Development of a beam ion velocity detector for the heavy ion beam probe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fimognari, P. J., E-mail: PJFimognari@XanthoTechnologies.com; Crowley, T. P.; Demers, D. R.

2016-11-15

In an axisymmetric plasma, the conservation of canonical angular momentum constrains heavy ion beam probe (HIBP) trajectories such that measurement of the toroidal velocity component of secondary ions provides a localized determination of the poloidal flux at the volume where they originated. We have developed a prototype detector which is designed to determine the beam angle in one dimension through the detection of ion current landing on two parallel planes of detecting elements. A set of apertures creates a pattern of ion current on wires in the first plane and solid metal plates behind them; the relative amounts detected bymore » the wires and plates determine the angle which beam ions enter the detector, which is used to infer the toroidal velocity component. The design evolved from a series of simulations within which we modeled ion beam velocity changes due to equilibrium and fluctuating magnetic fields, along with the ion beam profile and velocity dispersion, and studied how these and characteristics such as the size, cross section, and spacing of the detector elements affect performance.« less

Local modifications of magnetism and structure in FePt (001) epitaxial thin films by focused ion beam: Two-dimensional perpendicular patterns

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albertini, F.; Nasi, L.; Casoli, F.

Focused ion beam was utilized to locally modify magnetism and structure of L1{sub 0} FePt perpendicular thin films. As a first step, we have performed a magnetic, morphological, and structural study of completely irradiated FePt films with different Ga{sup +} doses (1x10{sup 13} -4x10{sup 16} ions/cm{sup 2}) and ion beam energy of 30 keV. For doses of 1x10{sup 14} ions/cm{sup 2} and above a complete transition from the ordered L1{sub 0} to the disordered A1 phase was found to occur, resulting in a drop of magnetic anisotropy and in the consequent moment reorientation from out-of-plane to in-plane. The lowest effectivemore » dose in disordering the structure (1x10{sup 14} ions/cm{sup 2}) was found not to affect the film morphology. Taking advantage of these results, continuous two-dimensional (2D) patterns of perpendicular magnetic structures (250 nm dots, 1 {mu}m dots, 1 {mu}m-large stripes) were produced by focused ion beam without affecting the morphology. The 2D patterns were revealed by means of magnetic force microscopy, that evidenced peculiar domain structures in the case of 1 {mu}m dots.« less

Three-dimensional patterning in polymer optical waveguides using focused ion beam milling

NASA Astrophysics Data System (ADS)

Kruse, Kevin; Burrell, Derek; Middlebrook, Christopher

2016-07-01

Waveguide (WG) photonic-bridge taper modules are designed for symmetric planar coupling between silicon WGs and single-mode fibers (SMFs) to minimize photonic chip and packaging footprint requirements with improving broadband functionality. Micromachined fabrication and evaluation of polymer WG tapers utilizing high-resolution focused ion beam (FIB) milling is performed and presented. Polymer etch rates utilizing the FIB and optimal methods for milling polymer tapers are identified for three-dimensional patterning. Polymer WG tapers with low sidewall roughness are manufactured utilizing FIB milling and optically tested for fabrication loss. FIB platforms utilize a focused beam of ions (Ga+) to etch submicron patterns into substrates. Fabricating low-loss polymer WG taper prototypes with the FIB before moving on to mass-production techniques provides theoretical understanding of the polymer taper and its feasibility for connectorization devices between silicon WGs and SMFs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bischoff, Lothar, E-mail: l.bischoff@hzdr.de; Mazarov, Paul, E-mail: Paul.Mazarov@raith.de; Bruchhaus, Lars, E-mail: Lars.Bruchhaus@raith.de

Today, Focused Ion Beam (FIB) processing is nearly exclusively based on gallium Liquid Metal Ion Sources (LMIS). But, many applications in the μm- or nm range could benefit from ion species other than gallium: local ion implantation, ion beam mixing, ion beam synthesis, or Focused Ion Beam Lithography (IBL). Therefore, Liquid Metal Alloy Ion Sources (LMAIS) represent a promising alternative to expand the remarkable application fields for FIB. Especially, the IBL process shows potential advantages over, e.g., electron beam or other lithography techniques: direct, resistless, and three-dimensional patterning, enabling a simultaneous in-situ process control by cross-sectioning and inspection. Taking additionallymore » into account that the used ion species influences significantly the physical and chemical nature of the resulting nanostructures—in particular, the electrical, optical, magnetic, and mechanic properties leading to a large potential application area which can be tuned by choosing a well suited LMAIS. Nearly half of the elements of the periodic table are recently available in the FIB technology as a result of continuous research in this area during the last forty years. Key features of a LMAIS are long life-time, high brightness, and stable ion current. Recent developments could make these sources feasible for nano patterning issues as an alternative technology more in research than in industry. The authors will review existing LMAIS, LMIS other than Ga, and binary and ternary alloys. These physical properties as well as the fabrication technology and prospective domains for modern FIB applications will similarly be reviewed. Other emerging ion sources will be also presented and their performances discussed.« less

Formation and characterization of perpendicular mode Si ripples by glancing angle O{sub 2}{sup +} sputtering at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mollick, S. A.; Ghose, D.

Off-normal low energy ion beam sputtering of solid surfaces often leads to morphological instabilities resulting in the spontaneous formation of ripple structures in nanometer length scales. In the case of Si surfaces at ambient temperature, ripple formation is found to take place normally at lower incident angles with the wave vector parallel to the ion beam direction. The absence of ripple pattern on Si surface at larger angles is due to the dominance of ion beam polishing effect. We have shown that a gentle chemical roughening of the starting surface morphology can initiate ripple pattern under grazing incidence ion beammore » sputtering (theta>64 deg. with respect to the surface normal), where the ripple wave vector is perpendicular to the ion beam direction. The characteristics of the perpendicular mode ripples are studied as a function of pristine surface roughness (2-30 nm) and projectile fluence (5x10{sup 16}-1.5x10{sup 18} O atoms cm{sup -2}). The quality of the morphological structure is assessed from the analysis of ion induced topological defects.« less

Matrices pattern using FIB; 'Out-of-the-box' way of thinking.

PubMed

Fleger, Y; Gotlib-Vainshtein, K; Talyosef, Y

2017-03-01

Focused ion beam (FIB) is an extremely valuable tool in nanopatterning and nanofabrication for potentially high-resolution patterning, especially when refers to He ion beam microscopy. The work presented here demonstrates an 'out-of-the-box' method of writing using FIB, which enables creating very large matrices, up to the beam-shift limitation, in short times and with high accuracy unachievable by any other writing technique. The new method allows combining different shapes in nanometric dimensions and high resolutions for wide ranges. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Direct nano-patterning of graphene with helium ion beams

NASA Astrophysics Data System (ADS)

Naitou, Y.; Iijima, T.; Ogawa, S.

2015-01-01

Helium ion microscopy (HIM) was used for direct nano-patterning of single-layer graphene (SLG) on SiO2/Si substrates. This technique involves irradiation of the sample with accelerated helium ions (He+). Doses of 2.0 × 1016 He+ cm-2 from a 30 kV beam induced a metal-insulator transition in the SLG. The resolution of HIM patterning on SLG was investigated by fabricating nanoribbons and nanostructures. Analysis of scanning capacitance microscopy measurements revealed that the spatial resolution of HIM patterning depended on the dosage of He+ in a non-monotonic fashion. Increasing the dose from 2.0 × 1016 to 5.0 × 1016 He+ cm-2 improved the spatial resolution to several tens of nanometers. However, doses greater than 1.0 × 1017 He+ cm-2 degraded the patterning characteristics. Direct patterning using HIM is a versatile approach to graphene fabrication and can be applied to graphene-based devices.

Self-organised silicide nanodot patterning by medium-energy ion beam sputtering of Si(100): local correlation between the morphology and metal content.

PubMed

Redondo-Cubero, A; Galiana, B; Lorenz, K; Palomares, F J; Bahena, D; Ballesteros, C; Hernandez-Calderón, I; Vázquez, L

2016-11-04

We have produced self-organised silicide nanodot patterns by medium-energy ion beam sputtering (IBS) of silicon targets with a simultaneous and isotropic molybdenum supply. Atomic force microscopy (AFM) studies show that these patterns are qualitatively similar to those produced thus far at low ion energies. We have determined the relevance of the ion species on the pattern ordering and properties. For the higher ordered patterns produced by Xe(+) ions, the pattern wavelength depends linearly on the ion energy. The dot nanostructures are silicide-rich as assessed by x-ray photoelectron spectroscopy (XPS) and emerge in height due to their lower sputtering yield, as observed by electron microscopy. Remarkably, a long wavelength corrugation is observed on the surface which is correlated with both the Mo content and the dot pattern properties. Thus, as assessed by electron microscopy, the protrusions are Mo-rich with higher and more spaced dots on their surface whereas the valleys are Mo-poor with smaller dots that are closer to each other. These findings indicate that there is a correlation between the local metal content of the surface and the nanodot pattern properties both at the nanodot and the large corrugation scales. These results contribute to advancing the understanding of this interesting nanofabrication method and aid in developing a comprehensive theory of nanodot pattern formation and evolution.

Concurrent segregation and erosion effects in medium-energy iron beam patterning of silicon surfaces

NASA Astrophysics Data System (ADS)

Redondo-Cubero, A.; Lorenz, K.; Palomares, F. J.; Muñoz, A.; Castro, M.; Muñoz-García, J.; Cuerno, R.; Vázquez, L.

2018-07-01

We have bombarded crystalline silicon targets with a 40 keV Fe+ ion beam at different incidence angles. The resulting surfaces have been characterized by atomic force, current-sensing and magnetic force microscopies, scanning electron microscopy, and x-ray photoelectron spectroscopy. We have found that there is a threshold angle smaller than 40° for the formation of ripple patterns, which is definitely lower than those frequently reported for noble gas ion beams. We compare our observations with estimates of the value of the critical angle and of additional basic properties of the patterning process, which are based on a continuum model whose parameters are obtained from binary collision simulations. We have further studied experimentally the ripple structures and measured how the surface slopes change with the ion incidence angle. We explore in particular detail the fluence dependence of the pattern for an incidence angle value (40°) close to the threshold. Initially, rimmed holes appear randomly scattered on the surface, which evolve into large, bug-like structures. Further increasing the ion fluence induces a smooth, rippled background morphology. By means of microscopy techniques, a correlation between the morphology of these structures and their metal content can be unambiguously established.

Evaluating focused ion beam patterning for position-controlled nanowire growth using computer vision

NASA Astrophysics Data System (ADS)

Mosberg, A. B.; Myklebost, S.; Ren, D.; Weman, H.; Fimland, B. O.; van Helvoort, A. T. J.

2017-09-01

To efficiently evaluate the novel approach of focused ion beam (FIB) direct patterning of substrates for nanowire growth, a reference matrix of hole arrays has been used to study the effect of ion fluence and hole diameter on nanowire growth. Self-catalyzed GaAsSb nanowires were grown using molecular beam epitaxy and studied by scanning electron microscopy (SEM). To ensure an objective analysis, SEM images were analyzed with computer vision to automatically identify nanowires and characterize each array. It is shown that FIB milling parameters can be used to control the nanowire growth. Lower ion fluence and smaller diameter holes result in a higher yield (up to 83%) of single vertical nanowires, while higher fluence and hole diameter exhibit a regime of multiple nanowires. The catalyst size distribution and placement uniformity of vertical nanowires is best for low-value parameter combinations, indicating how to improve the FIB parameters for positioned-controlled nanowire growth.

Kinetic Monte Carlo simulation of self-organized pattern formation induced by ion beam sputtering using crater functions

NASA Astrophysics Data System (ADS)

Yang, Zhangcan; Lively, Michael A.; Allain, Jean Paul

2015-02-01

The production of self-organized nanostructures by ion beam sputtering has been of keen interest to researchers for many decades. Despite numerous experimental and theoretical efforts to understand ion-induced nanostructures, there are still many basic questions open to discussion, such as the role of erosion or curvature-dependent sputtering. In this work, a hybrid MD/kMC (molecular dynamics/kinetic Monte Carlo) multiscale atomistic model is developed to investigate these knowledge gaps, and its predictive ability is validated across the experimental parameter space. This model uses crater functions, which were obtained from MD simulations, to model the prompt mass redistribution due to single-ion impacts. Defect migration, which is missing from previous models that use crater functions, is treated by a kMC Arrhenius method. Using this model, a systematic study was performed for silicon bombarded by Ar+ ions of various energies (100 eV, 250 eV, 500 eV, 700 eV, and 1000 eV) at incidence angles of 0∘ to 80∘. The simulation results were compared with experimental findings, showing good agreement in many aspects of surface evolution, such as the phase diagram. The underestimation of the ripple wavelength by the simulations suggests that surface diffusion is not the main smoothening mechanism for ion-induced pattern formation. Furthermore, the simulated results were compared with moment-description continuum theory and found to give better results, as the simulation did not suffer from the same mathematical inconsistencies as the continuum model. The key finding was that redistributive effects are dominant in the formation of flat surfaces and parallel-mode ripples, but erosive effects are dominant at high angles when perpendicular-mode ripples are formed. Ion irradiation with simultaneous sample rotation was also simulated, resulting in arrays of square-ordered dots. The patterns obtained from sample rotation were strongly correlated to the rotation speed and to the pattern types formed without sample rotation, and a critical value of about 5 rpm was found between disordered ripples and square-ordered dots. Finally, simulations of dual-beam sputtering were performed, with the resulting patterns determined by the flux ratio of the two beams and the pattern types resulting from single-beam sputtering under the same conditions.

Experimental Study of Proton Acceleration from Ultra Intense Laser Matter Interactions

NASA Astrophysics Data System (ADS)

Paudel, Yadab Kumar

This dissertation describes proton and ion acceleration measurements from high intensity (˜ 1019 Wcm-2) laser interactions with thin foil targets. Protons and ions accelerated from the back surface of a target driven by a high intensity laser are detected using solid-state nuclear track detector CR39. A simple digital imaging technique, with an adjustable halogen light source shined on CR39 and use of a digital camera with suitable f-number and exposure time, is used to detect particles tracks. This new technique improves the quality 2D image with vivid track patterns in CR39. Our technique allows us to quickly record and sort CR39 pieces for further analysis. This is followed by detailed quantitative information on the protons and ions. Protons and multicharged ions generated from high-intensity laser interactions with thin foil targets have been studied with a 100 TW laser system. Protons/ions with energies up to 10 MeV are accelerated either from the front or the rear surface of the target material. We have observed for the first time a self-radiograph of the target with a glass stalk holding the target itself in the stacked radiochromic films (RCF) placed behind the target. The self-radiography indicates that the fast ions accelerated backward, in a direction opposite to the laser propagation, are turning around in strong magnetic fields. This unique result is a signature of long-living (ns time scale) magnetic fields in the expanding plasma, which are important in energy transport during the intense laser irradiation and have never been considered in the previous studies. The magnetic fields induced by the main pulse near the absorption point expand rapidly with the backward accelerated protons in the pre-formed plasma. The protons are rotated by these magnetic fields and they are recorded in the RCF, making the self-radiography. Angular profiles of protons and multicharged ions accelerated from the target rear surface have been studied with the subpicosecond laser pulse produced by the 100 TW laser system. The protons/ions beam features recorded on CR39 show the hollow beam structure at the center of the beam pattern. This hollow structure in the proton/ion beam pattern associates to the electron transport inside the solid target, which affects the target's rear-surface emission or the electrostatic profile on the target rear-surface. The proton/ion beam filamentation has been seen clearly outside the hollow beam pattern in the CR39 images processed by the new digital imaging technique.

Silicon patterning using ion blistering and e-beam lithography

NASA Astrophysics Data System (ADS)

Giguere, A.; Terreault, B.; Beerens, J.; Aimez, V.; Beauvais, J.

2004-03-01

We explore the limits of silicon patterning using ion blistering in conjunction with e-beam lithography. In a first approach, we implanted 3.5E16 H/cm**2 at 5 keV through variable width (0.1-10 micron) e-beam written PMMA masks. The resist was then removed and the samples were rapid-thermal-annealed (RTA) up to 650 °C. In the wider trenches, round blisters with 800-900 nm diameter and 15 nm height and a few exfoliations are observed, which are similar to those observed on an unmasked surface. In submicron trenches (500-1000 nm), there is a transition in morphology created by the proximity to the border; the blisters are smaller and they are densely aligned along the trench direction ("pearl-string" pattern). No effect is observed in the lowest dimension trenches. The results are discussed in terms of stress/strain fields, defect configuration, and mask shadowing and charging effects. Ultimate pattern resolution will be limited by lateral straggling of the ions in and by the mechanics of lateral crack propagation.

Polyatomic ions from a high current ion implanter driven by a liquid metal ion source.

PubMed

Pilz, W; Laufer, P; Tajmar, M; Böttger, R; Bischoff, L

2017-12-01

High current liquid metal ion sources are well known and found their first application as field emission electric propulsion thrusters in space technology. The aim of this work is the adaption of such kind of sources in broad ion beam technology. Surface patterning based on self-organized nano-structures on, e.g., semiconductor materials formed by heavy mono- or polyatomic ion irradiation from liquid metal (alloy) ion sources (LMAISs) is a very promising technique. LMAISs are nearly the only type of sources delivering polyatomic ions from about half of the periodic table elements. To overcome the lack of only very small treated areas by applying a focused ion beam equipped with such sources, the technology taken from space propulsion systems was transferred into a large single-end ion implanter. The main component is an ion beam injector based on high current LMAISs combined with suited ion optics allocating ion currents in the μA range in a nearly parallel beam of a few mm in diameter. Different types of LMAIS (needle, porous emitter, and capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a 200 kV high current ion implanter operating at the HZDR Ion Beam Center. Finally, the obtained results of large area surface modification of Ge using polyatomic Bi 2 + ions at room temperature from a GaBi capillary LMAIS will be presented and discussed.

Polyatomic ions from a high current ion implanter driven by a liquid metal ion source

NASA Astrophysics Data System (ADS)

Pilz, W.; Laufer, P.; Tajmar, M.; Böttger, R.; Bischoff, L.

2017-12-01

High current liquid metal ion sources are well known and found their first application as field emission electric propulsion thrusters in space technology. The aim of this work is the adaption of such kind of sources in broad ion beam technology. Surface patterning based on self-organized nano-structures on, e.g., semiconductor materials formed by heavy mono- or polyatomic ion irradiation from liquid metal (alloy) ion sources (LMAISs) is a very promising technique. LMAISs are nearly the only type of sources delivering polyatomic ions from about half of the periodic table elements. To overcome the lack of only very small treated areas by applying a focused ion beam equipped with such sources, the technology taken from space propulsion systems was transferred into a large single-end ion implanter. The main component is an ion beam injector based on high current LMAISs combined with suited ion optics allocating ion currents in the μA range in a nearly parallel beam of a few mm in diameter. Different types of LMAIS (needle, porous emitter, and capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a 200 kV high current ion implanter operating at the HZDR Ion Beam Center. Finally, the obtained results of large area surface modification of Ge using polyatomic Bi2+ ions at room temperature from a GaBi capillary LMAIS will be presented and discussed.

Channeling STIM analysis of radiation damage in single crystal diamond membrane

NASA Astrophysics Data System (ADS)

Sudić, I.; Cosic, D.; Ditalia Tchernij, S.; Olivero, P.; Pomorski, M.; Skukan, N.; Jakšić, M.

2017-08-01

The use of focused ion beam transmission channeling patterns to monitor the damage creation process in thin diamond single crystal membrane is described. A 0.8 MeV proton beam from the Ruđer Bošković Institute nuclear microprobe was used to perform Channeling Scanning Transmission Ion Microscopy (CSTIM) measurements. CSTIM was used instead of RBS channeling because of (several orders of magnitude) lower damage done to the sample during the measurements. Damage was introduced in selected areas by 15 MeV carbon beam in range of fluences 3·1015-2·1017 ions/cm2. Contrary to Ion Beam Induced Charge (IBIC), CSTIM is shown to be sensitive to the large fluences of ion beam radiation. Complementary studies of both IBIC and CSTIM are presented to show that very high fluence range can be covered by these two microprobe techniques, providing much wider information about the diamond radiation hardness. In addition micro Raman measurements were performed and the height of the GR 1 peak was correlated to the ion beam fluence.

Synthesis of metal nanoparticle and patterning in polymeric films induced by electron beam

NASA Astrophysics Data System (ADS)

Yamamoto, Hiroki; Kozawa, Takahiro; Tagawa, Seiichi; Marignier, Jean-Louis; Mostafavi, Mehran; Belloni, Jacqueline

2018-03-01

Using an electron beam, thin polymeric films loaded with metal nanoparticles of silver were prepared by a one-step irradiation-induced reduction of the metal ions embedded in the polymer. The metal nanoparticles were observed by either optical absorption or microscopy. The mechanism of the reduction of metal ions and of the polymer crosslinking were deduced from the average absorbance measurements. In view of realizing specific patterns of high resolution using the electron beam, electron beam produces 200 nm wide lines that can be separated by unexposed spaces of adjustable width, where precursors were dissolved. The resolution of the electron beam has been exploited to demonstrate the achievement of nanopatterning on polymer films using a direct-writing process. This method supplies interesting applications such as masks, replicas, or imprint molds of improved density and contrast.

Operation of the CAPRICE electron cyclotron resonance ion source applying frequency tuning and double frequency heating.

PubMed

Maimone, F; Tinschert, K; Celona, L; Lang, R; Mäder, J; Rossbach, J; Spädtke, P

2012-02-01

The properties of the electromagnetic waves heating the electrons of the ECR ion sources (ECRIS) plasma affect the features of the extracted ion beams such as the emittance, the shape, and the current, in particular for higher charge states. The electron heating methods such as the frequency tuning effect and the double frequency heating are widely used for enhancing the performances of ECRIS or even for the routine operation during the beam production. In order to better investigate these effects the CAPRICE ECRIS has been operated using these techniques. The ion beam properties for highly charged ions have been measured with beam diagnostic tools. The reason of the observed variations of this performance can be related to the different electromagnetic field patterns, which are changing inside the plasma chamber when the frequency is varying.

Patterned microstructures formed with MeV Au implantation in Si(1 0 0)

NASA Astrophysics Data System (ADS)

Rout, Bibhudutta; Greco, Richard R.; Zachry, Daniel P.; Dymnikov, Alexander D.; Glass, Gary A.

2006-09-01

Energetic (MeV) Au implantation in Si(1 0 0) (n-type) through masked micropatterns has been used to create layers resistant to KOH wet etching. Microscale patterns were produced in PMMA and SU(8) resist coatings on the silicon substrates using P-beam writing and developed. The silicon substrates were subsequently exposed using 1.5 MeV Au 3+ ions with fluences as high as 1 × 10 16 ions/cm 2 and additional patterns were exposed using copper scanning electron microscope calibration grids as masks on the silicon substrates. When wet etched with KOH microstructures were created in the silicon due to the resistance to KOH etching cause by the Au implantation. The process of combining the fabrication of masked patterns with P-beam writing with broad beam Au implantation through the masks can be a promising, cost-effective process for nanostructure engineering with Si.

Arc-based smoothing of ion beam intensity on targets

DOE PAGES

Friedman, Alex

2012-06-20

Manipulating a set of ion beams upstream of a target, makes it possible to arrange a smoother deposition pattern, so as to achieve more uniform illumination of the target. A uniform energy deposition pattern is important for applications including ion-beam-driven high energy density physics and heavy-ion beam-driven inertial fusion energy (“heavy-ion fusion”). Here, we consider an approach to such smoothing that is based on rapidly “wobbling” each of the beams back and forth along a short arc-shaped path, via oscillating fields applied upstream of the final pulse compression. In this technique, uniformity is achieved in the time-averaged sense; this ismore » sufficient provided the beam oscillation timescale is short relative to the hydrodynamic timescale of the target implosion. This work builds on two earlier concepts: elliptical beams applied to a distributed-radiator target [D. A. Callahan and M. Tabak, Phys. Plasmas 7, 2083 (2000)] and beams that are wobbled so as to trace a number of full rotations around a circular or elliptical path [R. C. Arnold et al., Nucl. Instrum. Methods 199, 557 (1982)]. Here, we describe the arc-based smoothing approach and compare it to results obtainable using an elliptical-beam prescription. In particular, we assess the potential of these approaches for minimization of azimuthal asymmetry, for the case of a ring of beams arranged on a cone. We also found that, for small numbers of beams on the ring, the arc-based smoothing approach offers superior uniformity. In contrast with the full-rotation approach, arc-based smoothing remains usable when the geometry precludes wobbling the beams around a full circle, e.g., for the X-target [E. Henestroza, B. G. Logan, and L. J. Perkins, Phys. Plasmas 18, 032702 (2011)] and some classes of distributed-radiator targets.« less

Ripple coarsening on ion beam-eroded surfaces.

PubMed

Teichmann, Marc; Lorbeer, Jan; Frost, Frank; Rauschenbach, Bernd

2014-01-01

The temporal evolution of ripple pattern on Ge, Si, Al 2 O 3, and SiO 2 by low-energy ion beam erosion with Xe (+) ions is studied. The experiments focus on the ripple dynamics in a fluence range from 1.1 × 10(17) cm(-2) to 1.3 × 10(19) cm(-2) at ion incidence angles of 65° and 75° and ion energies of 600 and 1,200 eV. At low fluences a short-wavelength ripple structure emerges on the surface that is superimposed and later on dominated by long wavelength structures for increasing fluences. The coarsening of short wavelength ripples depends on the material system and angle of incidence. These observations are associated with the influence of reflected primary ions and gradient-dependent sputtering. The investigations reveal that coarsening of the pattern is a universal behavior for all investigated materials, just at the earliest accessible stage of surface evolution.

Analysis of TOF-SIMS spectra from fullerene compounds

NASA Astrophysics Data System (ADS)

Kato, N.; Yamashita, Y.; Iida, S.; Sanada, N.; Kudo, M.

2008-12-01

We analyzed TOF-SIMS spectra obtained from three different size of fullerenes (C 60, C 70 and C 84) by using Ga +, Au + and Au 3+ primary ion beams and investigated the fragmentation patterns, the enhancement of secondary ion yields and the restraint of fragmentation by using cluster primary ion beams compared with monoatomic primary ion beams. In the TOS-SIMS spectra from C 70 and C 84, it was found that a fragment ion, identified as C 60+ ( m/ z = 720), showed a relatively high intensity compared with that of other fragment ions related to C 2 depletion. It was also found that the Au 3+ bombardment caused intensity enhancement of intact molecules (C 60+, C 70+ and C 84+) and restrained the fragmentation due to C 2 depletion.

Focused ion beam-assisted technology in sub-picolitre micro-dispenser fabrication

NASA Astrophysics Data System (ADS)

Lopez, M. J.; Caballero, D.; Campo, E. M.; Perez-Castillejos, R.; Errachid, A.; Esteve, J.; Plaza, J. A.

