livermore National Laboratory. To investigate whether fundamental energy deposition differences between pulsed power and lasers could account for the yield differences, we consider the Kr plasma on the two machines. The analysis assumes the plasma not in local thermodynamic equilibrium, with a detailed coupling between the hydrodynamics, the radiation field, and the ionization physics. While for the plasma parameters of interest the details of krypton's M-shell are not crucial, both the L-shell and the K-shell must be modeled in reasonable detail, including the state-specific dielectronic recombination processes that significantly affect Kr's ionization balance and the resulting X-ray spectrum. We present a detailed description of the atomic model, provide synthetic K- and L-shell spectra, and compare these with the available experimental data from the Z-machine and from NIF to show that the K-shell yield behavior versus ZA is indeed related to the energy input characteristics. This work aims at understanding the probable causes that might explain the differences in the X-ray conversion efficiencies of several radiation sources on Z and NIF.

  7. A non-LTE analysis of high energy density Kr plasmas on Z and NIF

    SciTech Connect

    Dasgupta, A.; Clark, R. W.; Ouart, N.; Giuliani, J.; Velikovich, A.; Ampleford, D. J.; Hansen, S. B.; Jennings, C.; Harvey-Thompson, A. J.; Jones, B.; Flanagan, T. M.; Bell, K. S.; Apruzese, J. P.; Fournier, K. B.; Scott, H. A.; May, M. J.; Barrios, M. A.; Colvin, J. D.; Kemp, G. E.

    2016-10-20

    We report that multi-keV X-ray radiation sources have a wide range of applications, from biomedical studies and research on thermonuclear fusion to materials science and astrophysics. The refurbished Z pulsed power machine at the Sandia National Laboratories produces intense multi-keV X-rays from argon Z-pinches, but for a krypton Z-pinch, the yield decreases much faster with atomic number ZA than similar sources on the National Ignition Facility (NIF) laser at the Lawrence Livermore National Laboratory. To investigate whether fundamental energy deposition differences between pulsed power and lasers could account for the yield differences, we consider the Kr plasma on the two machines. The analysis assumes the plasma not in local thermodynamic equilibrium, with a detailed coupling between the hydrodynamics, the radiation field, and the ionization physics. While for the plasma parameters of interest the details of krypton’s M-shell are not crucial, both the L-shell and the K-shell must be modeled in reasonable detail, including the state-specific dielectronic recombination processes that significantly affect Kr’s ionization balance and the resulting X-ray spectrum. We present a detailed description of the atomic model, provide synthetic K- and L-shell spectra, and compare these with the available experimental data from the Z-machine and from NIF to show that the K-shell yield behavior versus ZA is indeed related to the energy input characteristics. In conclusion, this work aims at understanding the probable causes that might explain the differences in the X-ray conversion efficiencies of several radiation sources on Z and

  8. A high-resolution imaging x-ray crystal spectrometer for high energy density plasmas

    SciTech Connect

    Chen, Hui E-mail: bitter@pppl.gov; Magee, E.; Nagel, S. R.; Park, J.; Schneider, M. B.; Stone, G.; Williams, G. J.; Beiersdorfer, P.; Bitter, M. E-mail: bitter@pppl.gov; Hill, K. W.; Kerr, S.

    2014-11-15

    Adapting a concept developed for magnetic confinement fusion experiments, an imaging crystal spectrometer has been designed and tested for HED plasmas. The instrument uses a spherically bent quartz [211] crystal with radius of curvature of 490.8 mm. The instrument was tested at the Titan laser at Lawrence Livermore National Laboratory by irradiating titanium slabs with laser intensities of 10{sup 19}–10{sup 20} W/cm{sup 2}. He-like and Li-like Ti lines were recorded, from which the spectrometer performance was evaluated. This spectrometer provides very high spectral resolving power (E/dE > 7000) while acquiring a one-dimensional image of the source.

  9. Calculation of thermodynamic functions of aluminum plasma for high-energy-density systems

    SciTech Connect

    Shumaev, V. V.

    2016-12-15

    The results of calculating the degree of ionization, the pressure, and the specific internal energy of aluminum plasma in a wide temperature range are presented. The TERMAG computational code based on the Thomas–Fermi model was used at temperatures T > 105 K, and the ionization equilibrium model (Saha model) was applied at lower temperatures. Quantitatively similar results were obtained in the temperature range where both models are applicable. This suggests that the obtained data may be joined to produce a wide-range equation of state.

  10. A high-resolution imaging x-ray crystal spectrometer for high energy density plasmas.

    PubMed

    Chen, Hui; Bitter, M; Hill, K W; Kerr, S; Magee, E; Nagel, S R; Park, J; Schneider, M B; Stone, G; Williams, G J; Beiersdorfer, P

    2014-11-01

    Adapting a concept developed for magnetic confinement fusion experiments, an imaging crystal spectrometer has been designed and tested for HED plasmas. The instrument uses a spherically bent quartz [211] crystal with radius of curvature of 490.8 mm. The instrument was tested at the Titan laser at Lawrence Livermore National Laboratory by irradiating titanium slabs with laser intensities of 10(19)-10(20) W/cm(2). He-like and Li-like Ti lines were recorded, from which the spectrometer performance was evaluated. This spectrometer provides very high spectral resolving power (E/dE > 7000) while acquiring a one-dimensional image of the source.

  11. Raman backscatter as a remote laser power sensor in high-energy-density plasmas.

    PubMed

    Moody, J D; Strozzi, D J; Divol, L; Michel, P; Robey, H F; LePape, S; Ralph, J; Ross, J S; Glenzer, S H; Kirkwood, R K; Landen, O L; MacGowan, B J; Nikroo, A; Williams, E A

    2013-07-12

    Stimulated Raman backscatter is used as a remote sensor to quantify the instantaneous laser power after transfer from outer to inner cones that cross in a National Ignition Facility (NIF) gas-filled hohlraum plasma. By matching stimulated Raman backscatter between a shot reducing outer versus a shot reducing inner power we infer that about half of the incident outer-cone power is transferred to inner cones, for the specific time and wavelength configuration studied. This is the first instantaneous nondisruptive measure of power transfer in an indirect drive NIF experiment using optical measurements.

  12. Electric and Magnetic Field Measurements in High Energy Electron Beam Diode Plasmas using Optical Spectroscopy

    NASA Astrophysics Data System (ADS)

    Johnston, Mark; Patel, Sonal; Kiefer, Mark; Biswas, S.; Doron, R.; Stambulchik, E.; Bernshtam, V.; Maron, Yitzhak

    2016-10-01

    The RITS accelerator (5-11MV, 100-200kA) at Sandia National Laboratories is being used to evaluate the Self-Magnetic Pinch (SMP) diode as a potential flash x-ray radiography source. This diode consists of a small, hollowed metal cathode and a planar, high atomic mass anode, with a small vacuum gap of approximately one centimeter. The electron beam is focused, due to its self-field, to a few millimeters at the target, generating bremsstrahlung x-rays. During this process, plasmas form on the electrode surfaces and propagate into the vacuum gap, with a velocity of a 1-10 cm's/microseconds. These plasmas are measured spectroscopically using a Czerny-Turner spectrometer with a gated, ICCD detector, and input optical fiber array. Local magnetic and electric fields of several Tesla and several MV/cm were measured through Zeeman splitting and Stark shifting of spectral lines. Specific transitions susceptible to quantum magnetic and electric field effects were utilized through the application of dopants. Data was analyzed using detailed, time-dependent, collisional-radiative (CR) and radiation transport modeling. Recent results will be presented. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  13. THE IRON PROJECT: High-Energy-Density (HED) Plasma Opacities and Diagnostics

    NASA Astrophysics Data System (ADS)

    Gokce, Yasin; Bostelmann, T.; Nahar, S.; Pradhan, A.; Bailey, J.

    2014-05-01

    The composition of the Sun, the benchmark for astronomical objects, has been a longstanding problem for the last few decades. The abundances of common elements in the Sun, such as, carbon, nitrogen, oxygen, supported by helioseismology are at discrepant by up to 50% higher from those derived from state-of-the-art spectroscopy and elaborate 3-D radiative transfer models. The uncertainty is compounded by recent experiments at the Sandia National Laboratory on the Z-pinch inertial confinement fusion device which is able to re-create the HED plasma conditions existing at the solar radiative-convection zone boundary. Measured monochromatic iron opacities disagree with all known theoretical opacities models. The abundance problem and potential solution are related to radiative opacities. Uur continued investigation of the problem will be presented. We will also present collision strengths of carbon-like silicon which shows new resonances in the low energy region introduced by relativistic effects in the Breit-Pauli R-matrix method. Line intensity ratios of this ion, obtained for optically allowed transitions as seen in astronomical spectra, are the diagnostics for the density and termperature of the plasmas will be reported. Partial support of NSF, DOE.

  14. Observation of Enhanced Transformer Ratio in Collinear Wakefield Acceleration

    NASA Astrophysics Data System (ADS)

    Jing, C.; Kanareykin, A.; Power, J. G.; Conde, M.; Yusof, Z.; Schoessow, P.; Gai, W.

    2007-04-01

    One approach to future high energy particle accelerators is based on the wakefield principle: a leading high-charge drive bunch is used to excite fields in an accelerating structure or plasma that in turn accelerates a trailing low-charge witness bunch. The transformer ratio R is defined as the ratio of the maximum energy gain of the witness bunch to the maximum energy loss of the drive bunch. In general, R<2 for this configuration. A number of techniques have been proposed to overcome the transformer ratio limitation. We report here the first experimental study of the ramped bunch train (RBT) technique in a dielectric based accelerating structure. A single drive bunch was replaced by two bunches with charge ratio of 1∶2.5 and a separation of 10.5 wavelengths of the fundamental mode. An average measured transformer ratio enhancement by a factor of 1.31 over the single drive bunch case was obtained.

  15. High Energy Plasmas in the Surroundings of Black Holes: Composite Disk Structures and Characteristic Modes*

    NASA Astrophysics Data System (ADS)

    Coppi, Bruno

    2009-11-01

    Theoretically finding of composite disk structures around compact objects (e.g. black holes) and recent experimental observations indicate that highly coherent and dynamically important magnetic field configurations exist in the core of these structures [1]. These coherent configurations provide a means to resolve the ``accretion paradox'' for a magnetized disk [2] while the formation of jets that are emitted in the close vicinity of the compact object is related to them. The absence of vigorous accretion activity in the presence of black holes in old galaxies can be attributed to the loss of the surrounding coherent magnetic configurations during their history. As for relevant dynamics, axisymmetric (ballooning) modes as well as tri-dimensional spirals can be excited from disks with a ``seed'' magnetic field, under the effects of differential rotation and of the vertical plasma pressure gradient. The properties of these spirals are strongly dependent on their vertical structure. Axisymmetric modes can produce vertical flows of thermal energy [3] and particles in opposing directions that can be connected to the winds emanating from disks in Active Galactic Nuclei (AGN's). A similarity with the effects of temperature gradient driven modes in magnetically confined laboratory plasmas is pointed out. Spiral modes that are oscillatory in time and in the radial direction can produce transport of angular momentum toward the outer region of the disk structure, a necessary process for the occurrence of accretion [3]. The excitation of radially localized density spirals co-rotating with the plasma, at a distance related to the Schwartzchild radius RS=2GM*/c^2 where M* is the black hole mass, is proposed [4] as the explanation for High Frequency Quasi Periodic Oscillations (HFQPOs) of non-thermal X-ray emission from compact objects. *Sponsored in part by the U.S. Department of Energy.[4pt] [1] B. Coppi and F. Rousseau Ap. J. 641 458 (2006)[0pt] [2] B. Coppi to be published in

  16. Corrosion behavior of magnesium powder fabricated by high-energy ball milling and spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Kim, Ka Ram; Ahn, Jin Woo; Kim, Gyeung-Ho; Han, Jun Hyun; Cho, Kwon Koo; Roh, Jae-Seung; Kim, Woo Jin; Kim, Hye Sung

    2014-11-01

    Microstructural changes and corrosion behavior of pure magnesium for different milling times were investigated. The samples with a finer grain size showed poor corrosion resistance because of unstable or metastable protective film formation after immersion in 0.8 wt% NaCl solution. The corrosion resistance did not improve despite the strong (0002) texture of the sample prepared by spark plasma sintering at 500 °C for 0.3 Ks and milling for 2 h. By studying the microstructural changes and texture development, we concluded that the deformation-dependent grain size is the dominant factor controlling the corrosion properties of mechanically milled magnesium. Increased grain boundary densities lead to an enhancement of the overall surface reactivity and, consequently, the corrosion rate.

  17. Talbot-Lau based Moiré deflectometry with non-coherent sources as potential High Energy Density plasma diagnostic

    SciTech Connect

    Valdivia, M. P.; Stutman, D.; Finkenthal, M.

    2013-10-28

    X-ray phase-contrast radiography could better characterize highly localized density gradients expected in High Energy Density (HED) plasma experiments than conventional attenuation radiography. In particular, the Talbot-Lau (TL) grating interferometer, which works with extended and polychromatic x-ray sources, is a potentially attractive HED diagnostic due to its high sensitivity. For HED characterization the TL setup and imaging techniques must be changed from the recently studied medical system. The object magnification must be increased greatly in order to resolve μm scale gradients while the Talbot magnification must be increased in order to keep the gratings away from the plasma. Additionally, techniques for retrieving the density profile from a single plasma image must be developed. We thus study the performance of high magnification TL interferometers, in conjunction with Moiré fringe deflectometry for single image phase retrieval. The results show a very good interferometer contrast (≤30%) at high magnification. The Moiré technique enables measuring both sharp and mild density gradients with good accuracy and spatial resolution. Both the laboratory and simulation studies indicate that the TL based Moiré deflectometry is more sensitive than the propagation phase-contrast method when utilizing an extended x-ray source (∼80 μm). In HED experiments this would allow for less demanding X-ray backlighters than those used at present.

  18. Spectral and Atomic Physics Analysis of Xenon L-Shell Emission From High Energy Laser Produced Plasmas

    NASA Astrophysics Data System (ADS)

    Thorn, Daniel; Kemp, G. E.; Widmann, K.; Benjamin, R. D.; May, M. J.; Colvin, J. D.; Barrios, M. A.; Fournier, K. B.; Liedahl, D.; Moore, A. S.; Blue, B. E.

    2016-10-01

    The spectrum of the L-shell (n =2) radiation in mid to high-Z ions is useful for probing plasma conditions in the multi-keV temperature range. Xenon in particular with its L-shell radiation centered around 4.5 keV is copiously produced from plasmas with electron temperatures in the 5-10 keV range. We report on a series of time-resolved L-shell Xe spectra measured with the NIF X-ray Spectrometer (NXS) in high-energy long-pulse (>10 ns) laser produced plasmas at the National Ignition Facility. The resolving power of the NXS is sufficiently high (E/ ∂E >100) in the 4-5 keV spectral band that the emission from different charge states is observed. An analysis of the time resolved L-shell spectrum of Xe is presented along with spectral modeling by detailed radiation transport and atomic physics from the SCRAM code and comparison with predictions from HYDRA a radiation-hydrodynamics code with inline atomic-physics from CRETIN. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

  19. Monoenergetic proton backlighter for measuring E and B fields and for radiographing implosions and high-energy density plasmas (invited)

    SciTech Connect

    Li, C. K.; Seguin, F. H.; Frenje, J. A.; Rygg, J. R.; Petrasso, R. D.; Town, R. P. J.; Amendt, P. A.; Hatchett, S. P.; Landen, O. L.; Mackinnon, A. J.; Patel, P. K.; Smalyuk, V. A.; Knauer, J. P.; Sangster, T. C.; Stoeckl, C.

    2006-10-15

    A novel monoenergetic proton backlighter source and matched imaging detector have been utilized on the OMEGA laser system to study electric (E) and magnetic (B) fields generated by laser-plasma interactions and will be utilized in the future to radiograph implosions and high-energy density (HED) plasmas. The backlighter consists of an imploding glass microballoon with D {sup 3}He fuel, producing 14.7 MeV D {sup 3}He protons and 3 MeV DD protons that are then passed through a mesh that divides the protons into beamlets. For quantitative study of E+B field structure, monoenergetic protons have several unique advantages compared to the broad energy spectrum used in previous experiments. Recent experiments have been performed with a single laser beam (intensity of {approx}10{sup 14} W/cm{sup 2}) interacting with a CH foil, and B fields of {approx}0.5 MG and E fields of {approx}1.5x10{sup 8} V/m have been measured using proton deflectometry. LASNEX simulations are being used to interpret these experiments. Additional information will also be presented on the application of this technique to measuring E and B fields associated with Hohlraums and directly driven implosions, to radiographically mapping the areal density ({rho}R) distribution in imploded capsules, and to radiographing HED plasmas.

  20. High energy density capacitors for vacuum operation with a pulsed plasma load

    NASA Technical Reports Server (NTRS)

    Guman, W. J.

    1976-01-01

    Results of the effort of designing, fabricating, and testing of a 40 joules/lb (88.2 joules/Kg) high voltage energy storage capacitor suitable for operating a pulsed plasma thruster in a vacuum environment for millions of pulses are presented. Using vacuum brazing and heli-arc welding techniques followed by vacuum and high pressure helium leak tests it was possible to produce a hermetically sealed relatively light weight enclosure for the dielectric system. An energy density of 40 joules/lb was realized with a KF-polyvinylidene fluoride dielectric system. One capacitor was D.C. life tested at 4 KV (107.8 joules/lb) for 2,000 hours before it failed. Another exceeded 2,670 hours without failure at 38.3 joules/lb. Pulse life testing in a vacuum exceeded 300,000 discharges with testing still in progress. The D.C. life test data shows a small decrease in capacitance and an increase in dissipation factor with time. Heat transfer from the load to the capacitor must also be considered besides the self-heat generated by the capacitor.

  1. Observation of a high-energy tail in ion energy distribution in the cylindrical Hall thruster plasma

    SciTech Connect

    Lim, Youbong; Kim, Holak; Choe, Wonho Lee, Seung Hun; Seon, Jongho; Lee, Hae June

    2014-10-15

    A novel method is presented to determine populations and ion energy distribution functions (IEDFs) of individual ion species having different charge states in an ion beam from the measured spectrum of an E × B probe. The inversion of the problem is performed by adopting the iterative Tikhonov regularization method with the characteristic matrices obtained from the calculated ion trajectories. In a cylindrical Hall thruster plasma, an excellent agreement is observed between the IEDFs by an E × B probe and those by a retarding potential analyzer. The existence of a high-energy tail in the IEDF is found to be mainly due to singly charged Xe ions, and is interpreted in terms of non-linear ion acceleration.

  2. Observation of a high-energy tail in ion energy distribution in the cylindrical Hall thruster plasma

    NASA Astrophysics Data System (ADS)

    Lim, Youbong; Kim, Holak; Choe, Wonho; Lee, Seung Hun; Seon, Jongho; Lee, Hae June

    2014-10-01

    A novel method is presented to determine populations and ion energy distribution functions (IEDFs) of individual ion species having different charge states in an ion beam from the measured spectrum of an E × B probe. The inversion of the problem is performed by adopting the iterative Tikhonov regularization method with the characteristic matrices obtained from the calculated ion trajectories. In a cylindrical Hall thruster plasma, an excellent agreement is observed between the IEDFs by an E × B probe and those by a retarding potential analyzer. The existence of a high-energy tail in the IEDF is found to be mainly due to singly charged Xe ions, and is interpreted in terms of non-linear ion acceleration.

  3. High-energy-density electron jet generation from an opening gold cone filled with near-critical-density plasma

    SciTech Connect

    Yu, T. P. Shao, F. Q.; Zou, D. B.; Ge, Z. Y.; Zhang, G. B.; Wang, W. Q.; Li, X. H.; Liu, J. X.; Ouyang, J. M.; Yu, W.; Luan, S. X.; Wang, J. W.; Wong, A. Y.

    2015-01-14

    By using two-dimensional particle-in-cell simulations, we propose a scheme for strong coupling of a petawatt laser with an opening gold cone filled with near-critical-density plasmas. When relevant parameters are properly chosen, most laser energy can be fully deposited inside the cone with only 10% leaving the tip opening. Due to the asymmetric ponderomotive acceleration by the strongly decayed laser pulse, high-energy-density electrons with net laser energy gain are accumulated inside the cone, which then stream out of the tip opening continuously, like a jet. The jet electrons are fully relativistic, with speeds around 0.98−0.998 c and densities at 10{sup 20}/cm{sup 3} level. The jet can keep for a long time over 200 fs, which may have diverse applications in practice.

  4. High-energy-density electron beam from interaction of two successive laser pulses with subcritical-density plasma

    NASA Astrophysics Data System (ADS)

    Wang, J. W.; Yu, W.; Yu, M. Y.; Xu, H.; Ju, J. J.; Luan, S. X.; Murakami, M.; Zepf, M.; Rykovanov, S.

    2016-02-01

    It is shown by particle-in-cell simulations that a narrow electron beam with high energy and charge density can be generated in a subcritical-density plasma by two consecutive laser pulses. Although the first laser pulse dissipates rapidly, the second pulse can propagate for a long distance in the thin wake channel created by the first pulse and can further accelerate the preaccelerated electrons therein. Given that the second pulse also self-focuses, the resulting electron beam has a narrow waist and high charge and energy densities. Such beams are useful for enhancing the target-back space-charge field in target normal sheath acceleration of ions and bremsstrahlung sources, among others.

  5. Effects of high energy photon emissions in laser generated ultra-relativistic plasmas: Real-time synchrotron simulations

    NASA Astrophysics Data System (ADS)

    Wallin, Erik; Gonoskov, Arkady; Marklund, Mattias

    2015-03-01

    We model the emission of high energy photons due to relativistic charged particle motion in intense laser-plasma interactions. This is done within a particle-in-cell code, for which high frequency radiation normally cannot be resolved due to finite time steps and grid size. A simple expression for the synchrotron radiation spectra is used together with a Monte-Carlo method for the emittance. We extend previous work by allowing for arbitrary fields, considering the particles to be in instantaneous circular motion due to an effective magnetic field. Furthermore, we implement noise reduction techniques and present validity estimates of the method. Finally, we perform a rigorous comparison to the mechanism of radiation reaction, and find the emitted energy to be in excellent agreement with the losses calculated using radiation reaction.

  6. Relativistic quantum corrections to laser wakefield acceleration.

    PubMed

    Zhu, Jun; Ji, Peiyong

    2010-03-01

    The influence of quantum effects on the interaction of intense laser fields with plasmas is investigated by using a hydrodynamic model based on the framework of the relativistic quantum theory. Starting from the covariant Wigner function and Dirac equation, the hydrodynamic equations for relativistic quantum plasmas are derived. Based on the relativistic quantum hydrodynamic equations and Poisson equation, the perturbations of electron number densities and the electric field of the laser wakefield containing quantum effects are deduced. It is found that the corrections generated by the quantum effects to the perturbations of electron number densities and the accelerating field of the laser wakefield cannot be neglected. Quantum effects will suppress laser wakefields, which is a classical manifestation of quantum decoherence effects, however, the contribution of quantum effects for the laser wakefield correction will been partially counteracted by the relativistic effects. The analysis also reveals that quantum effects enlarge the effective frequencies of plasmas, and the quantum behavior appears a screening effect for plasma electrons.

  7. Relativistic quantum corrections to laser wakefield acceleration

    SciTech Connect

    Zhu Jun; Ji Peiyong

    2010-03-15

    The influence of quantum effects on the interaction of intense laser fields with plasmas is investigated by using a hydrodynamic model based on the framework of the relativistic quantum theory. Starting from the covariant Wigner function and Dirac equation, the hydrodynamic equations for relativistic quantum plasmas are derived. Based on the relativistic quantum hydrodynamic equations and Poisson equation, the perturbations of electron number densities and the electric field of the laser wakefield containing quantum effects are deduced. It is found that the corrections generated by the quantum effects to the perturbations of electron number densities and the accelerating field of the laser wakefield cannot be neglected. Quantum effects will suppress laser wakefields, which is a classical manifestation of quantum decoherence effects, however, the contribution of quantum effects for the laser wakefield correction will been partially counteracted by the relativistic effects. The analysis also reveals that quantum effects enlarge the effective frequencies of plasmas, and the quantum behavior appears a screening effect for plasma electrons.

  8. First-principles equation-of-state table of silicon and its effects on high-energy-density plasma simulations

    DOE PAGES

    Hu, S. X.; Gao, R.; Princeton Univ., Princeton, NJ; ...

    2017-04-21

    Using density-functional theory–based molecular-dynamics simulations, we have investigated the equation of state for silicon in a wide range of plasma density and temperature conditions of ρ=0.001–500g/cm3 and T=2000–108K. With these calculations, we have established a first-principles equation-of-state (FPEOS) table of silicon for high-energy-density (HED) plasma simulations. When compared with the widely used SESAME-EOS model (Table 3810), we find that the FPEOS-predicted Hugoniot is ~20% softer; for off-Hugoniot plasma conditions, the pressure and internal energy in FPEOS are lower than those of SESAME EOS for temperatures above T ≈ 1–10 eV (depending on density), while the former becomes higher in themore » low-T regime. The pressure difference between FPEOS and SESAME 3810 can reach to ~50%, especially in the warm-dense-matter regime. Implementing the FPEOS table of silicon into our hydrocodes, we have studied its effects on Si-target implosions. When compared with the one-dimensional radiation-hydrodynamics simulation using the SESAME 3810 EOS model, the FPEOS simulation showed that (1) the shock speed in silicon is ~10% slower; (2) the peak density of an in-flight Si shell during implosion is ~20% higher than the SESAME 3810 simulation; (3) the maximum density reached in the FPEOS simulation is ~40% higher at the peak compression; and (4) the final areal density and neutron yield are, respectively, ~30% and ~70% higher predicted by FPEOS versus the traditional simulation using SESAME 3810. All of these features can be attributed to the larger compressibility of silicon predicted by FPEOS. Furthermore, these results indicate that an accurate EOS table, like the FPEOS presented here, could be essential for the precise design of targets for HED experiments.« less

  9. The EPQ Code System for Simulating the Thermal Response of Plasma-Facing Components to High-Energy Electron Impact

    SciTech Connect

    Ward, Robert Cameron; Steiner, Don

    2004-06-15

    The generation of runaway electrons during a thermal plasma disruption is a concern for the safe and economical operation of a tokamak power system. Runaway electrons have high energy, 10 to 300 MeV, and may potentially cause extensive damage to plasma-facing components (PFCs) through large temperature increases, melting of metallic components, surface erosion, and possible burnout of coolant tubes. The EPQ code system was developed to simulate the thermal response of PFCs to a runaway electron impact. The EPQ code system consists of several parts: UNIX scripts that control the operation of an electron-photon Monte Carlo code to calculate the interaction of the runaway electrons with the plasma-facing materials; a finite difference code to calculate the thermal response, melting, and surface erosion of the materials; a code to process, scale, transform, and convert the electron Monte Carlo data to volumetric heating rates for use in the thermal code; and several minor and auxiliary codes for the manipulation and postprocessing of the data. The electron-photon Monte Carlo code used was Electron-Gamma-Shower (EGS), developed and maintained by the National Research Center of Canada. The Quick-Therm-Two-Dimensional-Nonlinear (QTTN) thermal code solves the two-dimensional cylindrical modified heat conduction equation using the Quickest third-order accurate and stable explicit finite difference method and is capable of tracking melting or surface erosion. The EPQ code system is validated using a series of analytical solutions and simulations of experiments. The verification of the QTTN thermal code with analytical solutions shows that the code with the Quickest method is better than 99.9% accurate. The benchmarking of the EPQ code system and QTTN versus experiments showed that QTTN's erosion tracking method is accurate within 30% and that EPQ is able to predict the occurrence of melting within the proper time constraints. QTTN and EPQ are verified and validated as able

  10. First-principles equation-of-state table of silicon and its effects on high-energy-density plasma simulations

    NASA Astrophysics Data System (ADS)

    Hu, S. X.; Gao, R.; Ding, Y.; Collins, L. A.; Kress, J. D.

    2017-04-01

    Using density-functional theory-based molecular-dynamics simulations, we have investigated the equation of state for silicon in a wide range of plasma density and temperature conditions of ρ =0.001 -500 g /c m3 and T =2000 -108K . With these calculations, we have established a first-principles equation-of-state (FPEOS) table of silicon for high-energy-density (HED) plasma simulations. When compared with the widely used SESAME-EOS model (Table 3810), we find that the FPEOS-predicted Hugoniot is ˜20% softer; for off-Hugoniot plasma conditions, the pressure and internal energy in FPEOS are lower than those of SESAME EOS for temperatures above T ≈ 1-10 eV (depending on density), while the former becomes higher in the low-T regime. The pressure difference between FPEOS and SESAME 3810 can reach to ˜50%, especially in the warm-dense-matter regime. Implementing the FPEOS table of silicon into our hydrocodes, we have studied its effects on Si-target implosions. When compared with the one-dimensional radiation-hydrodynamics simulation using the SESAME 3810 EOS model, the FPEOS simulation showed that (1) the shock speed in silicon is ˜10% slower; (2) the peak density of an in-flight Si shell during implosion is ˜20% higher than the SESAME 3810 simulation; (3) the maximum density reached in the FPEOS simulation is ˜40% higher at the peak compression; and (4) the final areal density and neutron yield are, respectively, ˜30% and ˜70% higher predicted by FPEOS versus the traditional simulation using SESAME 3810. All of these features can be attributed to the larger compressibility of silicon predicted by FPEOS. These results indicate that an accurate EOS table, like the FPEOS presented here, could be essential for the precise design of targets for HED experiments.

  11. First-principles equation-of-state table of silicon and its effects on high-energy-density plasma simulations.

    PubMed

    Hu, S X; Gao, R; Ding, Y; Collins, L A; Kress, J D

    2017-04-01

    Using density-functional theory-based molecular-dynamics simulations, we have investigated the equation of state for silicon in a wide range of plasma density and temperature conditions of ρ=0.001-500g/cm^{3} and T=2000-10^{8}K. With these calculations, we have established a first-principles equation-of-state (FPEOS) table of silicon for high-energy-density (HED) plasma simulations. When compared with the widely used SESAME-EOS model (Table 3810), we find that the FPEOS-predicted Hugoniot is ∼20% softer; for off-Hugoniot plasma conditions, the pressure and internal energy in FPEOS are lower than those of SESAME EOS for temperatures above T ≈ 1-10 eV (depending on density), while the former becomes higher in the low-T regime. The pressure difference between FPEOS and SESAME 3810 can reach to ∼50%, especially in the warm-dense-matter regime. Implementing the FPEOS table of silicon into our hydrocodes, we have studied its effects on Si-target implosions. When compared with the one-dimensional radiation-hydrodynamics simulation using the SESAME 3810 EOS model, the FPEOS simulation showed that (1) the shock speed in silicon is ∼10% slower; (2) the peak density of an in-flight Si shell during implosion is ∼20% higher than the SESAME 3810 simulation; (3) the maximum density reached in the FPEOS simulation is ∼40% higher at the peak compression; and (4) the final areal density and neutron yield are, respectively, ∼30% and ∼70% higher predicted by FPEOS versus the traditional simulation using SESAME 3810. All of these features can be attributed to the larger compressibility of silicon predicted by FPEOS. These results indicate that an accurate EOS table, like the FPEOS presented here, could be essential for the precise design of targets for HED experiments.

  12. Betatron x-ray radiation in the self-modulated wakefield acceleration regime (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Albert, Felicie

    2017-05-01

    Betatron x-ray radiation, driven by electrons from laser-wakefield acceleration, has unique properties to probe high energy density (HED) plasmas and warm dense matter. Betatron radiation is produced when relativistic electrons oscillate in the plasma wake of a laser pulse. Its properties are similar to those of synchrotron radiation, with a 1000 fold shorter pulse. This presentation will focus on the experimental challenges and results related to the development of betatron radiation in the self modulated regime of laser wakefield acceleration. We observed multi keV Betatron x-rays from a self-modulated laser wakefield accelerator. The experiment was performed at the Jupiter Laser Facility, LLNL, by focusing the Titan short pulse beam (4-150 J, 1 ps) onto the edge of a Helium gas jet at electronic densities around 1019 cm-3. For the first time on this laser system, we used a long focal length optic, which produced a laser normalized potential a0 in the range 1-3. Under these conditions, electrons are accelerated by the plasma wave created in the wake of the light pulse. As a result, intense Raman satellites, which measured shifts depend on the electron plasma density, were observed on the laser spectrum transmitted through the target. Electrons with energies up to 200 MeV, as well as Betatron x-rays with critical energies around 20 keV, were measured. OSIRIS 2D PIC simulations confirm that the electrons gain energy both from the plasma wave and from their interaction with the laser field.

  13. Observation of a Kelvin-Helmholtz Instability in a High-Energy-Density Plasma on the Omega Laser

    SciTech Connect

    Harding, E C; Hansen, J F; Hurricane, O A; Drake, R P; Robey, H F; Kuranz, C C; Remington, B A; Bono, M J; Grosskopf, M J; Gillespie, R S

    2009-02-12

    A laser initiated experiment is described in which an unstable plasma shear layer is produced by driving a blast wave along a plastic surface with sinusoidal perturbations. In response to the vorticity deposited and the shear flow established by the blast wave, the interface rolls up into large vortices characteristic of the Kelvin-Helmholtz (KH) instability. The experiment used x ray radiography to capture the first well-resolved images of KH vortices in a high-energy-density plasma, and possibly the first images of transonic shocks generated by large-scale structures in a shear layer. The physical processes governing the evolution of a stratified fluid flow with a large velocity gradient (i.e., a shear flow) are of fundamental interest to a wide range of research areas including combustion, inertial confinement fusion (ICF), stellar supernovae, and geophysical fluid dynamics. Traditional experiments have used inclined tanks of fluid to initiate a flow, generally at low Reynolds numbers, or wind tunnels that combine two parallel gas flows at the end of a thin wedge, known as a splitter plate. The splitter plate experiments have explored flows with maximum shear velocities on the order of 10{sup 3} m/s and Reynolds numbers up to 10{sup 6}. Here we report the creation of a novel type of shear flow, achieved by confining a laser driven blast wave in a millimeter-sized shock tube, which produced shear velocities on the order of 10{sup 4} m/s and Reynolds numbers of 10{sup 6} in a plasma. This system enabled the first apparent observation of transonic shocklets, which are small, localized shocks believed to develop in response to a local supersonic flow occurring over a growing perturbation. These shocklets have been predicted previously in simulations, but have never to our knowledge been observed. These experiments are also the first to observe the growth of perturbations by the Kelvin-Helmholtz (KH) instability under high-energy-density (HED) conditions. In all

  14. Closed cycle MHD generator with nonuniform gas-plasma flow driving recombinated plasma clots formed by high-energy electron beams

    SciTech Connect

    Danilov, V.V.; Laptev, S.S.; Slavin, V.S.

    1996-12-31

    A new concept of a closed cycle MHD generator without alkali seed has been suggested. The essence of it is the use of the high-energy electron beams technology for a nonuniform gas-plasma flow in MHD channel creation. At the inlet of MHD channel in supersonic flow of noble gas (He) the plasma clots with a density about 10{sup 15} cm{sup {minus}3} are formed by pulsed intense electron beams with energy about 100 keV. Gas flow drives these clots in a cross magnetic field along the MHD channel which has electrodes connected with a load by Faraday`s scheme. Because the nonuniform gas-plasma flow has not the conductivity in the Hall`s EMF direction a Faraday`s current can flow only through the narrow plasma layers. The energy dissipation and Joule`s heating in MHD channel support the nonequilibrium conductivity in these plasma layers. a gas flow pushes current layers and produces electric power at the expense of enthalpy extraction. The key element is a question of plasma layers stability in MHD channel. The most dangerous instability is the overheating instability. it is shown that taking into account the phenomenon of frozen conductivity for recombinated plasma which appears for noble gas at T{sub e} > 4,000 K the regime with {partial_derivative}{sigma}/{partial_derivative}T{sub e} < 0 can be realized. Due to the fulfillment of this condition the overheating instability is effectively suppressed. The numerical simulation has shown that a supersonic gas flow, containing about 4 current layers in MHD channel simultaneously, is braked without shock waves creation. Current layers provide no less than 30% enthalpy extraction and about 80% isentropic efficiency.

  15. Nonlinear dynamics of circularly polarized laser pulse propagating in a magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons distributions

    SciTech Connect

    Etemadpour, R.; Dorranian, D.; Sepehri Javan, N.

    2016-05-15

    The nonlinear dynamics of a circularly polarized laser pulse propagating in the magnetized plasmas whose constituents are superthermal ions and mixed nonthermal high-energy tail electrons is studied theoretically. A nonlinear equation which describes the dynamics of the slowly varying amplitude is obtained using a relativistic two-fluid model. Based on this nonlinear equation and taking into account some nonlinear phenomena such as modulational instability, self-focusing and soliton formation are investigated. Effect of the magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons on these phenomena is considered. It is shown that the nonthermality and superthermality of particles can substantially change the nonlinearity of medium.

  16. Noise effects, emittance control, and luminosity issues in laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Cheshkov, Sergey Valeriev

    2001-09-01

    To reach the new high energy frontiers (higher than a TeV center of mass energy) new acceleration methods seem to be needed. Plasma based wakefield accelerator is one possible candidate which can provide an ultra high gradient acceleration and thus make the total acceleration distance reasonable. However, the final energy is not the only requirement. The accelerator should maintain an excellent beam quality to meet the luminosity requirements at the Inter action Point (IP). One of the most important figures of merit which describe the quality of the beam is its emittance. We study the particle dynamics in laser pulse-driven wakefields over multi-stages in a several TeV range center of mass energy e+e - collider. The approach is based on a map of phase space dynamics over a stage of wakefield acceleration induced by a laser pulse (or electron beam). The entire system of the collider is generated with a product of multiple maps of wakefields, drifts, and magnets, etc. This systems map may include offsets of various elements of the accelerator, representing noise and errors arising from the operation of such a complex device. We find that an unmitigated strong focusing of the wakefield coupled with the alignment errors of the position (or laser beam aiming) of each Wakefield stage and the unavoidable dispersion in individual particle betatron frequencies leads to a phase space mixing and causes a transverse emittance degradation. The rate of the emittance increase in the limit of constant energy is proportional to the number of stages, the energy of the particles, the betatron frequency, the square of the misalignment amplitude, and the square of the betatron phase shift over a single stage. The accelerator with a weakened focusing force in a channel can, therefore, largely suppress the emittance degradation. To improve the emittance we introduce several methods: a mitigated wakefield focusing by working with a plasma channel, an approximately synchronous acceleration

  17. The Ion Wakefield Inside a Glass Box

    NASA Astrophysics Data System (ADS)

    Chen, Mudi; Matthews, Lorin; Hyde, Truell

    2016-10-01

    The formation of an ion wakefield downstream of dust particles in a complex plasma sheath has long been understood to have strong implications on their structure, stability and dynamics . The presence of the ion wake introduces interesting phenomena such as charge reduction on downstream particles and asymmetric interaction forces between upstream and downstream particles. Many of the self-ordered dust particle structures observed in complex plasma experiments are the result of the combination of the ion-wakefield and the external confinement; unfortunately, few experimental measurements isolating the effect of the wakefield have been conducted. In this experiment, 1-D dust particle structures (i.e., vertically aligned particle chains) are formed in a GEC RF reference cell within a glass box sitting on the powered lower electrode. A diode pumped, solid-state laser is used to perturb individual particles within the particle chain, allowing a map of the ion wakefield inside the glass box to be generated. The implications of these results will be discussed. NSF / DOE funding is gratefully acknowledged - PHY1414523 & PHY1262031.

  18. Emittance control in Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Cheshkov, S.; Tajima, T.; Chiu, C.; Breitling, F.

    2001-05-01

    In this paper we summarize our recent effort and results in theoretical study of the emittance issues of multistaged Laser Wakefield Accelerator (LWFA) in TeV energy range. In such an energy regime the luminosity and therefore the emittance requirements become very stringent and tantamount to the success or failure of such an accelerator. The system of such a machine is very sensitive to jitters due to misalignment between the beam and the wakefield. In particular, the effect of jitters in the presence of a strong focusing wakefield and initial longitudinal phase space spread of the beam leads to severe transverse emittance degradation of the beam. To improve the emittance we introduce several methods: a mitigated wakefield focusing by working with a plasma channel, an approximately synchronous acceleration in a superunit setup, the "horn" model based on exactly synchronous acceleration achieved through plasma density variation and lastly an algorithm based on minimization of the final beam emittance to actively control the stage displacement of such an accelerator.

  19. Argonne Wakefield Accelerator Update `92

    SciTech Connect

    Rosing, M.; Balka, L.; Chojnacki, E.; Gai, W.; Ho, C.; Konecny, R.; Power, J.; Schoessow, P.; Simpson, J.

    1992-09-01

    The Argonne Wakefield Accelerator (AWA) is an experiment designed to test various ideas related to wakefield technology. Construction is now underway for a 100 nC electron beam in December of 1992. This report updates this progress.

  20. Argonne Wakefield Accelerator Update '92

    SciTech Connect

    Rosing, M.; Balka, L.; Chojnacki, E.; Gai, W.; Ho, C.; Konecny, R.; Power, J.; Schoessow, P.; Simpson, J.

    1992-01-01

    The Argonne Wakefield Accelerator (AWA) is an experiment designed to test various ideas related to wakefield technology. Construction is now underway for a 100 nC electron beam in December of 1992. This report updates this progress.