2008-07-01

Novel medical and biological applications are driving increased interest in the fabrication of micropipette or micro-dispensers. Reduced volume samples and drug dosages are prime motivators in this effort. We have combined microfabrication technology with ion beam milling techniques to successfully produce cantilever-type polysilicon micro-dispensers with 3D enclosed microchannels. The microfabrication technology described here allows for the designing of nozzles with multiple shapes. The contribution of ion beam milling has had a large impact on the fabrication process and on further customizing shapes of nozzles and inlet ports. Functionalization tests were conducted to prove the viability of ion beam-fabricated micro-dispensers. Self-assembled monolayers were successfully formed when a gold surface was patterned with a thiol solution dispensed by the fabricated micro-dispensers.

Interference patterns in the Spacelab 2 plasma wave data - Oblique electrostatic waves generated by the electron beam

NASA Technical Reports Server (NTRS)

Feng, Wei; Gurnett, Donald A.; Cairns, Iver H.

1992-01-01

During the Spacelab 2 mission the University of Iowa's Plasma Diagnostics Package (PDP) explored the plasma environment around the shuttle. Wideband spectrograms of plasma waves were obtained from the PDP at frequencies of 0-30 kHz and at distances up to 400 m from the shuttle. Strong low-frequency (below 10 kHz) electric field noise was observed in the wideband data during two periods in which an electron beam was ejected from the shuttle. This noise shows clear evidence of interference patterns caused by the finite (3.89 m) antenna length. The low-frequency noise was the most dominant type of noise produced by the ejected electron beam. Analysis of antenna interference patterns generated by these waves permits a determination of the wavelength, the direction of propagation, and the location of the source region. The observed waves have a linear dispersion relation very similar to that of ion acoustic waves. The waves are believed to be oblique ion acoustic or high-order ion cyclotron waves generated by a current of ambient electrons returning to the shuttle in response to the ejected electron beam.

Adaptation of ion beam technology to microfabrication of solid state devices and transducers

NASA Technical Reports Server (NTRS)

Topich, J. A.

1978-01-01

A number of areas were investigated to determine the potential uses of ion beam techniques in the construction of solid state devices and transducers and the packaging of implantable electronics for biomedical applications. The five areas investigated during the past year were: (1) diode-like devices fabricated on textured silicon; (2) a photolithographic technique for patterning ion beam sputtered PVC (polyvinyl chloride); (3) use of sputtered Teflon as a protective coating for implantable pressure sensors; (4) the sputtering of Macor to seal implantable hybrid circuits; and (5) the use of sputtered Teflon to immobilize enzymes.

Development of economic MeV-ion microbeam technology at Chiang Mai University

NASA Astrophysics Data System (ADS)

Singkarat, S.; Puttaraksa, N.; Unai, S.; Yu, L. D.; Singkarat, K.; Pussadee, N.; Whitlow, H. J.; Natyanum, S.; Tippawan, U.

2017-08-01

Developing high technologies but in economic manners is necessary and also feasible for developing countries. At Chiang Mai University, Thailand, we have developed MeV-ion microbeam technology based on a 1.7-MV Tandetron tandem accelerator with our limited resources in a cost-effective manner. Instead of using expensive and technically complex electrostatic or magnetic quadrupole focusing lens systems, we have developed cheap MeV-ion microbeams using programmed L-shaped blade aperture and capillary techniques for MeV ion beam lithography or writing and mapping. The programmed L-shaped blade micro-aperture system consists of a pair of L-shaped movable aperture pieces which are controlled by computer to cut off the ion beam for controlling the beam size down to the micrometer order. The capillary technique utilizes our home-fabricated tapered glass capillaries to realize microbeams. Either system can be installed inside the endstation of the MeV ion beam line of the accelerator. Both systems have been applied to MeV-ion beam lithography or writing of micro-patterns for microfluidics applications to fabricate lab-on-chip devices. The capillary technique is being developed for MeV-ion beam mapping of biological samples. The paper reports details of the techniques and introduces some applications.

Chemical degradation and morphological instabilities during focused ion beam prototyping of polymers.

PubMed

Orthacker, A; Schmied, R; Chernev, B; Fröch, J E; Winkler, R; Hobisch, J; Trimmel, G; Plank, H

2014-01-28

Focused ion beam processing of low melting materials, such as polymers or biological samples, often leads to chemical and morphological instabilities which prevent the straight-forward application of this versatile direct-write structuring method. In this study the behaviour of different polymer classes under ion beam exposure is investigated using different patterning parameters and strategies with the aim of (i) correlating local temperatures with the polymers' chemistry and its morphological consequences; and (ii) finding a way of processing sensitive polymers with lowest chemical degradation while maintaining structuring times. It is found that during processing of polymers three temperature regimes can be observed: (1) at low temperatures all polymers investigated show stable chemical and morphological behaviour; (2) very high temperatures lead to strong chemical degradation which entails unpredictable morphologies; and (3) in the intermediate temperature regime the behaviour is found to be strongly material dependent. A detailed look reveals that polymers which rather cross-link in the proximity of the beam show stable morphologies in this intermediate regime, while polymers that rather undergo chain scission show tendencies to develop a creeping phase, where material follows the ion beam movement leading to instable and unpredictable morphologies. Finally a simple, alternative patterning strategy is suggested, which allows stable processing conditions with lowest chemical damage even for challenging polymers undergoing chain scission.

All Ultra-High Vacuum In-Situ Growth & Processing Approaches to Realization of Semiconductor Nanostructure Arrays

DTIC Science & Technology

1997-05-15

Quantum Box/Dot, Strained Epitaxy , 3D islands, Patterned Substrates, Molecular Beam Epitaxy Focused Ion Beam , In-Situ Processing, Quantum Box Lasers...Grown on Planar and Patterned GaAs(100) Substrates by Molecular Beam Epitaxy ", J. Vac. Sei. Technol. B13, 642(1995) 5. A. Madhukar, P. Chen, Q. Xie...Formation and Vertical Self-Organization on GaAs(lOO) via Molecular Beam Epitaxy ", Paper presented at MRS Spring 󈨣 Meeting (Apr. 17-21, 1995, San

Physics-based investigation of negative ion behavior in a negative-ion-rich plasma using integrated diagnostics

NASA Astrophysics Data System (ADS)

Tsumori, K.; Takeiri, Y.; Ikeda, K.; Nakano, H.; Geng, S.; Kisaki, M.; Nagaoka, K.; Tokuzawa, T.; Wada, M.; Sasaki, K.; Nishiyama, S.; Goto, M.; Osakabe, M.

2017-08-01

Total power of 16 MW has been successfully delivered to the plasma confined in the Large Helical Device (LHD) from three Neutral Beam Injectors (NBIs) equipped with negative hydrogen (H-) ion sources. However, the detailed mechanisms from production through extraction of H- ions are still yet to be clarified and a similar size ion source on an independent acceleration test bench called Research and development Negative Ion Source (RNIS) serves as the facility to study physics related to H- production and transport for further improvement of NBI. The production of negative-ion-rich plasma and the H- ions behavior in the beam extraction region in RNIS is being investigated by employing an integrated diagnostic system. Flow patterns of electrons, positive ions and H- ions in the extraction region are described in a two-dimensional map. The measured flow patterns indicate the existence a stagnation region, where the H- flow changes the direction at a distance about 20 mm from the plasma grid. The pattern also suggested the H- flow originated from plasma grid (PG) surface that turned back toward extraction apertures. The turning region seems formed by a layer of combined magnetic field produced by the magnetic filter field and the Electron-Deflection Magnetic (EDM) field created by magnets installed in the extraction electrode.

The role of phase separation for self-organized surface pattern formation by ion beam erosion and metal atom co-deposition

NASA Astrophysics Data System (ADS)

Hofsäss, H.; Zhang, K.; Pape, A.; Bobes, O.; Brötzmann, M.

2013-05-01

We investigate the ripple pattern formation on Si surfaces at room temperature during normal incidence ion beam erosion under simultaneous deposition of different metallic co-deposited surfactant atoms. The co-deposition of small amounts of metallic atoms, in particular Fe and Mo, is known to have a tremendous impact on the evolution of nanoscale surface patterns on Si. In previous work on ion erosion of Si during co-deposition of Fe atoms, we proposed that chemical interactions between Fe and Si atoms of the steady-state mixed Fe x Si surface layer formed during ion beam erosion is a dominant driving force for self-organized pattern formation. In particular, we provided experimental evidence for the formation of amorphous iron disilicide. To confirm and generalize such chemical effects on the pattern formation, in particular the tendency for phase separation, we have now irradiated Si surfaces with normal incidence 5 keV Xe ions under simultaneous gracing incidence co-deposition of Fe, Ni, Cu, Mo, W, Pt, and Au surfactant atoms. The selected metals in the two groups (Fe, Ni, Cu) and (W, Pt, Au) are very similar regarding their collision cascade behavior, but strongly differ regarding their tendency to silicide formation. We find pronounced ripple pattern formation only for those co deposited metals (Fe, Mo, Ni, W, and Pt), which are prone to the formation of mono and disilicides. In contrast, for Cu and Au co-deposition the surface remains very flat, even after irradiation at high ion fluence. Because of the very different behavior of Cu compared to Fe, Ni and Au compared to W, Pt, phase separation toward amorphous metal silicide phases is seen as the relevant process for the pattern formation on Si in the case of Fe, Mo, Ni, W, and Pt co-deposition.

Effects of polycrystallinity in nano patterning by ion-beam sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Sun Mi; Kim, J.-S., E-mail: jskim@sm.ac.kr; Yoon, D.

Employing graphites with distinctly different mean grain sizes, we study the effects of polycrystallinity on the pattern formation by ion-beam sputtering. The grains influence the growth of the ripples in a highly anisotropic fashion; both the mean uninterrupted ripple length along the ridges and the surface width depend on the mean size of the grains, which is attributed to the large sputter yield at the grain boundary compared with that on the terrace. In contrast, the ripple wavelength does not depend on the mean size of the grains, indicating that the mass transport across the grain boundaries should efficiently proceedmore » by both thermal diffusion and ion-induced processes.« less

Nanofabrication with a helium ion microscope

NASA Astrophysics Data System (ADS)

Maas, Diederik; van Veldhoven, Emile; Chen, Ping; Sidorkin, Vadim; Salemink, Huub; van der Drift, Emile..; Alkemade, Paul

2010-03-01

The recently introduced helium ion microscope (HIM) is capable of imaging and fabrication of nanostructures thanks to its sub-nanometer sized ion probe. The unique interaction of the helium ions with the sample material provides very localized secondary electron emission, thus providing a valuable signal for high-resolution imaging as well as a mechanism for very precise nanofabrication. The low proximity effects, due to the low yield of backscattered ions and the confinement of the forward scattered ions into a narrow cone, enable patterning of ultra-dense sub-10 nm structures. This paper presents various nanofabrication results obtained with direct-write, with scanning helium ion beam lithography, and with helium ion beam induced deposition.

Enhanced modified faraday cup for determination of power density distribution of electron beams

DOEpatents

Elmer, John W.; Teruya, Alan T.

2001-01-01

An improved tomographic technique for determining the power distribution of an electron or ion beam using electron beam profile data acquired by an enhanced modified Faraday cup to create an image of the current density in high and low power ion or electron beams. A refractory metal disk with a number of radially extending slits, one slit being about twice the width of the other slits, is placed above a Faraday cup. The electron or ion beam is swept in a circular pattern so that its path crosses each slit in a perpendicular manner, thus acquiring all the data needed for a reconstruction in one circular sweep. The enlarged slit enables orientation of the beam profile with respect to the coordinates of the welding chamber. A second disk having slits therein is positioned below the first slit disk and inside of the Faraday cup and provides a shield to eliminate the majority of secondary electrons and ions from leaving the Faraday cup. Also, a ring is located below the second slit disk to help minimize the amount of secondary electrons and ions from being produced. In addition, a beam trap is located in the Faraday cup to provide even more containment of the electron or ion beam when full beam current is being examined through the center hole of the modified Faraday cup.

Differentiation of the Stereochemistry and Anomeric Configuration for 1-3 Linked Disaccharides Via Tandem Mass Spectrometry and 18O-labeling

NASA Astrophysics Data System (ADS)

Konda, Chiharu; Bendiak, Brad; Xia, Yu

2012-02-01

Collision-induced dissociation (CID) of deprotonated hexose-containing disaccharides ( m/z 341) with 1-2, 1-4, and 1-6 linkages yields product ions at m/z 221, which have been identified as glycosyl-glycolaldehyde anions. From disaccharides with these linkages, CID of m/z 221 ions produces distinct fragmentation patterns that enable the stereochemistries and anomeric configurations of the non-reducing sugar units to be determined. However, only trace quantities of m/z 221 ions can be generated for 1-3 linkages in Paul or linear ion traps, preventing further CID analysis. Here we demonstrate that high intensities of m/z 221 ions can be built up in the linear ion trap (Q3) from beam-type CID of a series of 1-3 linked disaccharides conducted on a triple quadrupole/linear ion trap mass spectrometer. 18O-labeling at the carbonyl position of the reducing sugar allowed mass-discrimination of the "sidedness" of dissociation events to either side of the glycosidic linkage. Under relatively low energy beam-type CID and ion trap CID, an m/z 223 product ion containing 18O predominated. It was a structural isomer that fragmented quite differently than the glycosyl-glycolaldehydes and did not provide structural information about the non-reducing sugar. Under higher collision energy beam-type CID conditions, the formation of m/z 221 ions, which have the glycosyl-glycolaldehyde structures, were favored. Characteristic fragmentation patterns were observed for each m/z 221 ion from higher energy beam-type CID of 1-3 linked disaccharides and the stereochemistry of the non-reducing sugar, together with the anomeric configuration, were successfully identified both with and without 18O-labeling of the reducing sugar carbonyl group.

Variable-spot ion beam figuring

NASA Astrophysics Data System (ADS)

Wu, Lixiang; Qiu, Keqiang; Fu, Shaojun

2016-03-01

This paper introduces a new scheme of ion beam figuring (IBF), or rather variable-spot IBF, which is conducted at a constant scanning velocity with variable-spot ion beam collimated by a variable diaphragm. It aims at improving the reachability and adaptation of the figuring process within the limits of machine dynamics by varying the ion beam spot size instead of the scanning velocity. In contrast to the dwell time algorithm in the conventional IBF, the variable-spot IBF adopts a new algorithm, which consists of the scan path programming and the trajectory optimization using pattern search. In this algorithm, instead of the dwell time, a new concept, integral etching time, is proposed to interpret the process of variable-spot IBF. We conducted simulations to verify its feasibility and practicality. The simulation results indicate the variable-spot IBF is a promising alternative to the conventional approach.

Experimental evidence of ion-induced instabilities in the NSLS-II storage ring

DOE PAGES

Cheng, Weixing; Li, Yongjun; Podobedov, Boris

2017-03-12

Fast ion instability has been identified as one of the most prominent instabilities in the recently constructed NSLS-II storage ring at Brookhaven National Laboratory. At a relatively low beam current (~ 25 mA) multi-bunch fills, ion-induced instabilities have already been observed during the early stages of machine commissioning. At present user operation with 250 mA in ~1000 bunches, the fast ion still remains the dominant instability, even after months of vacuum conditioning at high current. Ion-induced dipole motions of the electron beam have been suppressed using the transverse bunch-by-bunch (BxB) feedback system. However other adverse effects of this instability, suchmore » as the vertical beam size increase along the bunch train cannot be cured by the feedback system. Therefore, to achieve the NSLS-II design current of 500 mA while maintaining a small vertical beam emittance, it is important to further understand the fast ion instability and develop mitigation techniques. This paper reports on a series of ion-instability observations at various fill patterns and beam currents using start-of-art NSLS-II diagnostic tools.« less

Experimental evidence of ion-induced instabilities in the NSLS-II storage ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Weixing; Li, Yongjun; Podobedov, Boris

Fast ion instability has been identified as one of the most prominent instabilities in the recently constructed NSLS-II storage ring at Brookhaven National Laboratory. At a relatively low beam current (~ 25 mA) multi-bunch fills, ion-induced instabilities have already been observed during the early stages of machine commissioning. At present user operation with 250 mA in ~1000 bunches, the fast ion still remains the dominant instability, even after months of vacuum conditioning at high current. Ion-induced dipole motions of the electron beam have been suppressed using the transverse bunch-by-bunch (BxB) feedback system. However other adverse effects of this instability, suchmore » as the vertical beam size increase along the bunch train cannot be cured by the feedback system. Therefore, to achieve the NSLS-II design current of 500 mA while maintaining a small vertical beam emittance, it is important to further understand the fast ion instability and develop mitigation techniques. This paper reports on a series of ion-instability observations at various fill patterns and beam currents using start-of-art NSLS-II diagnostic tools.« less

Focused ion beam micromachining of TiNi film on Si( 1 1 1 )

NASA Astrophysics Data System (ADS)

Xie, D. Z.; Ngoi, B. K. A.; Ong, A. S.; Fu, Y. Q.; Lim, B. H.

2003-11-01

Having an excellent shape memory effect, titanium-nickel (TiNi) thin films are often used for fabrication of microactuators in microelectromechanical systems. In this work, the Ga + focused ion beam (FIB) etching characteristics of TiNi thin films has been investigated. The thin films were deposited on Si(1 1 1) wafers by co-sputtering NiTi and Ti targets using a magnetron-sputtering system. Some patterns have been etched on the surface of the films by FIB. Atomic force microscopy has been used to analyze the surface morphology of the etched areas. It is found that the etched depth depends linearly on the ion dose per area with a slope of 0.259 μm/(nC/μm 2). However, the etching depth decreases with increasing the ion beam current. The root-mean-square (RMS) surface roughness changes nonlinearly with ion dose and reaches a minimum of about 5.00 nm at a dose of about 0.45 nC/μm 2. The RMS decreases with increasing ion beam current and reaches about 4.00 nm as the ion beam current is increased to 2 nA.

Development of a MeV proton beam irradiation system.

PubMed

Park, Bum-Sik; Cho, Yong-Sub; Hong, In-Seok

2008-02-01

A proton beam irradiation system for the application of the MeV class proton beam, such as an implantation for a power semiconductor device and a smart-cut technology for a semiconductor production process, has been developed. This system consists of a negative ion source, an Einzel lens for a low energy beam transport, accelerating tubes, a gas stripper, a Cockroft-Walton high voltage power supply with 1 MV, a vacuum pumping system, and a high pressure insulating gas system. The negative hydrogen ion source is based on TRIUMF's design. Following the tandem accelerator, a pair of magnets is installed for raster scanning of the MeV proton beam to obtain a uniform irradiation pattern on the target. The system is 7 m long from the ion source to the target and is optimized for the proton beam irradiation. The details of the system development will be described.

Exploring proximity effects and large depth of field in helium ion beam lithography: large-area dense patterns and tilted surface exposure.

PubMed

Flatabø, Ranveig; Agarwal, Akshay; Hobbs, Richard; Greve, Martin M; Holst, Bodil; Berggren, Karl K

2018-07-06

Helium ion beam lithography (HIL) is an emerging nanofabrication technique. It benefits from a reduced interaction volume compared to that of an electron beam of similar energy, and hence reduced long-range scattering (proximity effect), higher resist sensitivity and potentially higher resolution. Furthermore, the small angular spread of the helium ion beam gives rise to a large depth of field. This should enable patterning on tilted and curved surfaces without the need of any additional adjustments, such as laser-auto focus. So far, most work on HIL has been focused on exploiting the reduced proximity effect to reach single-digit nanometer resolution, and has thus been concentrated on single-pixel exposures over small areas. Here we explore two new areas of application. Firstly, we investigate the proximity effect in large-area exposures and demonstrate HIL's capabilities in fabricating precise high-density gratings on large planar surfaces (100 μm × 100 μm, with pitch down to 35 nm) using an area dose for exposure. Secondly, we exploit the large depth of field by making the first HIL patterns on tilted surfaces (sample stage tilted 45°). We demonstrate a depth of field greater than 100 μm for a resolution of about 20 nm.

LET and ion-species dependence for mutation induction and mutation spectrum on hprt locus in normal human fibroblasts.

PubMed

Tsuruoka, Chizuru; Suzuki, Masao; Fujitaka, Kazunobu

2004-11-01

We have been studying LET and ion species dependence of RBE in mutation frequency and mutation spectrum of deletion pattern of exons in hprt locus. Normal human skin fibroblasts were irradiated with heavy-ion beams, such as carbon- (290 MeV/u and 135 MeV/u), neon- (230 MeV/u and 400 MeV/u), silicon- (490 MeV/u) and iron- (500 MeV/u) ion beams, generated by Heavy Ion Medical Accelerator in Chiba (HIMAC) at national Institute of Radiological Sciences (NIRS). Mutation induction in hprt locus was detected to measure 6-thioguanine resistant colonies and deletion spectrum of exons was analyzed by multiplex PCR. The LET-RBE curves of mutation induction for carbon- and neon-ion beams showed a peak around 75 keV/micrometers and 155 keV/micrometers, respectively. On the other hand, there observed no clear peak for silicon-ion beams. The deletion spectrum of exons was different in induced mutants among different ion species. These results suggested that quantitative and qualitative difference in mutation occurred when using different ion species even if similar LET values.

Creating nanostructures on silicon using ion blistering and electron beam lithography

NASA Astrophysics Data System (ADS)

Giguère, Alexandre; Beerens, Jean; Terreault, Bernard

2006-01-01

We have investigated the patterning of silicon surfaces using ion blistering in conjunction with e-beam lithography. Variable width (150-5000 nm) trenches were first written in 500 nm thick PMMA resist spin coated on silicon, using an electron beam. Next, 10 keV H2+ ions were implanted to various fluences through the masks. The resist was then removed and the samples were rapidly thermally annealed at 900 °C. The resulting surface morphologies were investigated by atomic force microscopy. In the wider trenches, round blisters with 600-900 nm diameter are observed, which are similar to those observed on unmasked surfaces. In submicron trenches, there is a transition in morphology, caused by the proximity to the border. The blisters are smaller and they are densely aligned along the trench direction ('string of pearls' pattern). Unusual blister geometries are observed in the narrowest trenches (150 nm) at higher H doses (>=1 × 1017 H cm-2)—such as tubular blisters aligned along the trench. It was also found that for H doses of >=6 × 1016 H cm-2 the surface swells uniformly, which has implications for the blistering mechanism. The prospects for accomplishing ion cutting, layer transfer and bonding of finely delineated patterns of silicon onto another material are discussed in the light of the above results.

Silicide induced ion beam patterning of Si(001).

PubMed

Engler, Martin; Frost, Frank; Müller, Sven; Macko, Sven; Will, Moritz; Feder, René; Spemann, Daniel; Hübner, René; Facsko, Stefan; Michely, Thomas

2014-03-21

Low energy ion beam pattern formation on Si with simultaneous co-deposition of Ag, Pd, Pb, Ir, Fe or C impurities was investigated by in situ scanning tunneling microscopy as well as ex situ atomic force microscopy, scanning electron microscopy, transmission electron microscopy and Rutherford backscattering spectrometry. The impurities were supplied by sputter deposition. Additional insight into the mechanism of pattern formation was obtained by more controlled supply through e-beam evaporation. For the situations investigated, the ability of the impurity to react with Si, i.e. to form a silicide, appears to be a necessary, but not a sufficient condition for pattern formation. Comparing the effects of impurities with similar mass and nuclear charge, the collision kinetics is shown to be not of primary importance for pattern formation. To understand the observed phenomena, it is necessary to assume a bi-directional coupling of composition and height fluctuations. This coupling gives rise to a sensitive dependence of the final morphology on the conditions of impurity supply. Because of this history dependence, the final morphology cannot be uniquely characterized by a steady state impurity concentration.

Ion irradiation effects on a magnetic Si/Ni/Si trilayer and lateral magnetic-nonmagnetic multistrip patterning by focused ion beam

NASA Astrophysics Data System (ADS)

Dev, B. N.; Banu, Nasrin; Fassbender, J.; Grenzer, J.; Schell, N.; Bischoff, L.; Groetzschel, R.; McCord, J.

2017-10-01

Fabrication of a multistrip magnetic/nonmagnetic structure in a thin sandwiched Ni layer [Si(5 nm)/Ni(15 nm)/Si] by a focused ion beam (FIB) irradiation has been attempted. A control experiment was initially performed by irradiation with a standard 30 keV Ga ion beam at various fluences. Analyses were carried out by Rutherford backscattering spectrometry, X-ray reflectivity, magnetooptical Kerr effect (MOKE) measurements and MOKE microscopy. With increasing ion fluence, the coercivity as well as Kerr rotation decreases. A threshold ion fluence has been identified, where ferromagnetism of the Ni layer is lost at room temperature and due to Si incorporation into the Ni layer, a Ni0.68Si0.32 alloy layer is formed. This fluence was used in FIB irradiation of parallel 50 nm wide stripes, leaving 1 µm wide unirradiated stripes in between. MOKE microscopy on this FIB-patterned sample has revealed interacting magnetic domains across several stripes. Considering shape anisotropy effects, which would favour an alignment of magnetization parallel to the stripe axis, the opposite behaviour is observed. Magneto-elastic effects introducing a stress-induced anisotropy component oriented perpendicular to the stripe axis are the most plausible explanation for the observed behaviour.