  1. Efficient production of high-energy nonthermal particles during magnetic reconnection in a magnetically dominated ion-electron plasma

    DOE PAGES

    Guo, Fan; Li, Xiaocan; Li, Hui; ...

    2016-02-03

    Magnetic reconnection is a leading mechanism for dissipating magnetic energy and accelerating nonthermal particles in Poynting-flux-dominated flows. We investigate nonthermal particle acceleration during magnetic reconnection in a magnetically dominated ion–electron plasma using fully kinetic simulations. For an ion–electron plasma with a total magnetization ofmore » $${\\sigma }_{0}={B}^{2}/(4\\pi n({m}_{i}+{m}_{e}){c}^{2})$$, the magnetization for each species is $${\\sigma }_{i}\\sim {\\sigma }_{0}$$ and $${\\sigma }_{e}\\sim ({m}_{i}/{m}_{e}){\\sigma }_{0}$$, respectively. We have studied the magnetically dominated regime by varying σe = 103–105 with initial ion and electron temperatures $${T}_{i}={T}_{e}=5-20{m}_{e}{c}^{2}$$ and mass ratio $${m}_{i}/{m}_{e}=1-1836$$. Our results demonstrate that reconnection quickly establishes power-law energy distributions for both electrons and ions within several (2–3) light-crossing times. For the cases with periodic boundary conditions, the power-law index is $$1\\lt s\\lt 2$$ for both electrons and ions. The hard spectra limit the power-law energies for electrons and ions to be $${\\gamma }_{{be}}\\sim {\\sigma }_{e}$$ and $${\\gamma }_{{bi}}\\sim {\\sigma }_{i}$$, respectively. The main acceleration mechanism is a Fermi-like acceleration through the drift motions of charged particles. When comparing the spectra for electrons and ions in momentum space, the spectral indices sp are identical as predicted in Fermi acceleration. We also find that the bulk flow can carry a significant amount of energy during the simulations. Finally, we discuss the implication of this study in the context of Poynting-flux dominated jets and pulsar winds, especially the applications for explaining nonthermal high-energy emissions.« less

  2. Efficient production of high-energy nonthermal particles during magnetic reconnection in a magnetically dominated ion-electron plasma

    SciTech Connect

    Guo, Fan; Li, Xiaocan; Li, Hui; Daughton, William; Zhang, Bing; Lloyd-Ronning, Nicole; Liu, Yi-Hsin; Zhang, Haocheng; Deng, Wei

    2016-02-03

    Magnetic reconnection is a leading mechanism for dissipating magnetic energy and accelerating nonthermal particles in Poynting-flux-dominated flows. We investigate nonthermal particle acceleration during magnetic reconnection in a magnetically dominated ion–electron plasma using fully kinetic simulations. For an ion–electron plasma with a total magnetization of ${\\sigma }_{0}={B}^{2}/(4\\pi n({m}_{i}+{m}_{e}){c}^{2})$, the magnetization for each species is ${\\sigma }_{i}\\sim {\\sigma }_{0}$ and ${\\sigma }_{e}\\sim ({m}_{i}/{m}_{e}){\\sigma }_{0}$, respectively. We have studied the magnetically dominated regime by varying σe = 103–105 with initial ion and electron temperatures ${T}_{i}={T}_{e}=5-20{m}_{e}{c}^{2}$ and mass ratio ${m}_{i}/{m}_{e}=1-1836$. Our results demonstrate that reconnection quickly establishes power-law energy distributions for both electrons and ions within several (2–3) light-crossing times. For the cases with periodic boundary conditions, the power-law index is $1\\lt s\\lt 2$ for both electrons and ions. The hard spectra limit the power-law energies for electrons and ions to be ${\\gamma }_{{be}}\\sim {\\sigma }_{e}$ and ${\\gamma }_{{bi}}\\sim {\\sigma }_{i}$, respectively. The main acceleration mechanism is a Fermi-like acceleration through the drift motions of charged particles. When comparing the spectra for electrons and ions in momentum space, the spectral indices sp are identical as predicted in Fermi acceleration. We also find that the bulk flow can carry a significant amount of energy during the simulations. Finally, we discuss the implication of this study in the context of Poynting-flux dominated jets and pulsar winds, especially the applications for explaining nonthermal high-energy emissions.

  3. Efficient Production of High-energy Nonthermal Particles during Magnetic Reconnection in a Magnetically Dominated Ion-Electron Plasma

    NASA Astrophysics Data System (ADS)

    Guo, Fan; Li, Xiaocan; Li, Hui; Daughton, William; Zhang, Bing; Lloyd-Ronning, Nicole; Liu, Yi-Hsin; Zhang, Haocheng; Deng, Wei

    2016-02-01

    Magnetic reconnection is a leading mechanism for dissipating magnetic energy and accelerating nonthermal particles in Poynting-flux-dominated flows. In this Letter, we investigate nonthermal particle acceleration during magnetic reconnection in a magnetically dominated ion-electron plasma using fully kinetic simulations. For an ion-electron plasma with a total magnetization of {σ }0={B}2/(4π n({m}i+{m}e){c}2), the magnetization for each species is {σ }i˜ {σ }0 and {σ }e˜ ({m}i/{m}e){σ }0, respectively. We have studied the magnetically dominated regime by varying σe = 103-105 with initial ion and electron temperatures {T}i={T}e=5-20{m}e{c}2 and mass ratio {m}i/{m}e=1-1836. The results demonstrate that reconnection quickly establishes power-law energy distributions for both electrons and ions within several (2-3) light-crossing times. For the cases with periodic boundary conditions, the power-law index is 1\\lt s\\lt 2 for both electrons and ions. The hard spectra limit the power-law energies for electrons and ions to be {γ }{be}˜ {σ }e and {γ }{bi}˜ {σ }i, respectively. The main acceleration mechanism is a Fermi-like acceleration through the drift motions of charged particles. When comparing the spectra for electrons and ions in momentum space, the spectral indices sp are identical as predicted in Fermi acceleration. We also find that the bulk flow can carry a significant amount of energy during the simulations. We discuss the implication of this study in the context of Poynting-flux dominated jets and pulsar winds, especially the applications for explaining nonthermal high-energy emissions.

  4. A multi-dimensional Vlasov-Fokker-Planck code for arbitrarily anisotropic high-energy-density plasmas

    SciTech Connect

    Tzoufras, M.; Tableman, A.; Tsung, F. S.; Mori, W. B.; Bell, A. R.

    2013-05-15

    To study the kinetic physics of High-Energy-Density Laboratory Plasmas, we have developed the parallel relativistic 2D3P Vlasov-Fokker-Planck code Oshun. The numerical scheme uses a Cartesian mesh in configuration-space and incorporates a spherical harmonic expansion of the electron distribution function in momentum-space. The expansion is truncated such that the necessary angular resolution of the distribution function is retained for a given problem. Finite collisionality causes rapid decay of the high-order harmonics, thereby providing a natural truncation mechanism for the expansion. The code has both fully explicit and implicit field-solvers and employs a linearized Fokker-Planck collision operator. Oshun has been benchmarked against well-known problems, in the highly kinetic limit to model collisionless relativistic instabilities, and in the hydrodynamic limit to recover transport coefficients. The performance of the code, its applicability, and its limitations are discussed in the context of simple problems with relevance to inertial fusion energy.

  5. Generation of laser pulse trains for tests of multi-pulse laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Shalloo, R. J.; Corner, L.; Arran, C.; Cowley, J.; Cheung, G.; Thornton, C.; Walczak, R.; Hooker, S. M.

    2016-09-01

    In multi-pulse laser wakefield acceleration (MP-LWFA) a plasma wave is driven by a train of low-energy laser pulses separated by the plasma period, an approach which offers a route to driving plasma accelerators with high efficiency and at high pulse repetition rates using emerging technologies such as fibre and thin-disk lasers. Whilst these laser technologies are in development, proof-of-principle tests of MP-LWFA require a pulse train to be generated from a single, high-energy ultrafast pulse. Here we demonstrate the generation of trains of up to 7 pulses with pulse separations in the range 150-170 fs from single 40 fs pulses produced by a Ti:sapphire laser.

  6. Chirp Mitigation of Plasma-Accelerated Beams by a Modulated Plasma Density.

    PubMed

    Brinkmann, R; Delbos, N; Dornmair, I; Kirchen, M; Assmann, R; Behrens, C; Floettmann, K; Grebenyuk, J; Gross, M; Jalas, S; Mehrling, T; Martinez de la Ossa, A; Osterhoff, J; Schmidt, B; Wacker, V; Maier, A R

    2017-05-26

    Plasma-based accelerators offer the possibility to drive future compact light sources and high-energy physics applications. Achieving good beam quality, especially a small beam energy spread, is still one of the major challenges. Here, we propose to use a periodically modulated plasma density to shape the longitudinal fields acting on an electron bunch in the linear wakefield regime. With simulations, we demonstrate an on-average flat accelerating field that maintains a small beam energy spread.

  7. Donut wakefields generated by intense laser pulses with orbital angular momentum

    SciTech Connect

    Mendonça, J. T.; Vieira, J.

    2014-03-15

    We study the wakefields produced in a plasma by intense laser pulses carrying a finite amount of orbital angular momentum. We show that these wakefields have new donut-like shapes, different from those usually considered in the literature, and could be used to accelerate hollow electron beams. Wakefields with a more general angular structure were also considered. The analytical solutions are corroborated by relativistic particle-in-cell simulations using OSIRIS.

  8. Transverse wakefield of waveguide damped structures and beam dynamics

    SciTech Connect

    Lin, Xintian

    1995-08-01

    In the design of new high energy particle colliders with higher luminosity one is naturally led to consider multi-bunch operation. However, the passage of a leading bunch through an accelerator cavity Generates a wakefield that may have a deleterious effect on the motion of the subsequent bunches. Therefore, the suppression of the wakefield is an essential requirement for beam stability. One solution to this problem, which has been studied extensively is to drain the wakefield energy out of the cavity by means of waveguides coupled with the cavity and fed into matched terminations. Waveguide dimensions are chosen to yield a cutoff frequency well above the frequency of the accelerating mode so that the latter is undamped. This paper presents a thorough investigation of the wakefield for this configuration. The effectiveness of waveguide damping has typically been assessed by evaluating the resultant Qext of higher order cavity modes to determine their exponential damping rate. We have developed an efficient method to calculate Qext of the damped modes from popular computer simulation codes such as MAFIA. This method has been successively applied to the B-factory RF cavity We have also found another type of wakefield, associated with waveguide cut-off, which decays as t-3/2 rather than in the well-known exponentially damped manner. Accordingly, we called it the persistent Wakefield. A similar phenomenon with essentially the same physical origin but occurring in the decay of unstable quantum states, has received extensive study. Then we have developed various methods of calculating this persistent wakefield, including mode matching and computer simulation. Based on a circuit model we estimate the limit that waveguide damping can reach to reduce the wakefield.

  9. High Energy Density Plasmas (HEDP) for studies of basic nuclear science relevant to Stellar and Big Bang Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Frenje, Johan

    2014-06-01

    Thermonuclear reaction rates and nuclear processes have been explored traditionally by means of conventional accelerator experiments, which are difficult to execute at conditions relevant to stellar nucleosynthesis. Thus, nuclear reactions at stellar energies are often studied through extrapolations from higher-energy data or in low-background underground experiments. Even when measurements are possible using accelerators at relevant energies, thermonuclear reaction rates in stars are inherently different from those in accelerator experiments. The fusing nuclei are surrounded by bound electrons in accelerator experiments, whereas electrons occupy mainly continuum states in a stellar environment. Nuclear astrophysics research will therefore benefit from an enlarged toolkit for studies of nuclear reactions. In this presentation, we report on the first use of High Energy Density Plasmas for studies of nuclear reactions relevant to basic nuclear science, stellar and Big Bang nucleosynthesis. These experiments were carried out at the OMEGA laser facility at University of Rochester and the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, in which spherical capsules were irradiated with powerful lasers to compress and heat the fuel to high enough temperatures and densities for nuclear reactions to occur. Four experiments will be highlighted in this presentation. In the first experiment, the differential cross section for the elastic neutron-triton (n-T) scattering at 14.1 MeV was measured with significantly higher accuracy than achieved in accelerator experiments. In the second experiment, the T(t,2n)4He reaction, a mirror reaction to the 3He(3He,2p)4He reaction that plays an important role in the proton-proton chain that transforms hydrogen into ordinary 4He in stars like our Sun, was studied at energies in the range 15-40 keV. In the third experiment, the 3He+3He solar fusion reaction was studied directly, and in the fourth experiment, we

  10. Ultra-high energy probes of classicalization

    SciTech Connect

    Dvali, Gia; Gomez, Cesar E-mail: cesar.gomez@uam.es

    2012-07-01

    Classicalizing theories are characterized by a rapid growth of the scattering cross section. This growth converts these sort of theories in interesting probes for ultra-high energy experiments even at relatively low luminosity, such as cosmic rays or Plasma Wakefield accelerators. The microscopic reason behind this growth is the production of N-particle states, classicalons, that represent self-sustained lumps of soft Bosons. For spin-2 theories this is the quantum portrait of what in the classical limit are known as black holes. We emphasize the importance of this quantum picture which liberates us from the artifacts of the classical geometric limit and allows to scan a much wider landscape of experimentally-interesting quantum theories. We identify a phenomenologically-viable class of spin-2 theories for which the growth of classicalon production cross section can be as efficient as to compete with QCD cross section already at 100TeV energy, signaling production of quantum black holes with graviton occupation number N ∼ 10{sup 4}.

  11. Basic concepts in plasma accelerators.

    PubMed

    Bingham, Robert

    2006-03-15

    In this article, we present the underlying physics and the present status of high gradient and high-energy plasma accelerators. With the development of compact short pulse high-brightness lasers and electron and positron beams, new areas of studies for laser/particle beam-matter interactions is opening up. A number of methods are being pursued vigorously to achieve ultra-high-acceleration gradients. These include the plasma beat wave accelerator (PBWA) mechanism which uses conventional long pulse ( approximately 100 ps) modest intensity lasers (I approximately 10(14)-10(16) W cm(-2)), the laser wakefield accelerator (LWFA) which uses the new breed of compact high-brightness lasers (<1 ps) and intensities >10(18) W cm(-2), self-modulated laser wakefield accelerator (SMLWFA) concept which combines elements of stimulated Raman forward scattering (SRFS) and electron acceleration by nonlinear plasma waves excited by relativistic electron and positron bunches the plasma wakefield accelerator. In the ultra-high intensity regime, laser/particle beam-plasma interactions are highly nonlinear and relativistic, leading to new phenomenon such as the plasma wakefield excitation for particle acceleration, relativistic self-focusing and guiding of laser beams, high-harmonic generation, acceleration of electrons, positrons, protons and photons. Fields greater than 1 GV cm(-1) have been generated with monoenergetic particle beams accelerated to about 100 MeV in millimetre distances recorded. Plasma wakefields driven by both electron and positron beams at the Stanford linear accelerator centre (SLAC) facility have accelerated the tail of the beams.

  12. Group velocity dispersion and relativistic effects on the wakefield induced by chirped laser pulse in parabolic plasma channel

    SciTech Connect

    Sohbatzadeh, F.; Akou, H.

    2013-04-15

    The excitation of wake field plasma waves by a short laser pulse propagating through a parabolic plasma channel is studied. The laser pulse is assumed to be initially chirped. In this regard, the effects of initial and induced chirp on the plasma wake field as well as the laser pulse parameters are investigated. The group velocity dispersion and nonlinear relativistic effects were taken into account to evaluate the excited wake field in two dimension using source dependent expansion method. Positive, negative, and un-chirped laser pulses were employed in numerical code to evaluate the effectiveness of the initial chirp on 2-D wake field excitation. Numerical results showed that for laser irradiances exceeding 10{sup 18}W/cm{sup 2}, an intense laser pulse with initial positive chirp generates larger wake field compared to negatively and un-chirped pulses.

  13. Undulator radiation driven by laser-wakefield accelerator electron beams

    NASA Astrophysics Data System (ADS)

    Wiggins, S. M.; Anania, M. P.; Welsh, G. H.; Brunetti, E.; Cipiccia, S.; Grant, P. A.; Reboredo, D.; Manahan, G.; Grant, D. W.; Jaroszynski, D. A.

    2015-05-01

    The Advanced Laser-Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme is developing laserplasma accelerators for the production of ultra-short electron bunches with subsequent generation of coherent, bright, short-wavelength radiation pulses. The new Scottish Centre for the Application of Plasma-based Accelerators (SCAPA) will develop a wide range of applications utilising such light sources. Electron bunches can be propagated through a magnetic undulator with the aim of generating fully coherent free-electron laser (FEL) radiation in the ultra-violet and Xrays spectral ranges. Demonstration experiments producing spontaneous undulator radiation have been conducted at visible and extreme ultra-violet wavelengths but it is an on-going challenge to generate and maintain electron bunches of sufficient quality in order to stimulate FEL behaviour. In the ALPHA-X beam line experiments, a Ti:sapphire femtosecond laser system with peak power 20 TW has been used to generate electron bunches of energy 80-150 MeV in a 2 mm gas jet laser-plasma wakefield accelerator and these bunches have been transported through a 100 period planar undulator. High peak brilliance, narrow band spontaneous radiation pulses in the vacuum ultra-violet wavelength range have been generated. Analysis is provided with respect to the magnetic quadrupole beam transport system and subsequent effect on beam emittance and duration. Requirements for coherent spontaneous emission and FEL operation are presented.

  14. Laser Wakefield Accelerator Injection Control and X-Ray Sources

    NASA Astrophysics Data System (ADS)

    Geddes, C. G. R.; Cormier-Michel, E.; Esarey, E. H.; Le Corre, T.; Lin, C.; Matlis, N. H.; Nakamura, K.; Plateau, G. R.; Schroeder, C. B.; van Mourik, R. A.; Leemans, W. P.; Thorn, D. B.; Bruhwiler, D. L.; Cowan, B.; Paul, K.; Cary, J. R.

    2009-11-01

    Reduced beam energy spread, fluctuation, and emittance are important to applications of compact, high gradient laser-plasma wakefield accelerators including Thomson gamma sources and high energy colliders. Experiments and simulations will be presented on control of injection to improve beam quality compared to use of self-injection by the wake. Trapping of electrons in the wake can be controlled using the beat between multiple laser pulses to via kick electrons in momentum and phase into the wake accelerating phase. Laser and gas target shaping and control are used to further control the accelerator structure. Simulations demonstrate the tuning of accelerator structure required to accelerate such bunches to high energies while retaining high bunch quality. Electron beam source size and position are measured using betatron X-ray emission produced when electrons oscillate in the focusing field of the wake to improve understanding of beam emittance and stability, while also producing a broadband, synchronized fs source of keV X-rays. Supported by US DOE NA-22 and HEP including DE-AC02-05CH11231, SciDAC, and SBIR.

  15. Formation of electrostatic structures by wakefield acceleration in ultrarelativistic plasma flows: Electron acceleration to cosmic ray energies

    SciTech Connect

    Dieckmann, M.E.; Shukla, P.K.; Eliasson, B.

    2006-06-15

    The ever increasing performance of supercomputers is now enabling kinetic simulations of extreme astrophysical and laser produced plasmas. Three-dimensional particle-in-cell (PIC) simulations of relativistic shocks have revealed highly filamented spatial structures and their ability to accelerate particles to ultrarelativistic speeds. However, these PIC simulations have not yet revealed mechanisms that could produce particles with tera-electron volt energies and beyond. In this work, PIC simulations in one dimension (1D) of the foreshock region of an internal shock in a gamma ray burst are performed to address this issue. The large spatiotemporal range accessible to a 1D simulation enables the self-consistent evolution of proton phase space structures that can accelerate particles to giga-electron volt energies in the jet frame of reference, and to tens of tera-electron volt in the Earth's frame of reference. One potential source of ultrahigh energy cosmic rays may thus be the thermalization of relativistically moving plasma.

  16. Photon acceleration in laser wakefield accelerators

    SciTech Connect

    Trines, R. M. G. M.

    2007-07-11

    If the index of a refraction of a dispersive medium, such as a plasma, changes in time, it can be used to change the frequency of light propagating through the medium. This effect is called photon acceleration. It has been predicted in both theory and simulations, and also been demonstrated experimentally for the case of moving ionization fronts in gases (the so-called ionization blueshift) as well as for laser-driven wakefields.Here, we present studies of photon acceleration in laser-driven plasma wakefields. The unique spectral characteristics of this process will be discussed, to distinguish it from e.g. photon acceleration by ionization fronts, frequency domain interferometry or self-phase modulation. The dynamics of the photons in laser-wakefield interaction are studied through both regular particle-in-cell and wave-kinetic simulations. The latter approach provides a powerful, versatile, and easy-to-use method to track the propagation of individual spectral components, providing new insight into the physics of laser-plasma interaction. Theory, simulations and experimental results will be brought together to provide a full understanding of the dynamics of a laser pulse in its own wakefield.Even though the wave-kinetic approach mentioned above has mainly been developed for the description of laser-plasma interaction, it can be applied to a much wider range of fast wave-slow wave interaction processes: Langmuir waves-ion acoustic waves, drift waves-zonal flow, Rossby waves-zonal flow, or even photons-gravitational waves. Several recent results in these areas will be shown, often with surprising results.