--No Title--

Science.gov Websites

beam diameter? Which ion beams are available and how long does it take to change from one to another connector is inverted. Adapters are available to invert the pins again resulting in a one-to-one pin pattern one-to-one pin pattern. Maximim current rating is 1 amp per pin. Five 37-pin D subminiature connectors

Resolution Improvement and Pattern Generator Development for theMaskless Micro-Ion-Beam Reduction Lithography System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Ximan

The shrinking of IC devices has followed the Moore's Law for over three decades, which states that the density of transistors on integrated circuits will double about every two years. This great achievement is obtained via continuous advance in lithography technology. With the adoption of complicated resolution enhancement technologies, such as the phase shifting mask (PSM), the optical proximity correction (OPC), optical lithography with wavelength of 193 nm has enabled 45 nm printing by immersion method. However, this achievement comes together with the skyrocketing cost of masks, which makes the production of low volume application-specific IC (ASIC) impractical. In ordermore » to provide an economical lithography approach for low to medium volume advanced IC fabrication, a maskless ion beam lithography method, called Maskless Micro-ion-beam Reduction Lithography (MMRL), has been developed in the Lawrence Berkeley National Laboratory. The development of the prototype MMRL system has been described by Dr. Vinh Van Ngo in his Ph.D. thesis. But the resolution realized on the prototype MMRL system was far from the design expectation. In order to improve the resolution of the MMRL system, the ion optical system has been investigated. By integrating a field-free limiting aperture into the optical column, reducing the electromagnetic interference and cleaning the RF plasma, the resolution has been improved to around 50 nm. Computational analysis indicates that the MMRL system can be operated with an exposure field size of 0.25 mm and a beam half angle of 1.0 mrad on the wafer plane. Ion-ion interactions have been studied with a two-particle physics model. The results are in excellent agreement with those published by the other research groups. The charge-interaction analysis of MMRL shows that the ion-ion interactions must be reduced in order to obtain a throughput higher than 10 wafers per hour on 300-mm wafers. In addition, two different maskless lithography strategies have been studied. The dependence of the throughput with the exposure field size and the speed of the mechanical stage has been investigated. In order to perform maskless lithography, different micro-fabricated pattern generators have been developed for the MMRL system. Ion beamlet switching has been successfully demonstrated on the MMRL system. A positive bias voltage around 10 volts is sufficient to switch off the ion current on the micro-fabricated pattern generators. Some unexpected problems, such as the high-energy secondary electron radiations, have been discovered during the experimental investigation. Thermal and structural analysis indicates that the aperture displacement error induced by thermal expansion can satisfy the 3δ CD requirement for lithography nodes down to 25 nm. The cross-talking effect near the surface and inside the apertures of the pattern generator has been simulated in a 3-D ray-tracing code. New pattern generator design has been proposed to reduce the cross-talking effect. In order to eliminate the surface charging effect caused by the secondary electrons, a new beam-switching scheme in which the switching electrodes are immersed in the plasma has been demonstrated on a mechanically fabricated pattern generator.« less

Effect of the helically-trapped energetic-ion-driven resistive interchange modes on energetic ion confinement in the Large Helical Device

NASA Astrophysics Data System (ADS)

Ogawa, K.; Isobe, M.; Kawase, H.; Nishitani, T.; Seki, R.; Osakabe, M.; LHD Experiment Group

2018-04-01

The effect of the helically-trapped energetic-ion-driven resistive interchange modes (EICs) on energetic ion confinement is studied in the Large Helical Device deuterium plasmas. Neutron diagnostics such as the neutron flux monitor and the vertical neutron camera (VNC) are used in order to measure neutrons mainly created by beam-plasma reactions. The line-integrated neutron profiles are obtained by VNC in magnetohydrodynamic-quiet plasma with various neutral beam (NB) injection patterns. The profiles are consistent with that expected by the beam ion density calculated using orbit-following simulations. Significant decreases of the total neutron emission rate (S n) and the neutron counting rate of the VNC (C n) in central cords are observed to be synchronized with EIC bursts with perpendicular-NB injection. The drop rates of both S n and C n increase with EIC amplitude and reach around 50%. The line-integrated neutron profiles before and after EIC burst show that in the central cords, C n decrease due to EIC burst whereas there is almost no change in the other cords. The experimental results suggests that the effect of EIC on helically-trapped beam ion is substantial, however the effect of passing beam ion is not significant.

Evidence that Clouds of keV Hydrogen Ion Clusters Bounce Elastically from a Solid Surface

NASA Technical Reports Server (NTRS)

Lewis, R. A.; Martin, James J.; Chakrabarti, Suman; Rodgers, Stephen L. (Technical Monitor)

2002-01-01

The behavior of hydrogen ion clusters is tested by an inject/hold/extract technique in a Penning-Malmberg trap. The timing pattern of the extraction signals is consistent with the clusters bouncing elastically from a detector several times. The ion clusters behave more like an elastic fluid than a beam of ions.

Nanosilicon dot arrays with a bit pitch and a track pitch of 25 nm formed by electron-beam drawing and reactive ion etching for 1 Tbit/in.{sup 2} storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hosaka, Sumio; Sano, Hirotaka; Shirai, Masumi

2006-11-27

The formation of very fine Si dots with a bit pitch and a track pitch of less than 25 nm using electron-beam (EB) lithography on ZEP520 and calixarene EB resists and CF{sub 4} reactive ion etching has been demonstrated. The experimental results indicate that the calixarene resist is very suitable for forming an ultrahigh-packed bit array pattern of Si dots. This result promises to open the way toward 1 Tbit/in.{sup 2} storage using patterned media with a dot size of <15 nm.

Direct nano-patterning of graphene with helium ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naitou, Y., E-mail: yu-naitou@aist.go.jp; Iijima, T.; Ogawa, S.

2015-01-19

Helium ion microscopy (HIM) was used for direct nano-patterning of single-layer graphene (SLG) on SiO{sub 2}/Si substrates. This technique involves irradiation of the sample with accelerated helium ions (He{sup +}). Doses of 2.0 × 10{sup 16 }He{sup + }cm{sup −2} from a 30 kV beam induced a metal-insulator transition in the SLG. The resolution of HIM patterning on SLG was investigated by fabricating nanoribbons and nanostructures. Analysis of scanning capacitance microscopy measurements revealed that the spatial resolution of HIM patterning depended on the dosage of He{sup +} in a non-monotonic fashion. Increasing the dose from 2.0 × 10{sup 16} to 5.0 × 10{sup 16 }He{sup + }cm{sup −2} improved the spatialmore » resolution to several tens of nanometers. However, doses greater than 1.0 × 10{sup 17 }He{sup + }cm{sup −2} degraded the patterning characteristics. Direct patterning using HIM is a versatile approach to graphene fabrication and can be applied to graphene-based devices.« less

Transverse distribution of beam current oscillations of a 14 GHz electron cyclotron resonance ion source.

PubMed

Tarvainen, O; Toivanen, V; Komppula, J; Kalvas, T; Koivisto, H

2014-02-01

The temporal stability of oxygen ion beams has been studied with the 14 GHz A-ECR at JYFL (University of Jyvaskyla, Department of Physics). A sector Faraday cup was employed to measure the distribution of the beam current oscillations across the beam profile. The spatial and temporal characteristics of two different oscillation "modes" often observed with the JYFL 14 GHz ECRIS are discussed. It was observed that the low frequency oscillations below 200 Hz are distributed almost uniformly. In the high frequency oscillation "mode," with frequencies >300 Hz at the core of the beam, carrying most of the current, oscillates with smaller amplitude than the peripheral parts of the beam. The results help to explain differences observed between the two oscillation modes in terms of the transport efficiency through the JYFL K-130 cyclotron. The dependence of the oscillation pattern on ion source parameters is a strong indication that the mechanisms driving the fluctuations are plasma effects.

Synthesis and patterning of polymers for biomedical applications

NASA Astrophysics Data System (ADS)

He, Wei

The goal of this dissertation is to synthesize and characterize novel polymers, as well as to explore alternative techniques for biomedical applications. Although significant progress has been achieved in the design and preparation of new biomaterials over the past years, much remains to be accomplished. The interactions between biomaterials and cells are very important, especially in the emerging field of tissue engineering. The focus of this research is to improve such interactions via several different approaches. One way to engineer cellular interaction is by modifying surface topography through micro-patterning. Although photolithography is widely used for patterning, it is not suitable for direct cell and protein patterning because of the usage of organic solvent for feature development. To address this issue, a biocompatible chemically amplified resist derived from N-vinyl-2-pyrrolidone (NVP) was prepared. The results have shown that no organic solvent development was required to reveal the patterns and cells can be cultured on these patterned surfaces directly. Strong cell alignment was observed. The other issue addressed in this research is to develop a technique that can modify surface morphology and surface chemistry simultaneously. Such a technique is called masked ion beam lithography (MIBL). By implanting phosphorous ions on polymeric substrates through masks, not only micron/nano size patterns were generated on the surface, but also the phosphorous ions were incorporated. Incubation of bone forming osteoblast cells on these ion beam processed samples has shown that osteoblast cell attachment to the substrate was enhanced, as a consequence of the increased surface roughness as well as the implanted phosphorous ions. This indicates that MIBL can not only generate micro/nanostructures on the surface of a biocompatible polymer, but can also selectively modify the surface chemistry by implanting with specific ions. These factors can contribute to an osteogenic environment.

Near-surface density profiling of Fe ion irradiated Si (100) using extremely asymmetric x-ray diffraction by variation of the wavelength

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khanbabaee, B., E-mail: khanbabaee@physik.uni-siegen.de; Pietsch, U.; Facsko, S.

2014-10-20

In this work, we report on correlations between surface density variations and ion parameters during ion beam-induced surface patterning process. The near-surface density variations of irradiated Si(100) surfaces were investigated after off-normal irradiation with 5 keV Fe ions at different fluences. In order to reduce the x-ray probing depth to a thickness below 5 nm, the extremely asymmetrical x-ray diffraction by variation of wavelength was applied, exploiting x-ray refraction at the air-sample interface. Depth profiling was achieved by measuring x-ray rocking curves as function of varying wavelengths providing incidence angles down to 0°. The density variation was extracted from the deviationsmore » from kinematical Bragg angle at grazing incidence angles due to refraction of the x-ray beam at the air-sample interface. The simulations based on the dynamical theory of x-ray diffraction revealed that while a net near-surface density decreases with increasing ion fluence which is accompanied by surface patterning, there is a certain threshold of ion fluence to surface density modulation. Our finding suggests that the surface density variation can be relevant with the mechanism of pattern formation.« less

Cross-beam energy transfer: On the accuracy of linear stationary models in the linear kinetic regime

NASA Astrophysics Data System (ADS)

Debayle, A.; Masson-Laborde, P.-E.; Ruyer, C.; Casanova, M.; Loiseau, P.

2018-05-01

We present an extensive numerical study by means of particle-in-cell simulations of the energy transfer that occurs during the crossing of two laser beams. In the linear regime, when ions are not trapped in the potential well induced by the laser interference pattern, a very good agreement is obtained with a simple linear stationary model, provided the laser intensity is sufficiently smooth. These comparisons include different plasma compositions to cover the strong and weak Landau damping regimes as well as the multispecies case. The correct evaluation of the linear Landau damping at the phase velocity imposed by the laser interference pattern is essential to estimate the energy transfer rate between the laser beams, once the stationary regime is reached. The transient evolution obtained in kinetic simulations is also analysed by means of a full analytical formula that includes 3D beam energy exchange coupled with the ion acoustic wave response. Specific attention is paid to the energy transfer when the laser presents small-scale inhomogeneities. In particular, the energy transfer is reduced when the laser inhomogeneities are comparable with the Landau damping characteristic length of the ion acoustic wave.

Study on radiation production in the charge stripping section of the RISP linear accelerator

NASA Astrophysics Data System (ADS)

Oh, Joo-Hee; Oranj, Leila Mokhtari; Lee, Hee-Seock; Ko, Seung-Kook

2015-02-01

The linear accelerator of the Rare Isotope Science Project (RISP) accelerates 200 MeV/nucleon 238U ions in a multi-charge states. Many kinds of radiations are generated while the primary beam is transported along the beam line. The stripping process using thin carbon foil leads to complicated radiation environments at the 90-degree bending section. The charge distribution of 238U ions after the carbon charge stripper was calculated by using the LISE++ program. The estimates of the radiation environments were carried out by using the well-proved Monte Carlo codes PHITS and FLUKA. The tracks of 238U ions in various charge states were identified using the magnetic field subroutine of the PHITS code. The dose distribution caused by U beam losses for those tracks was obtained over the accelerator tunnel. A modified calculation was applied for tracking the multi-charged U beams because the fundamental idea of PHITS and FLUKA was to transport fully-ionized ion beam. In this study, the beam loss pattern after a stripping section was observed, and the radiation production by heavy ions was studied. Finally, the performance of the PHITS and the FLUKA codes was validated for estimating the radiation production at the stripping section by applying a modified method.

Perspectives of the Pixel Detector Timepix for Needs of Ion Beam Therapy

NASA Astrophysics Data System (ADS)

Martišíková, M.; Hartmann, B.; Jäkel, O.; Granja, C.; Jakubek, J.

2012-08-01

Radiation therapy with ion beams is a highly precise kind of cancer treatment. In ion beam therapy the finite range of the ion beams in tissue and the increase of ionization density at the end of their path, the Bragg-peak, are exploited. Ions heavier than protons offer in addition increased biological effectiveness and decreased scattering. In this contribution we discuss the potential of a quantum counting and position sensitive semiconductor detector Timepix for its applications in ion beam therapy measurements. It provides high sensitivity and high spatial resolution (pixel pitch 55 μm). The detector, developed by the Medipix Collaboration, consists of a silicon sensor bump bonded to a pixelated readout chip (256 × 256 pixels with 55 μm pitch). An integrated USB-based readout interface together with the Pixelman software enable registering single particles online with 2D-track visualization. The experiments were performed at the Heidelberg Ion Beam Therapy Center (HIT), which is a modern ion beam therapy facility. Patient treatments are performed with proton and carbon ions, which are accelerated by a synchrotron. For dose delivery to the patient an active technique is used: narrow pencil-like beams are scanned over the target volume. The possibility to use the detector for two different applications was investigated: ion spectroscopy and beam delivery monitoring by measurement of secondary charged particles around the patient. During carbon ion therapy, a variety of ion species is created by nuclear fragmentation processes of the primary beam. Since they differ in their biological effectiveness, it is of large interest to measure the ion spectra created under different conditions and to visualize their spatial distribution. The possibility of measurements of ion energy loss in silicon makes Timepix a promising detector for ion-spectroscopic studies in patient-like phantoms. Unpredictable changes in the patient can alter the range of the ion beam in the body. Therefore it is desired to verify the actual ion range during the treatment, preferably in a non-invasive way. In order to overcome the limitations of the currently used PET technique, in this study we investigate the possibility to measure secondary charged particles emerging from the patient during irradiation. It was demonstrated that the Timepix detector is able to resolve and visualize this emerging radiation. The investigated dependence of the signal on the beam energy between 89 and 430 MeV/u shows that for all the investigated energies some signal was registered. Its pattern corresponds to ions. Differences in the total amount of signal for different beam energies were observed. The time-structure of the signal was moreover correlated with that of the incoming beam. This shows that we register products of prompt processes, which are less likely to be influenced by biological washout processes than the signal registered by the PET techniques coming from decays of beam-induced radioactive nuclei. The studies discussed in this contribution demonstrate that the Timepix detector provides measurements attractive for needs of ion beam therapy. To fully exploit its capabilities further research is needed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meisner, Ludmila, E-mail: llm@ispms.tsc.ru; Meisner, Stanislav, E-mail: msn@ispms.tsc.ru; Mironov, Yurii, E-mail: myp@ispms.tsc.ru

The paper considers the effects arising on X-ray diffraction patterns taken in different diffraction geometries and how these effects can be interpreted to judge structural states in NiTi near-surface regions after electron and ion beam treatment. It is shown that qualitative and quantitative analysis of phase composition, lattice parameters of main phases, elastic stress states, and their in-depth variation requires X-ray diffraction patterns in both symmetric Bragg–Brentano and asymmetric Lambot–Vassamilleta geometries with variation in X-ray wavelengths and imaging conditions (with and with no β-filter). These techniques of structural phase analysis are more efficient when the thickness of modified NiTi surfacemore » layers is 1–10 μm (after electron beam treatment) and requires special imaging conditions when the thickness of modified NiTi surface layers is no greater than 1 μm (after ion beam treatment)« less

Comparison of technologies for nano device prototyping with a special focus on ion beams: A review

NASA Astrophysics Data System (ADS)

Bruchhaus, L.; Mazarov, P.; Bischoff, L.; Gierak, J.; Wieck, A. D.; Hövel, H.

2017-03-01

Nano device prototyping (NDP) is essential for realizing and assessing ideas as well as theories in the form of nano devices, before they can be made available in or as commercial products. In this review, application results patterned similarly to those in the semiconductor industry (for cell phone, computer processors, or memory) will be presented. For NDP, some requirements are different: thus, other technologies are employed. Currently, in NDP, for many applications direct write Gaussian vector scan electron beam lithography (EBL) is used to define the required features in organic resists on this scale. We will take a look at many application results carried out by EBL, self-organized 3D epitaxy, atomic probe microscopy (scanning tunneling microscope/atomic force microscope), and in more detail ion beam techniques. For ion beam techniques, there is a special focus on those based upon liquid metal (alloy) ion sources, as recent developments have significantly increased their applicability for NDP.

Fast prototyping of high-aspect ratio, high-resolution x-ray masks by gas-assisted focused ion beam

NASA Technical Reports Server (NTRS)

Hartley, F.; Malek, C.; Neogi, J.

2001-01-01

The capacity of chemically-assisted focused ion beam (fib) etching systems to undertake direct and highly anisotropic erosion of thin and thick gold (or other high atomic number [Z])coatings on x-ray mask membranes/substrates provides new levels of precision, flexibility, simplification and rapidity in the manufacture of mask absorber patterns, allowing the fast prototyping of high aspect ratio, high-resolution masks for deep x-ray lithography.

The role of carbon in ion beam nano-patterning of silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhattacharjee, S.; UGC-DAE Consortium for Scientific Research, III/LB-8, Saltlake, Kolkata 700098; Karmakar, P.

2013-10-28

We report a comparative study of nano-pattern formations on a carbon film and a smooth Si(100) surface following inert and chemically active ion bombardment. For the case of carbon film, patterns could be formed both by inert (Ar{sup +}) and self (C{sup +}) ion bombardment with the former producing ripples at relatively lower fluence. In contrast, bombardment by inert Ar{sup +} failed to form the nano patterns on Si surface, while bombardment by the same energy C{sup +} generated the ripples. Thus, impurity induced chemical effect seems to be crucial rather than the Bradley-Harper or Carter-Vishnyakov effects for destabilizing themore » surface for ripple formation.« less

Fabrication of phonon-based metamaterial structures using focused ion beam patterning

NASA Astrophysics Data System (ADS)

Bassim, Nabil D.; Giles, Alexander J.; Ocola, Leonidas E.; Caldwell, Joshua D.

2018-02-01

The focused ion beam (FIB) is a powerful tool for rapid prototyping and machining of functional nanodevices. It is employed regularly to fabricate test metamaterial structures but, to date, has been unsuccessful in fabricating metamaterial structures with features at the nanoscale that rely on surface phonons as opposed to surface plasmons because of the crystalline damage that occurs with the collision cascade associated with ion sputtering. In this study, we employ a simple technique of protecting the crystalline substrate in single-crystal 4H-SiC to design surface phonon polariton-based optical resonance structures. By coating the material surface with a thin film of chromium, we have placed a material of high sputter resistance on the surface, which essentially absorbs the energy in the beam tails. When the beam ultimately punches through the Cr film, the hard walls in the film have the effect of channeling the beam to create smooth sidewalls. This demonstration opens the possibility of further rapid-prototyping of metamaterials using FIB.

Fabrication of plasmonic nanopore by using electron beam irradiation for optical bio-sensor

NASA Astrophysics Data System (ADS)

Choi, Seong Soo; Park, Myoung Jin; Han, Chul Hee; Oh, Seh Joong; Park, Nam Kyou; Park, Doo Jae; Choi, Soo Bong; Kim, Yong-Sang

2017-05-01

The Au nano-hole surrounded by the periodic nano-patterns would provide the enhanced optical intensity. Hence, the nano-hole surrounded with periodic groove patterns can be utilized as single molecule nanobio optical sensor device. In this report, the nano-hole on the electron beam induced membrane surrounded by periodic groove patterns were fabricated by focused ion beam technique (FIB), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Initially, the Au films with three different thickness of 40 nm, 60 nm, and 200 nm were deposited on the SiN film by using an electron beam sputter-deposition technique, followed by removal of the supporting SiN film. The nanopore was formed on the electron beam induced membrane under the FESEM electron beam irradiation. Nanopore formation inside the Au aperture was controlled down to a few nanometer, by electron beam irradiations. The optical intensities from the biomolecules on the surfaces including Au coated pyramid with periodic groove patterns were investigated via surface enhanced Raman spectroscopy (SERS). The fabricated nanopore surrounded by periodic patterns can be utilized as a next generation single molecule bio optical sensor.

Experimental observations of nonlinearly enhanced 2omega-UH electromagnetic radiation excited by steady-state colliding electron beams

NASA Technical Reports Server (NTRS)

Intrator, T.; Hershkowitz, N.; Chan, C.

1984-01-01

Counterstreaming large-diameter electron beams in a steady-state laboratory experiment are observed to generate transverse radiation at twice the upper-hybrid frequency (2omega-UH) with a quadrupole radiation pattern. The electromagnetic wave power density is nonlinearly enhanced over the power density obtained from a single beam-plasma system. Electromagnetic power density scales exponentially with beam energy and increases with ion mass. Weak turbulence theory can predict similar (but weaker) beam energy scaling but not the high power density, or the predominance of the 2omega-UH radiation peak over the omega-UH peak. Significant noise near the upper-hybrid and ion plasma frequencies is also measured, with normalized electrostatic wave energy density W(ES)/n(e)T(e) approximately 0.01.

Self-Assembled Gold Nano-Ripple Formation by Gas Cluster Ion Beam Bombardment.

PubMed

Tilakaratne, Buddhi P; Chen, Quark Y; Chu, Wei-Kan

2017-09-08

In this study, we used a 30 keV argon cluster ion beam bombardment to investigate the dynamic processes during nano-ripple formation on gold surfaces. Atomic force microscope analysis shows that the gold surface has maximum roughness at an incident angle of 60° from the surface normal; moreover, at this angle, and for an applied fluence of 3 × 10 16 clusters/cm², the aspect ratio of the nano-ripple pattern is in the range of ~50%. Rutherford backscattering spectrometry analysis reveals a formation of a surface gradient due to prolonged gas cluster ion bombardment, although the surface roughness remains consistent throughout the bombarded surface area. As a result, significant mass redistribution is triggered by gas cluster ion beam bombardment at room temperature. Where mass redistribution is responsible for nano-ripple formation, the surface erosion process refines the formed nano-ripple structures.

Low-Temperature Selective Growth of Tungsten Oxide Nanowires by Controlled Nanoscale Stress Induction

PubMed Central

Na, Hyungjoo; Eun, Youngkee; Kim, Min-Ook; Choi, Jungwook; Kim, Jongbaeg

2015-01-01

We report a unique approach for the patterned growth of single-crystalline tungsten oxide (WOx) nanowires based on localized stress-induction. Ions implanted into the desired growth area of WOx thin films lead to a local increase in the compressive stress, leading to the growth of nanowire at lower temperatures (600 °C vs. 750–900 °C) than for equivalent non-implanted samples. Nanowires were successfully grown on the microscale patterns using wafer-level ion implantation and on the nanometer scale patterns using a focused ion beam (FIB). Experimental results show that nanowire growth is influenced by a number of factors including the dose of the implanted ions and their atomic radius. The implanted-ion-assisted, stress-induced method proposed here for the patterned growth of WOx nanowires is simpler than alternative approaches and enhances the compatibility of the process by reducing the growth temperature. PMID:26666843

Physicochemical variation of mica surface by low energy ion beam irradiation

NASA Astrophysics Data System (ADS)

Bhowmik, Dipak; Karmakar, Prasanta

2018-05-01

We report the transformation of smooth and hydrophilic mica surface to a patterned and hydrophobic surface by 12 keV Ar+ and N+ ion bombardment at oblique ion incidence. Periodic ripple pattern has been found on the mica surface when nitrogen like lighter or argon like heavier ions are bombarded at an angle 60° with respect to the surface normal. During ion bombardment the different components of multi-elemental mica are eroded at different rate; as a result surface chemistry is changed, as well as a surface ripple pattern is developed on the surface due to the generation of surface instabilities. The change of surface chemistry and presence of pattern change the hydrophilic nature of the mica surface. X-ray photoelectron spectroscopy (XPS) study of irradiated mica surface shows that the upper K atoms are sputtered most. The vertical and lateral dimensions of the surface patterns are controlled by varying the ion fluence. Contact angle measurement of un-irradiated and irradiated mica surface shows a certain change from hydrophilicity to hydrophobicity. The physicochemical changes of mica surface due to Ar+ and N+ ion bombardment have been discussed.

Surface Modification of Silicone Rubber for Adhesion Patterning of Mesenchymal Stem Cells by Water Cluster Ion Beam

NASA Astrophysics Data System (ADS)

Sommani, Piyanuch; Ichihashi, Gaku; Ryuto, Hiromichi; Tsuji, Hiroshi; Gotoh, Yasuhito; Takaoka, Gikan H.

2011-01-01

Biocompatibility of silicone rubber sheet (SR) was improved by the water cluster ion irradiation for adhesion patterning of mesenchymal stem cells (MSCs). The water cluster ions were irradiated at acceleration voltage of 6 kV and doses of 1014-1016 ions/cm2. The effect of ion dose on changes in wettability and surface atomic bonding state was observed. Compared to the unirradiated SR, about four-time smoother surface on the irradiated one was observed. Water contact angle decreased with an increase in the ion dose up to 1×1015 ions/cm2. With an increase in ion dose, XPS showed decrease of atomic carbon due to lateral sputtering effect and increase of atomic oxygen due to surface oxidation. After 7 days in vitro culture, the complete adhesion pattern of the rat MSCs was obtained on the irradiated SR at dose of 1×1015 ions/cm2, corresponding to the low contact angle of 87°. At low dose, the partial pattern on the irradiated region was observed instead.

Fabrication of a negative PMMA master mold for soft-lithography by MeV ion beam lithography

NASA Astrophysics Data System (ADS)

Puttaraksa, Nitipon; Unai, Somrit; Rhodes, Michael W.; Singkarat, Kanda; Whitlow, Harry J.; Singkarat, Somsorn

2012-02-01

In this study, poly(methyl methacrylate) (PMMA) was investigated as a negative resist by irradiation with a high-fluence 2 MeV proton beam. The beam from a 1.7 MV Tandetron accelerator at the Plasma and Beam Physics Research Facility (PBP) of Chiang Mai University is shaped by a pair of computer-controlled L-shaped apertures which are used to expose rectangular pattern elements with 1-1000 μm side length. Repeated exposure of rectangular pattern elements allows a complex pattern to be built up. After subsequent development, the negative PMMA microstructure was used as a master mold for casting poly(dimethylsiloxane) (PDMS) following a standard soft-lithography process. The PDMS chip fabricated by this technique was demonstrated to be a microfluidic device.

Experimental investigation of the 2D ion beam profile generated by an ESI octopole-QMS system.

PubMed

Syed, Sarfaraz U A H; Eijkel, Gert B; Kistemaker, Piet; Ellis, Shane; Maher, Simon; Smith, Donald F; Heeren, Ron M A

2014-10-01

In this paper, we have employed an ion imaging approach to investigate the behavior of ions exiting from a quadrupole mass spectrometer (QMS) system that employs a radio frequency octopole ion guide before the QMS. An in-vacuum active pixel detector (Timepix) is employed at the exit of the QMS to image the ion patterns. The detector assembly simultaneously records the ion impact position and number of ions per pixel in every measurement frame. The transmission characteristics of the ion beam exiting the QMS are studied using this imaging detector under different operating conditions. Experimental results confirm that the ion spatial distribution exiting the QMS is heavily influenced by ion injection conditions. Furthermore, ion images from Timepix measurements of protein standards demonstrate the capability to enhance the quality of the mass spectral information and provide a detailed insight in the spatial distribution of different charge states (and hence different m/z) ions exiting the QMS.

Integration of Ion Implantation with Scanning ProbeAlignment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Persaud, A.; Rangelow, I.W.; Schenkel, T.

We describe a scanning probe instrument which integrates ion beams with imaging and alignment functions of a piezo resistive scanning probe in high vacuum. Energetic ions (1 to a few hundred keV) are transported through holes in scanning probe tips [1]. Holes and imaging tips are formed by Focused Ion Beam (FIB) drilling and ion beam assisted thin film deposition. Transport of single ions can be monitored through detection of secondary electrons from highly charged dopant ions (e. g., Bi{sup 45+}) enabling single atom device formation. Fig. 1 shows SEM images of a scanning probe tip formed by ion beammore » assisted Pt deposition in a dual beam FIB. Ion beam collimating apertures are drilled through the silicon cantilever with a thickness of 5 {micro}m. Aspect ratio limitations preclude the direct drilling of holes with diameters well below 1 {micro}m, and smaller hole diameters are achieved through local thin film deposition [2]. The hole in Fig. 1 was reduced from 2 {micro}m to a residual opening of about 300 nm. Fig. 2 shows an in situ scanning probe image of an alignment dot pattern taken with the tip from Fig. 1. Transport of energetic ions through the aperture in the scanning probe tip allows formation of arbitrary implant patterns. In the example shown in Fig. 2 (right), a 30 nm thick PMMA resist layer on silicon was exposed to 7 keV Ar{sup 2+} ions with an equivalent dose of 10{sup 14} ions/cm{sup 2} to form the LBL logo. An exciting goal of this approach is the placement of single dopant ions into precise locations for integration of single atom devices, such as donor spin based quantum computers [3, 4]. In Fig. 3, we show a section of a micron size dot area exposed to a low dose (10{sup 11}/cm{sup 2}) of high charge state dopant ions. The Bi{sup 45+} ions (200 keV) were extracted from a low emittance highly charged ions source [5]. The potential energy of B{sup 45+}, i. e., the sum of the binding energies required to remove the electrons, amounts to 36 keV. This energy is deposited within {approx}10 fs when an ion impinges on a target. The highly localized energy deposition results in efficient resist exposure, and is associated with strongly enhanced secondary electron emission, which allows monitoring of single ion impacts [4]. The ex situ scanning probe image with line scan in Fig. 3 shows a single ion impact site in PMMA (after standard development). In our presentation, we will discuss resolution requirements for ion placement in prototype quantum computer structures [3] with respect to resolution limiting factors in ion implantation with scanning probe alignment.« less

Effective beam separation schemes for the measurement of the electric Aharonov-Bohm effect in an ion interferometer.

PubMed

Schütz, G; Rembold, A; Pooch, A; Prochel, H; Stibor, A

2015-11-01

We propose an experiment for the first proof of the type I electric Aharonov-Bohm effect in an ion interferometer for hydrogen. The performances of three different beam separation schemes are simulated and compared. The coherent ion beam is generated by a single atom tip (SAT) source and separated by either two biprisms with a quadrupole lens, two biprisms with an einzel-lens or three biprisms. The beam path separation is necessary to introduce two metal tubes that can be pulsed with different electric potentials. The high time resolution of a delay line detector allows to work with a continuous ion beam and circumvents the pulsed beam operation as originally suggested by Aharonov and Bohm. We demonstrate that the higher mass and therefore lower velocity of ions compared to electrons combined with the high expected SAT ion emission puts the direct proof of this quantum effect for the first time into reach of current technical possibilities. Thereby a high detection rate of coherent ions is crucial to avoid long integration times that allow the influence of dephasing noise from the environment. We can determine the period of the expected matter wave interference pattern and the signal on the detector by determining the superposition angle of the coherent partial beams. Our simulations were tested with an electron interferometer setup and agree with the experimental results. We determine the separation scheme with three biprisms to be most efficient and predict a total signal acquisition time of only 80s to measure a phase shift from 0 to 2π due to the electric Aharonov-Bohm effect. Copyright © 2015 Elsevier B.V. All rights reserved.

Ion-beam-induced magnetic and structural phase transformation of Ni-stabilized face-centered-cubic Fe films on Cu(100)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gloss, Jonas; Institute of Physical Engineering, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2, 616 69 Brno; Shah Zaman, Sameena

2013-12-23

Metastable face-centered cubic (fcc) Fe/Cu(100) thin films are good candidates for ion-beam magnetic patterning due to their magnetic transformation upon ion-beam irradiation. However, pure fcc Fe films undergo spontaneous transformation when their thickness exceeds 10 ML. This limit can be extended to approximately 22 ML by deposition of Fe at increased CO background pressures. We show that much thicker films can be grown by alloying with Ni for stabilizing the fcc γ phase. The amount of Ni necessary to stabilize nonmagnetic, transformable fcc Fe films in dependence on the residual background pressure during the deposition is determined and a phasemore » diagram revealing the transformable region is presented.« less

Rapid Focused Ion Beam Milling Based Fabrication of Plasmonic Nanoparticles and Assemblies via "Sketch and Peel" Strategy.

PubMed

Chen, Yiqin; Bi, Kaixi; Wang, Qianjin; Zheng, Mengjie; Liu, Qing; Han, Yunxin; Yang, Junbo; Chang, Shengli; Zhang, Guanhua; Duan, Huigao

2016-12-27

Focused ion beam (FIB) milling is a versatile maskless and resistless patterning technique and has been widely used for the fabrication of inverse plasmonic structures such as nanoholes and nanoslits for various applications. However, due to its subtractive milling nature, it is an impractical method to fabricate isolated plasmonic nanoparticles and assemblies which are more commonly adopted in applications. In this work, we propose and demonstrate an approach to reliably and rapidly define plasmonic nanoparticles and their assemblies using FIB milling via a simple "sketch and peel" strategy. Systematic experimental investigations and mechanism studies reveal that the high reliability of this fabrication approach is enabled by a conformally formed sidewall coating due to the ion-milling-induced redeposition. Particularly, we demonstrated that this strategy is also applicable to the state-of-the-art helium ion beam milling technology, with which high-fidelity plasmonic dimers with tiny gaps could be directly and rapidly prototyped. Because the proposed approach enables rapid and reliable patterning of arbitrary plasmonic nanostructures that are not feasible to fabricate via conventional FIB milling process, our work provides the FIB milling technology an additional nanopatterning capability and thus could greatly increase its popularity for utilization in fundamental research and device prototyping.

Nanofabrication on unconventional substrates using transferred hard masks

DOE PAGES

Li, Luozhou; Bayn, Igal; Lu, Ming; ...

2015-01-15

Here, a major challenge in nanofabrication is to pattern unconventional substrates that cannot be processed for a variety of reasons, such as incompatibility with spin coating, electron beam lithography, optical lithography, or wet chemical steps. Here, we present a versatile nanofabrication method based on re-usable silicon membrane hard masks, patterned using standard lithography and mature silicon processing technology. These masks, transferred precisely onto targeted regions, can be in the millimetre scale. They allow for fabrication on a wide range of substrates, including rough, soft, and non-conductive materials, enabling feature linewidths down to 10 nm. Plasma etching, lift-off, and ion implantationmore » are realized without the need for scanning electron/ion beam processing, UV exposure, or wet etching on target substrates.« less

Morphological transitions in nanoscale patterns produced by concurrent ion sputtering and impurity co-deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradley, R. Mark

2016-04-07

We modify the theory of nanoscale patterns produced by ion bombardment with concurrent impurity deposition to take into account the effect that the near-surface impurities have on the collision cascades. As the impurity concentration is increased, the resulting theory successively yields a flat surface, a rippled surface with its wavevector along the projected direction of ion incidence, and a rippled surface with its wavevector rotated by 90°. Exactly the same morphological transitions were observed in recent experiments in which silicon was bombarded with an argon ion beam and gold was co-deposited [Moon et al., e-print arXiv:1601.02534].

Lateral damage in graphene carved by high energy focused gallium ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liao, Zhongquan, E-mail: zhongquan.liao@ikts-md.fraunhofer.de; Dresden Center for Nanoanalysis; Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Hallwachsstraße 3, 01069 Dresden

2015-07-06

Raman mapping is performed to study the lateral damage in supported monolayer graphene carved by 30 keV focused Ga{sup +} beams. The evolution of the lateral damage is tracked based on the profiles of the intensity ratio between the D (1341 cm{sup −1}) and G (1582 cm{sup −1}) peaks (I{sub D}/I{sub G}) of the Raman spectra. The I{sub D}/I{sub G} profile clearly reveals the transition from stage 2 disorder into stage 1 disorder in graphene along the direction away from the carved area. The critical lateral damage distance spans from <1 μm up to more than 30 μm in the experiment, depending on the parametersmore » used for carving the graphene. The wide damage in the lateral direction is attributed to the deleterious tail of unfocused ions in the ion beam probe. The study raises the attention on potential sample damage during direct patterning of graphene nanostructures using the focused ion beam technique. Minimizing the total carving time is recommended to mitigate the lateral damage.« less

Marching of the microlithography horses: electron, ion, and photon: past, present, and future

NASA Astrophysics Data System (ADS)

Lin, Burn J.

2007-03-01

Microlithography patterning employs one of three media; electron, ion, and photon. They are in a way like horses, racing towards the mainstream. Some horses such as electrons run fast but repel each other. Ion beams behave like electron beams but are less developed. The photon beam is the undisputed workhorse, taking microlithography from the 5-μm minimum feature size to 32-nm half pitch. This paper examines the history of microlithography in pattern generation, proximity printing, and projection printing, then identifies the strong and weak points of each technology. In addition to ion-beam and e-beam lithography, the coverage of optical lithography spans the wavelength from 436 to 13.5 nm. Our learning from history helps us prevent mistakes in the future. In almost all cases, making or using the mask presents one of the limiting problems, no matter the type of beams or the replication method. Only the maskless method relieves us from mask-related problems. A way to overcome the low throughput handicap of maskless systems is to use multiple e-beam direct writing, whose imaging lens can be economically and compactly fabricated using MEMS techniques. In a way, the history of microlithography parallels that of aviation. Proximity printing is like the Wright-Brothers' plane; 1X projection printing, single-engine propeller plane with unitized body; reduction step-and-repeat projection printing, multi-engine commercial airliner; scanners, jet airliners. Optical lithography has improved in many ways than just increasing NA and reducing wavelength just as the commercial airliners improving in many other areas than just the speed. The SST increased the speed of airliners by more than a factor of two just as optical resolution doubled with double exposures. EUV lithography with the wavelength reduced by an order of magnitude is similar to the space shuttle increasing its speed to more than 10 times that of the SST. Multiple-beam direct write systems are like helicopters. They do not need airports(masks) but we need a lot of beams to carry the same payload.

Nanopatterning of swinging substrates by ion-beam sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Sun Mi; Kim, J.-S., E-mail: jskim@sm.ac.kr

Graphite substrates are azimuthally swung during ion-beam sputtering (IBS) at a polar angle θ = 78° from the surface normal. The swinging of the substrate not only causes quasi-two-dimensional mass transport but also makes various sputter effects from the different incident angles to work together. Through variation of the swing angle, both the transport and sputtering effects synergistically produce a series of salient patterns, such as asymmetric wall-like structures, which can grow to several tens of nanometers and exhibit a re-entrant orientational change with the increased swing angle. Thus, the present work demonstrates that dynamic variables such as the swing angle, whichmore » have been little utilized, offer an additional parameter space that can be exploited to diversify the sputtered patterns, thereby expanding the applicability of an IBS as well as the comprehension of the IBS nano patterning mechanism.« less

Argon ion beam induced surface pattern formation on Si

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hofsäss, H.; Bobes, O.; Zhang, K.

The development of self-organized surface patterns on Si due to noble gas ion irradiation has been studied extensively in the past. In particular, Ar ions are commonly used and the pattern formation was analyzed as function of ion incidence angle, ion fluence, and ion energies between 250 eV and 140 keV. Very few results exist for the energy regime between 1.5 keV and 10 keV and it appears that pattern formation is completely absent for these ion energies. In this work, we present experimental data on pattern formation for Ar ion irradiation between 1 keV and 10 keV and ion incidence angles between 50° and 75°.more » We confirm the absence of patterns at least for ion fluences up to 10{sup 18} ions/cm{sup 2}. Using the crater function formalism and Monte Carlo simulations, we calculate curvature coefficients of linear continuum models of pattern formation, taking into account contribution due to ion erosion and recoil redistribution. The calculations consider the recently introduced curvature dependence of the erosion crater function as well as the dynamic behavior of the thickness of the ion irradiated layer. Only when taking into account these additional contributions to the linear theory, our simulations clearly show that that pattern formation is strongly suppressed between about 1.5 keV and 10 keV, most pronounced at 3 keV. Furthermore, our simulations are now able to predict whether or not parallel oriented ripple patterns are formed, and in case of ripple formation the corresponding critical angles for the whole experimentally studied energies range between 250 eV and 140 keV.« less

Neon ion beam induced pattern formation on amorphous carbon surfaces

NASA Astrophysics Data System (ADS)

Bobes, Omar; Hofsäss, Hans; Zhang, Kun

2018-02-01

We investigate the ripple pattern formation on amorphous carbon surfaces at room temperature during low energy Ne ion irradiation as a function of the ion incidence angle. Monte Carlo simulations of the curvature coefficients applied to the Bradley-Harper and Cater-Vishnyakov models, including the recent extensions by Harrison-Bradley and Hofsäss predict that pattern formation on amorphous carbon thin films should be possible for low energy Ne ions from 250 eV up to 1500 eV. Moreover, simulations are able to explain the absence of pattern formation in certain cases. Our experimental results are compared with prediction using current linear theoretical models and applying the crater function formalism, as well as Monte Carlo simulations to calculate curvature coefficients using the SDTrimSP program. Calculations indicate that no patterns should be generated up to 45° incidence angle if the dynamic behavior of the thickness of the ion irradiated layer introduced by Hofsäss is taken into account, while pattern formation most pronounced from 50° for ion energy between 250 eV and 1500 eV, which are in good agreement with our experimental data.

Suppression of self-organized surface nanopatterning on GaSb/InAs multilayers induced by low energy oxygen ion bombardment by using simultaneously sample rotation and oxygen flooding

NASA Astrophysics Data System (ADS)

Beainy, Georges; Cerba, Tiphaine; Bassani, Franck; Martin, Mickaël; Baron, Thierry; Barnes, Jean-Paul

2018-05-01

Time of flight secondary ion mass spectrometry (ToF-SIMS) is a well-adapted analytical method for the chemical characterization of concentration profiles in layered or multilayered materials. However, under ion beam bombardment, initially smooth material surface becomes morphologically unstable. This leads to abnormal secondary ion yields and depth profile distortions. In this contribution, we explore the surface topography and roughening evolution induced by O2+ ion bombardment on GaSb/InAs multilayers. We demonstrate the formation of nanodots and ripples patterning according to the ion beam energy. Since the latter are undesirable for ToF-SIMS analysis, we managed to totally stop their growth by using simultaneously sample rotation and oxygen flooding. This unprecedented coupling between these two latter mechanisms leads to a significant enhancement in depth profiles resolution.

Effectiveness of respiratory-gated radiotherapy with audio-visual biofeedback for synchrotron-based scanned heavy-ion beam delivery

NASA Astrophysics Data System (ADS)

He, Pengbo; Li, Qiang; Zhao, Ting; Liu, Xinguo; Dai, Zhongying; Ma, Yuanyuan

2016-12-01

A synchrotron-based heavy-ion accelerator operates in pulse mode at a low repetition rate that is comparable to a patient’s breathing rate. To overcome inefficiencies and interplay effects between the residual motion of the target and the scanned heavy-ion beam delivery process for conventional free breathing (FB)-based gating therapy, a novel respiratory guidance method was developed to help patients synchronize their breathing patterns with the synchrotron excitation patterns by performing short breath holds with the aid of personalized audio-visual biofeedback (BFB) system. The purpose of this study was to evaluate the treatment precision, efficiency and reproducibility of the respiratory guidance method in scanned heavy-ion beam delivery mode. Using 96 breathing traces from eight healthy volunteers who were asked to breathe freely and guided to perform short breath holds with the aid of BFB, a series of dedicated four-dimensional dose calculations (4DDC) were performed on a geometric model which was developed assuming a linear relationship between external surrogate and internal tumor motions. The outcome of the 4DDCs was quantified in terms of the treatment time, dose-volume histograms (DVH) and dose homogeneity index. Our results show that with the respiratory guidance method the treatment efficiency increased by a factor of 2.23-3.94 compared with FB gating, depending on the duty cycle settings. The magnitude of dose inhomogeneity for the respiratory guidance methods was 7.5 times less than that of the non-gated irradiation, and good reproducibility of breathing guidance among different fractions was achieved. Thus, our study indicates that the respiratory guidance method not only improved the overall treatment efficiency of respiratory-gated scanned heavy-ion beam delivery, but also had the advantages of lower dose uncertainty and better reproducibility among fractions.

SU-E-T-590: Optimizing Magnetic Field Strengths with Matlab for An Ion-Optic System in Particle Therapy Consisting of Two Quadrupole Magnets for Subsequent Simulations with the Monte-Carlo Code FLUKA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baumann, K; Weber, U; Simeonov, Y

Purpose: Aim of this study was to optimize the magnetic field strengths of two quadrupole magnets in a particle therapy facility in order to obtain a beam quality suitable for spot beam scanning. Methods: The particle transport through an ion-optic system of a particle therapy facility consisting of the beam tube, two quadrupole magnets and a beam monitor system was calculated with the help of Matlab by using matrices that solve the equation of motion of a charged particle in a magnetic field and field-free region, respectively. The magnetic field strengths were optimized in order to obtain a circular andmore » thin beam spot at the iso-center of the therapy facility. These optimized field strengths were subsequently transferred to the Monte-Carlo code FLUKA and the transport of 80 MeV/u C12-ions through this ion-optic system was calculated by using a user-routine to implement magnetic fields. The fluence along the beam-axis and at the iso-center was evaluated. Results: The magnetic field strengths could be optimized by using Matlab and transferred to the Monte-Carlo code FLUKA. The implementation via a user-routine was successful. Analyzing the fluence-pattern along the beam-axis the characteristic focusing and de-focusing effects of the quadrupole magnets could be reproduced. Furthermore the beam spot at the iso-center was circular and significantly thinner compared to an unfocused beam. Conclusion: In this study a Matlab tool was developed to optimize magnetic field strengths for an ion-optic system consisting of two quadrupole magnets as part of a particle therapy facility. These magnetic field strengths could subsequently be transferred to and implemented in the Monte-Carlo code FLUKA to simulate the particle transport through this optimized ion-optic system.« less

Enhancement of optical absorption of Si (100) surfaces by low energy N+ ion beam irradiation

NASA Astrophysics Data System (ADS)

Bhowmik, Dipak; Karmakar, Prasanta

2018-05-01

The increase of optical absorption efficiency of Si (100) surface by 7 keV and 8 keV N+ ions bombardment has been reported here. A periodic ripple pattern on surface has been observed as well as silicon nitride is formed at the ion impact zones by these low energy N+ ion bombardment [P. Karmakar et al., J. Appl. Phys. 120, 025301 (2016)]. The light absorption efficiency increases due to the presence of silicon nitride compound as well as surface nanopatterns. The Atomic Force Microscopy (AFM) study shows the formation of periodic ripple pattern and increase of surface roughness with N+ ion energy. The enhancement of optical absorption by the ion bombarded Si, compared to the bare Si have been measured by UV - visible spectrophotometer.

Sub-nanometer milling of layered materials by a focused Helium Ion Beam

NASA Astrophysics Data System (ADS)

Zhang, Hongzhou; Fox, Daniel; Zhou, Yangbo; O'Connell, Robert

2014-03-01

The modification of the structure and geometry of materials at the nanoscale can be used to tailor their properties. A controllable process which can achieve this is required for the development of next generation nano-devices. We used the highly focused beam of helium ions in a helium ion microscope (HIM) to fabricate nanostructures within various layered materials such as graphene, MoS2, TiO2 and Mn2O3. Arbitrary patterns can be defined in order to produce structures such as nanoribbons. The edge configuration of atoms in such structures plays a large role in defining their properties. High resolution transmission electron microscopy (TEM) and scanning-TEM (STEM) were used to analyse the structure of the materials after milling. The direct milling of the materials by the helium ions means this approach is suitable for a wide range of nanomaterials. Complex structures can be realized via sophisticated beam control. This also results in the ability to mill along different directions in a crystal, producing edges with different configurations.

Ion beam sputter etching of orthopedic implanted alloy MP35N and resulting effects on fatigue

NASA Technical Reports Server (NTRS)

Wintucky, E. G.; Christopher, M.; Bahnuik, E.; Wang, S.

1981-01-01

The effects of two types of argon ion sputter etched surface structures on the tensile stress fatigue properties of orthopedic implant alloy MP35N were investigated. One surface structure was a natural texture resulting from direct bombardment by 1 keV argon ions. The other structure was a pattern of square holes milled into the surface by a 1 keV argon ion beam through a Ni screen mask. The etched surfaces were subjected to tensile stress only in fatigue tests designed to simulate the cyclic load conditions experienced by the stems of artificial hip joint implants. Both types of sputter etched surface structures were found to reduce the fatigue strength below that of smooth surface MP35N.

Fabrication and ab initio study of downscaled graphene nanoelectronic devices

NASA Astrophysics Data System (ADS)

Mizuta, Hiroshi; Moktadir, Zakaria; Boden, Stuart A.; Kalhor, Nima; Hang, Shuojin; Schmidt, Marek E.; Cuong, Nguyen Tien; Chi, Dam Hieu; Otsuka, Nobuo; Muruganathan, Manoharan; Tsuchiya, Yoshishige; Chong, Harold; Rutt, Harvey N.; Bagnall, Darren M.

2012-09-01

In this paper we first present a new fabrication process of downscaled graphene nanodevices based on direct milling of graphene using an atomic-size helium ion beam. We address the issue of contamination caused by the electron-beam lithography process to pattern the contact metals prior to the ultrafine milling process in the helium ion microscope (HIM). We then present our recent experimental study of the effects of the helium ion exposure on the carrier transport properties. By varying the time of helium ion bombardment onto a bilayer graphene nanoribbon transistor, the change in the transfer characteristics is investigated along with underlying carrier scattering mechanisms. Finally we study the effects of various single defects introduced into extremely-scaled armchair graphene nanoribbons on the carrier transport properties using ab initio simulation.

Engineering catalytic activity via ion beam bombardment of catalyst supports for vertically aligned carbon nanotube growth

NASA Astrophysics Data System (ADS)

Islam, A. E.; Nikolaev, P.; Amama, P. B.; Zakharov, D.; Sargent, G.; Saber, S.; Huffman, D.; Erford, M.; Semiatin, S. L.; Stach, E. A.; Maruyama, B.

2015-09-01

Carbon nanotube growth depends on the catalytic activity of metal nanoparticles on alumina or silica supports. The control on catalytic activity is generally achieved by variations in water concentration, carbon feed, and sample placement on a few types of alumina or silica catalyst supports obtained via thin film deposition. We have recently expanded the choice of catalyst supports by engineering inactive substrates like c-cut sapphire via ion beam bombardment. The deterministic control on the structure and chemistry of catalyst supports obtained by tuning the degree of beam-induced damage have enabled better regulation of the activity of Fe catalysts only in the ion beam bombarded areas and hence enabled controllable super growth of carbon nanotubes. A wide range of surface characterization techniques were used to monitor the catalytically active surface engineered via ion beam bombardment. The proposed method offers a versatile way to control carbon nanotube growth in patterned areas and also enhances the current understanding of the growth process. With the right choice of water concentration, carbon feed and sample placement, engineered catalyst supports may extend the carbon nanotube growth yield to a level that is even higher than the ones reported here, and thus offers promising applications of carbon nanotubes in electronics, heat exchanger, and energy storage.

SEE Observations of Ionospheric Heating from HAARP Using Orbital Angular Momentum

NASA Astrophysics Data System (ADS)

Briczinski, S. J.; Bernhardt, P. A.; Siefring, C. L.

2013-12-01

High power HF radio waves exciting the ionosphere provide aeronomers with a unique space-based laboratory capability. The High-Frequency Active Auroral Research Program (HAARP) in Gakona, Alaksa is the world's largest heating facility, providing effective radiated powers in the gigawatt range. Experiments performed at HAARP have allowed researchers to study many non-linear effects of wave-plasma interactions. Stimulated Electromagnetic Emission (SEE) is of interest to the ionospheric community for its diagnostic purposes. Typical SEE experiments at HAARP have focused on characterizing the parametric decay of the electromagnetic pump wave into several different wave modes such as upper and lower hybrid, ion acoustic, ion-Bernstein and electron-Bernstein. These production modes have been extensively studied at HAARP using traditional beam heating patterns and SEE detection. New results are present from HAARP experiments using an excitation mode that attempts to impart orbital angular momentum (OAM) into the heating region. This OAM mode is also referred to as a 'twisted beam.' Previous analysis of twisted beam heating shows that the SEE results obtained are nearly identical to the modes without OAM. Recent twisted beam heating experiments have produced SEE modes not previously characterized. These new modes are presented and discussed. One difference in the twisted beam mode is the heating region produced is in the shape of a ring as opposed to the more traditional 'solid spot' region. The ring heating pattern may be more conducive to the creation of artificial ionization clouds. The results of these runs include artificial ionization creation and evolution as pertaining to the twisted beam pattern.

The control system of the multi-strip ionization chamber for the HIMM

NASA Astrophysics Data System (ADS)

Li, Min; Yuan, Y. J.; Mao, R. S.; Xu, Z. G.; Li, Peng; Zhao, T. C.; Zhao, Z. L.; Zhang, Nong

2015-03-01

Heavy Ion Medical Machine (HIMM) is a carbon ion cancer treatment facility which is being built by the Institute of Modern Physics (IMP) in China. In this facility, transverse profile and intensity of the beam at the treatment terminals will be measured by the multi-strip ionization chamber. In order to fulfill the requirement of the beam position feedback to accomplish the beam automatic commissioning, less than 1 ms reaction time of the Data Acquisition (DAQ) of this detector must be achieved. Therefore, the control system and software framework for DAQ have been redesigned and developed with National Instruments Compact Reconfigurable Input/Output (CompactRIO) instead of PXI 6133. The software is Labview-based and developed following the producer-consumer pattern with message mechanism and queue technology. The newly designed control system has been tested with carbon beam at the Heavy Ion Research Facility at Lanzhou-Cooler Storage Ring (HIRFL-CSR) and it has provided one single beam profile measurement in less than 1 ms with 1 mm beam position resolution. The fast reaction time and high precision data processing during the beam test have verified the usability and maintainability of the software framework. Furthermore, such software architecture is easy-fitting to applications with different detectors such as wire scanner detector.