  17. Laser wakefield accelerator based light sources: potential applications and requirements

    SciTech Connect

    Albert, F.; Thomas, A. G.; Mangles, S. P.D.; Banerjee, S.; Corde, S.; Flacco, A.; Litos, M.; Neely, D.; Viera, J.; Najmudin, Z.; Bingham, R.; Joshi, C.; Katsouleas, T.

    2015-01-15

    In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.

  18. EXPERIMENTS ON LASER AND E-BEAM TRANSPORT AND INTERACTION IN A PLASMA CHANNEL.

    SciTech Connect

    POGORELSKY,I.V.; PAVLISHIN,I.V.; BEN-ZVI,I.; ET AL.

    2004-09-15

    An ablative capillary discharge is installed into a linac beamline and serves as a plasma source for generating and characterizing wakefields. Simultaneously, the electron beam is used as a tool for plasma diagnostics. A high-energy picosecond CO{sub 2} laser channeled within the same capillary strongly affects a counterpropagating electron beam. These observations, supported with simulations, suggest the possibility of manipulating relativistic electron beams by steep plasma channels ponderomotively produced by a laser.

  19. Intense γ ray generated by refocusing laser pulse on wakefield accelerated electrons

    NASA Astrophysics Data System (ADS)

    Feng, Jie; Wang, Jinguang; Li, Yifei; Zhu, Changqing; Li, Minghua; He, Yuhang; Li, Dazhang; Wang, Weimin; Chen, Liming

    2017-09-01

    Ultrafast x/γ ray emission from the combination of laser wake-field acceleration and plasma mirror has been investigated as a promising Thomson scattering source. However, the photon energy and yield of radiation are limited to the intensity of reflected laser pulses. We use the 2D particle in cell simulation to demonstrate that a 75TW driven laser pulse can be refocused on the accelerated electron bunches through a hemispherical plasma mirror with a small f number of 0.25. The energetic electrons with the maximum energy about 350 MeV collide with the reflected laser pulse of a0 = 3.82 at the focal spot, producing high order multi-photon Thomson scattering, and resulting in the scattering spectrum which extends up to 21.2 MeV. Such a high energy γ ray source could be applied to photonuclear reaction and materials science.

  20. Variations of High-Energy Ions during Fast Plasma Flows and Dipolarization in the Plasma Sheet: Comparison Among Different Ion Species

    NASA Astrophysics Data System (ADS)

    Ohtani, S.; Nose, M.; Miyashita, Y.; Lui, A.

    2014-12-01

    We investigate the responses of different ion species (H+, He+, He++, and O+) to fast plasma flows and local dipolarization in the plasma sheet in terms of energy density. We use energetic (9-210 keV) ion composition measurements made by the Geotail satellite at r = 10~31 RE. The results are summarized as follows: (1) whereas the O+-to-H+ ratio decreases with earthward flow velocity, it increases with tailward flow velocity with Vx dependence steeper for perpendicular flows than for parallel flows; (2) for fast earthward flows, the energy density of each ion species increases without any clear preference for heavy ions; (3) for fast tailward flows the ion energy density increases initially, then it decreases to below pre-flow levels except for O+; (4) the O+-to-H+ ratio does not increase through local dipolarization irrespective of dipolarization amplitude, background BZ, X distance, and VX; (5) in general, the H+ and He++ ions behave similarly. Result (1) can be attributed to radial transport along with the earthward increase of the background O+-to-H+ ratio. Results (2) and (4) indicate that ion energization associated with local dipolarization is not mass-dependent possibly because in the energy range of our interest the ions are not magnetized irrespective of species. In the tailward outflow region of reconnection, where the plasma sheet becomes thinner, the H+ ions escape along the field line more easily than the O+ ions, which possibly explains result (3). Result (5) suggests that the solar wind is the primary source of the high-energy H+ ions.

  1. A 1 GeV Laser Wakefield Accelerator: Experimental Progress at the l'OASIS Facility of LBNL

    NASA Astrophysics Data System (ADS)

    Leemans, W. P.; Geddes, C. G. R.; Toth, C. S.; van Tilborg, J.; Nagler, B.; Michel, P.; Nakamura, K.; Esarey, E.; Schroeder, C. B.; Gonsalves, A.; Spence, D. J.; Hooker, S. M.; Filip, C.; Cowan, T.

    2004-11-01

    Experimental progress towards a 1 GeV laser-driven plasma-based accelerator will be discussed. The design of the 1 GeV accelerator module consists of two components: (1) an all-optical electron injector and (2) a plasma channel for laser guiding and electron acceleration to high energy via the laser wakefield acceleration (LWFA) mechanism. Experimental results on the injector development include the demonstration of laser guiding at relativistic intensities in preformed plasmas and production of quasi-monochromatic electron beams with energy around 100 MeV. Progress on guiding 100 TW laser pulses in capillary-discharge-based plasma channels will be discussed and integration of these channels with the all-optical injector will be reported.

  2. Generating high-brightness electron beams via ionization injection by transverse colliding lasers in a plasma-wakefield accelerator.

    PubMed

    Li, F; Hua, J F; Xu, X L; Zhang, C J; Yan, L X; Du, Y C; Huang, W H; Chen, H B; Tang, C X; Lu, W; Joshi, C; Mori, W B; Gu, Y Q

    2013-07-05

    The production of ultrabright electron bunches using ionization injection triggered by two transversely colliding laser pulses inside a beam-driven plasma wake is examined via three-dimensional particle-in-cell simulations. The relatively low intensity lasers are polarized along the wake axis and overlap with the wake for a very short time. The result is that the residual momentum of the ionized electrons in the transverse plane of the wake is reduced, and the injection is localized along the propagation axis of the wake. This minimizes both the initial thermal emittance and the emittance growth due to transverse phase mixing. Simulations show that ultrashort (~8 fs) high-current (0.4 kA) electron bunches with a normalized emittance of 8.5 and 6 nm in the two planes, respectively, and a brightness of 1.7×10(19) A rad(-2) m(-2) can be obtained for realistic parameters.

  3. Generation of overdense and high-energy electron-positron-pair plasmas by irradiation of a thin foil with two ultraintense lasers.

    PubMed

    Chang, H X; Qiao, B; Xu, Z; Xu, X R; Zhou, C T; Yan, X Q; Wu, S Z; Borghesi, M; Zepf, M; He, X T

    2015-11-01

    A scheme for enhanced quantum electrodynamics (QED) production of electron-positron-pair plasmas is proposed that uses two ultraintense lasers irradiating a thin solid foil from opposite sides. In the scheme, under a proper matching condition, in addition to the skin-depth emission of γ-ray photons and Breit-Wheeler creation of pairs on each side of the foil, a large number of high-energy electrons and photons from one side can propagate through it and interact with the laser on the other side, leading to much enhanced γ-ray emission and pair production. More importantly, the created pairs can be collected later and confined to the center by opposite laser radiation pressures when the foil becomes transparent, resulting in the formation of unprecedentedly overdense and high-energy pair plasmas. Two-dimensional QED particle-in-cell simulations show that electron-positron-pair plasmas with overcritical density 10(22) cm(-3) and a high energy of 100s of MeV are obtained with 10 PW lasers at intensities 10(23) W/cm(2), which are of key significance for laboratory astrophysics studies.

  4. Relativistic harmonics for turbulent wakefield diagnostics

    NASA Astrophysics Data System (ADS)

    Kuramitsu, Yasuhiro; Chen, Shih-Hung

    2017-06-01

    The propagation properties of relativistic harmonics excited in a plasma with an intense laser pulse is investigated theoretically and numerically. Focusing on the frequency separation, a cold electron fluid model in two spatial dimension is discussed to obtain the harmonic amplitude. The theoretical predictions are verified by performing particle-in-cell simulations in two spatial dimensions. When the laser amplitude is large, the strong ponderomotive force expels the electrons, creating a large amplitude density structures associated with the wakefield. The harmonics propagate obliquely with respect to the laser propagation direction, which is well represented by the structure of the high density layer resulting from the transverse poderomotive force. We also discuss a possible experimental setup to observe the density structures relevant to wakefield.

  5. Argonne`s new Wakefield Test Facility

    SciTech Connect

    Simpson, J.D.

    1992-07-20

    The first phase of a high current, short bunch length electron beam research facility, the AWA, is near completion at Argonne. At the heart of the facility is a photocathode based electron gun and accelerating sections designed to deliver 20 MeV pulses with up to 100 nC per pulse and with pulse lengths of approximately 15 ps (fw). Using a technique similar to that originated at Argonne`s AATF facility, a separate weak probe pulse can be generated and used to diagnose wake effects produced by the intense pulses. Initial planned experiments include studies of plasma wakefields and dielectric wakefield devices, and expect to demonstrate large, useful accelerating gradients (> 100 MeV/m). Later phases of the facility will increase the drive bunch energy to more than 100 MeV to enable acceleration experiments up to the GeV range. Specifications, design details, and commissioning progress are presented.

  6. Laser Wakefield diagnostic using holographic longitudinal interferometry

    SciTech Connect

    Volfbeyn, P.; Esarey, E.; Leemans, W.P.

    1999-03-26

    We propose a diagnostic technique for wakefield measurement in plasma channels. A new technique for plasma channel creation, the Ignitor Heater scheme was proposed and experimentally tested in hydrogen and nitrogen previously. It makes use of two laser pulses. The Ignitor, an ultrashort (sub 100 fs) laser pulse, is brought to a line focus using a cylindrical lens to ionize the gas. The Heater pulse (160 ps long) is used to heat the existing spark via in-verse Bremsstrahlung. The hydrodynamic shock expansion creates a partially evacuated plasma channel with a density minimum on axis. Such a channel has properties of an optical waveguide. This technique allows creation of plasma channels in low atomic number gases, such as hydrogen, which is of importance for guiding of highly intense laser pulses. Laser pulses injected into such plasma channels produce a plasma wake that has a phase velocity close to the speed of light. A discussion of plasma wake measurements, using a Longitudinal Interferometry Wakefield Diagnostic Based on Time Domain Rayleigh Refractometry with Holographic Inversion, will be presented.

  7. Energy spread minimization in a cascaded laser wakefield accelerator via velocity bunching (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zhang, Zhijun

    2017-05-01

    We report the observation of energy-spread compensation of electron bunches in a laser wakefield accelerator in experiment. The compensation was caused by the gradient wakefield in plasma wake, and the energy spectra of the bunches evolved during the acceleration so that we propose a new method to diagnose the longitudinal length of the ultrashort electron bunch. By analyzing the energy spectra of electron bunches with different acceleration length, the wakefield gradient difference and the wakefield slope of the bunch could be estimated by combining with the slippage between the plasma wave and the electron bunch, thus the electron bunches' longitudinal length could be estimated. By applying this new method, the longitudinal length of electron bunches with charge of about 40 pC generated from a laser wakefield accelerator was estimated to be (2.4 ± 2.2) μm in experiment, which was in good agreement with three-dimension particle-in-cell simulations.

  8. RF power generation and coupling measurements for the dielectric wakefield step-up transformer.

    SciTech Connect

    Conde, M. E.

    1998-06-16

    The dielectric wakefield transformer (DWT) is one route to practical high energy wakefield-based accelerators. Progress has been made in a number of areas relevant to the demonstration of this device. In this article we describe recent bench measurements and beam experiments using 7.8 and 15.6 GHz structures and discuss some remaining technical challenges in the development of the DWT.

  9. High energy density laboratory astrophysics experiments with supersonic magnetized plasmas on the MAGPIE pulsed-power facility

    NASA Astrophysics Data System (ADS)

    Lebedev, S. V.; Burdiak, G. C.; Chittenden, J. P.; Clayson, T.; Garcia, C.; Hare, J. D.; Suttle, L. G.; Suzuki-Vidal, F.; Frank, A.; Ciardi, A.; Loureiro, N. F.

    2016-10-01

    The use of plasma flows generated by pulsed-power facilities provides a natural platform for designing magnetized HEDLA experiments. The plasma in this case is created and accelerated by the JxB force of the driving, Mega-Ampere level currents, forming plasma flows with embedded, frozen-in magnetic fields. Here we present several recent experiments performed on the MAGPIE pulsed-power facility focusing on studies of the structure of magnetized bow shocks, the dynamics of counter-streaming plasma jets, the formation of shocks in inverse liners, and magnetic reconnection in colliding plasmas. The relatively large spatial and temporal scales characterizing these experimental platforms, together with excellent diagnostic access, allow detailed characterization of the key plasma parameters and quantitative comparison of the experimental results with numerical simulations. Work supported by DOE cooperative Agreements No. DE-F03-02NA00057 and No. DE-SC-0001063.

  10. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Implantation of high-energy ions produced by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Volkov, Roman V.; Golishnikov, D. M.; Gordienko, Vyacheslav M.; Savel'ev, Andrei B.; Chernysh, V. S.

    2005-01-01

    Germanium ions of an expanding plasma were implanted in a silicon collector. The plasma was produced by a femtosecond laser pulse with an intensity of ~1015 W cm-2 at the surface of the solid-state target. A technique was proposed for determining the energy characteristics of the ion component of the laser plasma from the density profile of the ions implanted in the substrate.

  11. A Langmuir Probe Diagnostic for Use in Inhomogeneous, Time-Varying Plasmas Produced by High-Energy Laser Ablation

    SciTech Connect

    Patterson, J R; Emig, J A; Fournier, K B; Jenkins, P P; Trautz, K M; Seiler, S W; Davis, J F

    2012-05-01

    Langmuir probes (LP) are used extensively to characterize plasma environments produced by radio frequency, pulsed plasma thrusters, and laser ablation. We discuss here the development of a LP diagnostic to examine high-density, high-temperature inhomogeneous plasmas such as those that can be created at the University of Rochester's Laboratory for Laser Energetics OMEGA facility. We have configured our diagnostic to examine the velocity of the plasma expanding from the target. We observe velocities of approximately 16-17 cm/{micro}s, with individual LP currents displaying complex structures, perhaps due to the multiple atomic species and ionization states that exist.

  12. Plasma density gradient injection of low absolute momentum spread electron bunches

    SciTech Connect

    Geddes, C.G.R.; Nakamura, K.; Plateau, G.R.; Toth, Cs.; Cormier-Michel, E.; Esarey, E.; Schroeder, C.B.; Cary, J.R.; Leemans, W.P.

    2007-12-22

    Plasma density gradients in a gas jet were used to control the wake phase velocity and trapping threshold in a laser wakefield accelerator, producing stable electron bunches with longitudinal and transverse momentum spreads more than ten times lower than in previous experiments (0.17 and 0.02 MeV/c FWHM, respectively) and with central momenta of 0.76 +- 0.02 MeV/c. Transition radiation measurements combined with simulations indicated that the bunches can be used as a wakefield accelerator injector to produce stable beams with 0.2 MeV/c-class momentum spread at high energies.

  13. Investigation of the 2p_{32}-3d_{52} line emission of Au;{53+}-Au;{69+} for diagnosing high energy density plasmas.

    PubMed

    Brown, G V; Hansen, S B; Träbert, E; Beiersdorfer, P; Widmann, K; Chen, H; Chung, H K; Clementson, J H T; Gu, M F; Thorn, D B

    2008-06-01

    Measurements of the L -shell emission of highly charged gold ions were made under controlled laboratory conditions using the SuperEBIT electron beam ion trap, allowing detailed spectral observations of lines from Fe-like Au53+ through Ne-like Au69+ . Using atomic data from the Flexible Atomic Code, we have identified strong 3d_{52}-->2p_{32} emission features that can be used to diagnose the charge state distribution in high energy density plasmas, such as those found in the laser entrance hole of hot hohlraum radiation sources. We provide collisional-radiative calculations of the average ion charge Z as a function of temperature and density, which can be used to relate charge state distributions inferred from 3d_{52}-->2p_{32} emission features to plasma conditions, and investigate the effects of plasma density on calculated L -shell Au emission spectra.

  14. Control of focusing forces and emittances in plasma-based accelerators using near-hollow plasma channels

    SciTech Connect

    Schroeder, Carl; Esarey, Eric; Benedetti, Carlo; Leemans, Wim

    2013-08-06

    A near-hollow plasma channel, where the plasma density in the channel is much less than the plasma density in the walls, is proposed to provide independent control over the focusing and accelerating forces in a plasma accelerator. In this geometry the low density in the channel contributes to the focusing forces, while the accelerating fields are determined by the high density in the channel walls. The channel also provides guiding for intense laser pulses used for wakefield excitation. Both electron and positron beams can be accelerated in a nearly symmetric fashion. Near-hollow plasma channels can effectively mitigate emittance growth due to Coulomb scattering for high energy physics applications.

  15. Photoionized plasmas induced in neon with extreme ultraviolet and soft X-ray pulses produced using low and high energy laser systems

    SciTech Connect

    Bartnik, A.; Wachulak, P.; Fok, T.; Węgrzyński, Ł.; Fiedorowicz, H.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Dudzak, R.; Dostal, J.; Krousky, E.; Skala, J.; Ullschmied, J.; Hrebicek, J.; Medrik, T.

    2015-04-15

    A comparative study of photoionized plasmas created by two soft X-ray and extreme ultraviolet (SXR/EUV) laser plasma sources with different parameters is presented. The two sources are based on double-stream Xe/He gas-puff targets irradiated with high (500 J/0.3 ns) and low energy (10 J/1 ns) laser pulses. In both cases, the SXR/EUV beam irradiated the gas stream, injected into a vacuum chamber synchronously with the radiation pulse. Irradiation of gases resulted in formation of photoionized plasmas emitting radiation in the SXR/EUV range. The measured Ne plasma radiation spectra are dominated by emission lines corresponding to radiative transitions in singly charged ions. A significant difference concerns origin of the lines: K-shell or L-shell emissions occur in case of the high and low energy irradiating system, respectively. In high energy system, the electron density measurements were also performed by laser interferometry, employing a femtosecond laser system. A maximum electron density for Ne plasma reached the value of 2·10{sup 18 }cm{sup −3}. For the low energy system, a detection limit was too high for the interferometric measurements, thus only an upper estimation for electron density could be made.

  16. Photoionized plasmas induced in neon with extreme ultraviolet and soft X-ray pulses produced using low and high energy laser systems

    NASA Astrophysics Data System (ADS)

    Bartnik, A.; Wachulak, P.; Fok, T.; Wegrzyński, Ł.; Fiedorowicz, H.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Dudzak, R.; Dostal, J.; Krousky, E.; Skala, J.; Ullschmied, J.; Hrebicek, J.; Medrik, T.

    2015-04-01

    A comparative study of photoionized plasmas created by two soft X-ray and extreme ultraviolet (SXR/EUV) laser plasma sources with different parameters is presented. The two sources are based on double-stream Xe/He gas-puff targets irradiated with high (500 J/0.3 ns) and low energy (10 J/1 ns) laser pulses. In both cases, the SXR/EUV beam irradiated the gas stream, injected into a vacuum chamber synchronously with the radiation pulse. Irradiation of gases resulted in formation of photoionized plasmas emitting radiation in the SXR/EUV range. The measured Ne plasma radiation spectra are dominated by emission lines corresponding to radiative transitions in singly charged ions. A significant difference concerns origin of the lines: K-shell or L-shell emissions occur in case of the high and low energy irradiating system, respectively. In high energy system, the electron density measurements were also performed by laser interferometry, employing a femtosecond laser system. A maximum electron density for Ne plasma reached the value of 2.1018 cm-3. For the low energy system, a detection limit was too high for the interferometric measurements, thus only an upper estimation for electron density could be made.

  17. Quasimonoenergetic electron beams from laser wakefield acceleration in pure nitrogen

    SciTech Connect

    Mo, M. Z.; Ali, A.; Fedosejevs, R.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.

    2012-02-13

    Quasimonoenergetic electron beams with maximum energy >0.5 GeV and 2 mrad divergence have been generated in pure nitrogen gas via wakefield acceleration with 80 TW, 30 fs laser pulses. Long low energy tail features were typically observed due to continuous ionization injection. The measured peak electron energy decreased with the plasma density, agreeing with the predicted scaling for electrons. The experiments showed a threshold electron density of 3x10{sup 18}cm{sup -3} for self-trapping. Our experiments suggest that pure Nitrogen is a potential candidate gas to achieve GeV monoenergetic electrons using the ionization induced injection scheme for laser wakefield acceleration.