Thermal, mechanical and fluid flow aspects of the high power beam dump for FRIB

NASA Astrophysics Data System (ADS)

Avilov, Mikhail; Aaron, Adam; Amroussia, Aida; Bergez, Wladimir; Boehlert, Carl; Burgess, Thomas; Carroll, Adam; Colin, Catherine; Durantel, Florent; Ferrante, Paride; Fourmeau, Tiffany; Graves, Van; Grygiel, Clara; Kramer, Jacob; Mittig, Wolfgang; Monnet, Isabelle; Patel, Harsh; Pellemoine, Frederique; Ronningen, Reginald; Schein, Mike

2016-06-01

The Facility for Rare Isotope Beams (FRIB) under construction at Michigan State University is based on a 400 kW heavy ion accelerator and uses in-flight production and separation to generate rare isotope beams. The first section of the fragment separator houses the rare isotope production target, and the primary beam dump to stop the unreacted primary beam. The experimental program will use 400 kW ion beams from 16O to 238U. After interaction with the production target, over 300 kW in remaining beam power must be absorbed by the beam dump. A rotating water-cooled thin-shell metal drum was chosen as the basic concept for the beam dump. Extensive thermal, mechanical and fluid flow analyses were performed to evaluate the effects of the high power density in the beam dump shell and in the water. Many properties were optimized simultaneously, such as shell temperature, mechanical strength, fatigue strength, and radiation resistance. Results of the analyses of the beam dump performance with different design options will be discussed. For example, it was found that a design modification to the initial water flow pattern resulted in a substantial increase in the wall heat transfer coefficient. A detailed evaluation of materials for the shell is in progress. The widely used titanium alloy, Ti-6Al-4V (wt%), is presently considered as the best candidate, and is the subject of specific tests, such as studies of performance under heavy ion irradiation.

An automated single ion hit at JAERI heavy ion microbeam to observe individual radiation damage

NASA Astrophysics Data System (ADS)

Kamiya, Tomihiro; Sakai, Takuro; Naitoh, Yutaka; Hamano, Tsuyoshi; Hirao, Toshio

1999-10-01

Microbeam scanning and a single ion hit technique have been combined to establish an automated beam positioning and single ion hit system at the JAERI Takasaki heavy ion microbeam system. Single ion irradiation on preset points of a sample in various patterns can be performed automatically in a short period. The reliability of the system was demonstrated using CR-39 nuclear track detectors. Single ion hit patterns were achieved with a positioning accuracy of 2 μm or less. In measurement of single event transient current using this system, the reduction of the pulse height by accumulation of radiation damages was observed by single ion injection to the same local areas. This technique showed a possibility to get some quantitative information about the lateral displacement of an individual radiation effect in silicon PIN photodiodes. This paper will give details of the irradiation system and present results from several experiments.

Relativistic Shear Flow between Electron-Ion and Electron-Positron Plasmas and Astrophysical Applications

NASA Astrophysics Data System (ADS)

Liang, Edison; Fu, Wen; Böttcher, Markus

2017-10-01

We present particle-in-cell simulation results of relativistic shear boundary layers between electron-ion and electron-positron plasmas and discuss their potential applications to astrophysics. Specifically, we find that in the case of a fast electron-positron spine surrounded by a slow-moving or stationary electron-ion sheath, lepton acceleration proceeds in a highly anisotropic manner due to electromagnetic fields created at the shear interface. While the highest-energy leptons still produce a beaming pattern (as seen in the quasi-stationary frame of the sheath) of order 1/Γ, where Γ is the bulk Lorentz factor of the spine, for lower-energy particles, the beaming is much less pronounced. This is in stark contrast to the case of pure electron-ion shear layers, in which anisotropic particle acceleration leads to significantly narrower beaming patterns than 1/Γ for the highest-energy particles. In either case, shear-layer acceleration is expected to produce strongly angle-dependent lepton (hence, emanating radiation) spectra, with a significantly harder spectrum in the forward direction than viewed from larger off-axis angles, much beyond the regular Doppler boosting effect from a co-moving isotropic lepton distribution. This may solve the problem of the need for high (and apparently arbitrarily chosen) minimum Lorentz factors of radiating electrons, often plaguing current blazar and GRB jet modeling efforts.

Relativistic Shear Flow between Electron–Ion and Electron–Positron Plasmas and Astrophysical Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Edison; Fu, Wen; Böttcher, Markus

We present particle-in-cell simulation results of relativistic shear boundary layers between electron–ion and electron–positron plasmas and discuss their potential applications to astrophysics. Specifically, we find that in the case of a fast electron–positron spine surrounded by a slow-moving or stationary electron–ion sheath, lepton acceleration proceeds in a highly anisotropic manner due to electromagnetic fields created at the shear interface. While the highest-energy leptons still produce a beaming pattern (as seen in the quasi-stationary frame of the sheath) of order 1/Γ, where Γ is the bulk Lorentz factor of the spine, for lower-energy particles, the beaming is much less pronounced. Thismore » is in stark contrast to the case of pure electron–ion shear layers, in which anisotropic particle acceleration leads to significantly narrower beaming patterns than 1/Γ for the highest-energy particles. In either case, shear-layer acceleration is expected to produce strongly angle-dependent lepton (hence, emanating radiation) spectra, with a significantly harder spectrum in the forward direction than viewed from larger off-axis angles, much beyond the regular Doppler boosting effect from a co-moving isotropic lepton distribution. This may solve the problem of the need for high (and apparently arbitrarily chosen) minimum Lorentz factors of radiating electrons, often plaguing current blazar and GRB jet modeling efforts.« less

Fragmentation pathways of tungsten hexacarbonyl clusters upon electron ionization.

PubMed

Neustetter, M; Jabbour Al Maalouf, E; Limão-Vieira, P; Denifl, S

2016-08-07

Electron ionization of neat tungsten hexacarbonyl (W(CO)6) clusters has been investigated in a crossed electron-molecular beam experiment coupled with a mass spectrometer system. The molecule is used for nanofabrication processes through electron beam induced deposition and ion beam induced deposition techniques. Positive ion mass spectra of W(CO)6 clusters formed by electron ionization at 70 eV contain the ion series of the type W(CO)n (+) (0 ≤ n ≤ 6) and W2(CO)n (+) (0 ≤ n ≤ 12). In addition, a series of peaks are observed and have been assigned to WC(CO)n (+) (0 ≤ n ≤ 3) and W2C(CO)n (+) (0 ≤ n ≤ 10). A distinct change of relative fragment ion intensity can be observed for clusters compared to the single molecule. The characteristic fragmentation pattern obtained in the mass spectra can be explained by a sequential decay of the ionized organometallic, which is also supported by the study of the clusters when embedded in helium nanodroplets. In addition, appearance energies for the dissociative ionization channels for singly charged ions have been estimated from experimental ion efficiency curves.

Exploring Cryogenic Focused Ion Beam Milling as a Group III-V Device Fabrication Tool

DTIC Science & Technology

2013-09-01

boiling, triple , and critical points of the elements” in CRC Handbook of Chemistry and Physics, 92nd ed., Boca Raton, FL: CRC press, 2011-2012, p. 4...The most widely used ion source in FIB instruments is a gallium (Ga) liquid metal ion source (LMIS) [4]. Gallium is attractive as an ion source...Figure 3b. EDS spectra were captured at different points across the patterned region of the room temperature milled sample, as indicated in Figure 4

An image filtering technique for SPIDER visible tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fonnesu, N., E-mail: nicola.fonnesu@igi.cnr.it; Agostini, M.; Brombin, M.

2014-02-15

The tomographic diagnostic developed for the beam generated in the SPIDER facility (100 keV, 50 A prototype negative ion source of ITER neutral beam injector) will characterize the two-dimensional particle density distribution of the beam. The simulations described in the paper show that instrumental noise has a large influence on the maximum achievable resolution of the diagnostic. To reduce its impact on beam pattern reconstruction, a filtering technique has been adapted and implemented in the tomography code. This technique is applied to the simulated tomographic reconstruction of the SPIDER beam, and the main results are reported.

The influence of projectile ion induced chemistry on surface pattern formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karmakar, Prasanta, E-mail: prasantak@vecc.gov.in; Satpati, Biswarup

We report the critical role of projectile induced chemical inhomogeneity on surface nanostructure formation. Experimental inconsistency is common for low energy ion beam induced nanostructure formation in the presence of uncontrolled and complex contamination. To explore the precise role of contamination on such structure formation during low energy ion bombardment, a simple and clean experimental study is performed by selecting mono-element semiconductors as the target and chemically inert or reactive ion beams as the projectile as well as the source of controlled contamination. It is shown by Atomic Force Microscopy, Cross-sectional Transmission Electron Microscopy, and Electron Energy Loss Spectroscopy measurementsmore » that bombardment of nitrogen-like reactive ions on Silicon and Germanium surfaces forms a chemical compound at impact zones. Continuous bombardment of the same ions generates surface instability due to unequal sputtering and non-uniform re-arrangement of the elemental atom and compound. This instability leads to ripple formation during ion bombardment. For Argon-like chemically inert ion bombardment, the chemical inhomogeneity induced boost is absent; as a result, no ripples are observed in the same ion energy and fluence.« less

Critical aspects of substrate nanopatterning for the ordered growth of GaN nanocolumns.

PubMed

Barbagini, Francesca; Bengoechea-Encabo, Ana; Albert, Steven; Martinez, Javier; Sanchez García, Miguel Angel; Trampert, Achim; Calleja, Enrique

2011-12-14

Precise and reproducible surface nanopatterning is the key for a successful ordered growth of GaN nanocolumns. In this work, we point out the main technological issues related to the patterning process, mainly surface roughness and cleaning, and mask adhesion to the substrate. We found that each of these factors, process-related, has a dramatic impact on the subsequent selective growth of the columns inside the patterned holes. We compare the performance of e-beam lithography, colloidal lithography, and focused ion beam in the fabrication of hole-patterned masks for ordered columnar growth. These results are applicable to the ordered growth of nanocolumns of different materials.

New 3D structuring process for non-integrated circuit related technologies (Conference Presentation)

NASA Astrophysics Data System (ADS)

Nouri, Lamia; Possémé, Nicolas; Landis, Stéfan; Milesi, Frédéric; Gaillard, Frédéric-Xavier

2017-04-01

Fabrication processes that microelectronic developed for Integrated circuit (IC) technologies for decades, do not meet the new emerging structuration's requirements, in particular non-IC related technologies one, such as MEMS/NEMS, Micro-Fluidics, photovoltaics, lenses. Actually complex 3D structuration requires complex lithography patterning approaches such as gray-scale electron beam lithography, laser ablation, focused ion beam lithography, two photon polymerization. It is now challenging to find cheaper and easiest technique to achieve 3D structures. In this work, we propose a straightforward process to realize 3D structuration, intended for silicon based materials (Si, SiN, SiOCH). This structuration technique is based on nano-imprint lithography (NIL), ion implantation and selective wet etching. In a first step a pattern is performed by lithography on a substrate, then ion implantation is realized through a resist mask in order to create localized modifications in the material, thus the pattern is transferred into the subjacent layer. Finally, after the resist stripping, a selective wet etching is carried out to remove selectively the modified material regarding the non-modified one. In this paper, we will first present results achieved with simple 2D line array pattern processed either on Silicon or SiOCH samples. This step have been carried out to demonstrate the feasibility of this new structuration process. SEM pictures reveals that "infinite" selectivity between the implanted areas versus the non-implanted one could be achieved. We will show that a key combination between the type of implanted ion species and wet etching chemistries is required to obtain such results. The mechanisms understanding involved during both implantation and wet etching processes will also be presented through fine characterizations with Photoluminescence, Raman and Secondary Ion Mass Spectrometry (SIMS) for silicon samples, and ellipso-porosimetry and Fourier Transform InfraRed spectroscopy (FTIR) for SiOCH samples. Finally the benefit of this new patterning approach will be presented on 3D patterns structures.

Initial clinical evaluation of PET-based ion beam therapy monitoring under consideration of organ motion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurz, Christopher, E-mail: christopher.kurz@physik.uni-muenchen.de; Bauer, Julia; Unholtz, Daniel

2016-02-15

Purpose: Intrafractional organ motion imposes considerable challenges to scanned ion beam therapy and demands for a thorough verification of the applied treatment. At the Heidelberg Ion-Beam Therapy Center (HIT), the scanned ion beam delivery is verified by means of postirradiation positron-emission-tomography (PET) imaging. This work presents a first clinical evaluation of PET-based treatment monitoring in ion beam therapy under consideration of target motion. Methods: Three patients with mobile liver lesions underwent scanned carbon ion irradiation at HIT and postirradiation PET/CT (x-ray-computed-tomography) imaging with a commercial scanner. Respiratory motion was recorded during irradiation and subsequent image acquisition. This enabled a time-resolvedmore » (4D) calculation of the expected irradiation-induced activity pattern and, for one patient where an additional 4D CT was acquired at the PET/CT scanner after treatment, a motion-compensated PET image reconstruction. For the other patients, PET data were reconstructed statically. To verify the treatment, calculated prediction and reconstructed measurement were compared with a focus on the ion beam range. Results: Results in the current three patients suggest that for motion amplitudes in the order of 2 mm there is no benefit from incorporating respiratory motion information into PET-based treatment monitoring. For a target motion in the order of 10 mm, motion-related effects become more severe and a time-resolved modeling of the expected activity distribution can lead to an improved data interpretation if a sufficient number of true coincidences is detected. Benefits from motion-compensated PET image reconstruction could not be shown conclusively at the current stage. Conclusions: The feasibility of clinical PET-based treatment verification under consideration of organ motion has been shown for the first time. Improvements in noise-robust 4D PET image reconstruction are deemed necessary to enhance the clinical potential.« less

Engineering catalytic activity via ion beam bombardment of catalyst supports for vertically aligned carbon nanotube growth

DOE PAGES

Islam, A. E.; Zakharov, D.; Stach, E. A.; ...

2015-09-16

Carbon nanotube growth depends on the catalytic activity of metal nanoparticles on alumina or silica supports. The control on catalytic activity is generally achieved by variations in water concentration, carbon feed, and sample placement on a few types of alumina or silica catalyst supports obtained via thin film deposition. We have recently expanded the choice of catalyst supports by engineering inactive substrates like c-cut sapphire via ion beam bombardment. The deterministic control on the structure and chemistry of catalyst supports obtained by tuning the degree of beam-induced damage have enabled better regulation of the activity of Fe catalysts only inmore » the ion beam bombarded areas and hence enabled controllable super growth of carbon nanotubes. A wide range of surface characterization techniques were used to monitor the catalytically active surface engineered via ion beam bombardment. The proposed method offers a versatile way to control carbon nanotube growth in patterned areas and also enhances the current understanding of the growth process. As a result, with the right choice of water concentration, carbon feed and sample placement, engineered catalyst supports may extend the carbon nanotube growth yield to a level that is even higher than the ones reported here, and thus offers promising applications of carbon nanotubes in electronics, heat exchanger, and energy storage.« less

Measurement of ultra-low ion energy of decelerated ion beam using a deflecting electric field

NASA Astrophysics Data System (ADS)

Thopan, P.; Suwannakachorn, D.; Tippawan, U.; Yu, L. D.

2015-12-01

In investigation on ultra-low-energy ion bombardment effect on DNA, an ion beam deceleration lens was developed for high-quality ultra-low-energy ion beam. Measurement of the ion energy after deceleration was necessary to confirm the ion beam really decelerated as theoretically predicted. In contrast to conventional methods, this work used a simple deflecting electrostatic field after the deceleration lens to bend the ion beam. The beam bending distance depended on the ion energy and was described and simulated. A system for the measurement of the ion beam energy was constructed. It consisted of a pair of parallel electrode plates to generate the deflecting electrical field, a copper rod measurement piece to detect ion beam current, a vernier caliper to mark the beam position, a stepping motor to translate the measurement rod, and a webcam-camera to read the beam bending distance. The entire system was installed after the ion-beam deceleration lens inside the large chamber of the bioengineering vertical ion beam line. Moving the measurement rod across the decelerated ion beam enabled to obtain beam profiles, from which the beam bending distance could be known and the ion beam energy could be calculated. The measurement results were in good agreement with theoretical and simulated results.

Beam energy dependence of pseudorapidity distributions of charged particles produced in relativistic heavy-ion collisions

NASA Astrophysics Data System (ADS)

Basu, Sumit; Nayak, Tapan K.; Datta, Kaustuv

2016-06-01

Heavy-ion collisions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN probe matter at extreme conditions of temperature and energy density. Most of the global properties of the collisions can be extracted from the measurements of charged-particle multiplicity and pseudorapidity (η ) distributions. We have shown that the available experimental data on beam energy and centrality dependence of η distributions in heavy-ion (Au +Au or Pb +Pb ) collisions from √{sNN}=7.7 GeV to 2.76 TeV are reasonably well described by the AMPT model, which is used for further exploration. The nature of the η distributions has been described by a double Gaussian function using a set of fit parameters, which exhibit a regular pattern as a function of beam energy. By extrapolating the parameters to a higher energy of √{sNN}=5.02 TeV, we have obtained the charged-particle multiplicity densities, η distributions, and energy densities for various centralities. Incidentally, these results match well with some of the recently published data by the ALICE Collaboration.

Ion Implantation Technology: Proceedings of the International Conference on Ion Implantation Technology (8th) Held at the University of Surrey, Guildford, UK on 30 July - 3 August 1990

DTIC Science & Technology

1991-01-01

contamination precipitates (fig. 10a): the defect image resembles that pattern was due to the manual loading system of the of a banana , and it appears that mainly...assumed that the origin in which the growth of current is exponential. outer edges of the ion beam peel off into the sheath and The almost flat region to

Impingement-Current-Erosion Characteristics of Accelerator Grids on Two-Grid Ion Thrusters

NASA Technical Reports Server (NTRS)

Barker, Timothy

1996-01-01

Accelerator grid sputter erosion resulting from charge-exchange-ion impingement is considered to be a primary cause of failure for electrostatic ion thrusters. An experimental method was developed and implemented to measure erosion characteristics of ion-thruster accel-grids for two-grid systems as a function of beam current, accel-grid potential, and facility background pressure. Intricate accelerator grid erosion patterns, that are typically produced in a short time (a few hours), are shown. Accelerator grid volumetric and depth-erosion rates are calculated from these erosion patterns and reported for each of the parameters investigated. A simple theoretical volumetric erosion model yields results that are compared to experimental findings. Results from the model and experiments agree to within 10%, thereby verifying the testing technique. In general, the local distribution of erosion is concentrated in pits between three adjacent holes and trenches that join pits. The shapes of the pits and trenches are shown to be dependent upon operating conditions. Increases in beam current and the accel-grid voltage magnitude lead to deeper pits and trenches. Competing effects cause complex changes in depth-erosion rates as background pressure is increased. Shape factors that describe pits and trenches (i.e. ratio of the average erosion width to the maximum possible width) are also affected in relatively complex ways by changes in beam current, ac tel-grid voltage magnitude, and background pressure. In all cases, however, gross volumetric erosion rates agree with theoretical predictions.

Fragmentation pathways of tungsten hexacarbonyl clusters upon electron ionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neustetter, M.; Jabbour Al Maalouf, E.; Denifl, S., E-mail: Stephan.Denifl@uibk.ac.at, E-mail: plimaovieira@fct.unl.pt

2016-08-07

Electron ionization of neat tungsten hexacarbonyl (W(CO){sub 6}) clusters has been investigated in a crossed electron-molecular beam experiment coupled with a mass spectrometer system. The molecule is used for nanofabrication processes through electron beam induced deposition and ion beam induced deposition techniques. Positive ion mass spectra of W(CO){sub 6} clusters formed by electron ionization at 70 eV contain the ion series of the type W(CO){sub n}{sup +} (0 ≤ n ≤ 6) and W{sub 2}(CO){sub n}{sup +} (0 ≤ n ≤ 12). In addition, a series of peaks are observed and have been assigned to WC(CO){sub n}{sup +} (0 ≤more » n ≤ 3) and W{sub 2}C(CO){sub n}{sup +} (0 ≤ n ≤ 10). A distinct change of relative fragment ion intensity can be observed for clusters compared to the single molecule. The characteristic fragmentation pattern obtained in the mass spectra can be explained by a sequential decay of the ionized organometallic, which is also supported by the study of the clusters when embedded in helium nanodroplets. In addition, appearance energies for the dissociative ionization channels for singly charged ions have been estimated from experimental ion efficiency curves.« less

Fully Scalable Porous Metal Electrospray Propulsion

DTIC Science & Technology

2012-03-20

particular emphasis on the variation of specific impulse for multi-modal propulsion is currently carried out by MIT and the Busek Company under an...Beam profile distributions in the negative (left) and positive (center) modes as visualized directly thorough a multi-channel plate and phosphor...screen. These profiles are parabolic (right) indicating the non-thermal character of these type of ion beams. Microscopic Image of pattern imprinted on Si

Patterned Growth of Carbon Nanotubes or Nanofibers

NASA Technical Reports Server (NTRS)

Delzeit, Lance D.

2004-01-01

A method and apparatus for the growth of carbon nanotubes or nanofibers in a desired pattern has been invented. The essence of the method is to grow the nanotubes or nanofibers by chemical vapor deposition (CVD) onto a patterned catalyst supported by a substrate. The figure schematically depicts salient aspects of the method and apparatus in a typical application. A substrate is placed in a chamber that contains both ion-beam sputtering and CVD equipment. The substrate can be made of any of a variety of materials that include several forms of silicon or carbon, and selected polymers, metals, ceramics, and even some natural minerals and similar materials. Optionally, the substrate is first coated with a noncatalytic metal layer (which could be a single layer or could comprise multiple different sublayers) by ion-beam sputtering. The choice of metal(s) and thickness(es) of the first layer (if any) and its sublayers (if any) depends on the chemical and electrical properties required for subsequent deposition of the catalyst and the subsequent CVD of the carbon nanotubes. A typical first-sublayer metal is Pt, Pd, Cr, Mo, Ti, W, or an alloy of two or more of these elements. A typical metal for the second sublayer or for an undivided first layer is Al at a thickness .1 nm or Ir at a thickness .5 nm. Proper choice of the metal for a second sublayer of a first layer makes it possible to use a catalyst that is chemically incompatible with the substrate. In the next step, a mask having holes in the desired pattern is placed over the coated substrate. The catalyst is then deposited on the coated substrate by ion-beam sputtering through the mask. Optionally, the catalyst could be deposited by a technique other than sputtering and/or patterned by use of photolithography, electron- beam lithography, or another suitable technique. The catalytic metal can be Fe, Co, Ni, or an alloy of two or more of these elements, deposited to a typical thickness in the range from 0.1 to 20 nm.

Tailoring plasmonic nanoparticles and fractal patterns

NASA Astrophysics Data System (ADS)

Rosa, Lorenzo; Juodkazis, Saulius

2011-12-01

We studied new three-dimensional tailoring of nano-particles by ion-beam and electron-beam lithographies, aiming for features and nano-gaps down to 10 nm size. Electron-beam patterning is demonstrated for 2D fabrication in combination with plasmonic metal deposition and lift-off, with full control of spectral features of plasmonic nano-particles and patterns on dielectric substrates. We present wide-angle bow-tie rounded nano-antennas whose plasmonic resonances achieve strong field enhancement at engineered wavelength range, and show how the addition of fractal patterns defined by standard electron beam lithography achieve light field enhancement from visible to far-IR spectral range and scalable up towards THz band. Field enhancement is evaluated by FDTD modeling on full-3D simulation domains using complex material models, showing the modeling method capabilities and the effect of staircase approximations on field enhancement and resonance conditions, especially at metal corners, where a minimum rounding radius of 2 nm is resolved and a five-fold reduction of spurious ringing at sharp corners is obtained by the use of conformal meshing.

Effect of heavy ion beam irradiation on germination of local Toraja rice seed (M1-M2) mutant generation

NASA Astrophysics Data System (ADS)

Sjahril, R.; Riadi, M.; Rafiuddin; Sato, T.; Toriyama, K.; Abe, T.; Trisnawaty, A. R.

2018-05-01

Local rice in general has several weaknesses among others, long life, high plant posture and low yield result. The character is a limiting factor that causes farmers low interest to grow local rice. It is feared this will cause the lack of local rice cultivars as germplasm materials. Therefore, there is an effort to create a diversity of morphological characters, as the character of selection, especially related to the age of harvest and plant posture. One method is through breeding mutation by irradiation using ion beam. The objective of this research is to evaluate seed germination resulted after irradiation using ion beam in two varieties of Toraja local rice. The study was prepared based on a randomized block design pattern consisting of six treatments by testing two local Toraja rice varieties namely Pare Ambok and Pare Lea treated with ion beam irradiation of Argon and Carbon ion and control plant as comparison. Each grain from one panicle was germinated in one line method on a Ø15 cm Petri dish and transplanted into small plastic bags. Each treatment was repeated as much as 20 times which was then considered as a strain. The results showed that irradiation using Argon ion in local rice seed of Pare Ambok variety and of Pare Lea varieties produce better seedlings sprouts than irradiation using Carbon ion. Further M2 seed germination shows uniqueness in some seedlings produced such as lighter leaf color, albinism, wrinkled leaf, etc. which could prove potential mutant lines in tested M2 lines seed.

Fabrication of YBa2Cu3O7 twin-boundary-junction dc SQUID by using a focused-ion-beam pattern technique

NASA Astrophysics Data System (ADS)

Lee, Sung Hoon; Lee, Soon-Gul

2017-09-01

We have fabricated YBa2Cu3O7 (YBCO) dc SQUIDs containing nanobridges across twin boundaries of LaAlO3 (LAO) substrates as Josephson elements by using a focused ion beam (FIB) etching method and measured their transport properties. The beam energy was 30 keV and the current was 1.5 pA for the nanobridge pattern. Each bridge with a nominal width of 200 nm crossed a twin boundary in the (100) direction. The SQUID loop had a 10 μm × 10 μm hole with a 5.7 μm average linewidth. The SQUID voltage showed modulations in response to the external flux with a maximum modulation depth of 350 μV at 77.0 K. HR-XRD spectra showed that the epitaxially grown YBCO film was twinned in commensurate with the twinning of the LAO substrate. Tilting of the c-axis of YBCO across the twin boundary is believed to play a role as a tunnel barrier.

Role of isolated and clustered DNA damage and the post-irradiating repair process in the effects of heavy ion beam irradiation.

PubMed

Tokuyama, Yuka; Furusawa, Yoshiya; Ide, Hiroshi; Yasui, Akira; Terato, Hiroaki

2015-05-01

Clustered DNA damage is a specific type of DNA damage induced by ionizing radiation. Any type of ionizing radiation traverses the target DNA molecule as a beam, inducing damage along its track. Our previous study showed that clustered DNA damage yields decreased with increased linear energy transfer (LET), leading us to investigate the importance of clustered DNA damage in the biological effects of heavy ion beam radiation. In this study, we analyzed the yield of clustered base damage (comprising multiple base lesions) in cultured cells irradiated with various heavy ion beams, and investigated isolated base damage and the repair process in post-irradiation cultured cells. Chinese hamster ovary (CHO) cells were irradiated by carbon, silicon, argon and iron ion beams with LETs of 13, 55, 90 and 200 keV µm(-1), respectively. Agarose gel electrophoresis of the cells with enzymatic treatments indicated that clustered base damage yields decreased as the LET increased. The aldehyde reactive probe procedure showed that isolated base damage yields in the irradiated cells followed the same pattern. To analyze the cellular base damage process, clustered DNA damage repair was investigated using DNA repair mutant cells. DNA double-strand breaks accumulated in CHO mutant cells lacking Xrcc1 after irradiation, and the cell viability decreased. On the other hand, mouse embryonic fibroblast (Mef) cells lacking both Nth1 and Ogg1 became more resistant than the wild type Mef. Thus, clustered base damage seems to be involved in the expression of heavy ion beam biological effects via the repair process. © The Author 2015. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

High-energy radiation and polymers: A review of commercial processes and emerging applications

NASA Astrophysics Data System (ADS)

Clough, R. L.

2001-12-01

Ionizing radiation has been found to be widely applicable in modifying the structure and properties of polymers, and can be used to tailor the performance of either bulk materials or surfaces. Fifty years of research in polymer radiation chemistry has led to numerous applications of commercial and economic importance, and work remains active in the application of radiation to practical uses involving polymeric materials. This paper provides a survey of radiation-processing methods of industrial interest, ranging from technologies already commercially well established, through innovations in the active R&D stage which show exceptional promise for future commercial use. Radiation-processing technologies are discussed under the following categories: cross-linking of plastics and rubbers, curing of coatings and inks, heat-shrink products, fiber-matrix composites, chain-scission for processing control, surface modification, grafting, hydrogels, sterilization, natural product enhancement, plastics recycling, ceramic precursors, electronic property materials, ion-track membranes and lithography for microdevice production. In addition to new technological innovations utilizing conventional gamma and e-beam sources, a number of promising new applications make use of novel radiation types which include ion beams (heavy ions, light ions, highly focused microscopic beams and high-intensity pulses), soft X-rays which are focused, coherent X-rays (from a synchrotron) and e-beams which undergo scattering to generate patterns.

Measurement of Heavy Ion Irradiation Induced In-Plane Strain in Patterned Face-Centered-Cubic Metal Films: An in Situ Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, K. Y.; Chen, Y.; Li, J.

Nanocrystalline Ag, Cu, and Ni thin films and their coarse grained counterparts are patterned in this paper using focused ion beam and then irradiated by Kr ions within an electron microscope at room temperature. Irradiation induced in-plane strain of the films is measured by tracking the location of nanosized holes. The magnitude of the strain in all specimens is linearly dose-dependent and the strain rates of nanocrystalline metals are significantly greater as compared to that of the coarse grained metals. Finally, real-time microscopic observation suggests that substantial grain boundary migration and grain rotation are responsible for the significant in-plane strain.

Measurement of Heavy Ion Irradiation Induced In-Plane Strain in Patterned Face-Centered-Cubic Metal Films: An in Situ Study

DOE PAGES

Yu, K. Y.; Chen, Y.; Li, J.; ...

2016-11-28

Nanocrystalline Ag, Cu, and Ni thin films and their coarse grained counterparts are patterned in this paper using focused ion beam and then irradiated by Kr ions within an electron microscope at room temperature. Irradiation induced in-plane strain of the films is measured by tracking the location of nanosized holes. The magnitude of the strain in all specimens is linearly dose-dependent and the strain rates of nanocrystalline metals are significantly greater as compared to that of the coarse grained metals. Finally, real-time microscopic observation suggests that substantial grain boundary migration and grain rotation are responsible for the significant in-plane strain.

Critical aspects of substrate nanopatterning for the ordered growth of GaN nanocolumns

PubMed Central

2011-01-01

Precise and reproducible surface nanopatterning is the key for a successful ordered growth of GaN nanocolumns. In this work, we point out the main technological issues related to the patterning process, mainly surface roughness and cleaning, and mask adhesion to the substrate. We found that each of these factors, process-related, has a dramatic impact on the subsequent selective growth of the columns inside the patterned holes. We compare the performance of e-beam lithography, colloidal lithography, and focused ion beam in the fabrication of hole-patterned masks for ordered columnar growth. These results are applicable to the ordered growth of nanocolumns of different materials. PMID:22168918

Nanoimprint lithography for nanodevice fabrication

NASA Astrophysics Data System (ADS)

Barcelo, Steven; Li, Zhiyong

2016-09-01

Nanoimprint lithography (NIL) is a compelling technique for low cost nanoscale device fabrication. The precise and repeatable replication of nanoscale patterns from a single high resolution patterning step makes the NIL technique much more versatile than other expensive techniques such as e-beam or even helium ion beam lithography. Furthermore, the use of mechanical deformation during the NIL process enables grayscale lithography with only a single patterning step, not achievable with any other conventional lithography techniques. These strengths enable the fabrication of unique nanoscale devices by NIL for a variety of applications including optics, plasmonics and even biotechnology. Recent advances in throughput and yield in NIL processes demonstrate the potential of being adopted for mainstream semiconductor device fabrication as well.

Post-ion beam induced degradation of copper layers in transmission electron microscopy specimens

NASA Astrophysics Data System (ADS)

Seidel, F.; Richard, O.; Bender, H.; Vandervorst, W.

2015-11-01

Copper containing transmission electron microscopy (TEM) specimens frequently show corrosion after focused ion beam (FIB) preparation. This paper reveals that the corrosion product is a Cu-S phase growing over the specimen surface. The layer is identified by energy-dispersive x-ray spectroscopy, and lattice spacing indexing of power spectra patterns. The corrosion process is further studied by TEM on cone-shaped specimens, which are intentionally stored after FIB preparation with S flakes for short time. Furthermore, a protective method against corrosion is developed by varying the time in the FIB vacuum and the duration of a subsequent plasma cleaning.

High brightness--multiple beamlets source for patterned X-ray production

DOEpatents

Leung, Ka-Ngo [Hercules, CA; Ji, Qing [Albany, CA; Barletta, William A [Oakland, CA; Jiang, Ximan [El Cerrito, CA; Ji, Lili [Albany, CA

2009-10-27

Techniques for controllably directing beamlets to a target substrate are disclosed. The beamlets may be either positive ions or electrons. It has been shown that beamlets may be produced with a diameter of 1 .mu.m, with inter-aperture spacings of 12 .mu.m. An array of such beamlets, may be used for maskless lithography. By step-wise movement of the beamlets relative to the target substrate, individual devices may be directly e-beam written. Ion beams may be directly written as well. Due to the high brightness of the beamlets from extraction from a multicusp source, exposure times for lithographic exposure are thought to be minimized. Alternatively, the beamlets may be electrons striking a high Z material for X-ray production, thereafter collimated to provide patterned X-ray exposures such as those used in CAT scans. Such a device may be used for remote detection of explosives.

STRUCTURAL, OPTICAL AND ELECTRICAL PROPERTIES OF PET POLYMER FILMS MODIFIED BY LOW ENERGY Ar+ ION BEAMS

NASA Astrophysics Data System (ADS)

Fawzy, Y. H. A.; Abdel-Hamid, H. M.; El-Okr, M. M.; Atta, A.

Polyethylene terephthalate (PET) films with thickness 40μm are irradiated with 3keV argon ion beams with different fluence ranging from 0.5×1018ions.cm-2 to 2×1018ions.cm-2 using locally designed broad ion source. The changes in the PET structure are characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscope (SEM) techniques. The XRD patterns show that the peak intensity decreases with irradiation and the particle size decreases from 65.75 Å for the un-irradiated to 52.80 Å after irradiation. The FTIR indicates partial decrease and reduction in the intensity of the bands due to the degradation of the polymer after ion irradiation. The optical energy band gap decreases from 3.14eV to 3.05eV and the number of carbon cluster increases from 119 to 126 after ion irradiation. The results show a slight increase in the electrical conductivities and the dielectric constant (ɛ). The results indicate the effectiveness of using PET films as capacitors and resistors in industrial applications.

Atomic-scale thermocapillary flow in focused ion beam milling

NASA Astrophysics Data System (ADS)

Das, Kallol; Johnson, Harley; Freund, Jonathan

2016-11-01

Focused ion beams (FIB) offer an attractive tool for nanometer-scale manufacturing and material processing, particularly because they can be focused to a few nanometer diameter spot. This motivates their use for many applications, such as sample preparation for transmission electron microscopy (TEM), forming nanometer scale pores in thin films for DNA sequencing. Despite its widespread use, the specific mechanisms of FIB milling, especially at high ion fluxes for which significant phase change might occur, remains incompletely understood. Here we investigate the process of nanopore fabrication in thin Si films using molecular dynamics simulation where Ga+ ions are used as the focused ions. For a range of ion intensities in a realistic configuration, a recirculating melt region develops, which is seen to flow with a symmetrical pattern, counter to how it would flow were it is driven by the ion momentum flux. Such flow is potentially important for the shape and composition of the formed structures. Relevant stress scales and estimated physical properties of silicon under these extreme conditions support the importance thermocapillary effects. A continuum flow model with Marangoni forcing reproduces the flow.

Method and apparatus for efficient photodetachment and purification of negative ion beams

DOEpatents

Beene, James R [Oak Ridge, TN; Liu, Yuan [Knoxville, TN; Havener, Charles C [Knoxville, TN

2008-02-26

Methods and apparatus are described for efficient photodetachment and purification of negative ion beams. A method of purifying an ion beam includes: inputting the ion beam into a gas-filled multipole ion guide, the ion beam including a plurality of ions; increasing a laser-ion interaction time by collisional cooling the plurality of ions using the gas-filled multipole ion guide, the plurality of ions including at least one contaminant; and suppressing the at least one contaminant by selectively removing the at least one contaminant from the ion beam by electron photodetaching at least a portion of the at least one contaminant using a laser beam.

Nanoscale topographic pattern formation on Kr{sup +}-bombarded germanium surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perkinson, Joy C.; Madi, Charbel S.; Aziz, Michael J.

2013-03-15

The nanoscale pattern formation of Ge surfaces uniformly irradiated by Kr{sup +} ions was studied in a low-contamination environment at ion energies of 250 and 500 eV and at angles of 0 Degree-Sign through 80 Degree-Sign . The authors present a phase diagram of domains of pattern formation occurring as these two control parameters are varied. The results are insensitive to ion energy over the range covered by the experiments. Flat surfaces are stable from normal incidence up to an incidence angle of {theta} = 55 Degree-Sign from normal. At higher angles, the surface is linearly unstable to the formationmore » of parallel-mode ripples, in which the wave vector is parallel to the projection of the ion beam on the surface. For {theta} {>=} 75 Degree-Sign the authors observe perpendicular-mode ripples, in which the wave vector is perpendicular to the ion beam. This behavior is qualitatively similar to those of Madi et al. for Ar{sup +}-irradiated Si but is inconsistent with those of Ziberi et al. for Kr{sup +}-irradiated Ge. The existence of a window of stability is qualitatively inconsistent with a theory based on sputter erosion [R. M. Bradley and J. M. Harper, J. Vac. Sci. Technol. A 6, 2390 (1988)] and qualitatively consistent with a model of ion impact-induced mass redistribution [G. Carter and V. Vishnyakov, Phys. Rev. B 54, 17647 (1996)] as well as a crater function theory incorporating both effects [S. A. Norris et al., Nat. Commun. 2, 276 (2011)]. The critical transition angle between stable and rippled surfaces occurs 10 Degree-Sign -15 Degree-Sign above the value of 45 Degree-Sign predicted by the mass redistribution model.« less

Metal oxide multilayer hard mask system for 3D nanofabrication

NASA Astrophysics Data System (ADS)

Han, Zhongmei; Salmi, Emma; Vehkamäki, Marko; Leskelä, Markku; Ritala, Mikko

2018-02-01

We demonstrate the preparation and exploitation of multilayer metal oxide hard masks for lithography and 3D nanofabrication. Atomic layer deposition (ALD) and focused ion beam (FIB) technologies are applied for mask deposition and mask patterning, respectively. A combination of ALD and FIB was used and a patterning procedure was developed to avoid the ion beam defects commonly met when using FIB alone for microfabrication. ALD grown Al2O3/Ta2O5/Al2O3 thin film stacks were FIB milled with 30 keV gallium ions and chemically etched in 5% tetramethylammonium hydroxide at 50 °C. With metal evaporation, multilayers consisting of amorphous oxides Al2O3 and Ta2O5 can be tailored for use in 2D lift-off processing, in preparation of embedded sub-100 nm metal lines and for multilevel electrical contacts. Good pattern transfer was achieved by lift-off process from the 2D hard mask for micro- and nano-scaled fabrication. As a demonstration of the applicability of this method to 3D structures, self-supporting 3D Ta2O5 masks were made from a film stack on gold particles. Finally, thin film resistors were fabricated by utilizing controlled stiction of suspended Ta2O5 structures.

Nanostructures by ion beams

NASA Astrophysics Data System (ADS)

Schmidt, B.

Ion beam techniques, including conventional broad beam ion implantation, ion beam synthesis and ion irradiation of thin layers, as well as local ion implantation with fine-focused ion beams have been applied in different fields of micro- and nanotechnology. The ion beam synthesis of nanoparticles in high-dose ion-implanted solids is explained as phase separation of nanostructures from a super-saturated solid state through precipitation and Ostwald ripening during subsequent thermal treatment of the ion-implanted samples. A special topic will be addressed to self-organization processes of nanoparticles during ion irradiation of flat and curved solid-state interfaces. As an example of silicon nanocrystal application, the fabrication of silicon nanocrystal non-volatile memories will be described. Finally, the fabrication possibilities of nanostructures, such as nanowires and chains of nanoparticles (e.g. CoSi2), by ion beam synthesis using a focused Co+ ion beam will be demonstrated and possible applications will be mentioned.

Development of dual-beam system using an electrostatic accelerator for in-situ observation of swift heavy ion irradiation effects on materials

NASA Astrophysics Data System (ADS)

Matsuda, M.; Asozu, T.; Sataka, M.; Iwase, A.

2013-11-01

We have developed the dual beam system which accelerates two kinds of ion beams simultaneously especially for real-time ion beam analysis. We have also developed the alternating beam system which can efficiently change beam species in a short time in order to realize efficient ion beam analysis in a limited beam time. The acceleration of the dual beam is performed by the 20 UR Pelletron™ tandem accelerator in which an ECR ion source is mounted at the high voltage terminal [1,2]. The multi-charged ions of two or more elements can be simultaneously generated from the ECR ion source, so dual-beam irradiation is achieved by accelerating ions with the same charge to mass ratio (for example, 132Xe11+ and 12C+). It enables us to make a real-time beam analysis such as Rutherford Back Scattering (RBS) method, while a target is irradiated with swift heavy ions. For the quick change of the accelerating ion beam, the program of automatic setting of the optical parameter of the accelerator has been developed. The switchover time for changing the ion beam is about 5 min. These developments have been applied to the study on the ion beam mixing caused by high-density electronic excitation induced by swift heavy ions.

Phase Space Generation for Proton and Carbon Ion Beams for External Users' Applications at the Heidelberg Ion Therapy Center.

PubMed

Tessonnier, Thomas; Marcelos, Tiago; Mairani, Andrea; Brons, Stephan; Parodi, Katia

2015-01-01

In the field of radiation therapy, accurate and robust dose calculation is required. For this purpose, precise modeling of the irradiation system and reliable computational platforms are needed. At the Heidelberg Ion Therapy Center (HIT), the beamline has been already modeled in the FLUKA Monte Carlo (MC) code. However, this model was kept confidential for disclosure reasons and was not available for any external team. The main goal of this study was to create efficiently phase space (PS) files for proton and carbon ion beams, for all energies and foci available at HIT. PSs are representing the characteristics of each particle recorded (charge, mass, energy, coordinates, direction cosines, generation) at a certain position along the beam path. In order to achieve this goal, keeping a reasonable data size but maintaining the requested accuracy for the calculation, we developed a new approach of beam PS generation with the MC code FLUKA. The generated PSs were obtained using an infinitely narrow beam and recording the desired quantities after the last element of the beamline, with a discrimination of primaries or secondaries. In this way, a unique PS can be used for each energy to accommodate the different foci by combining the narrow-beam scenario with a random sampling of its theoretical Gaussian beam in vacuum. PS can also reproduce the different patterns from the delivery system, when properly combined with the beam scanning information. MC simulations using PS have been compared to simulations, including the full beamline geometry and have been found in very good agreement for several cases (depth dose distributions, lateral dose profiles), with relative dose differences below 0.5%. This approach has also been compared with measured data of ion beams with different energies and foci, resulting in a very satisfactory agreement. Hence, the proposed approach was able to fulfill the different requirements and has demonstrated its capability for application to clinical treatment fields. It also offers a powerful tool to perform investigations on the contribution of primary and secondary particles produced in the beamline. These PSs are already made available to external teams upon request, to support interpretation of their measurements.

Surface modifications of ultra-thin gold films by swift heavy ion irradiation

NASA Astrophysics Data System (ADS)

Dash, P.; Mallick, P.; Rath, H.; Dash, B. N.; Tripathi, A.; Prakash, Jai; Avasthi, D. K.; Satyam, P. V.; Mishra, N. C.

2010-10-01

Gold films of thickness 10 and 20 nm grown on float glass substrate by thermal evaporation technique were irradiated with 107 MeV Ag8+ and 58 MeV Ni5+ ions at different fluences and characterized by Grazing Incidence X-ray Diffraction (GIXRD) and Atomic Force Microscopy (AFM). The pristine films were continuous and no island structures were found even at these small thicknesses. The surface roughness estimated from AFM data did not show either monotonic increase or decrease with ion fluences. Instead, it increased at low fluences and decreased at high fluences for 20 nm thick film. In the 10 nm film roughness first increased with ion fluence, then decreased and again increased at higher fluences. The pattern of variation, however, was identical for Ni and Ag beams. Both the beams led to the formation of cracks on the film surface at intermediate fluences. The observed ion-irradiation induced thickness dependent topographic modification is explained by the spatial confinement of the energy deposited by ions in the reduced dimension of the films.

A specialized bioengineering ion beam line

NASA Astrophysics Data System (ADS)

Yu, L. D.; Sangyuenyongpipat, S.; Sriprom, C.; Thongleurm, C.; Suwanksum, R.; Tondee, N.; Prakrajang, K.; Vilaithong, T.; Brown, I. G.; Wiedemann, H.

2007-04-01

A specialized bioengineering ion beam line has recently been completed at Chiang Mai University to meet rapidly growing needs of research and application development in low-energy ion beam biotechnology. This beam line possesses special features: vertical main beam line, low-energy (30 keV) ion beams, double swerve of the beam, a fast pumped target chamber, and an in-situ atomic force microscope (AFM) system chamber. The whole beam line is situated in a bioclean environment, occupying two stories. The quality of the ion beam has been studied. It has proved that this beam line has significantly contributed to our research work on low-energy ion beam biotechnology.

Selective formation of porous silicon

NASA Technical Reports Server (NTRS)

Fathauer, Jones (Inventor)

1993-01-01

A pattern of porous silicon is produced in the surface of a silicon substrate by forming a pattern of crystal defects in said surface, preferably by applying an ion milling beam through openings in a photoresist layer to the surface, and then exposing said surface to a stain etchant, such as HF:HNO3:H20. The defected crystal will preferentially etch to form a pattern of porous silicon. When the amorphous content of the porous silicon exceeds 70 percent, the porous silicon pattern emits visible light at room temperature.

Coarsening of ion-beam-induced surface ripple in Si: Nonlinear effect vs. geometrical shadowing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Datta, Debi Prasad; Chini, Tapas Kumar

The temporal evolution of a periodic ripple pattern on a silicon surface undergoing erosion by 30 keV argon ion bombardment has been studied for two angles of ion incidence of 60 deg. and 70 deg. using ex situ atomic force microscopy (AFM) in ambient condition. The roughness amplitude (w) grows exponentially with sputtering time for both the angle of ion incidence followed by a slow growth process that saturates eventually with almost constant amplitude. Within the exponential growth regime of amplitude, however, ripple wavelength (l) remains constant initially and increases subsequently as a power law fashion l{proportional_to}t{sup n}, where n=0.47{+-}0.02more » for a 60 deg. angle of ion incidence followed by a saturation. Wavelength coarsening was also observed for 70 deg. but ordering in the periodic ripple pattern is destroyed quickly for 70 deg. as compared to 60 deg. . The ripple orientation, average ripple wavelength at the initial stage of ripple evolution, and the exponential growth of ripple amplitude can be described by a linear continuum model. While the wavelength coarsening could possibly be explained in the light of recent hydrodynamic model based continuum theory, the subsequent saturation of wavelength and amplitude was attributed to the effect of geometrical shadowing. This is an experimental result that probably gives a hint about the upper limit of the energy of ion beam rippling for applying the recently developed type of nonlinear continuum model.« less

A comparative study on low-energy ion beam and neutralized beam modifications of naked DNA and biological effect on mutation

NASA Astrophysics Data System (ADS)

Sarapirom, S.; Thongkumkoon, P.; Prakrajang, K.; Anuntalabhochai, S.; Yu, L. D.

2012-02-01

DNA conformation change or damage induced by low-energy ion irradiation has been of great interest owing to research developments in ion beam biotechnology and ion beam application in biomedicine. Mechanisms involved in the induction of DNA damage may account for effect from implanting ion charge. In order to check this effect, we used both ion beam and neutralized beam at keV energy to bombard naked DNA. Argon or nitrogen ion beam was generated and extracted from a radiofrequency (RF) ion source and neutralized by microwave-driven plasma in the beam path. Plasmid DNA pGFP samples were irradiated with the ion or neutralized beam in vacuum, followed by gel electrophoresis to observe changes in the DNA conformations. It was revealed that the ion charge played a certain role in inducing DNA conformation change. The subsequent DNA transfer into bacteria Escherichia coli ( E. coli) for mutation analysis indicated that the charged ion beam induced DNA change had high potential in mutation induction while neutralized beam did not. The intrinsic reason was attributed to additional DNA deformation and contortion caused by ion charge exchange effect so that the ion beam induced DNA damage could hardly be completely repaired, whereas the neutralized beam induced DNA change could be more easily recoverable owing to absence of the additional DNA deformation and contortion.

Electrochemical electron beam lithography: Write, read, and erase metallic nanocrystals on demand

PubMed Central

Park, Jeung Hun; Steingart, Daniel A.; Kodambaka, Suneel; Ross, Frances M.

2017-01-01

We develop a solution-based nanoscale patterning technique for site-specific deposition and dissolution of metallic nanocrystals. Nanocrystals are grown at desired locations by electron beam–induced reduction of metal ions in solution, with the ions supplied by dissolution of a nearby electrode via an applied potential. The nanocrystals can be “erased” by choice of beam conditions and regrown repeatably. We demonstrate these processes via in situ transmission electron microscopy using Au as the model material and extend to other metals. We anticipate that this approach can be used to deposit multicomponent alloys and core-shell nanostructures with nanoscale spatial and compositional resolutions for a variety of possible applications. PMID:28706992

Slit disk for modified faraday cup diagnostic for determining power density of electron and ion beams

DOEpatents

Teruya, Alan T [Livermore, CA; Elmer,; John, W [Danville, CA; Palmer, Todd A [State College, PA

2011-03-08

A diagnostic system for characterization of an electron beam or an ion beam includes an electrical conducting disk of refractory material having a circumference, a center, and a Faraday cup assembly positioned to receive the electron beam or ion beam. At least one slit in the disk provides diagnostic characterization of the electron beam or ion beam. The at least one slit is located between the circumference and the center of the disk and includes a radial portion that is in radial alignment with the center and a portion that deviates from radial alignment with the center. The electron beam or ion beam is directed onto the disk and translated to the at least one slit wherein the electron beam or ion beam enters the at least one slit for providing diagnostic characterization of the electron beam or ion beam.

A Particle-in-Cell Simulation for the Traveling Wave Direct Energy Converter (TWDEC) for Fusion Propulsion

NASA Technical Reports Server (NTRS)

Chap, Andrew; Tarditi, Alfonso G.; Scott, John H.

2013-01-01

A Particle-in-cell simulation model has been developed to study the physics of the Traveling Wave Direct Energy Converter (TWDEC) applied to the conversion of charged fusion products into electricity. In this model the availability of a beam of collimated fusion products is assumed; the simulation is focused on the conversion of the beam kinetic energy into alternating current (AC) electric power. The model is electrostatic, as the electro-dynamics of the relatively slow ions can be treated in the quasistatic approximation. A two-dimensional, axisymmetric (radial-axial coordinates) geometry is considered. Ion beam particles are injected on one end and travel along the axis through ring-shaped electrodes with externally applied time-varying voltages, thus modulating the beam by forming a sinusoidal pattern in the beam density. Further downstream, the modulated beam passes through another set of ring electrodes, now electrically oating. The modulated beam induces a time alternating potential di erence between adjacent electrodes. Power can be drawn from the electrodes by connecting a resistive load. As energy is dissipated in the load, a corresponding drop in beam energy is measured. The simulation encapsulates the TWDEC process by reproducing the time-dependent transfer of energy and the particle deceleration due to the electric eld phase time variations.

Nanofabrication and ion milling introduced effects on magnetic properties in magnetic recording

NASA Astrophysics Data System (ADS)

Sun, Zhenzhong

Perpendicular magnetic nanostructures have played an important role in magnetic recording technologies. In this dissertation, a systematic study on the CoPt magnetic nanostructures from fabrication, characterization to computer simulation has been performed. During the fabrication process, ion irradiation/bombardment in ion mill can cause physical damage to the magnetic nanostructures and degrade their magnetic properties. To study the effect of ion damage on CoPt nanostructures, different degrees of ion damage are introduced into CoPt nanopillars by varying the accelerating voltage in ion mill. The results demonstrate that the ion damage can reduce the coercivity by softening circumferential edge, and therefore changes the switching mechanism from coherent rotation to nucleation followed by rapid domain wall propagation. The SFD of CoPt nanostructures is independent of ion damage and is mainly determined by the intrinsic anisotropy distribution of the film rather than the nanostructure size distribution. Anisotropy-graded bit-patterned media are fabricated and studied based on high anisotropy L10-FePt material system. L10-FePt thin films with linearly and quadratically distributed anisotropy are achieved by varying substrate temperature during film growth. After patterning, the anisotropy-graded L10-FePt nanopillars display a reduced switching field and maintain a good thermal stability compared to the non-graded one. Experimental investigation and comparison further prove the concept of "anisotropy-graded" bit-patterned media and their potential application in the future magnetic recording. During magnetic write head fabrication, ion-beam damage may degrade the performance of the magnetic write pole. A surface sensitive MOKE is used to characterize the magnetic properties of these etched FeCo films. MOKE measurement shows a hard axis hysteresis loop with a high Mr in the high power etched film due to the ion beam introduced defects. The high power etched film also shows the highest RMS by AFM measurement. The geometric peaks at the top surface may have shape anisotropy and serve as the pinning sites. These magnetic pinning sites can prevent the nucleation center forming at the top surface during the switching process and lead to a high Mr in the top surface region.