  18. Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited)

    NASA Astrophysics Data System (ADS)

    Valdivia, M. P.; Stutman, D.; Stoeckl, C.; Mileham, C.; Begishev, I. A.; Theobald, W.; Bromage, J.; Regan, S. P.; Klein, S. R.; Muñoz-Cordovez, G.; Vescovi, M.; Valenzuela-Villaseca, V.; Veloso, F.

    2016-11-01

    Talbot-Lau X-ray deflectometry (TXD) has been developed as an electron density diagnostic for High Energy Density (HED) plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping were demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moiré pattern formation and grating survival were also observed using a copper x-pinch driven at 400 kA, ˜1 kA/ns. These results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

  19. Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited)

    SciTech Connect

    Valdivia, M. P. Stutman, D.; Stoeckl, C.; Mileham, C.; Begishev, I. A.; Theobald, W.; Bromage, J.; Regan, S. P.; Klein, S. R.; Muñoz-Cordovez, G.; Vescovi, M.; Valenzuela-Villaseca, V.; Veloso, F.

    2016-11-15

    Talbot-Lau X-ray deflectometry (TXD) has been developed as an electron density diagnostic for High Energy Density (HED) plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping were demonstrated for 25–29 J, 8–30 ps laser pulses using copper foil targets. Moiré pattern formation and grating survival were also observed using a copper x-pinch driven at 400 kA, ∼1 kA/ns. These results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

  20. Talbot-Lau x-ray deflectometer electron density diagnostic for laser and pulsed power high energy density plasma experiments (invited).

    PubMed

    Valdivia, M P; Stutman, D; Stoeckl, C; Mileham, C; Begishev, I A; Theobald, W; Bromage, J; Regan, S P; Klein, S R; Muñoz-Cordovez, G; Vescovi, M; Valenzuela-Villaseca, V; Veloso, F

    2016-11-01

    Talbot-Lau X-ray deflectometry (TXD) has been developed as an electron density diagnostic for High Energy Density (HED) plasmas. The technique can deliver x-ray refraction, attenuation, elemental composition, and scatter information from a single Moiré image. An 8 keV Talbot-Lau interferometer was deployed using laser and x-pinch backlighters. Grating survival and electron density mapping were demonstrated for 25-29 J, 8-30 ps laser pulses using copper foil targets. Moiré pattern formation and grating survival were also observed using a copper x-pinch driven at 400 kA, ∼1 kA/ns. These results demonstrate the potential of TXD as an electron density diagnostic for HED plasmas.

  1. A study of the methods for the production and confinement of high energy plasmas. [injection of dense plasma into long magnetic field

    NASA Technical Reports Server (NTRS)

    Cheng, D. Y.; Wang, P.

    1972-01-01

    The injection of dense plasmas into a B sub z long magnetic field from both ends of the field coil was investigated. Deflagration plasma guns and continuous flow Z-pinch are discussed along with the possibility of a continuous flow Z-pinch fusion reactor. The injection experiments are described with emphasis on the synchronization of the two plasma deflagration guns, the collision of the two plasma beams, and the determination of plasma density.

  2. Ultrafast science using Laser Wakefield Accelerators

    NASA Astrophysics Data System (ADS)

    Thomas, Alec G. R.

    2016-10-01

    Recent progress in laser wakefield acceleration has led to the emergence of a new generation of electron and X-ray sources that may have considerable benefits for ultrafast science. Laser wakefield acceleration provides radiation pulses that have femtosecond duration and intrinsic synchronisation with the laser source, allowing for pump-probe measurements with unprecedented temporal resolution. These pulses can be used to study ultrafast dynamical phenomena in plasma and dense material, such as transient magnetic fields, rapidly evolving plasma dynamics and crystal lattice oscillations. In this talk, I will review recent experiments in laser wakefield acceleration and energetic photon generation using the laser systems HERCULES and Lambda-Cubed at the University of Michigan and their use for capturing the dynamics of laser-pumped samples. Studies of the electron beam hosing instability and the generation of annular phase space distributions increase X-ray flux while maintaining its femtosecond duration. Single-shot, spectrally resolved absorption measurements in laser pumped foils can be made on ultrafast timescales using this broadband photon source. Ultrafast electron radiography is able to temporally resolve relativistically expanding magnetic fields in high-intensity laser-solid interactions and the evolution of electric fields in low density plasma. Time-resolved electron diffraction captures structural dynamics in crystalline silicon. I will also discuss the technological needs for and potential impact of such revolutionary compact radiation sources for ultrafast science in the future. US Air Force Office of Scientific Research under Award Number FA9550-12-1-0310, the US National Science Foundation Grants No. 1054164, 0935197, 1535628 and 0810979, US Department of Energy Grant No. DE-NA0002372 and Army Research Office Grant No. W911NF1.

  3. Electron Rephasing in a Laser-Wakefield Accelerator.

    PubMed

    Guillaume, E; Döpp, A; Thaury, C; Ta Phuoc, K; Lifschitz, A; Grittani, G; Goddet, J-P; Tafzi, A; Chou, S W; Veisz, L; Malka, V

    2015-10-09

    An important limit for energy gain in laser-plasma wakefield accelerators is the dephasing length, after which the electron beam reaches the decelerating region of the wakefield and starts to decelerate. Here, we propose to manipulate the phase of the electron beam in the wakefield, in order to bring the beam back into the accelerating region, hence increasing the final beam energy. This rephasing is operated by placing an upward density step in the beam path. In a first experiment, we demonstrate the principle of this technique using a large energy spread electron beam. Then, we show that it can be used to increase the energy of monoenergetic electron beams by more than 50%.

  4. Observation of acceleration and deceleration in gigaelectron-volt-per-metre gradient dielectric wakefield accelerators.

    PubMed

    O'Shea, B D; Andonian, G; Barber, S K; Fitzmorris, K L; Hakimi, S; Harrison, J; Hoang, P D; Hogan, M J; Naranjo, B; Williams, O B; Yakimenko, V; Rosenzweig, J B

    2016-09-14

    There is urgent need to develop new acceleration techniques capable of exceeding gigaelectron-volt-per-metre (GeV m(-1)) gradients in order to enable future generations of both light sources and high-energy physics experiments. To address this need, short wavelength accelerators based on wakefields, where an intense relativistic electron beam radiates the demanded fields directly into the accelerator structure or medium, are currently under intense investigation. One such wakefield based accelerator, the dielectric wakefield accelerator, uses a dielectric lined-waveguide to support a wakefield used for acceleration. Here we show gradients of 1.347±0.020 GeV m(-1) using a dielectric wakefield accelerator of 15 cm length, with sub-millimetre transverse aperture, by measuring changes of the kinetic state of relativistic electron beams. We follow this measurement by demonstrating accelerating gradients of 320±17 MeV m(-1). Both measurements improve on previous measurements by and order of magnitude and show promise for dielectric wakefield accelerators as sources of high-energy electrons.

  5. Observation of acceleration and deceleration in gigaelectron-volt-per-metre gradient dielectric wakefield accelerators

    DOE PAGES

    O’Shea, B. D.; Andonian, G.; Barber, S. K.; ...

    2016-09-14

    There is urgent need to develop new acceleration techniques capable of exceeding gigaelectron-volt-per-metre (GeV m–1) gradients in order to enable future generations of both light sources and high-energy physics experiments. To address this need, short wavelength accelerators based on wakefields, where an intense relativistic electron beam radiates the demanded fields directly into the accelerator structure or medium, are currently under intense investigation. One such wakefield based accelerator, the dielectric wakefield accelerator, uses a dielectric lined-waveguide to support a wakefield used for acceleration. Here we show gradients of 1.347±0.020 GeV m–1 using a dielectric wakefield accelerator of 15 cm length, withmore » sub-millimetre transverse aperture, by measuring changes of the kinetic state of relativistic electron beams. We follow this measurement by demonstrating accelerating gradients of 320±17 MeV m–1. As a result, both measurements improve on previous measurements by and order of magnitude and show promise for dielectric wakefield accelerators as sources of high-energy electrons.« less

  6. Observation of acceleration and deceleration in gigaelectron-volt-per-metre gradient dielectric wakefield accelerators

    PubMed Central

    O'Shea, B. D.; Andonian, G.; Barber, S. K.; Fitzmorris, K. L.; Hakimi, S.; Harrison, J.; Hoang, P. D.; Hogan, M. J.; Naranjo, B.; Williams, O. B.; Yakimenko, V.; Rosenzweig, J. B.

    2016-01-01

    There is urgent need to develop new acceleration techniques capable of exceeding gigaelectron-volt-per-metre (GeV m−1) gradients in order to enable future generations of both light sources and high-energy physics experiments. To address this need, short wavelength accelerators based on wakefields, where an intense relativistic electron beam radiates the demanded fields directly into the accelerator structure or medium, are currently under intense investigation. One such wakefield based accelerator, the dielectric wakefield accelerator, uses a dielectric lined-waveguide to support a wakefield used for acceleration. Here we show gradients of 1.347±0.020 GeV m−1 using a dielectric wakefield accelerator of 15 cm length, with sub-millimetre transverse aperture, by measuring changes of the kinetic state of relativistic electron beams. We follow this measurement by demonstrating accelerating gradients of 320±17 MeV m−1. Both measurements improve on previous measurements by and order of magnitude and show promise for dielectric wakefield accelerators as sources of high-energy electrons. PMID:27624348

  7. Observation of acceleration and deceleration in gigaelectron-volt-per-metre gradient dielectric wakefield accelerators

    SciTech Connect

    O’Shea, B. D.; Andonian, G.; Barber, S. K.; Fitzmorris, K. L.; Hakimi, S.; Harrison, J.; Hoang, P. D.; Hogan, M. J.; Naranjo, B.; Williams, O. B.; Yakimenko, V.; Rosenzweig, J. B.

    2016-09-14

    There is urgent need to develop new acceleration techniques capable of exceeding gigaelectron-volt-per-metre (GeV m–1) gradients in order to enable future generations of both light sources and high-energy physics experiments. To address this need, short wavelength accelerators based on wakefields, where an intense relativistic electron beam radiates the demanded fields directly into the accelerator structure or medium, are currently under intense investigation. One such wakefield based accelerator, the dielectric wakefield accelerator, uses a dielectric lined-waveguide to support a wakefield used for acceleration. Here we show gradients of 1.347±0.020 GeV m–1 using a dielectric wakefield accelerator of 15 cm length, with sub-millimetre transverse aperture, by measuring changes of the kinetic state of relativistic electron beams. We follow this measurement by demonstrating accelerating gradients of 320±17 MeV m–1. As a result, both measurements improve on previous measurements by and order of magnitude and show promise for dielectric wakefield accelerators as sources of high-energy electrons.

  8. High energy from space

    NASA Technical Reports Server (NTRS)

    Margon, Bruce; Canizares, Claude; Catura, Richard C.; Clark, George W.; Fichtel, Carl E.; Friedman, Herbert; Giacconi, Riccardo; Grindlay, Jonathan E.; Helfand, David J.; Holt, Stephen S.

    1991-01-01

    The following subject areas are covered: (1) important scientific problems for high energy astrophysics (stellar activity, the interstellar medium in galaxies, supernovae and endpoints of stellar evolution, nucleosynthesis, relativistic plasmas and matter under extreme conditions, nature of gamma-bursts, identification of black holes, active nuclei, accretion physics, large-scale structures, intracluster medium, nature of dark matter, and the X- and gamma-ray background); (2) the existing experimental programs (Advanced X-Ray Astrophysics Facility (AXAF), Gamma Ray Observatory (GRO), X-Ray Timing Explorer (XTE), High Energy Transient Experiment (HETE), U.S. participation in foreign missions, and attached Shuttle and Space Station Freedom payloads); (3) major missions for the 1990's; (4) a new program of moderate missions; (5) new opportunities for small missions; (6) technology development issues; and (7) policy issues.

  9. Precision Mapping of Laser-Driven Magnetic Fields and Their Evolution in High-Energy-Density Plasmas

    NASA Astrophysics Data System (ADS)

    Gao, Lan; Nilson, P.; Igumenshchev, I.; Haines, M. G.; Froula, D. H.; Betti, R.; Meyerhofer, D. D.

    2016-10-01

    The magnetic fields generated at the surface of a laser-irradiated planar solid target are mapped using ultrafast proton radiography. Thick (50 μm) plastic foils are irradiated with 4-kJ, 2.5-ns laser pulses focused to an intensity of 4 x 1014 W/cm2. The data show magnetic fields concentrated at the edge of the laser-focal region, well within the expanding coronal plasma. The magnetic-field spatial distribution is tracked and shows good agreement with 2D resistive magnetohydrodynamic simulations using the code DRACO when the Biermann battery source, fluid and Nernst advection, resistive magnetic diffusion, and Righi-Leduc heat flow are included. The work provides significant insight into the generation and transport of Biermann fields in laser-produced plasmas, particularly those used in laser-driven magnetic reconnection and laboratory astrophysics experiments. deceased.

  10. The use of high energy laser-plasma sources in soft X-ray contact microscopy of living biological samples

    NASA Astrophysics Data System (ADS)

    Batani, D.; Botto, C.; Moret, M.; Milani, M.; Lucchini, G.; Eidmann, K.; Cotelli, F.; Lora Lamia Donin, C.; Poletti, G.; Ford, T.; Stead, A.

    2002-11-01

    In this paper the results of an experiment on soft X-ray contact microscopy using a laser-plasma source are presented. A resolution of 50 nm has been achieved imaging pig sperm cells, while other specimens, such as algae and yeast cells, showed internal details, proving the technique to be a powerful tool for biological investigations. Original biological information has been obtained and the conditions for optimal image formation have been studied.

  11. Spectroscopic investigations of high-energy-density plasma transformations in a simulated early reducing atmosphere containing methane, nitrogen and water.

    PubMed

    Civiš, Martin; Ferus, Martin; Knížek, Antonín; Kubelík, Petr; Kamas, Michal; Španěl, Patrik; Dryahina, Ksenia; Shestivska, Violetta; Juha, Libor; Skřehot, Petr; Laitl, Vojtěch; Civiš, Svatopluk

    2016-10-05

    Large-scale plasma was created in gas mixtures containing methane using high-power laser-induced dielectric breakdown (LIDB). The composition of the mixtures corresponded to a cometary and/or meteoritic impact into the early atmosphere of either Titan or Earth. A multiple-centimeter-sized fireball was created by focusing a single 100 J, 450 ps near-infrared laser pulse into the center of a 15 L gas cell. The excited reaction intermediates formed during the various stages of the LIDB plasma chemical evolution were investigated using optical emission spectroscopy (OES) with temporal resolution. The chemical consequences of laser-produced plasma generation in a CH4-N2-H2O mixture were investigated using high resolution Fourier-transform infrared absorption spectroscopy (FTIR) and gas selected ion flow tube spectrometry (SIFT). Several simple inorganic and organic compounds were identified in the reaction mixture exposed to ten laser sparks. Deuterated water (D2O) in a gas mixture was used to separate several of the produced isotopomers of acetylene, which were then quantified using the FTIR technique.

  12. Plasma-Based Generation and Control of a Single Few-Cycle High-Energy Ultrahigh-Intensity Laser Pulse

    NASA Astrophysics Data System (ADS)

    Tamburini, M.; Di Piazza, A.; Liseykina, T. V.; Keitel, C. H.

    2014-07-01

    A laser-boosted relativistic solid-density paraboloidal foil is known to efficiently reflect and focus a counterpropagating laser pulse. Here we show that in the case of an ultrarelativistic counterpropagating pulse, a high-energy and ultrahigh-intensity reflected pulse can be more effectively generated by a relatively slow and heavy foil than by a fast and light one. This counterintuitive result is explained with the larger reflectivity of a heavy foil, which compensates for its lower relativistic Doppler factor. Moreover, since the counterpropagating pulse is ultrarelativistic, the foil is abruptly dispersed and only the first few cycles of the counterpropagating pulse are reflected. Our multidimensional particle-in-cell simulations show that even few-cycle counterpropagating laser pulses can be further shortened (both temporally and in the number of laser cycles) with pulse amplification. A single few-cycle, multipetawatt laser pulse with several joules of energy and with a peak intensity exceeding 1023 W/cm2 can be generated already employing next-generation high-power laser systems. In addition, the carrier-envelope phase of the generated few-cycle pulse can be tuned provided that the carrier-envelope phase of the initial counterpropagating pulse is controlled.

  13. Modeling laser wakefield accelerators in a Lorentz boosted frame

    SciTech Connect

    Vay, J.-L.; Geddes, C.G.R.; Cormier-Michel, E.; Grotec, D. P.

    2010-06-15

    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high-frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing the frame of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.

  14. Modeling laser wakefield accelerators in a Lorentz boosted frame

    SciTech Connect

    Vay, J.-L.; Geddes, C.G.R.; Cormier-Michel, E.; Grote, D.P.

    2010-09-15

    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [1] is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing theframe of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.

  15. Laser-plasma experiments to study super high-energy phenomena during extreme compression of the Earth's magnetosphere by Coronal Mass Ejections*

    NASA Astrophysics Data System (ADS)

    Zakharov, Yu P.; Ponomarenko, A. G.; Antonov, V. M.; Boyarintsev, E. L.; Melekhov, A. V.; Posukh, V. G.; Shaikhislamov, I. F.

    2016-03-01

    Problem of the global and even catastrophic modification of the Earth's magnetosphere (into Artificial one) by impulsive and huge plasma ejecta, was proposed for the first time during our study of possible after-effects of high-energy explosions against asteroids at near-Earth space. Later, a similar problem of extreme compression of the Earth's magnetopause from its usual Rmp ≈ 10RE up to new stand-off distance Rm * ∼ 3RE, by plasma of giant Coronal Mass Ejections (CME, with effective energy E0 ∼1028 J), was considered for its simulations by Laser-Produced Plasma (LPP) at KI-1 facility of ILP, that were done initially without “Solar Wind” (in AMEX experiment). Here we present the first results of the “full” laboratory simulations of the CME-problem with the up-stream impact of LPP (with E0 ∼ 1 kJ) onto classical terrella-model of “stationary” magnetopause (with Rmp ≈ 17 cm), formed near compact dipole in a flow of background H+-plasma, imitated Solar Wind. As a result, we have observed for the first time a two-fold compression of magnetopause size, accompanied by very strong and near expected value of dipole magnetic field's compression up to the factor 7÷8 ≈ (Rmp/Rm *)3 inside of magnetopause. Our data allow to predict a global CME-effect at E0∼1029J.

  16. Progress of Laser-Driven Plasma Accelerators

    SciTech Connect

    Nakajima, Kazuhisa

    2007-07-11

    There is a great interest worldwide in plasma accelerators driven by ultra-intense lasers which make it possible to generate ultra-high gradient acceleration and high quality particle beams in a much more compact size compared with conventional accelerators. A frontier research on laser and plasma accelerators is focused on high energy electron acceleration and ultra-short X-ray and Tera Hertz radiations as their applications. These achievements will provide not only a wide range of sciences with benefits of a table-top accelerator but also a basic science with a tool of ultrahigh energy accelerators probing an unknown extremely microscopic world.Harnessing the recent advance of ultra-intense ultra-short pulse lasers, the worldwide research has made a tremendous breakthrough in demonstrating high-energy high-quality particle beams in a compact scale, so called ''dream beams on a table top'', which represents monoenergetic electron beams from laser wakefield accelerators and GeV acceleration by capillary plasma-channel laser wakefield accelerators. This lecture reviews recent progress of results on laser-driven plasma based accelerator experiments to quest for particle acceleration physics in intense laser-plasma interactions and to present new outlook for the GeV-range high-energy laser plasma accelerators.

  17. High energy electron cooling

    SciTech Connect

    Parkhomchuk, V.

    1997-09-01

    High energy electron cooling requires a very cold electron beam. The questions of using electron cooling with and without a magnetic field are presented for discussion at this workshop. The electron cooling method was suggested by G. Budker in the middle sixties. The original idea of the electron cooling was published in 1966. The design activities for the NAP-M project was started in November 1971 and the first run using a proton beam occurred in September 1973. The first experiment with both electron and proton beams was started in May 1974. In this experiment good result was achieved very close to theoretical prediction for a usual two component plasma heat exchange.

  18. Precision mapping of laser-driven magnetic fields and their evolution in high-energy-density plasmas

    SciTech Connect

    Gao, L.; Nilson, P. M.; Igumenshchev, I. V.; Haines, M. G.; Froula, D. H.; Betti, R.; Meyerhofer, D. D.

    2015-05-29

    The magnetic fields generated at the surface of a laser-irradiated planar solid target are mapped using ultrafast proton radiography. Thick (50 μm) plastic foils are irradiated with 4-kJ, 2.5-ns laser pulses focused to an intensity of 4 x 10¹⁴ W/cm². The data show magnetic fields concentrated at the edge of the laser-focal region, well within the expanding coronal plasma. The magnetic-field spatial distribution is tracked and shows good agreement with 2D resistive magnetohydrodynamic simulations using the code DRACO when the Biermann battery source, fluid and Nernst advection, resistive magnetic diffusion, and Righi-Leduc heat flow are included.

  19. Precision mapping of laser-driven magnetic fields and their evolution in high-energy-density plasmas.

    PubMed

    Gao, L; Nilson, P M; Igumenshchev, I V; Haines, M G; Froula, D H; Betti, R; Meyerhofer, D D

    2015-05-29

    The magnetic fields generated at the surface of a laser-irradiated planar solid target are mapped using ultrafast proton radiography. Thick (50  μm) plastic foils are irradiated with 4-kJ, 2.5-ns laser pulses focused to an intensity of 4×10^{14}  W/cm^{2}. The data show magnetic fields concentrated at the edge of the laser-focal region, well within the expanding coronal plasma. The magnetic-field spatial distribution is tracked and shows good agreement with 2D resistive magnetohydrodynamic simulations using the code draco when the Biermann battery source, fluid and Nernst advection, resistive magnetic diffusion, and Righi-Leduc heat flow are included.

  20. Proton radiography of dynamic electric and magnetic fields in laser-produced high-energy-density plasmas

    SciTech Connect

    Li, C. K.; Seguin, F. H.; Frenje, J. A.; Manuel, M.; Casey, D.; Sinenian, N.; Petrasso, R. D.; Amendt, P. A.; Landen, O. L.; Rygg, J. R.; Town, R. P. J.; Betti, R.; Meyerhofer, D. D.; Delettrez, J.; Knauer, J. P.; Marshall, F.; Sangster, T. C.; Smalyuk, V. A.; Soures, J. M.; Shvarts, D.

    2009-05-15

    Time-gated, monoenergetic-proton radiography provides unique measurements of the electric (E) and magnetic (B) fields produced in laser-foil interactions and during the implosion of inertial-confinement-fusion capsules. These experiments resulted in the first observations of several new and important features: (1) observations of the generation, decay dynamics, and instabilities of megagauss B fields in laser-driven planar plastic foils, (2) the observation of radial E fields inside an imploding capsule, which are initially directed inward, reverse direction during deceleration, and are likely related to the evolution of the electron pressure gradient, and (3) the observation of many radial filaments with complex electromagnetic field striations in the expanding coronal plasmas surrounding the capsule. The physics behind and implications of such observed fields are discussed.

  1. Proton radiography of dynamic electric and magnetic fields in laser-produced high-energy-density plasmas

    SciTech Connect

    Li, C. K.; Séguin, F. H.; Frenje, J. A.; Manuel, M.; Casey, D.; Sinenian, N.; Petrasso, R. D.; Amendt, P. A.; Landen, O. L.; Rygg, J. R.; Town, R. P. J.; Betti, R.; Delettrez, J.; Knauer, J. P.; Marshall, F.; Meyerhofer, D. D.; Sangster, T. C.; Shvarts, D.; Smalyuk, V. A.; Soures, J. M.; Back, C. A.; Kilkenny, J. D.; Nikroo, A.

    2009-01-01

    Time-gated, monoenergetic-proton radiography provides unique measurements of the electric (E) and magnetic (B) fields produced in laser-foil interactions and during the implosion of inertial-confinement-fusion capsules. These experiments resulted in the first observations of several new and important features: (1) observations of the generation, decay dynamics, and instabilities of megagauss B fields in laser-driven planar plastic foils, (2) the observation of radial E fields inside an imploding capsule, which are initially directed inward, reverse direction during deceleration, and are likely related to the evolution of the electron pressure gradient, and (3) the observation of many radial filaments with complex electromagnetic field striations in the expanding coronal plasmas surrounding the capsule. The physics behind and implications of such observed fields are discussed.

  2. Load management strategy for Particle-In-Cell simulations in high energy particle acceleration

    NASA Astrophysics Data System (ADS)

    Beck, A.; Frederiksen, J. T.; Dérouillat, J.

    2016-09-01

    In the wake of the intense effort made for the experimental CILEX project, numerical simulation campaigns have been carried out in order to finalize the design of the facility and to identify optimal laser and plasma parameters. These simulations bring, of course, important insight into the fundamental physics at play. As a by-product, they also characterize the quality of our theoretical and numerical models. In this paper, we compare the results given by different codes and point out algorithmic limitations both in terms of physical accuracy and computational performances. These limitations are illustrated in the context of electron laser wakefield acceleration (LWFA). The main limitation we identify in state-of-the-art Particle-In-Cell (PIC) codes is computational load imbalance. We propose an innovative algorithm to deal with this specific issue as well as milestones towards a modern, accurate high-performance PIC code for high energy particle acceleration.

  3. Optimization and control of electron beams from laser wakefield accelerations using asymmetric laser pulses

    NASA Astrophysics Data System (ADS)

    Gopal, K.; Gupta, D. N.

    2017-10-01

    Optimization and control of electron beam quality in laser wakefield acceleration are explored by using a temporally asymmetric laser pulse of the sharp rising front portion. The temporally asymmetric laser pulse imparts stronger ponderomotive force on the ambient plasma electrons. The stronger ponderomotive force associated with the asymmetric pulse significantly affects the injection of electrons into the wakefield and consequently the quality of the injected bunch in terms of injected charge, mean energy, and emittance. Based on particle-in-cell simulations, we report to generate a monoenergetic electron beam with reduced emittance and enhanced charge in laser wakefield acceleration using an asymmetric pulse of duration 30 fs.

  4. Ion Acceleration by Ultra-intense Laser Pulse Interacting with Double-layer Near-critical Density Plasma

    NASA Astrophysics Data System (ADS)

    Gu, Y. J.; Kong, Q.; Kawata, S.; Izumiyama, T.; Nagashima, T.; Takano, M.; Li, X. F.; Yu, Q.; Barada, D.; Ma, Y. Y.; Wang, P. X.

    2016-03-01

    A collimated ion beam is generated through the interaction between ultra-intense laser pulse and a double layer plasma. The maximum energy is above 1GeV and the total charge of high energy protons is about several tens of nC/μm. The double layer plasma is combined with an underdense plasma and a thin overdense one. The wakefield traps and accelerates a bunch of electrons to high energy in the first underdense slab. When the well collimated electron beam accelerated by the wakefield penetrates through the second overdense slab, it enhances target normal sheath acceleration (TNSA) and breakout after-burner (BOA) regimes. The mechanism is simulated and analyzed by 2.5 dimensional Particle-in-cell code. Compared with single target TNSA or BOA, both the acceleration gradient and energy transfer efficiency are higher in the double layer regime.

  5. [Effects of gas composition and pressure on the intensity and quality of the plasma induced by a high-energy neodymium glass laser].

    PubMed

    Chen, Jin-zhong; Zhao, Shu-rui; Wei, Yan-hong; Guo, Qing-lin; Huai, Su-fang

    2005-03-01

    In this experiment, the effects of gas composition and pressure on the intensity and quality of the plasma induced by a high-energy neodymium glass laser were studied. The experimental results show that the spectral intensity of the plasma in the argon atmosphere is stronger than that in the air when the pressure is the same. For the steel alloy sample, the intensities of the emission spectrum reach the maximum values when the argon pressure is 0.8 x 10(5) Pa. The self-absorption phenomena of Al II 308.22 and Al II 309.27 nm lines strengthen with the increase of the pressure, and even serious self-reversal appears when the pressure is (0.8-0.9) x 10(5) Pa. The temperature of plasma also raises with the increase of the pressure. When the argon pressure is 0.93 x 10(5) Pa, t h e temperature is about 1500 K higher than that when the argon pressure is about 0.43 x 10(5) Pa.

  6. Investigation of the 2p3/2-3d5/2 line emission of Au53+ -- Au69+ for diagnosing high energy density plasmas

    SciTech Connect

    Brown, G V; Hansen, S B; Trabert, E; Beiersdorfer, P; Widmann, K; Chen, H; Chung, H K; Clementson, J T; Gu, M F; Thorn, D B

    2008-01-29

    Measurements of the L-shell emission of highly charged gold ions were made under controlled laboratory conditions using the SuperEBIT electron beam ion trap, allowing detailed spectral observations of lines from ironlike Au{sup 53+} through neonlike Au{sup 69+}. Using atomic data from the Flexible Atomic Code, we have identified strong 3d{sub 5/2} {yields} 2p{sub 3/2} emission features that can be used to diagnose the charge state distribution in high energy density plasmas, such as those found in the laser entrance hole of hot hohlraum radiation sources. We provide collisional-radiative calculations of the average ion charge as a function of temperature and density, which can be used to relate charge state distributions inferred from 3d{sub 5/2} {yields} 2p{sub 3/2} emission features to plasma conditions, and investigate the effects of plasma density on calculated L-shell Au emission spectra.

  7. A novel nuclear pyrometry for the characterization of high-energy bremsstrahlung and electrons produced in relativistic laser-plasma interactions

    SciTech Connect

    Guenther, M. M.; Sonnabend, K.; Harres, K.; Roth, M.; Brambrink, E.; Vogt, K.; Bagnoud, V.

    2011-08-15

    We present a novel nuclear activation-based method for the investigation of high-energy bremsstrahlung produced by electrons above 7 MeV generated by a high-power laser. The main component is a novel high-density activation target that is a pseudo alloy of several selected isotopes with different photo-disintegration reaction thresholds. The gamma spectrum emitted by the activated targets is used for the reconstruction of the bremsstrahlung spectrum using an analysis method based on Penfold and Leiss. This nuclear activation-based technique allows for the determination of the number of bremsstrahlung photons per energy bin in a wide range energy without any anticipated fit procedures. Furthermore, the analysis method also allows for the determination of the absolute yield, the energy distribution, and the temperature of high-energy electrons at the relativistic laser-plasma interaction region. The pyrometry is sensitive to energies above 7 MeV only, i.e., this diagnostic is insensitive to any low-energy processes.

  8. Trapping of high-energy electrons into regime of surfatron acceleration by electromagnetic waves in space plasma

    SciTech Connect

    Erokhin, A. N.; Erokhin, N. S.; Milant'ev, V. P.

    2012-05-15

    The phenomenon of trapping of weakly relativistic charged particles (with kinetic energies on the order of mc{sup 2}) into a regime of surfatron acceleration by an electromagnetic wave that propagates in plasma across a weak external magnetic field has been studied using nonlinear numerical calculations based on a solution of the relativistic equations of motion. Analysis showed that, for the wave amplitude above a certain threshold value and the initial wave phase outside the interval favorable for the surfing regime, the trajectory of a charged particle initially corresponds to its cyclotron rotation in the external magnetic field. For the initial particle energies studied, the period of this rotation is relatively short. After a certain number (from several dozen to several thousand and above) of periods of rotation, the wave phase takes a value that is favorable for trapping of the charged particle on its trajectory by the electromagnetic wave, provided the Cherenkov resonance conditions are satisfied. As a result, the wave traps the charged particle and imparts it an ultrarelativistic acceleration. In momentum space, the region of trapping into the regime of surfing on an electromagnetic wave turns out to be rather large.

  9. Effect of pulse profile and chirp on a laser wakefield generation

    SciTech Connect

    Zhang Xiaomei; Shen Baifei; Ji Liangliang; Wang Wenpeng; Xu Jiancai; Yu Yahong; Yi Longqing; Wang Xiaofeng; Hafz, Nasr A. M.; Kulagin, V.

    2012-05-15

    A laser wakefield driven by an asymmetric laser pulse with/without chirp is investigated analytically and through two-dimensional particle-in-cell simulations. For a laser pulse with an appropriate pulse length compared with the plasma wavelength, the wakefield amplitude can be enhanced by using an asymmetric un-chirped laser pulse with a fast rise time; however, the growth is small. On the other hand, the wakefield can be greatly enhanced for both positively chirped laser pulse having a fast rise time and negatively chirped laser pulse having a slow rise time. Simulations show that at the early laser-plasma interaction stage, due to the influence of the fast rise time the wakefield driven by the positively chirped laser pulse is more intense than that driven by the negatively chirped laser pulse, which is in good agreement with analytical results. At a later time, since the laser pulse with positive chirp exhibits opposite evolution to the one with negative chirp when propagating in plasma, the wakefield in the latter case grows more intensely. These effects should be useful in laser wakefield acceleration experiments operating at low plasma densities.

  10. The Structure and Mechanical Properties of High-Strength Bulk Ultrafine-Grained Cobalt Prepared Using High-Energy Ball Milling in Combination with Spark Plasma Sintering

    PubMed Central

    Marek, Ivo; Vojtěch, Dalibor; Michalcová, Alena; Kubatík, Tomáš František

    2016-01-01

    In this study, bulk ultrafine-grained and micro-crystalline cobalt was prepared using a combination of high-energy ball milling and subsequent spark plasma sintering. The average grain sizes of the ultrafine-grained and micro-crystalline materials were 200 nm and 1 μm, respectively. Mechanical properties such as the compressive yield strength, the ultimate compressive strength, the maximum compressive deformation and the Vickers hardness were studied and compared with those of a coarse-grained as-cast cobalt reference sample. The bulk ultrafine-grained sample showed an ultra-high compressive yield strength that was greater than 1 GPa, which is discussed with respect to the preparation technique and a structural investigation. PMID:28773514

  11. Structure-Property Correlation in Fe-Al2O3 In Situ Nanocomposite Synthesized by High-Energy Ball Milling and Spark Plasma Sintering

    NASA Astrophysics Data System (ADS)

    Udhayabanu, V.; Ravi, K. R.; Murty, B. S.

    2016-10-01

    In the present study, Fe-10 vol pct Al2O3 in situ nanocomposite has been derived by high-energy ball milling of Fe2O3-Fe-Al powder mixture followed by the consolidation using spark plasma sintering (SPS). The consolidated nanocomposite has bimodal-grained structure consisting of nanometer- and submicron-sized Fe grains along with nanometer-sized Al2O3, and Fe3O4 particles. The mechanical property analysis reveals that compressive yield strength of Fe-10 vol pct Al2O3 nanocomposite is 2100 MPa which is nearly two times higher than that of monolithic Fe processed by Mechanical Milling and SPS. The strengthening contributions obtained from matrix, grain size, and particles in the synthesized nanocomposite have been calculated theoretically, and are found to be matching well with the experimental strength levels.

  12. Study of corrosion resistance and microstructure of the 0.45 wt% C steel modified by pulsed high energy density plasma

    SciTech Connect

    Wei, K.; Fu, Y.; Wu, X.; Yang, S.Z.; Li, B.

    1999-10-01

    A 0.45 wt% C steel was modified by pulsed high energy density plasma (PHEDP), which was composed of particles of aluminum and nitrogen. A layer of thin film was formed on it. The modified steels were studied by an electrochemical corrosion test and transmission electron microscope (TEM) observations. Results showed that the corrosion resistance ability of 0.45 wt% C steel improved after modification, and the film was composed of nanocrystal-aluminum-nitride-phase (AlN), with crystal size of less than 20 nm. The nanocrystal-structured film contributes to the improvement of the corrosion resistance. The improvement is not only related to the microstructure of the film but also to its surface morphology, and both are controlled by the parameters of the PHEDP.

  13. Laser-plasma interactions from thin tapes for high-energy electron accelerators and seeding compact FELs

    NASA Astrophysics Data System (ADS)

    Shaw, Brian Henry

    This thesis comprises a detailed investigation of the physics of using a plasma mirror (PM) from a tape by reflecting ultrashort pulses from a laser-triggered surface plasma. The tapes used in the characterization of the PM are VHS and computer data storage tape. The tapes are 6.6 m (computer storage tape) and 15 m (VHS) thick. Each tape is 0.5 inches wide, and 10s of meters of tape are spooled using a tape drive; providing thousands of shots on a single reel of tape. The amount of reflected energy of the PM was studied for different input intensities. The fluence was varied by translating the focus of the laser upstream and downstream of the tape, which changed the spot size on the tape surface and hence changed the fluence. This study measured reflectances from both sides of the two tapes, and for input light of both s and p-polarizations. Lastly, an analytic model was developed to understand the reflectance as a function of fluence for each tape material and polarization. Another application that benefits from the advancements of LPA technology is an LPAbased FEL. By sending a high quality electron bunch through an undulator (a periodic structure of positive and negative magnetic poles), the electrons oscillate transversely to the propagation axis and produce radiation. The 1.5 m THUNDER undulator at the BELLA Center has been commissioned using electron beams of 400MeV beams with broad energy spread (35%). To produce a coherent LPA-based FEL, the beam quality would need to improve to sub-percent level energy spread. A seed source could be used to help induce bunching of the electron beam within the undulator. This thesis described the experimental investigation of the physics of using solid-based surface high-harmonic generation (SHHG) from a thin tape as a possible seed source for an FEL. A thin tape placed within centimeters of the undulator's entrance could act as a harmonic generating source, while simultaneously transmitting an electron beam. This removes

  14. High energy electron fluxes in dc-augmented capacitively coupled plasmas. II. Effects on twisting in high aspect ratio etching of dielectrics

    SciTech Connect

    Wang Mingmei; Kushner, Mark J.

    2010-01-15

    In high aspect ratio (HAR) plasma etching of holes and trenches in dielectrics, sporadic twisting is often observed. Twisting is the randomly occurring divergence of a hole or trench from the vertical. Many causes have been proposed for twisting, one of which is stochastic charging. As feature sizes shrink, the fluxes of plasma particles, and ions in particular, into the feature become statistical. Randomly deposited charge by ions on the inside of a feature may be sufficient to produce lateral electric fields which divert incoming ions and initiate nonvertical etching or twisting. This is particularly problematic when etching with fluorocarbon gas mixtures where deposition of polymer in the feature may trap charge. dc-augmented capacitively coupled plasmas (dc-CCPs) have been investigated as a remedy for twisting. In these devices, high energy electron (HEE) beams having narrow angular spreads can be generated. HEEs incident onto the wafer which penetrate into HAR features can neutralize the positive charge and so reduce the incidence of twisting. In this paper, we report on results from a computational investigation of plasma etching of SiO{sub 2} in a dc-CCP using Ar/C{sub 4}F{sub 8}/O{sub 2} gas mixtures. We found that HEE beams incident onto the wafer are capable of penetrating into features and partially neutralizing positive charge buildup due to sporadic ion charging, thereby reducing the incidence of twisting. Increasing the rf bias power increases the HEE beam energy and flux with some indication of improvement of twisting, but there are also changes in the ion energy and fluxes, so this is not an unambiguous improvement. Increasing the dc bias voltage while keeping the rf bias voltage constant increases the maximum energy of the HEE and its flux while the ion characteristics remain nearly constant. For these conditions, the occurrence of twisting decreases with increasing HEE energy and flux.

  15. Two-color beam generation based on wakefield excitation

    NASA Astrophysics Data System (ADS)

    Bettoni, S.; Prat, E.; Reiche, S.

    2016-05-01

    Several beam manipulation methods have been studied and experimentally tested to generate two-color photon beams in free electron laser facilities to accommodate the user requests. We propose to use the interaction of the beam with an oscillating longitudinal wakefield source to obtain a suitable electron beam structure. The bunch generates two subpulses with different energies and delayed in time passing through a magnetic chicane after its longitudinal phase space has been modulated by the wakefield source. According to this approach the power of the emitted radiation is not degraded compared to the monochromatic beam, and the setup in the machine is quite simple because the bunch is manipulated only in the high energy section, where it is more rigid. We present the design applied to SwissFEL. We identified the parameters and the corresponding range of tunability of the time and energy separation among the two subbunches.

  16. Dielectric Wakefield Accelerator to drive the future FEL Light Source.

    SciTech Connect

    Jing, C.; Power, J.; Zholents, A. )

    2011-04-20

    X-ray free-electron lasers (FELs) are expensive instruments and a large part of the cost of the entire facility is driven by the accelerator. Using a high-energy gain dielectric wake-field accelerator (DWA) instead of the conventional accelerator may provide a significant cost saving and reduction of the facility size. In this article, we investigate using a collinear dielectric wakefield accelerator to provide a high repetition rate, high current, high energy beam to drive a future FEL x-ray light source. As an initial case study, a {approx}100 MV/m loaded gradient, 850 GHz quartz dielectric based 2-stage, wakefield accelerator is proposed to generate a main electron beam of 8 GeV, 50 pC/bunch, {approx}1.2 kA of peak current, 10 x 10 kHz (10 beamlines) in just 100 meters with the fill factor and beam loading considered. This scheme provides 10 parallel main beams with one 100 kHz drive beam. A drive-to-main beam efficiency {approx}38.5% can be achieved with an advanced transformer ratio enhancement technique. rf power dissipation in the structure is only 5 W/cm{sup 2} in the high repetition rate, high gradient operation mode, which is in the range of advanced water cooling capability. Details of study presented in the article include the overall layout, the transform ratio enhancement scheme used to increase the drive to main beam efficiency, main wakefield linac design, cooling of the structure, etc.