Making AlN(x) Tunnel Barriers Using a Low-Energy Nitrogen-Ion Beam

NASA Technical Reports Server (NTRS)

Kaul, Anupama; Kleinsasser, Alan; Bumble, Bruce; LeDuc, Henry; Lee, Karen

2005-01-01

A technique based on accelerating positive nitrogen ions onto an aluminum layer has been demonstrated to be effective in forming thin (<2 nm thick) layers of aluminum nitride (AlN(x)) for use as tunnel barriers in Nb/Al-AlN(x)/Nb superconductor/insulator/ superconductor (SIS) Josephson junctions. AlN(x) is the present material of choice for tunnel barriers because, to a degree greater than that of any other suitable material, it offers the required combination of low leakage current at high current density and greater thermal stability. While ultra-thin AlN films with good thickness and stoichiometry control are easily formed using techniques such as reactive molecular beam epitaxy and chemical vapor deposition, growth temperatures of 900 C are necessary for the dissociative adsorption of nitrogen from either nitrogen (N2) or ammonia (NH3). These growth temperatures are prohibitively high for the formation of tunnel barriers on Nb films because interfacial reactions at temperatures as low as 200 to 300 C degrade device properties. Heretofore, deposition by reactive sputtering and nitridation of thin Al layers with DC and RF nitrogen plasmas have been successfully used to form AlN barriers in SIS junctions. However, precise control over critical current density Jc has proven to be a challenge, as is attaining adequate process reproducibility from system to system. The present ion-beam technique is an alternative to the plasma or reactive sputtering techniques as it provides a highly controlled arrival of reactive species, independent of the electrical conditions of the substrate or vacuum chamber. Independent and accurate control of parameters such as ion energy, flux, species, and direction promises more precise control of film characteristics such as stoichiometry and thickness than is the case with typical plasma processes. In particular, the background pressure during ion-beam nitride growth is 2 or 3 orders of magnitude lower, minimizing the formation of compounds with contaminants, which is critical in devices the performance of which is dictated by interfacial characteristics. In addition, the flux of incoming species can be measured in situ using ion probes so that the dose can be controlled accurately. The apparatus used in the present ion-beam technique includes a vacuum chamber containing a commercial collimated- ion-beam source, a supply of nitrogen and argon, and an ion probe for measuring the ion dose. Either argon or nitrogen can be used as the feed gases for the ion source, depending on whether cleaning of the substrate or growth of the nitride, respectively, is desired. Once the Nb base electrode and Al proximity layer have been deposited, the N2 gas line to the ion beam is vented and purged, and the ion-source is turned on until a stable discharge is obtained. The substrate is moved over the ion-beam source to expose the Al surface layer to the ion beam (see figure) for a specified duration for the formation of the nitride tunnel barrier. Next, the Nb counter-electrode layer is deposited on the nitride surface layer. The Nb/Al- AlN(x)/Nb-trilayer-covered substrate is then patterned into individual devices by use of conventional integrated-circuit processing techniques.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prost, Lionel; Carneiro, Jean-Paul; Shemyakin, Alexander

In a Low Energy Beam Transport line (LEBT), the emittance growth due to the beam's own space charge is typically suppressed by way of neutralization from either electrons or ions, which originate from ionization of the background gas. In cases where the beam is chopped, the neutralization pattern changes throughout the beginning of the pulse, causing the Twiss parameters to differ significantly from their steady state values, which, in turn, may result in beam losses downstream. For a modest beam perveance, there is an alternative solution, in which the beam is kept un-neutralized in the portion of the LEBT thatmore » contains the chopper. The emittance can be nearly preserved if the transition to the un-neutralized section occurs where the beam exhibits low transverse tails. This report discusses the experimental realization of such a scheme at Fermilab's PXIE, where low beam emittance dilution was demonstrated« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, A. L.; Chen, J. E.; State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871

Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Montemore » Carlo collision code which has been successfully applied to H{sup +} beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H{sup −} beam from a 2.45 GHz microwave driven H{sup −} ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results.« less

Beam brilliance investigation of high current ion beams at GSI heavy ion accelerator facility.

PubMed

Adonin, A A; Hollinger, R

2014-02-01

In this work the emittance measurements of high current Ta-beam provided by VARIS (Vacuum Arc Ion Source) ion source are presented. Beam brilliance as a function of beam aperture at various extraction conditions is investigated. Influence of electrostatic ion beam compression in post acceleration gap on the beam quality is discussed. Use of different extraction systems (single aperture, 7 holes, and 13 holes) in order to achieve more peaked beam core is considered. The possible ways to increase the beam brilliance are discussed.

Ion Beam Propulsion Study

NASA Technical Reports Server (NTRS)

2008-01-01

The Ion Beam Propulsion Study was a joint high-level study between the Applied Physics Laboratory operated by NASA and ASRC Aerospace at Kennedy Space Center, Florida, and Berkeley Scientific, Berkeley, California. The results were promising and suggested that work should continue if future funding becomes available. The application of ion thrusters for spacecraft propulsion is limited to quite modest ion sources with similarly modest ion beam parameters because of the mass penalty associated with the ion source and its power supply system. Also, the ion source technology has not been able to provide very high-power ion beams. Small ion beam propulsion systems were used with considerable success. Ion propulsion systems brought into practice use an onboard ion source to form an energetic ion beam, typically Xe+ ions, as the propellant. Such systems were used for steering and correction of telecommunication satellites and as the main thruster for the Deep Space 1 demonstration mission. In recent years, "giant" ion sources were developed for the controlled-fusion research effort worldwide, with beam parameters many orders of magnitude greater than the tiny ones of conventional space thruster application. The advent of such huge ion beam sources and the need for advanced propulsion systems for exploration of the solar system suggest a fresh look at ion beam propulsion, now with the giant fusion sources in mind.

Neutralized ion beam modification of cellulose membranes for study of ion charge effect on ion-beam-induced DNA transfer

NASA Astrophysics Data System (ADS)

Prakrajang, K.; Sangwijit, K.; Anuntalabhochai, S.; Wanichapichart, P.; Yu, L. D.

2012-02-01

Low-energy ion beam biotechnology (IBBT) has recently been rapidly developed worldwide. Ion-beam-induced DNA transfer is one of the important applications of IBBT. However, mechanisms involved in this application are not yet well understood. In this study plasma-neutralized ion beam was applied to investigate ion charge effect on induction of DNA transfer. Argon ion beam at 7.5 keV was neutralized by RF-driven plasma in the beam path and then bombarded cellulose membranes which were used as the mimetic plant cell envelope. Electrical properties such as impedance and capacitance of the membranes were measured after the bombardment. An in vitro experiment on plasmid DNA transfer through the cellulose membrane was followed up. The results showed that the ion charge input played an important role in the impedance and capacitance changes which would affect DNA transfer. Generally speaking, neutral particle beam bombardment of biologic cells was more effective in inducing DNA transfer than charged ion beam bombardment.

FIB-SEM cathodoluminescence tomography: practical and theoretical considerations.

PubMed

De Winter, D A M; Lebbink, M N; Wiggers De Vries, D F; Post, J A; Drury, M R

2011-09-01

Focused ion beam-scanning electron microscope (FIB-SEM) tomography is a powerful application in obtaining three-dimensional (3D) information. The FIB creates a cross section and subsequently removes thin slices. The SEM takes images using secondary or backscattered electrons, or maps every slice using X-rays and/or electron backscatter diffraction patterns. The objective of this study is to assess the possibilities of combining FIB-SEM tomography with cathodoluminescence (CL) imaging. The intensity of CL emission is related to variations in defect or impurity concentrations. A potential problem with FIB-SEM CL tomography is that ion milling may change the defect state of the material and the CL emission. In addition the conventional tilted sample geometry used in FIB-SEM tomography is not compatible with conventional CL detectors. Here we examine the influence of the FIB on CL emission in natural diamond and the feasibility of FIB-SEM CL tomography. A systematic investigation establishes that the ion beam influences CL emission of diamond, with a dependency on both the ion beam and electron beam acceleration voltage. CL emission in natural diamond is enhanced particularly at low ion beam and electron beam voltages. This enhancement of the CL emission can be partly explained by an increase in surface defects induced by ion milling. CL emission enhancement could be used to improve the CL image quality. To conduct FIB-SEM CL tomography, a recently developed novel specimen geometry is adopted to enable sequential ion milling and CL imaging on an untilted sample. We show that CL imaging can be manually combined with FIB-SEM tomography with a modified protocol for 3D microstructure reconstruction. In principle, automated FIB-SEM CL tomography should be feasible, provided that dedicated CL detectors are developed that allow subsequent milling and CL imaging without manual intervention, as the current CL detector needs to be manually retracted before a slice can be milled. Due to the required high electron beam acceleration voltage for CL emission, the resolution for FIB-SEM CL tomography is currently limited to several hundreds of nm in XY and up to 650 nm in Z for diamonds. Opaque materials are likely to have an improved Z resolution, as CL emission generated deeper in the material is not able to escape from it. © 2011 The Authors Journal of Microscopy © 2011 Royal Microscopical Society.

Generation of forerunner electron beam during interaction of ion beam pulse with plasma

NASA Astrophysics Data System (ADS)

Hara, Kentaro; Kaganovich, Igor D.; Startsev, Edward A.

2018-01-01

The long-time evolution of the two-stream instability of a cold tenuous ion beam pulse propagating through the background plasma with density much higher than the ion beam density is investigated using a large-scale one-dimensional electrostatic kinetic simulation. The three stages of the instability are investigated in detail. After the initial linear growth and saturation by the electron trapping, a portion of the initially trapped electrons becomes detrapped and moves ahead of the ion beam pulse forming a forerunner electron beam, which causes a secondary two-stream instability that preheats the upstream plasma electrons. Consequently, the self-consistent nonlinear-driven turbulent state is set up at the head of the ion beam pulse with the saturated plasma wave sustained by the influx of the cold electrons from upstream of the beam that lasts until the final stage when the beam ions become trapped by the plasma wave. The beam ion trapping leads to the nonlinear heating of the beam ions that eventually extinguishes the instability.

Diagnosis of high-intensity pulsed heavy ion beam generated by a novel magnetically insulated diode with gas puff plasma gun.

PubMed

Ito, H; Miyake, H; Masugata, K

2008-10-01

Intense pulsed heavy ion beam is expected to be applied to materials processing including surface modification and ion implantation. For those applications, it is very important to generate high-purity ion beams with various ion species. For this purpose, we have developed a new type of a magnetically insulated ion diode with an active ion source of a gas puff plasma gun. When the ion diode was operated at a diode voltage of about 190 kV, a diode current of about 15 kA, and a pulse duration of about 100 ns, the ion beam with an ion current density of 54 A/cm(2) was obtained at 50 mm downstream from the anode. By evaluating the ion species and the energy spectrum of the ion beam via a Thomson parabola spectrometer, it was confirmed that the ion beam consists of nitrogen ions (N(+) and N(2+)) of energy of 100-400 keV and the proton impurities of energy of 90-200 keV. The purity of the beam was evaluated to be 94%. The high-purity pulsed nitrogen ion beam was successfully obtained by the developed ion diode system.

The automated array assembly task of the low-cost silicon solar array project, phase 2

NASA Technical Reports Server (NTRS)

Coleman, M. G.; Pryor, R. A.; Sparks, T. G.; Legge, R.; Saltzman, D. L.

1980-01-01

Several specific processing steps as part of a total process sequence for manufacturing silicon solar cells were studied. Ion implantation was identified as the preferred process step for impurity doping. Unanalyzed beam ion implantation was shown to have major cost advantages over analyzed beam implantation. Further, high quality cells were fabricated using a high current unanalyzed beam. Mechanically masked plasma patterning of silicon nitride was shown to be capable of forming fine lines on silicon surfaces with spacings between mask and substrate as great as 250 micrometers. Extensive work was performed on advances in plated metallization. The need for the thick electroless palladium layer was eliminated. Further, copper was successfully utilized as a conductor layer utilizing nickel as a barrier to copper diffusion into the silicon. Plasma etching of silicon for texturing and saw damage removal was shown technically feasible but not cost effective compared to wet chemical etching techniques.

Multiple ion beam irradiation for the study of radiation damage in materials

NASA Astrophysics Data System (ADS)

Taller, Stephen; Woodley, David; Getto, Elizabeth; Monterrosa, Anthony M.; Jiao, Zhijie; Toader, Ovidiu; Naab, Fabian; Kubley, Thomas; Dwaraknath, Shyam; Was, Gary S.

2017-12-01

The effects of transmutation produced helium and hydrogen must be included in ion irradiation experiments to emulate the microstructure of reactor irradiated materials. Descriptions of the criteria and systems necessary for multiple ion beam irradiation are presented and validated experimentally. A calculation methodology was developed to quantify the spatial distribution, implantation depth and amount of energy-degraded and implanted light ions when using a thin foil rotating energy degrader during multi-ion beam irradiation. A dual ion implantation using 1.34 MeV Fe+ ions and energy-degraded D+ ions was conducted on single crystal silicon to benchmark the dosimetry used for multi-ion beam irradiations. Secondary Ion Mass Spectroscopy (SIMS) analysis showed good agreement with calculations of the peak implantation depth and the total amount of iron and deuterium implanted. The results establish the capability to quantify the ion fluence from both heavy ion beams and energy-degraded light ion beams for the purpose of using multi-ion beam irradiations to emulate reactor irradiated microstructures.

Positive and negative ion beam merging system for neutral beam production

DOEpatents

Leung, Ka-Ngo; Reijonen, Jani

2005-12-13

The positive and negative ion beam merging system extracts positive and negative ions of the same species and of the same energy from two separate ion sources. The positive and negative ions from both sources pass through a bending magnetic field region between the pole faces of an electromagnet. Since the positive and negative ions come from mirror image positions on opposite sides of a beam axis, and the positive and negative ions are identical, the trajectories will be symmetrical and the positive and negative ion beams will merge into a single neutral beam as they leave the pole face of the electromagnet. The ion sources are preferably multicusp plasma ion sources. The ion sources may include a multi-aperture extraction system for increasing ion current from the sources.

Ion Beam Measurements of a Dense Plasma Focus Device Using CR 39 Nuclear Track Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ngoi, S. K.; Yap, S. L.; Wong, C. S.

The project is carried out using a small Mather type plasma focus device powered by a 15 kV, 30 {mu}F capacitor. The filling gas used is argon. The ion beam generated is investigated by both time resolved and time integrated methods. Investigation on the dynamic of the current sheath is also carried out in order to obtain an optimum condition for ion beam production. The angular distribution of the ion emission is measured at positions of 0 deg. (end-on), 45 deg. and 90 deg. (side-on) by using CR-39 nuclear track detectors. The divergence of the ion beam is also determinedmore » using these detectors. A biased ion collector is used for time resolved measurement of the ion beam. Time of flight technique is employed for the determination of the ion beam energy. Average ion beam energy obtained is about 180 keV. The ion beam produced can be used for applications such as material surface modification and ion implantation.« less

Strategies for gallium removal after focused ion beam patterning of ferroelectric oxide nanostructures

NASA Astrophysics Data System (ADS)

Schilling, A.; Adams, T.; Bowman, R. M.; Gregg, J. M.

2007-01-01

As part of a study into the properties of ferroelectric single crystals at nanoscale dimensions, the effects that focused ion beam (FIB) processing can have, in terms of structural damage and ion implantation, on perovskite oxide materials has been examined, and a post-processing procedure developed to remove such effects. Single crystal material of the perovskite ferroelectric barium titanate (BaTiO3) has been patterned into thin film lamellae structures using a FIB microscope. Previous work had shown that FIB patterning induced gallium impregnation and associated creation of amorphous layers in a surface region of the single crystal material some 20 nm thick, but that both recrystallization and expulsion of gallium could be achieved through thermal annealing in air. Here we confirm this observation, but find that thermally induced gallium expulsion is associated with the formation of gallium-rich platelets on the surface of the annealed material. These platelets are thought to be gallium oxide. Etching using nitric and hydrochloric acids had no effect on the gallium-rich platelets. Effective platelet removal involved thermal annealing at 700 °C for 1 h in a vacuum followed by 1 h in oxygen, and then a post-annealing low-power plasma clean in an Ar/O atmosphere. Similar processing is likely to be necessary for the full recovery of post FIB-milled nanostructures in oxide ceramic systems in general.

Ion beam sputter etching and deposition of fluoropolymers

NASA Technical Reports Server (NTRS)

Banks, B. A.; Sovey, J. S.; Miller, T. B.; Crandall, K. S.

1978-01-01

Fluoropolymer etching and deposition techniques including thermal evaporation, RF sputtering, plasma polymerization, and ion beam sputtering are reviewed. Etching and deposition mechanism and material characteristics are discussed. Ion beam sputter etch rates for polytetrafluoroethylene (PTFE) were determined as a function of ion energy, current density and ion beam power density. Peel strengths were measured for epoxy bonds to various ion beam sputtered fluoropolymers. Coefficients of static and dynamic friction were measured for fluoropolymers deposited from ion bombarded PTFE.

An electron cyclotron resonance ion source based low energy ion beam platform.

PubMed

Sun, L T; Shang, Y; Ma, B H; Zhang, X Z; Feng, Y C; Li, X X; Wang, H; Guo, X H; Song, M T; Zhao, H Y; Zhang, Z M; Zhao, H W; Xie, D Z

2008-02-01

To satisfy the requirements of surface and atomic physics study in the field of low energy multiple charge state ion incident experiments, a low energy (10 eV/q-20 keV/q) ion beam platform is under design at IMP. A simple test bench has been set up to test the ion beam deceleration systems. Considering virtues such as structure simplicity, easy handling, compactness, cost saving, etc., an all-permanent magnet ECRIS LAPECR1 [Lanzhou all-permanent magnet electron cyclotron resonance (ECR) ion source No. 1] working at 14.5 GHz has been adopted to produce intense medium and low charge state ion beams. LAPECR1 source has already been ignited. Some intense low charge state ion beams have been produced on it, but the first test also reveals that many problems are existing on the ion beam transmission line. The ion beam transmission mismatches result in the depressed performance of LAPECR1, which will be discussed in this paper. To obtain ultralow energy ion beam, after being analyzed by a double-focusing analyzer magnet, the selected ion beam will be further decelerated by two afocal deceleration lens systems, which is still under design. This design has taken into consideration both ions slowing down and also ion beam focusing. In this paper, the conceptual design of deceleration system will be discussed.

Two-dimensional silicon-based detectors for ion beam therapy

NASA Astrophysics Data System (ADS)

Martišíková, M.; Granja, C.; Jakůbek, J.; Hartmann, B.; Telsemeyer, J.; Huber, L.; Brons, S.; Pospíšil, S.; Jäkel, O.

2012-02-01

Radiation therapy with ion beams is a highly precise kind of cancer treatment. As ion beams traverse material, the highest ionization density occurs at the end of their path. Due to this Bragg-peak, ion beams enable higher dose conformation to the tumor and increased sparing of the surrounding tissue, in comparison to standard radiation therapy using high energy photons. Ions heavier than protons offer in addition increased biological effectiveness and lower scattering. The Heidelberg Ion Beam Therapy Center (HIT) is a state-of-the-art ion beam therapy facility and the first hospital-based facility in Europe. It provides proton and carbon ion treatments. A synchrotron is used for ion acceleration. For dose delivery to the patient, narrow pencil-like beams are scanned over the target volume.

Low energy ion beam dynamics of NANOGAN ECR ion source

NASA Astrophysics Data System (ADS)

Kumar, Sarvesh; Mandal, A.

2016-04-01

A new low energy ion beam facility (LEIBF) has been developed for providing the mass analyzed highly charged intense ion beams of energy ranging from a few tens of keV to a few MeV for atomic, molecular and materials sciences research. The new facility consists of an all permanent magnet 10 GHz electron cyclotron resonance (ECR) ion source (NANOGAN) installed on a high voltage platform (400 kV) which provides large currents of multiply charged ion beams. Higher emittance at low energy of intense ion beam puts a tremendous challenge to the beam optical design of this facility. The beam line consists of mainly the electrostatic quadrupoles, an accelerating section, analyzing cum switching magnet and suitable beam diagnostics including vacuum components. The accelerated ion beam is analyzed for a particular mass to charge (m/q) ratio as well as guided to three different lines along 75°, 90° and 105° using a large acceptance analyzing cum switching magnet. The details of transverse beam optics to all the beam lines with TRANSPORT and GICOSY beam optics codes are being described. Field computation code, OPERA 3D has been utilized to design the magnets and electrostatic quadrupoles. A theoretical estimation of emittance for optimized geometry of ion source is given so as to form the basis of beam optics calculations. The method of quadrupole scan of the beam is used to characterize the emittance of the final beam on the target. The measured beam emittance increases with m/q ratios of various ion beams similar to the trend observed theoretically.

MASS SPECTROMETER

DOEpatents

White, F.A.

1960-08-23

A mass spectrometer is designed with a first adjustable magnetic field for resolving an ion beam into beams of selected masses, a second adjustable magnetic field for further resolving the ion beam from the first field into beams of selected masses, a thin foil disposed in the path of the beam between the first and second magnets to dissociate molecular ions incident thereon, an electrostatic field for further resolving the ion beam from the second field into beams of selected masses, and a detector disposed adjacent to the electrostatic field to receive the ion beam.

Study of beam optics and beam halo by integrated modeling of negative ion beams from plasma meniscus formation to beam acceleration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyamoto, K.; Okuda, S.; Hatayama, A.

2013-01-14

To understand the physical mechanism of the beam halo formation in negative ion beams, a two-dimensional particle-in-cell code for simulating the trajectories of negative ions created via surface production has been developed. The simulation code reproduces a beam halo observed in an actual negative ion beam. The negative ions extracted from the periphery of the plasma meniscus (an electro-static lens in a source plasma) are over-focused in the extractor due to large curvature of the meniscus.

Graphene Nanoribbons Fabricated by Helium Ion microscope

NASA Astrophysics Data System (ADS)

Pickard, D.; Oezyilmaz, B.; Thong, J.; Loh, K. P.; Viswanathan, V.; Zhongkai, A.; Mathew, S.; Kundu, T.; Park, C.; Yi, Z.; Xu, X.; Zhang, K.; Tat, T. C.; Wang, H.; Venkatesan, T.; Botton, G.; Couillard, M.

2010-03-01

Graphene, a monolayer graphitic lattice of carbon atoms has tremendous promise for a variety of applications on account of the zero mass of electrons, high mobility and the sensitivity of transport to perturbations at the interface. Patterning graphene is an obvious challenge and mesoscopic devices based on graphene require high spatial resolution patterning that will induce as little damage as possible. We use a helium ion microscope with its 0.4nm spot size beam to directly write patterns on free standing graphene films. TEM images of the patterns reveal holes as small as 4 nm and ribbons with line widths as narrow as 3 nm. The images show recovery of the graphene lattice at a distance of about a nm from the patterned edge. The linewidths of the ribbon can be varied considerably in a controllable fashion over ribbon lengths of the order of microns. . .

Broad beam ion implanter

DOEpatents

Leung, K.N.

1996-10-08

An ion implantation device for creating a large diameter, homogeneous, ion beam is described, as well as a method for creating same, wherein the device is characterized by extraction of a diverging ion beam and its conversion by ion beam optics to an essentially parallel ion beam. The device comprises a plasma or ion source, an anode and exit aperture, an extraction electrode, a divergence-limiting electrode and an acceleration electrode, as well as the means for connecting a voltage supply to the electrodes. 6 figs.

Broad beam ion implanter

DOEpatents

Leung, Ka-Ngo

1996-01-01

An ion implantation device for creating a large diameter, homogeneous, ion beam is described, as well as a method for creating same, wherein the device is characterized by extraction of a diverging ion beam and its conversion by ion beam optics to an essentially parallel ion beam. The device comprises a plasma or ion source, an anode and exit aperture, an extraction electrode, a divergence-limiting electrode and an acceleration electrode, as well as the means for connecting a voltage supply to the electrodes.

Epitaxial graphene growth on FIB patterned 3C-SiC nanostructures on Si (111): reducing milling damage.

PubMed

Amjadipour, Mojtaba; MacLeod, Jennifer; Lipton-Duffin, Josh; Iacopi, Francesca; Motta, Nunzio

2017-08-25

Epitaxial growth of graphene on SiC is a scalable procedure that does not require any further transfer step, making this an ideal platform for graphene nanostructure fabrication. Focused ion beam (FIB) is a very promising tool for exploring the reduction of the lateral dimension of graphene on SiC to the nanometre scale. However, exposure of graphene to the Ga + beam causes significant surface damage through amorphisation and contamination, preventing epitaxial graphene growth. In this paper we demonstrate that combining a protective silicon layer with FIB patterning implemented prior to graphene growth can significantly reduce the damage associated with FIB milling. Using this approach, we successfully achieved graphene growth over 3C-SiC/Si FIB patterned nanostructures.

Investigations of the emittance and brightness of ion beams from an electron beam ion source of the Dresden EBIS type.

PubMed

Silze, Alexandra; Ritter, Erik; Zschornack, Günter; Schwan, Andreas; Ullmann, Falk

2010-02-01

We have characterized ion beams extracted from the Dresden EBIS-A, a compact room-temperature electron beam ion source (EBIS) with a permanent magnet system for electron beam compression, using a pepper-pot emittance meter. The EBIS-A is the precursor to the Dresden EBIS-SC in which the permanent magnets have been replaced by superconducting solenoids for the use of the source in high-ion-current applications such as heavy-ion cancer therapy. Beam emittance and brightness values were calculated from data sets acquired for a variety of source parameters, in leaky as well as pulsed ion extraction mode. With box shaped pulses of C(4+) ions at an energy of 39 keV root mean square emittances of 1-4 mm mrad and a brightness of 10 nA mm(-2) mrad(-2) were achieved. The results meet the expectations for high quality ion beams generated by an electron beam ion source.

Mass spectrometer with electron source for reducing space charge effects in sample beam

DOEpatents

Houk, Robert S.; Praphairaksit, Narong

2003-10-14

A mass spectrometer includes an ion source which generates a beam including positive ions, a sampling interface which extracts a portion of the beam from the ion source to form a sample beam that travels along a path and has an excess of positive ions over at least part of the path, thereby causing space charge effects to occur in the sample beam due to the excess of positive ions in the sample beam, an electron source which adds electrons to the sample beam to reduce space charge repulsion between the positive ions in the sample beam, thereby reducing the space charge effects in the sample beam and producing a sample beam having reduced space charge effects, and a mass analyzer which analyzes the sample beam having reduced space charge effects.

Selective formation of porous silicon

NASA Technical Reports Server (NTRS)

Fathauer, Robert W. (Inventor); Jones, Eric W. (Inventor)

1993-01-01

A pattern of porous silicon is produced in the surface of a silicon substrate by forming a pattern of crystal defects in said surface, preferably by applying an ion milling beam through openings in a photoresist layer to the surface, and then exposing said surface to a stain etchant, such as HF:HNO3:H2O. The defected crystal will preferentially etch to form a pattern of porous silicon. When the amorphous content of the porous silicon exceeds 70 percent, the porous silicon pattern emits visible light at room temperature.

CVD diamond detector with interdigitated electrode pattern for time-of-flight energy-loss measurements of low-energy ion bunches

NASA Astrophysics Data System (ADS)

Cayzac, W.; Pomorski, M.; Blažević, A.; Canaud, B.; Deslandes, D.; Fariaut, J.; Gontier, D.; Lescoute, E.; Marmouget, J. G.; Occelli, F.; Oudot, G.; Reverdin, C.; Sauvestre, J. E.; Sollier, A.; Soullié, G.; Varignon, C.; Villette, B.