  17. Analyzing non-LTE Kr plasmas produced in high energy density experiments: from the Z machine to the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Dasgupta, Arati

    2015-11-01

    Designing high fluence photon sources above 10 keV are a challenge for High Energy Density plasmas. This has motivated radiation source development investigations of Kr with K-shell energies around 13 keV. Recent pulsed power driven gas-puff experiments on the refurbished Z machine at Sandia have produced intense X-rays in the multi-keV photon energy range. K-shell radiative yields and efficiencies are very high for Ar, but rapidly decrease for higher atomic number (ZA) elements such as Kr. It has been suggested that an optimum exists corresponding to a trade-off between the increase of photon energy for higher ZA elements and the corresponding fall off in radiative power. However the conversion efficiency on NIF, where the drive, energy deposition process, and target dynamics are different, does not fall off with higher ZA as rapidly as on Z. We have developed detailed atomic structure and collisional data for the full K-, L- and partial M-shell of Kr using the Flexible Atomic Code (FAC). Our non-LTE atomic model includes all collisional and recombination processes, including state-specific dielectronic recombination (DR), that significantly affect ionization balance and spectra of Kr plasmas at the temperatures and densities of concern. The model couples ionization physics, radiation production and transport, and magnetohydrodynamics. In this talk, I will give a detailed description of the model and discuss 1D Kr simulations employing a multifrequency radiation transport scheme. Synthetic K- and L-shell spectra will be compared with available experimental data. This talk will analyze experimental data indicative of the differences between Z and NIF experimental data and discuss how they affect the K-shell radiative output of Kr plasma. Work supported by DOE/NNSA.

  18. High-energy-density plasmas generation on GEKKO-LFEX laser facility for fast-ignition laser fusion studies and laboratory astrophysics

    NASA Astrophysics Data System (ADS)

    Fujioka, S.; Zhang, Z.; Yamamoto, N.; Ohira, S.; Fujii, Y.; Ishihara, K.; Johzaki, T.; Sunahara, A.; Arikawa, Y.; Shigemori, K.; Hironaka, Y.; Sakawa, Y.; Nakata, Y.; Kawanaka, J.; Nagatomo, H.; Shiraga, H.; Miyanaga, N.; Norimatsu, T.; Nishimura, H.; Azechi, H.

    2012-12-01

    The world's largest peta watt (PW) laser LFEX, which delivers energy up to 2 kJ in a 1.5 ps pulse, has been constructed beside the GEKKO XII laser at the Institute of Laser Engineering, Osaka University. The GEKKO-LFEX laser facility enables the creation of materials having high-energy-density which do not exist naturally on the Earth and have an energy density comparable to that of stars. High-energy-density plasma is a source of safe, secure, environmentally sustainable fusion energy. Direct-drive fast-ignition laser fusion has been intensively studied at this facility under the auspices of the Fast Ignition Realization Experiment (FIREX) project. In this paper, we describe improvement of the LFEX laser and investigations of advanced target design to increase the energy coupling efficiency of the fast-ignition scheme. The pedestal of the LFEX pulse, which produces a long preformed plasma and results in the generation of electrons too energetic to heat the fuel core, was reduced by introducing an amplified optical parametric fluorescence quencher and saturable absorbers in the front-end system of the LFEX laser. Since fast electrons are scattered and stopped by the strong electric field of highly ionized high-Z (i.e. gold) ions, a low-Z cone was studied for reducing the energy loss of fast electrons in the cone tip region. A diamond-like carbon cone was fabricated for the fast-ignition experiment. An external magnetic field, which is demonstrated to be generated by a laser-driven capacitor-coil target, will be applied to the compression of the fuel capsule to form a strong magnetic field to guide the fast electrons to the fuel core. In addition, the facility offers a powerful means to test and validate astronomical models and computations in the laboratory. As well as demonstrating the ability to recreate extreme astronomical conditions by the facilities, our theoretical description of the laboratory experiment was compared with the generally accepted explanation

  19. Temporal Evolution of Self-Modulated Laser Wakefields Measured by Coherent Thomson Scattering

    SciTech Connect

    Ting, A.; Krushelnick, K.; Moore, C.I.; Burris, H.R.; Esarey, E.; Krall, J.; Sprangle, P. |

    1996-12-01

    Coherent Thomson scattering of a picosecond probe laser was used to measure the time evolution of plasma wakefields produced by a high intensity laser pulse (7{times}10{sup 18} W/cm{sup 2}) in an underdense plasma ({ital n}{sub {ital e}}{approx_equal}10{sup 19} cm{sup {minus}3}) in the self-modulated laser wakefield accelerator configuration. Large amplitude plasma wakefields which lasted less than 5ps were observed to decay into ion acoustic waves. The time scales associated with these measurements were consistent with the effects of the modulational instability and the enhancement of scattered signal from plasma channel formation. {copyright} {ital 1996 The American Physical Society.}

  20. A table-top x-ray FEL based on a laser wakefield accelerator-undulator system

    SciTech Connect

    Nakajima, K.; Kawakubo, T.; Nakanishi, H.

    1995-12-31

    Ultrahigh-gradient electron acceleration has been confirmed owing to the laser wakefield acceleration mechanism driven by an intense short laser wakefield acceleration mechanism driven by an intense short laser pulse in an underdense plasma. The laser wakefield acceleration makes it possible to build a compact electron linac capable of producing an ultra-short bunched electron beam. While the accelerator is attributed to longitudinal wakefields, transverse wakefields simultaneously generated by a short laser pulse can serve as a plasma undulator with a very short wavelength equal to a half of the plasma wavelength. We propose a new FEL concept for X-rays based on a laser wakefield accelerator-undulator system driven by intense short laser pulses delivered from table-top terawatt lasers. The system is composed of the accelerator stage and the undulator stage in a table-top size. A low energy electron beam is accelerated an bunched into microbunches due to laser wakefields in the accelerator stage. A micro-bunched beam travelling to the opposite direction of driving laser pulses produces coherent X-ray radiation in the undulator stage. A practical configuration and its analyses are presented.

  1. Direct Acceleration of Electrons in a Corrugated Plasma Channel

    SciTech Connect

    Palastro, J. P.; Antonsen, T. M.; Morshed, S.; York, A. G.; Layer, B.; Aubuchon, M.; Milchberg, H. M.; Froula, D. H.

    2009-01-22

    Direct laser acceleration of electrons provides a low power tabletop alternative to laser wakefield accelerators. Until recently, however, direct acceleration has been limited by diffraction, phase matching, and material damage thresholds. The development of the corrugated plasma channel [B. Layer et al., Phys. Rev. Lett. 99, 035001 (2007)] has removed all of these limitations and promises to allow direct acceleration of electrons over many centimeters at high gradients using femtosecond lasers [A. G. York et al., Phys Rev. Lett 100, 195001 (2008), J. P. Palastro et al., Phys. Rev. E 77, 036405 (2008)]. We present a simple analytic model of laser propagation in a corrugated plasma channel and examine the laser-electron beam interaction. Simulations show accelerating gradients of several hundred MeV/cm for laser powers much lower than required by standard laser wakefield schemes. In addition, the laser provides a transverse force that confines the high energy electrons on axis, while expelling low energy electrons.

  2. Moiré deflectometry using the Talbot-Lau interferometer as refraction diagnostic for High Energy Density plasmas at energies below 10 keV

    SciTech Connect

    Valdivia, M. P.; Stutman, D.; Finkenthal, M.

    2014-07-15

    The highly localized density gradients expected in High Energy Density (HED) plasma experiments can be characterized by x-ray phase-contrast imaging in addition to conventional attenuation radiography. Moiré deflectometry using the Talbot-Lau grating interferometer setup is an attractive HED diagnostic due to its high sensitivity to refraction induced phase shifts. We report on the adaptation of such a system for operation in the sub-10 keV range by using a combination of free standing and ultrathin Talbot gratings. This new x-ray energy explored matches well the current x-ray backlighters used for HED experiments, while also enhancing phase effects at lower electron densities. We studied the performance of the high magnification, low energy Talbot-Lau interferometer, for single image phase retrieval using Moiré fringe deflectometry. Our laboratory and simulation studies indicate that such a device is able to retrieve object electron densities from phase shift measurements. Using laboratory x-ray sources from 7 to 15 μm size we obtained accurate simultaneous measurements of refraction and attenuation for both sharp and mild electron density gradients.

  3. Moiré deflectometry using the Talbot-Lau interferometer as refraction diagnostic for high energy density plasmas at energies below 10 keV.

    PubMed

    Valdivia, M P; Stutman, D; Finkenthal, M

    2014-07-01

    The highly localized density gradients expected in High Energy Density (HED) plasma experiments can be characterized by x-ray phase-contrast imaging in addition to conventional attenuation radiography. Moiré deflectometry using the Talbot-Lau grating interferometer setup is an attractive HED diagnostic due to its high sensitivity to refraction induced phase shifts. We report on the adaptation of such a system for operation in the sub-10 keV range by using a combination of free standing and ultrathin Talbot gratings. This new x-ray energy explored matches well the current x-ray backlighters used for HED experiments, while also enhancing phase effects at lower electron densities. We studied the performance of the high magnification, low energy Talbot-Lau interferometer, for single image phase retrieval using Moiré fringe deflectometry. Our laboratory and simulation studies indicate that such a device is able to retrieve object electron densities from phase shift measurements. Using laboratory x-ray sources from 7 to 15 μm size we obtained accurate simultaneous measurements of refraction and attenuation for both sharp and mild electron density gradients.

  4. Demonstration of a narrow energy spread, ∼0.5  GeV electron beam from a two-stage laser wakefield accelerator.

    PubMed

    Pollock, B B; Clayton, C E; Ralph, J E; Albert, F; Davidson, A; Divol, L; Filip, C; Glenzer, S H; Herpoldt, K; Lu, W; Marsh, K A; Meinecke, J; Mori, W B; Pak, A; Rensink, T C; Ross, J S; Shaw, J; Tynan, G R; Joshi, C; Froula, D H

    2011-07-22

    Laser wakefield acceleration of electrons holds great promise for producing ultracompact stages of GeV scale, high-quality electron beams for applications such as x-ray free electron lasers and high-energy colliders. Ultrahigh intensity laser pulses can be self-guided by relativistic plasma waves (the wake) over tens of vacuum diffraction lengths, to give >1  GeV energy in centimeter-scale low density plasmas using ionization-induced injection to inject charge into the wake even at low densities. By restricting electron injection to a distinct short region, the injector stage, energetic electron beams (of the order of 100 MeV) with a relatively large energy spread are generated. Some of these electrons are then further accelerated by a second, longer accelerator stage, which increases their energy to ∼0.5  GeV while reducing the relative energy spread to <5% FWHM.

  5. Wakefield: Community and Library Analysis.

    ERIC Educational Resources Information Center

    Trumpeter, Margo C.; Donahue, Mary Ellen

    This community analysis was conducted in order to characterize and identify the information needs of the Wakefield community, and library services and use were evaluated to determine how well the library meets these needs. The study included an examination of the history of the town and its physical characteristics, economic development, and…

  6. Group velocity effect on resonant, long-range wake-fields in slow wave structures

    NASA Astrophysics Data System (ADS)

    Smirnov, A. V.

    2002-03-01

    Synchronous wake-fields in a dispersive waveguide are derived in a general explicit form on the basis of a rigorous electro-dynamical approach using Fourier transformations. The fundamental role of group velocity in wake-field propagation, calculation of attenuation, amplitudes, form-factors and loss-factors is analyzed for single bunch radiation. Adiabatic tapering of the waveguide and bunch density variation is taken into account analytically for the time-domain fields. Effects of field "compression/expansion" and group delays are demonstrated. The role of these effects is discussed for single bunch wake-fields, transient beam loading, BBU and HOMs. A novel waveguide structure with central rf coupling and both positive and negative velocities is proposed. It can be used effectively in both high-energy accelerators and single-section linacs.

  7. High Transformer ratios in collinear wakefield accelerators.

    SciTech Connect

    Power, J. G.; Conde, M.; Yusof, Z.; Gai, W.; Jing, C.; Kanreykin, A.; Schoessow, P.; High Energy Physics; Euclid Techlabs, LLC

    2008-01-01

    Based on our previous experiment that successfully demonstrated wakefield transformer ratio enhancement in a 13.625 GHz dielectric-loaded collinear wakefield accelerator using the ramped bunch train technique, we present here a redesigned experimental scheme for even higher enhancement of the efficiency of this accelerator. Design of a collinear wakefield device with a transformer ratio R2, is presented. Using a ramped bunch train (RBT) rather than a single drive bunch, the enhanced transformer ratio (ETR) technique is able to increase the transformer ratio R above the ordinary limit of 2. To match the wavelength of the fundamental mode of the wakefield with the bunch length (sigmaz=2 mm) of the new Argonne wakefield accelerator (AWA) drive gun (where the experiment will be performed), a 26.625 GHz dielectric based accelerating structure is required. This transformer ratio enhancement technique based on our dielectric-loaded waveguide design will result in a compact, high efficiency accelerating structures for future wakefield accelerators.

  8. Development of High Gradient Laser Wakefield Accelerators Towards Nuclear Detection Applications at LBNL

    SciTech Connect

    Geddes, Cameron G. R.; Gonsalves, Anthony J.; Lin Chen; Cormier-Michel, Estelle; Matlis, Nicholas H.; Panasenko, Dmitriy; Plateau, Guillaume R.; Schroeder, Carl B.; Toth, Csaba; Bruhwiler, David L.; Cary, John R.; Esarey, Eric H.; Nakamura, Kei; Bakeman, Mike; Leemans, Wim P.

    2009-03-10

    Compact high-energy linacs are important to applications including monochromatic gamma sources for nuclear material security applications. Recent laser wakefield accelerator experiments at LBNL demonstrated narrow energy spread beams, now with energies of up to 1 GeV in 3 cm using a plasma channel at low density. This demonstrates the production of GeV beams from devices much smaller than conventional linacs, and confirms the anticipated scaling of laser driven accelerators to GeV energies. Stable performance at 0.5 GeV was demonstrated. Experiments and simulations are in progress to control injection of particles into the wake and hence to improve beam quality and stability. Using plasma density gradients to control injection, stable beams at 1 MeV over days of operation, and with an order of magnitude lower absolute momentum spread than previously observed, have been demonstrated. New experiments are post-accelerating the beams from controlled injection experiments to increase beam quality and stability. Thomson scattering from such beams is being developed to provide collimated multi-MeV monoenergetic gamma sources for security applications from compact devices. Such sources can reduce dose to target and increase accuracy for applications including photofission and nuclear resonance fluorescence.

  9. Generation of skewed laser pulses for laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Toth, C.; Faure, J.; Geddes, C. G. R.; van Tilborg, J.; Leemans, W. P.

    2002-11-01

    The effect of asymmetric laser pulses on electron yield from a laser wakefield accelerator has been experimentally studied (W.P. Leemans et al., submitted to Phys. Rev. Lett.) using > 10^19 cm-3 plasmas and a 10 TW, > 45 fs, Ti:Al_2O3 laser. The non-Gaussian laser pulse shapes were controlled through non-linear chirp with a grating pair compressor. Pulses (76 fs FWHM) with a steep rise (positive skew) were found to significantly enhance the electron yield compared to pulses with a gentle rise (negative skew). These results demonstrate that laser wakefield accelerator can be optimized using skewed laser pulses. Controlling the skewness of laser pulses can be done by appropriate choice of the higher order spectral phase coefficients. Details on how this is done using non-linear chirp using grating compressor, as well as an acousto-optic system (DAZZLER) will be presented.

  10. Numerical studies of density transition injection in laser wakefield acceleration

    NASA Astrophysics Data System (ADS)

    Massimo, F.; Lifschitz, A. F.; Thaury, C.; Malka, V.

    2017-08-01

    The quality of laser wakefield accelerated electrons beams is strongly determined by the physical mechanism exploited to inject electrons in the wakefield. One of the techniques used to improve the beam quality is the density transition injection, where the electron trapping occurs as the laser pulse passes a sharp density transition created in the plasma. Although this technique has been widely demonstrated experimentally, the literature lacks theoretical and numerical studies on the effects of all the transition parameters. We thus report and discuss the results of a series of particle in cell (PIC) simulations where the density transition height and downramp length are systematically varied, to show how the electron beam parameters and the injection mechanism are affected by the density transition parameters.

  11. Two-color hybrid laser wakefield and direct laser accelerator

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Khudik, V.; Bernstein, A.; Downer, M.; Shvets, G.

    2017-03-01

    We propose and investigate the concept of two-color laser wakefield and direct acceleration (LWDA) scheme in the regime of moderate (10 TW scale) laser powers. The concept utilizes two unequal frequency laser pulses: the leading long-wavelength (λ0 = 0.8 µm) wakefield laser pulse driving a nonlinear plasma wake, and a trailing short-wavelength (λDLA = λ0/2) DLA laser pulse. The combination of the large electric field, yet small ponderomotive pressure of the DLA pulse is shown to be advantageous for producing a higher energy and larger charge electron beam compared with the single frequency LWDA. The sensitivity of the dual-frequency LWDA to synchronization time jitter is also reduced.

  12. Recent Advances in Plasma Acceleration

    SciTech Connect

    Hogan, Mark

    2007-03-19

    The costs and the time scales of colliders intended to reach the energy frontier are such that it is important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators a drive beam, either laser or particle, produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultra-high accelerating fields over a substantial length to achieve a significant energy gain. More than 42 GeV energy gain was achieved in an 85 cm long plasma wakefield accelerator driven by a 42 GeV electron drive beam in the Final Focus Test Beam (FFTB) Facility at SLAC. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of {approx}52 GV/m. This effectively doubles their energy, producing the energy gain of the 3 km long SLAC accelerator in less than a meter for a small fraction of the electrons in the injected bunch. Prospects for a drive-witness bunch configuration and high-gradient positron acceleration experiments planned for the SABER facility will be discussed.

  13. High energy neutron radiography

    SciTech Connect

    Gavron, A.; Morley, K.; Morris, C.; Seestrom, S.; Ullmann, J.; Yates, G.; Zumbro, J.

    1996-06-01

    High-energy spallation neutron sources are now being considered in the US and elsewhere as a replacement for neutron beams produced by reactors. High-energy and high intensity neutron beams, produced by unmoderated spallation sources, open potential new vistas of neutron radiography. The authors discuss the basic advantages and disadvantages of high-energy neutron radiography, and consider some experimental results obtained at the Weapons Neutron Research (WNR) facility at Los Alamos.

  14. Applications of laser wakefield accelerators for biomedical imaging

    NASA Astrophysics Data System (ADS)

    Najmudin, Zulfikar

    2014-10-01

    Laser-wakefield accelerators driven by high-intensity short-pulse lasers are a proven compact source of high-energy electron beams, with energy gains of ~GeV energy in centimetres of plasma demonstrated. One of the main proposed applications for these accelerators is to drive synchrotron light sources, in particular for x-ray applications. It has also been shown that the same plasma accelerator can also act as a wigglers, capable of the production of high brightness and spatially coherent hard x-ray beams. In this latest work, we demonstrate the application of these unique light-sources for biological and medical applications. The experiments were performed with the Astra Gemini laser at the Rutherford Appleton Laboratory in the UK. Gemini produces laser pulses with energy exceeding 10 J in pulse lengths down to 40 fs. A long focal length parabola (f / 20) is used to focus the laser down to a spot of size approximately 25 μ m (fwhm) into a gas-cell of variable length. Electrons are accelerated to energies up to 1 GeV and a bright beam of x-rays is observed simultaneously with the accelerated beam. The length of the gas cell was optimised to produce high contrast x-ray images of radiographed test objects. This source was then used for imaging a number of interesting medical and biological samples. Full tomographic imaging of a human trabecular bone sample was made with resolution easily exceeding the ~100 μm level required for CT applications. Phase-contrast imaging of human prostrate and mouse neonates at the micron level was also demonstrated. These studies indicate the usefulness of these sources in research and clinical applications. They also show that full 3D imaging can be made possible with this source in a fraction of the time that it would take with a corresponding x-ray tube. The JAI is funded by STFC Grant ST/J002062/1.

  15. High Energy Missile Project

    DTIC Science & Technology

    2004-12-01

    hypervelocity missile concept has been investigated. This research and development project called High Energy Missile (HEMi) technology...currently valid OMB control number. 1. REPORT DATE 00 DEC 2004 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE High Energy

  16. Laser pulse propagation in inhomogeneous magnetoplasma channels and wakefield acceleration

    SciTech Connect

    Sharma, B. S. Jain, Archana; Jaiman, N. K.; Gupta, D. N.; Jang, D. G.; Suk, H.; Kulagin, V. V.

    2014-02-15

    Wakefield excitation in a preformed inhomogeneous parabolic plasma channel by an intense relativistic (≃10{sup 19} W/cm{sup 2}) circularly polarized Gaussian laser pulse is investigated analytically and numerically in the presence of an external longitudinal magnetic field. A three dimensional envelope equation for the evolution of the laser pulse is derived, which includes the effect of the nonparaxial and applied external magnetic field. A relation for the channel radius with the laser spot size is derived and examines numerically to see the external magnetic field effect. It is observed that the channel radius depends on the applied external magnetic field. An analytical expression for the wakefield is derived and validated with the help of a two dimensional particle in cell (2D PIC) simulation code. It is shown that the electromagnetic nature of the wakes in an inhomogeneous plasma channel makes their excitation nonlocal, which results in change of fields with time and external magnetic field due to phase mixing of the plasma oscillations with spatially varying frequencies. The magnetic field effect on perturbation of the plasma density and decreasing length is also analyzed numerically. In addition, it has been shown that the electron energy gain in the inhomogeneous parabolic magnetoplasma channel can be increased significantly compared with the homogeneous plasma channel.

  17. Laser Triggered Electron Injection into a Channel Guided Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Filip, C.

    2005-10-01

    Laser-plasma accelerators have demonstrated the generation of narrow energy spread (˜ few %) electron beams with considerable amount of charge (>100 pC). Stability of laser-plasma accelerators, as in the conventional accelerators, requires highly synchronized injection of electrons into the structured accelerating field. The Colliding Pulse Method[1] with pre-formed plasma channel guiding [2] can result in jitter-free injection in a dark-current-free accelerating structure. We report on experimental progress of laser triggered injection of electrons into a laser wakefield, where an intense laser pulse is guided by a pre-formed plasma channel. The experiments use the multi-beam, multi-terawatt Ti:Al2O3 laser at LOASIS facility of LBNL. The ignitor-heater method is used to first produce a pre-formed plasma channel in a hydrogen gas jet. Two counter propagating beams (wakefield driver:100-500mJ-50fs, injector:50-300mJ-50fs) then are focused onto the entrance of the channel. Preliminary results indicate that electron beam properties are affected by the second beam. Details of the experiment will be presented. [1]G.Fubiani, et al, Phys. Rev. E 70, 016402 (2004). [2]C.G.R. Geddes et al, Nature 431, 538 (2004). This work is supported by DoE under contract DE-AC02-05CH11231.

  18. High-resolution and ultrafast imaging using betatron x-rays from laser wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Najmudin, Zulfikar

    2015-11-01

    Laser wakefield accelerators now routinely produce ~GeV energy gain in ~cm plasmas. and are simultaneously capable of producing high brightness and spatially coherent hard x-ray beams. This unique light-source has been used for medical applications, and also for ultrafast imaging in high energy density science. The experiments were performed with the Astra Gemini laser producing 10 J pulses with duration ~ 40 fs focussed to produce a spot of 25 μ m (fwhm) in a gas-cell of variable length to produce a low divergence beam of x-rays. The length of the gas cell was optimised to produce high contrast x-ray images of radiographed test objects. This source was used for full tomographic imaging of a human trabecular bone sample, with resolution exceeding the ~ 100 μ m level required for CT applications. Phase-contrast imaging of human prostate and mouse neonates at the micron level was also demonstrated. These studies indicate the usefulness of these sources in research and clinical applications. The ultrafast nature of the source was also demonstrated by performing time resolved imaging of a laser driven shock. The ultrashort duration of the x-ray source essentially freeze the motion of these fast moving transient phenomena.

  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. Electron and Positron Beam-Driven Plasma Acceleration

    NASA Astrophysics Data System (ADS)

    Hogan, Mark J.

    Particle accelerators are the ultimate microscopes. They produce high energy beams of particles — or, in some cases, generate X-ray laser pulses — to probe the fundamental particles and forces that make up the universe and to explore the building blocks of life. But it takes huge accelerators, like the Large Hadron Collider or the two-mile-long SLAC linac, to generate beams with enough energy and resolving power. If we could achieve the same thing with accelerators just a few meters long, accelerators and particle colliders could be much smaller and cheaper. Since the first theoretical work in the early 1980s, an exciting series of experiments have aimed at accelerating electrons and positrons to high energies in a much shorter distance by having them "surf" on waves of hot, ionized gas like that found in fluorescent light tubes. Electron-beam-driven experiments have measured the integrated and dynamic aspects of plasma focusing, the bright flux of high energy betatron radiation photons, particle beam refraction at the plasma-neutral-gas interface, and the structure and amplitude of the accelerating wakefield. Gradients spanning kT/m to MT/m for focusing and 100MeV/m to 50 GeV/m for acceleration have been excited in meter-long plasmas with densities of 1014-1017 cm-3, respectively. Positron-beam-driven experiments have evidenced the more complex dynamic and integrated plasma focusing, 100MeV/m to 5 GeV/m acceleration in linear and nonlinear plasma waves, and explored the dynamics of hollow channel plasma structures. Strongly beam-loaded plasma waves have accelerated beams of electrons and positrons with hundreds of pC of charge to over 5 GeV in meter scale plasmas with high efficiency and narrow energy spread. These "plasma wakefield acceleration" experiments have been mounted by a diverse group of accelerator, laser and plasma researchers from national laboratories and universities around the world. This article reviews the basic principles of plasma wakefield

  1. Electron and Positron Beam-Driven Plasma Acceleration

    NASA Astrophysics Data System (ADS)

    Hogan, Mark J.

    Particle accelerators are the ultimate microscopes. They produce high energy beams of particles — or, in some cases, generate X-ray laser pulses — to probe the fundamental particles and forces that make up the universe and to explore the building blocks of life. But it takes huge accelerators, like the Large Hadron Collider or the two-mile-long SLAC linac, to generate beams with enough energy and resolving power. If we could achieve the same thing with accelerators just a few meters long, accelerators and particle colliders could be much smaller and cheaper. Since the first theoretical work in the early 1980s, an exciting series of experiments have aimed at accelerating electrons and positrons to high energies in a much shorter distance by having them “surf” on waves of hot, ionized gas like that found in fluorescent light tubes. Electron-beam-driven experiments have measured the integrated and dynamic aspects of plasma focusing, the bright flux of high energy betatron radiation photons, particle beam refraction at the plasma-neutral-gas interface, and the structure and amplitude of the accelerating wakefield. Gradients spanning kT/m to MT/m for focusing and 100MeV/m to 50GeV/m for acceleration have been excited in meter-long plasmas with densities of 1014-1017cm-3, respectively. Positron-beam-driven experiments have evidenced the more complex dynamic and integrated plasma focusing, 100MeV/m to 5GeV/m acceleration in linear and nonlinear plasma waves, and explored the dynamics of hollow channel plasma structures. Strongly beam-loaded plasma waves have accelerated beams of electrons and positrons with hundreds of pC of charge to over 5GeV in meter scale plasmas with high efficiency and narrow energy spread. These “plasma wakefield acceleration” experiments have been mounted by a diverse group of accelerator, laser and plasma researchers from national laboratories and universities around the world. This article reviews the basic principles of plasma

  2. Wakefield suppression using beatwave structures

    SciTech Connect

    Yu, D.; Kim, J.S.

    1991-12-31

    A proposed method of suppressing transverse wakefields in an accelerating structure makes use of the fact that superposition of long-range wakes excited by an electron bunch transversing a series of accelerating cells with different transverse frequencies can produce interference cancellation, thereby significantly reducing the magnitudes of the harmful wake potentials. Analytic calculations as well as time-domain and modal sum simulations are performed to the beatwave effects produced by detuned, disk-loaded cavities as function of their transverse frequency spread and the population density.

  3. Role of stochastic heating in wakefield acceleration when optical injection is used

    SciTech Connect

    Rassou, S.; Bourdier, A.; Drouin, M.

    2014-08-15

    The dynamics of an electron in two counterpropagating waves is investigated. Conditions for stochastic acceleration are derived. The possibility of stochastic heating is confirmed when two waves interact with low density plasma by performing PIC (Particle In Cell) code simulations. It is shown that stochastic heating can play an important role in laser wakefield acceleration. When considering low density plasma interacting with a high intensity wave perturbed by a low intensity counterpropagating wave, stochastic heating can provide electrons with the right momentum for trapping in the wakefield. The influence of stochastic acceleration on the trapping of electrons is compared to the one of the beatwave force which is responsible for cold injection. To do so, several polarizations for the colliding pulses are considered. For some value of the plasma density and pulse duration, a transition from an injection due to stochastic acceleration to a cold injection dominated regime—regarding the trapped charge—has been observed from 2D and 3D PIC code simulations. This transition is ruled by the ratio of the interaction length of the pulses to the longitudinal size of the bubble. When the interaction length of the laser pulses reaches the radius of the accelerating cavity stochastic heating becomes dominant, and might be necessary to get electrons trapped into the wakefield, when wakefield inhibition grows with plasma density.

  4. Generation of electron beams from a laser wakefield acceleration in pure neon gas

    SciTech Connect

    Li, Song; Hafz, Nasr A. M. Mirzaie, Mohammad; Elsied, Ahmed M. M.; Ge, Xulei; Liu, Feng; Sokollik, Thomas; Chen, Min; Sheng, Zhengming; Zhang, Jie; Tao, Mengze; Chen, Liming

    2014-08-15

    We report on the generation of quasimonoenergetic electron beams by the laser wakefield acceleration of 17–50 TW, 30 fs laser pulses in pure neon gas jet. The generated beams have energies in the range 40–120 MeV and up to ∼430 pC of charge. At a relatively high density, we observed multiple electron beamlets which has been interpreted by simulations to be the result of breakup of the laser pulse into multiple filaments in the plasma. Each filament drives its own wakefield and generates its own electron beamlet.

  5. Wakefields in Coherent Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Billinghurst, Brant E.; Bergstrom, J. C.; Baribeau, C.; Batten, T.; Dallin, L.; May, Tim E.; Vogt, J. M.; Wurtz, Ward A.; Warnock, Robert L.; Bizzozero, D. A.; Kramer, S.; Michaelian, K. H.

    2016-06-01

    When the electron bunches in a storage ring are sufficiently short the electrons act coherently producing radiation several orders of magnitude more intense than normal synchrotron radiation. This is referred to as Coherent Syncrotron Radiation (CSR). Due to the potential of CSR to provide a good source of Terahertz radiation for our users, the Canadian Light Source (CLS) has been researching the production and application of CSR. CSR has been produced at the CLS for many years, and has been used for a number of applications. However, resonances that permeate the spectrum at wavenumber intervals of 0.074 cm-1, and are highly stable under changes in the machine setup, have hampered some experiments. Analogous resonances were predicted long ago in an idealized theory. Through experiments and further calculations we elucidate the resonance and wakefield mechanisms in the CLS vacuum chamber. The wakefield is observed directly in the 30-110 GHz range by rf diodes. These results are consistent with observations made by the interferometer in the THz range. Also discussed will be some practical examples of the application of CSR for the study of condensed phase samples using both transmission and Photoacoustic techniques.

  6. Transformer ratio saturation in a beam-driven wakefield accelerator

    SciTech Connect

    Farmer, J. P.; Martorelli, R.; Pukhov, A.

    2015-12-15

    We show that for beam-driven wakefield acceleration, the linearly ramped, equally spaced train of bunches typically considered to optimise the transformer ratio only works for flat-top bunches. Through theory and simulation, we explain that this behaviour is due to the unique properties of the plasma response to a flat-top density profile. Calculations of the optimal scaling for a train of Gaussian bunches show diminishing returns with increasing bunch number, tending towards saturation. For a periodic bunch train, a transformer ratio of 23 was achieved for 50 bunches, rising to 40 for a fully optimised beam.

  7. High transformer ratio drive beams for wakefield accelerator studies

    SciTech Connect

    England, R. J.; Ng, C.-K.; Frederico, J.; Hogan, M. J.; Litos, M.; Muggli, P.; Joshi, C.; An, W.; Andonian, G.; Mori, W.; Lu, W.

    2012-12-21

    For wakefield based acceleration schemes, use of an asymmetric (or linearly ramped) drive bunch current profile has been predicted to enhance the transformer ratio and generate large accelerating wakes. We discuss plans and initial results for producing such bunches using the 20 to 23 GeV electron beam at the FACET facility at SLAC National Accelerator Laboratory and sending them through plasmas and dielectric tubes to generate transformer ratios greater than 2 (the limit for symmetric bunches). The scheme proposed utilizes the final FACET chicane compressor and transverse collimation to shape the longitudinal phase space of the beam.

  8. Quasi-stable injection channels in a wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Wiltshire-Turkay, Mara; Farmer, John P.; Pukhov, Alexander

    2016-05-01

    The influence of initial position on the acceleration of externally injected electrons in a plasma wakefield is investigated. Test-particle simulations show previously unobserved complex structure in the parameter space, with quasi-stable injection channels forming for particles injected in narrow regions away from the wake centre. Particles injected into these channels remain in the wake for a considerable time after dephasing and as a result achieve significantly higher energy than their neighbours. The result is relevant to both the planning and optimisation of experiments making use of external injection.

  9. Quasi-stable injection channels in a wakefield accelerator

    SciTech Connect

    Wiltshire-Turkay, Mara; Farmer, John P.; Pukhov, Alexander

    2016-05-15

    The influence of initial position on the acceleration of externally injected electrons in a plasma wakefield is investigated. Test-particle simulations show previously unobserved complex structure in the parameter space, with quasi-stable injection channels forming for particles injected in narrow regions away from the wake centre. Particles injected into these channels remain in the wake for a considerable time after dephasing and as a result achieve significantly higher energy than their neighbours. The result is relevant to both the planning and optimisation of experiments making use of external injection.

  10. High-energy detector

    DOEpatents

    Bolotnikov, Aleksey E [South Setauket, NY; Camarda, Giuseppe [Farmingville, NY; Cui, Yonggang [Upton, NY; James, Ralph B [Ridge, NY

    2011-11-22

    The preferred embodiments are directed to a high-energy detector that is electrically shielded using an anode, a cathode, and a conducting shield to substantially reduce or eliminate electrically unshielded area. The anode and the cathode are disposed at opposite ends of the detector and the conducting shield substantially surrounds at least a portion of the longitudinal surface of the detector. The conducting shield extends longitudinally to the anode end of the detector and substantially surrounds at least a portion of the detector. Signals read from one or more of the anode, cathode, and conducting shield can be used to determine the number of electrons that are liberated as a result of high-energy particles impinge on the detector. A correction technique can be implemented to correct for liberated electron that become trapped to improve the energy resolution of the high-energy detectors disclosed herein.

  11. High Energy Astrophysics Program

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This report reviews activities performed by members of the USRA (Universities Space Research Association) contract team during the six months during the reporting period (10/95 - 3/96) and projected activities during the coming six months. Activities take place at the Goddard Space Flight Center, within the Laboratory for High Energy Astrophysics. Developments concern instrumentation, observation, data analysis, and theoretical work in Astrophysics. Missions supported include: Advanced Satellite for Cosmology and Astrophysics (ASCA), X-ray Timing Experiment (XTE), X-ray Spectrometer (XRS), Astro-E, High Energy Astrophysics Science, Archive Research Center (HEASARC), and others.

  12. High Energy Astrophysics Program

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This report reviews activities performed-by members of the USRA contract team during the six months of the reporting period and projected activities during the coming six months. Activities take place at the Goddard Space Flight Center, visiting the Laboratory for High Energy Astrophysics. Developments concern instrumentation, observation, data analysis, and theoretical work in Astrophysics. Missions supported include: Advanced Satellite for Cosmology and Astrophysics (ASCA); X-ray Timing Experiment (XTE); X-ray Spectrometer (XRS); Astro-E; High Energy Astrophysics Science Archive Research Center (HEASARC), and others.

  13. The evolution of high energy accelerators

    SciTech Connect

    Courant, E.D.

    1994-08-01

    Accelerators have been devised and built for two reasons: In the first place, by physicists who needed high energy particles in order to have a means to explore the interactions between particles that probe the fundamental elementary forces of nature. And conversely, sometimes accelerator builders produce new machines for higher energy than ever before just because it can be done, and then challenge potential users to make new discoveries with the new means at hand. These two approaches or motivations have gone hand in hand. This lecture traces how high energy particle accelerators have grown from tools used for esoteric small-scale experiments to the gigantic projects of today. So far all the really high-energy machines built and planned in the world--except the SLC--have been ring accelerators and storage rings using the strong-focusing method. But this method has not removed the energy limit, it has only pushed it higher. It would seem unlikely that one can go beyond the Large Hadron Collider (LHC)--but in fact a workshop was held in Sicily in November 1991, concerned with the question of extrapolating to 100 TeV. Other acceleration and beam-forming methods are now being discussed--collective fields, laser acceleration, wake-field accelerators etc., all aimed primarily at making linear colliders possible and more attractive than with present radiofrequency methods. So far it is not entirely clear which of these schemes will dominate particle physics in the future--maybe something that has not been thought of as yet.

  14. Plasma undulator excited by high-order mode lasers

    NASA Astrophysics Data System (ADS)

    Wang, Jingwei; Rykovanov, Sergey

    2016-10-01

    A laser-created plasma undulator together with a laser-plasma accelerator makes it possible to construct an economical and extremely compact XFEL. However, the spectrum spread of the radiation from the current plasma undulators is too large for XFELs, because of the different values of strength parameters. The phase slippage between the electrons and the wakefield also limits the number of the electron oscillation cycles, thus reduces the performance of XFEL. Here we proposed a phase-locked plasma undulator created by high-order mode lasers. The modulating field is uniform along the transverse direction by choosing appropriate laser intensities of the modes, which enables all the electrons oscillate with the same strength parameter. The plasma density is tapered to lock the phase between the electrons and the wakefield, which signally increases the oscillation cycles. As a result, X-ray radiation with high brightness and narrow bandwidth is generated by injecting a high-energy electron beam into the novel plasma undulator. The beam loading limit indicates that the current of the electron beam could be hundreds of Ampere. These properties imply that such a plasma undulator may have great potential in compact XFELs. This work was supported by the Helmholtz Association (Young Investigator's Group No. VH-NG-1037).

  15. High Energy Exoplanet Transits

    NASA Astrophysics Data System (ADS)

    Llama, Joe; Shkolnik, Evgenya L.

    2017-10-01

    X-ray and ultraviolet transits of exoplanets allow us to probe the atmospheres of these worlds. High energy transits have been shown to be deeper but also more variable than in the optical. By simulating exoplanet transits using high-energy observations of the Sun, we can test the limits of our ability to accurately measure the properties of these planets in the presence of stellar activity. We use both disk-resolved images of the Solar disk spanning soft X-rays, the ultraviolet, and the optical and also disk-integrated Sun-as-a-star observations of the Lyα irradiance to simulate transits over a wide wavelength range. We find that for stars with activity levels similar to the Sun, the planet-to-star radius ratio can be overestimated by up to 50% if the planet occults an active region at high energies. We also compare our simulations to high energy transits of WASP-12b, HD 189733, 55 Cnc b, and GJ 436b.

  16. High energy colliders

    SciTech Connect

    Palmer, R.B.; Gallardo, J.C.

    1997-02-01

    The authors consider the high energy physics advantages, disadvantages and luminosity requirements of hadron (pp, p{anti p}), lepton (e{sup +}e{sup {minus}}, {mu}{sup +}{mu}{sup {minus}}) and photon-photon colliders. Technical problems in obtaining increased energy in each type of machine are presented. The machines relative size are also discussed.

  17. High energy particle astronomy.

    NASA Technical Reports Server (NTRS)

    Buffington, A.; Muller, R. A.; Smith, L. H.; Smoot, G. F.

    1972-01-01

    Discussion of techniques currently used in high energy particle astronomy for measuring charged and neutral cosmic rays and their isotope and momentum distribution. Derived from methods developed for accelerator experiments in particle physics, these techniques help perform important particle astronomy experiments pertaining to nuclear cosmic ray and gamma ray research, electron and position probes, and antimatter searches.

  18. High energy particle astronomy.

    NASA Technical Reports Server (NTRS)

    Buffington, A.; Muller, R. A.; Smith, L. H.; Smoot, G. F.

    1972-01-01

    Discussion of techniques currently used in high energy particle astronomy for measuring charged and neutral cosmic rays and their isotope and momentum distribution. Derived from methods developed for accelerator experiments in particle physics, these techniques help perform important particle astronomy experiments pertaining to nuclear cosmic ray and gamma ray research, electron and position probes, and antimatter searches.

  19. Inorganic High Energy Oxidisers,

    DTIC Science & Technology

    properties may contribute significantly to the energy of the whole system. A book entitled ’Inorganic High - Energy Oxidisers’ by E.W. Lawless and I.C. Smith is the subject of this Essay Review by W.E. Batty.

  20. High Energy Astronomy Observatory

    NASA Technical Reports Server (NTRS)

    1980-01-01

    An overview of the High Energy Astronomy Observatory 2 contributions to X-ray astronomy is presented along with a brief description of the satellite and onboard telescope. Observations relating to galaxies and galactic clusters, black holes, supernova remnants, quasars, and cosmology are discussed.