2018-05-01

Ion stopping experiments in plasma for beam energies of few hundred keV per nucleon are of great interest to benchmark the stopping-power models in the context of inertial confinement fusion and high-energy-density physics research. For this purpose, a specific ion detector on chemical-vapor-deposition diamond basis has been developed for precise time-of-flight measurements of the ion energy loss. The electrode structure is interdigitated for maximizing its sensitivity to low-energy ions, and it has a finger width of 100 μm and a spacing of 500 μm. A short single α-particle response is obtained, with signals as narrow as 700 ps at full width at half maximum. The detector has been tested with α-particle bunches at a 500 keV per nucleon energy, showing an excellent time-of-flight resolution down to 20 ps. In this way, beam energy resolutions from 0.4 keV to a few keV have been obtained in an experimental configuration using a 100 μg/cm2 thick carbon foil as an energy-loss target and a 2 m time-of-flight distance. This allows a highly precise beam energy measurement of δE/E ≈ 0.04%-0.2% and a resolution on the energy loss of 0.6%-2.5% for a fine testing of stopping-power models.

Crater function moments: Role of implanted noble gas atoms

NASA Astrophysics Data System (ADS)

Hobler, Gerhard; Maciążek, Dawid; Postawa, Zbigniew

2018-04-01

Spontaneous pattern formation by energetic ion beams is usually explained in terms of surface-curvature dependent sputtering and atom redistribution in the target. Recently, the effect of ion implantation on surface stability has been studied for nonvolatile ion species, but for the case of noble gas ion beams it has always been assumed that the implanted atoms can be neglected. In this work, we show by molecular dynamics (MD) and Monte Carlo (MC) simulations that this assumption is not valid in a wide range of implant conditions. Sequential-impact MD simulations are performed for 1-keV Ar, 2-keV Kr, and 2-keV Xe bombardments of Si, starting with a pure single-crystalline Si target and running impacts until sputtering equilibrium has been reached. The simulations demonstrate the importance of the implanted ions for crater-function estimates. The atomic volumes of Ar, Kr, and Xe in Si are found to be a factor of two larger than in the solid state. To extend the study to a wider range of energies, MC simulations are performed. We find that the role of the implanted ions increases with the ion energy although the increase is attenuated for the heavier ions. The analysis uses the crater function formalism specialized to the case of sputtering equilibrium.

Generation of forerunner electron beam during interaction of ion beam pulse with plasma

DOE PAGES

Hara, Kentaro; Kaganovich, Igor D.; Startsev, Edward A.

2018-01-01

The long-time evolution of the two-stream instability of a cold tenuous ion beam pulse propagating through the background plasma with density much higher than the ion beam density is investigated using a large-scale one-dimensional electrostatic kinetic simulation. The three stages of the instability are investigated in detail. After the initial linear growth and saturation by the electron trapping, a portion of the initially trapped electrons becomes detrapped and moves ahead of the ion beam pulse forming a forerunner electron beam, which causes a secondary two-stream instability that preheats the upstream plasma electrons. Consequently, the self-consistent nonlinear-driven turbulent state is setmore » up at the head of the ion beam pulse with the saturated plasma wave sustained by the influx of the cold electrons from upstream of the beam that lasts until the final stage when the beam ions become trapped by the plasma wave. Finally, the beam ion trapping leads to the nonlinear heating of the beam ions that eventually extinguishes the instability.« less

Generation of forerunner electron beam during interaction of ion beam pulse with plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hara, Kentaro; Kaganovich, Igor D.; Startsev, Edward A.

The long-time evolution of the two-stream instability of a cold tenuous ion beam pulse propagating through the background plasma with density much higher than the ion beam density is investigated using a large-scale one-dimensional electrostatic kinetic simulation. The three stages of the instability are investigated in detail. After the initial linear growth and saturation by the electron trapping, a portion of the initially trapped electrons becomes detrapped and moves ahead of the ion beam pulse forming a forerunner electron beam, which causes a secondary two-stream instability that preheats the upstream plasma electrons. Consequently, the self-consistent nonlinear-driven turbulent state is setmore » up at the head of the ion beam pulse with the saturated plasma wave sustained by the influx of the cold electrons from upstream of the beam that lasts until the final stage when the beam ions become trapped by the plasma wave. Finally, the beam ion trapping leads to the nonlinear heating of the beam ions that eventually extinguishes the instability.« less

A Multicusp Ion Source for Radioactive Ion Beams

NASA Astrophysics Data System (ADS)

Wutte, D.; Freedman, S.; Gough, R.; Lee, Y.; Leitner, M.; Leung, K. N.; Lyneis, C.; Picard, D. S.; Sun, L.; Williams, M. D.; Xie, Z. Q.

1997-05-01

In order to produce a radioactive ion beam of (14)O+, a 10-cm-diameter, 13.56 MHz radio frequency (rf) driven multicusp ion source is now being developed at Lawrence Berkeley National Laboratory. In this paper we describe the specific ion source design and the basic ion source characteristics using Ar, Xe and a 90types of measurements have been performed: extractable ion current, ion species distributions, gas efficiency, axial energy spread and ion beam emittance measurements. The source can generate ion current densities of approximately 60 mA/cm2 . In addition the design of the ion beam extraction/transport system for the actual experimental setup for the radioactive beam line will be presented.

Ion profiling in an ambient drift tube-ion mobility spectrometer using a high pixel density linear array detector IonCCD.

PubMed

Davila, Stephen J; Hadjar, Omar; Eiceman, Gary A

2013-07-16

A linear pixel-based detector array, the IonCCD, is characterized for use under ambient conditions with thermal (<1 eV) positive ions derived from purified air and a 10 mCi (63)Ni foil. The IonCCD combined with a drift tube-ion mobility spectrometer permitted the direct detection of gas phase ions at atmospheric pressure and confirmed a limit of detection of 3000 ions/pixel/frame established previously in both the keV (1-2 keV) and the hyper-thermal (10-40 eV) regimes. Results demonstrate the "broad-band" application of the IonCCD over 10(5) orders in ion energy and over 10(10) in operating pressure. The Faraday detector of a drift tube for an ion mobility spectrometer was replaced with the IonCCD providing images of ion profiles over the cross-section of the drift tube. Patterns in the ion profiles were developed in the drift tube cross-section by control of electric fields between wires of Bradbury Nielson and Tyndall Powell shutter designs at distances of 1-8 cm from the detector. Results showed that ion beams formed in wire sets, retained their shape with limited mixing by diffusion and Coulombic repulsion. Beam broadening determined as 95 μm/cm for hydrated protons in air with moisture of ~10 ppmv. These findings suggest a value of the IonCCD in further studies of ion motion and diffusion of thermalized ions, enhancing computational results from simulation programs, and in the design or operation of ion mobility spectrometers.

Heavy metal incorporated helium ion active hybrid non-chemically amplified resists: Nano-patterning with low line edge roughness

NASA Astrophysics Data System (ADS)

Reddy, Pulikanti Guruprasad; Thakur, Neha; Lee, Chien-Lin; Chien, Sheng-Wei; Pradeep, Chullikkattil P.; Ghosh, Subrata; Tsai, Kuen-Yu; Gonsalves, Kenneth E.

2017-08-01

Helium (He) ion lithography is being considered as one of the most promising and emerging technology for the manufacturing of next generation integrated circuits (ICs) at nanolevel. However, He-ion active resists are rarely reported. In this context, we are introducing a new non-chemically amplified hybrid resist (n-CAR), MAPDSA-MAPDST, for high resolution He-ion beam lithography (HBL) applications. In the resist architecture, 2.15 % antimony is incorporated as heavy metal in the form of antimonate. This newly developed resists has successfully used for patterning 20 nm negative tone features at a dose of 60 μC/cm2. The resist offered very low line edge roughness (1.27±0.31 nm) for 20 nm line features. To our knowledge, this is the first He-ion active hybrid resist for nanopatterning. The contrast (γ) and sensitivity (E0) of this resist were calculated from the contrast curve as 0.73 and 7.2 μC/cm2, respectively.

Focused electron and ion beam systems

DOEpatents

Leung, Ka-Ngo; Reijonen, Jani; Persaud, Arun; Ji, Qing; Jiang, Ximan

2004-07-27

An electron beam system is based on a plasma generator in a plasma ion source with an accelerator column. The electrons are extracted from a plasma cathode in a plasma ion source, e.g. a multicusp plasma ion source. The beam can be scanned in both the x and y directions, and the system can be operated with multiple beamlets. A compact focused ion or electron beam system has a plasma ion source and an all-electrostatic beam acceleration and focusing column. The ion source is a small chamber with the plasma produced by radio-frequency (RF) induction discharge. The RF antenna is wound outside the chamber and connected to an RF supply. Ions or electrons can be extracted from the source. A multi-beam system has several sources of different species and an electron beam source.

Ion Figuring of Replicated X-Ray Optics

NASA Technical Reports Server (NTRS)

Cantey, Thomas M.; Gregory, Don A.

1997-01-01

This investigation included experiments to demonstrate ion beam figuring effects on electroless nickel with the expressed desire to figure X-ray optic mandrels. It was important to establish that ion beam figuring did not induce any adverse effects to the nickel surface. The ion beam has consistently been shown to be an excellent indicator of the quality of the subsurface. Polishing is not the only cause for failure in the ion beam final figuring process, the material composition is equally important. Only by careful consideration of both these factors can the ion beam final figuring process achieve its greatest potential. The secondary goal was to construct a model for representing the ion beam material removal rate. Representing the ion beam removal rate is only an approximation and has a number of limiting factors. The resolution of the metrology apparatus limits the modeling of the beam function as well. As the surface error corrections demand more precision in the final figuring, the model representing beam function must be equally precise. The precision to which the beam function can be represented is not only determined by the model but also by the measurements producing that model. The method developed for determining the beam function has broad application to any material destined to be ion beam figured.

Mass spectrometer and methods of increasing dispersion between ion beams

DOEpatents

Appelhans, Anthony D.; Olson, John E.; Delmore, James E.

2006-01-10

A mass spectrometer includes a magnetic sector configured to separate a plurality of ion beams, and an electrostatic sector configured to receive the plurality of ion beams from the magnetic sector and increase separation between the ion beams, the electrostatic sector being used as a dispersive element following magnetic separation of the plurality of ion beams. Other apparatus and methods are provided.

A review of studies on ion thruster beam and charge-exchange plasmas

NASA Technical Reports Server (NTRS)

Carruth, M. R., Jr.

1982-01-01

Various experimental and analytical studies of the primary beam and charge-exchange plasmas of ion thrusters are reviewed. The history of plasma beam research is recounted, emphasizing experiments on beam neutralization, expansion of the beam, and determination of beam parameters such as electron temperature, plasma density, and plasma potential. The development of modern electron bombardment ion thrusters is treated, detailing experimental results. Studies on charge-exchange plasma are discussed, showing results such as the relationship between neutralizer emission current and plasma beam potential, ion energies as a function of neutralizer bias, charge-exchange ion current collected by an axially moving Faraday cup-RPA for 8-cm and 30-cm ion thrusters, beam density and potential data from a 15-cm ion thruster, and charge-exchange ion flow around a 30-cm thruster. A 20-cm thruster electrical configuration is depicted and facility effects are discussed. Finally, plasma modeling is covered in detail for plasma beam and charge-exchange plasma.

Production of negatively charged radioactive ion beams

DOE PAGES

Liu, Y.; Stracener, D. W.; Stora, T.

2017-02-15

Beams of short-lived radioactive nuclei are needed for frontier experimental research in nuclear structure, reactions, and astrophysics. Negatively charged radioactive ion beams have unique advantages and allow for the use of a tandem accelerator for post-acceleration, which can provide the highest beam quality and continuously variable energies. Negative ion beams can be obtained with high intensity and some unique beam purification techniques based on differences in electronegativity and chemical reactivity can be used to provide beams with high purity. This article describes the production of negative radioactive ion beams at the former holifield radioactive ion beam facility at Oak Ridgemore » National Laboratory and at the CERN ISOLDE facility with emphasis on the development of the negative ion sources employed at these two facilities.« less

Experimental Validation of an Ion Beam Optics Code with a Visualized Ion Thruster

NASA Astrophysics Data System (ADS)

Nakayama, Yoshinori; Nakano, Masakatsu

For validation of an ion beam optics code, the behavior of ion beam optics was experimentally observed and evaluated with a two-dimensional visualized ion thruster (VIT). Since the observed beam focus positions, sheath positions and measured ion beam currents were in good agreement with the numerical results, it was confirmed that the numerical model of this code was appropriated. In addition, it was also confirmed that the beam focus position was moved on center axis of grid hole according to the applied grid potentials, which differs from conventional understanding/assumption. The VIT operations may be useful not only for the validation of ion beam optics codes but also for the fundamental and intuitive understanding of the Child Law Sheath theory.

Nucleation Of Ge 3D-islands On Pit-patterned Si Substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Novikov, P. L.; Smagina, J. V.; Vlasov, D. Yu.

2011-12-23

Joint experimental and theoretical study of Ge nanoislands growth on pit-patterned Si substrate is carried out. Si substrates that have been templated by means of electron beam lithography and reactive ion etching have been used to grow Ge by molecular-beam epitaxy. Atomic-force-microscopy studies show that at Si(100) substrate temperature 550 deg. C, Ge nanoislands are formed at the pits' edges, rather than between the pits. The effect is interpreted in terms of energy barrier, that is formed near the edge of a pit and prevents Ge transport inside the pit. By molecular dynamics calculations the value of the energy barriermore » 0.9 eV was obtained.« less

New beam line for time-of-flight medium energy ion scattering with large area position sensitive detector

NASA Astrophysics Data System (ADS)

Linnarsson, M. K.; Hallén, A.; Åström, J.; Primetzhofer, D.; Legendre, S.; Possnert, G.

2012-09-01

A new beam line for medium energy ion mass scattering (MEIS) has been designed and set up at the Ångström laboratory, Uppsala University, Sweden. This MEIS system is based on a time-of-flight (ToF) concept and the electronics for beam chopping relies on a 4 MHz function generator. Repetition rates can be varied between 1 MHz and 63 kHz and pulse widths below 1 ns are typically obtained by including beam bunching. A 6-axis goniometer is used at the target station. Scattering angle and energy of backscattered ions are extracted from a time-resolved and position-sensitive detector. Examples of the performance are given for three kinds of probing ions, 1H+, 4He+, and 11B+. Depth resolution is in the nanometer range and 1 and 2 nm thick Pt layers can easily be resolved. Mass resolution between nearby isotopes can be obtained as illustrated by Ga isotopes in GaAs. Taking advantage of the large size detector, a direct imaging (blocking pattern) of crystal channels are shown for hexagonal, 4H-SiC. The ToF-MEIS system described in this paper is intended for use in semiconductor and thin film areas. For example, depth profiling in the sub nanometer range for device development of contacts and dielectric interfaces. In addition to applied projects, fundamental studies of stopping cross sections in this medium energy range will also be conducted.

Biological effects of mixed-ion beams. Part 1: Effect of irradiation of the CHO-K1 cells with a mixed-ion beam containing the carbon and oxygen ions.

PubMed

Czub, Joanna; Banaś, Dariusz; Braziewicz, Janusz; Buraczewska, Iwona; Jaskóła, Marian; Kaźmierczak, Urszula; Korman, Andrzej; Lankoff, Anna; Lisowska, Halina; Szefliński, Zygmunt; Wojewódzka, Maria; Wójcik, Andrzej

2018-05-30

Carbon and oxygen ions were accelerated simultaneously to estimate the effect of irradiation of living cells with the two different ions. This mixed ion beam was used to irradiate the CHO-K1 cells, and a survival test was performed. The type of the effect of the mixed ion beam on the cells was determined with the isobologram method, whereby survival curves for irradiations with individual ion beams were also used. An additive effect of irradiation with the two ions was found. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hollow structure formation of intense ion beams with sharp edge in background plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Zhang-Hu; Wang, You-Nian, E-mail: ynwang@dlut.edu.cn

The transport of intense ion beams with sharp radial beam edge in plasmas has been studied with two-dimensional electromagnetic particle simulations. The initial solid beam evolves into a hollow beam due to the nonlinear sharp transverse force peak in the regions of beam edge. The magnitude and nonlinearity of this peak are enhanced as the ion beam travels further into the plasma, due to the self-consistent interactions between the beam ions and the plasma electrons. This structure formation is shown to be independent on the beam radius.

ION BEAM FOCUSING MEANS FOR CALUTRON

DOEpatents

Backus, J.G.

1959-06-01

An ion beam focusing arrangement for calutrons is described. It provides a virtual focus of origin for the ion beam so that the ions may be withdrawn from an arc plasma of considerable width providing greater beam current and accuracy. (T.R.H.)

Comparison of Measurement And Modeling Of Current Profile Changes Due To Neutral Bean Ion Redistribution During TAE Avalanches in NSTX

DOE Office of Scientific and Technical Information (OSTI.GOV)

Darrow, Douglas

Brief "avalanches" of toroidal Alfven eigenmodes (TAEs) are observed in NSTX plasmas with several different n numbers simultaneously present. These affect the neutral beam ion distribution as evidenced by a concurrent drop in the neutron rate and, sometimes, beam ion loss. Guiding center orbit modeling has shown that the modes can transiently render portions of the beam ion phase space stochastic. The resulting redistribution of beam ions can also create a broader beam-driven current profile and produce other changes in the beam ion distribution function

Redundancy Technology With A Focused Ion Beam

NASA Astrophysics Data System (ADS)

Komano, Haruki; Hashimoto, Kazuhiko; Takigawa, Tadahiro

1989-08-01

Fuse cutting with a focused ion beam to activate redundancy circuits is proposed. In order to verify its potential usefulness, experiments have been performed. Fuse-cutting time was evaluated using aluminum fuses with a thin passivation layer, which are difficult to cut by conventional laser-beam technology due to the material's high reflectivity. The fuse width and thickness were 2 and 0.8 μm, respectively. The fuse was cut in 5 seconds with a 30 keV focused ion beam of 0.3 A/cm2 current density. Since the fuses used in DRAMs will be smaller, their cutting time will become shorter by scanning an ion beam on narrower areas. Moreover, it can be shortened by increasing current density. Fuses for redundancy technology in 256 k CMOS SRAMs were cut with a focused ion beam. The operation of the memories was checked with a memory tester. It was confirmed that memories which had failure cells operated normally after focused-ion-beam fuse-cutting. Focused ion beam irradiation effects upon a device have been studied. When a 30 keV gallium focused ion beam was irradiated near the gate of MOSFETs, a threshold voltage shift was not observed at an ion dose of 0.3 C/cm2 which corresponded to the ion dose in cutting a fuse. However, when irradiated on the gate, a threshold voltage shift was observed at ion doses of more than 8 x 10-4 C/cm2. The voltage shift was caused by the charge of ions within the passivation layer. It is necessary at least not to irradiate a focused ion beam on a device in cutting fuses. It is concluded that the focused-ion-beam method will be advantageous for future redundancy technology application.

A Lunar-Based Spacecraft Propulsion Concept - The Ion Beam Sail

NASA Technical Reports Server (NTRS)

Brown, Ian G.; Lane, John E.; Youngquist, Robert C.

2006-01-01

We describe a concept for spacecraft propulsion by means of an energetic ion beam, with the ion source fixed at the spacecraft starting point (e.g., a lunar-based ion beam generator) and not onboard the vessel. This approach avoids the substantial mass penalty associated with the onboard ion source and power supply hardware, and vastly more energetic ion beam systems can be entertained. We estimate the ion beam parameters required for various scenarios, and consider some of the constraints limiting the concept. We find that the "ion beam sail' approach can be viable and attractive for journey distances not too great, for example within the Earth-Moon system, and could potentially provide support for journeys to the inner planets.

Laser singular Theta-pinch

NASA Astrophysics Data System (ADS)

Okulov, A. Yu.

2010-10-01

The interaction of the two counter-propagating ultrashort laser pulses with singular wavefronts in the thin slice of the underdense plasma is considered. It is shown that ion-acoustic wave is excited via Brillouin three-wave resonance by corkscrew interference pattern of paraxial singular laser beams. The orbital angular momentum carried by light is transferred to plasma ion-acoustic vortex. The rotation of the density perturbations of electron fluid is the cause of helical current which produces the kilogauss axial quasi-static magnetic field. The exact analytical configurations are presented for an ion-acoustic current field and magnetic induction. The range of experimentally accessible parameters is evaluated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magallanes, L., E-mail: lorena.magallanes@med.uni-heidelberg.de; Rinaldi, I., E-mail: ilaria.rinaldi@med.uni-heidelberg.de; Brons, S., E-mail: stephan.brons@med.uni-heidelberg.de

External beam radiotherapy techniques have the common aim to maximize the radiation dose to the target while sparing the surrounding healthy tissues. The inverted and finite depth-dose profile of ion beams (Bragg peak) allows for precise dose delivery and conformai dose distribution. Furthermore, increased radiobiological effectiveness of ions enhances the capability to battle radioresistant tumors. Ion beam therapy requires a precise determination of the ion range, which is particularly sensitive to range uncertainties. Therefore, novel imaging techniques are currently investigated as a tool to improve the quality of ion beam treatments. Approaches already clinically available or under development are basedmore » on the detection of secondary particles emitted as a result of nuclear reactions (e.g., positron-annihilation or prompt gammas, charged particles) or transmitted high energy primary ion beams. Transmission imaging techniques make use of the beams exiting the patient, which have higher initial energy and lower fluence than the therapeutic ones. At the Heidelberg Ion Beam Therapy Center, actively scanned energetic proton and carbon ion beams provide an ideal environment for the investigation of ion-based radiography and tomography. This contribution presents the rationale of ion beam therapy, focusing on the role of ion-based transmission imaging methods towards the reduction of range uncertainties and potential improvement of treatment planning.« less

A novel method for assessment of fragmentation and beam-material interactions in helium ion radiotherapy with a miniaturized setup.

PubMed

Gallas, Raya R; Arico, Giulia; Burigo, Lucas N; Gehrke, Tim; Jakůbek, Jan; Granja, Carlos; Tureček, Daniel; Martišíková, Maria

2017-10-01

Radiotherapy with protons and carbon ions enables to deliver dose distributions of high conformation to the target. Treatment with helium ions has been suggested due to their physical and biological advantages. A reliable benchmarking of the employed physics models with experimental data is required for treatment planning. However, experimental data for helium interactions is limited, in part due to the complexity and large size of conventional experimental setups. We present a novel method for the investigation of helium interactions with matter using miniaturized instrumentation based on highly integrated pixel detectors. The versatile setup consisted of a monitoring detector in front of the PMMA phantom of varying thickness and a detector stack for investigation of outgoing particles. The ion type downstream from the phantom was determined by high-resolution pattern recognition analysis of the single particle signals in the pixelated detectors. The fractions of helium and hydrogen ions behind the used targets were determined. As expected for the stable helium nucleus, only a minor decrease of the primary ion fluence along the target depth was found. E.g. the detected fraction of hydrogen ions on axis of a 220MeV/u 4 He beam was below 6% behind 24.5cm of PMMA. Monte-Carlo simulations using Geant4 reproduce the experimental data on helium attenuation and yield of helium fragments qualitatively, but significant deviations were found for some combinations of target thickness and beam energy. The presented method is promising to contribute to the reduction of the uncertainty of treatment planning for helium ion radiotherapy. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Single-atom detection of isotopes

DOEpatents

Meyer, Fred W.

2002-01-01

A method for performing accelerator mass spectrometry, includes producing a beam of positive ions having different multiple charges from a multicharged ion source; selecting positive ions having a charge state of from +2 to +4 to define a portion of the beam of positive ions; and scattering at least a portion of the portion of the beam of positive ions off a surface of a target to directly convert a portion of the positive ions in the portion of the beam of positive ions to negative ions.

Kinetic energy offsets for multicharged ions from an electron beam ion source.

PubMed

Kulkarni, D D; Ahl, C D; Shore, A M; Miller, A J; Harriss, J E; Sosolik, C E; Marler, J P

2017-08-01

Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy). The electron beam current and electron beam energy were both varied to obtain electron beams of varying space charge and these were related to the observed kinetic energy offsets for Ar 4+ and Ar 8+ ion beams. Knowledge of these offsets is important for studies that seek to utilize slow, i.e., low kinetic energy, multicharged ions to exploit their high potential energies for processes such as surface modification. In addition, we show that these offsets can be utilized to estimate the effective radius of the electron beam inside the trap.

High sensitivity charge amplifier for ion beam uniformity monitor

DOEpatents

Johnson, Gary W.

2001-01-01

An ion beam uniformity monitor for very low beam currents using a high-sensitivity charge amplifier with bias compensation. The ion beam monitor is used to assess the uniformity of a raster-scanned ion beam, such as used in an ion implanter, and utilizes four Faraday cups placed in the geometric corners of the target area. Current from each cup is integrated with respect to time, thus measuring accumulated dose, or charge, in Coulombs. By comparing the dose at each corner, a qualitative assessment of ion beam uniformity is made possible. With knowledge of the relative area of the Faraday cups, the ion flux and areal dose can also be obtained.

An electron beam ion trap and source for re-acceleration of rare-isotope ion beams at TRIUMF

NASA Astrophysics Data System (ADS)

Blessenohl, M. A.; Dobrodey, S.; Warnecke, C.; Rosner, M. K.; Graham, L.; Paul, S.; Baumann, T. M.; Hockenbery, Z.; Hubele, R.; Pfeifer, T.; Ames, F.; Dilling, J.; Crespo López-Urrutia, J. R.

2018-05-01

Electron beam driven ionization can produce highly charged ions (HCIs) in a few well-defined charge states. Ideal conditions for this are maximally focused electron beams and an extremely clean vacuum environment. A cryogenic electron beam ion trap fulfills these prerequisites and delivers very pure HCI beams. The Canadian rare isotope facility with electron beam ion source-electron beam ion sources developed at the Max-Planck-Institut für Kernphysik (MPIK) reaches already for a 5 keV electron beam and a current of 1 A with a density in excess of 5000 A/cm2 by means of a 6 T axial magnetic field. Within the trap, the beam quickly generates a dense HCI population, tightly confined by a space-charge potential of the order of 1 keV times the ionic charge state. Emitting HCI bunches of ≈107 ions at up to 100 Hz repetition rate, the device will charge-breed rare-isotope beams with the mass-over-charge ratio required for re-acceleration at the Advanced Rare IsotopE Laboratory (ARIEL) facility at TRIUMF. We present here its design and results from commissioning runs at MPIK, including X-ray diagnostics of the electron beam and charge-breeding process, as well as ion injection and HCI-extraction measurements.

A vacuum spark ion source: High charge state metal ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yushkov, G. Yu., E-mail: gyushkov@mail.ru; Nikolaev, A. G.; Frolova, V. P.

2016-02-15

High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less thanmore » 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.« less

Prototyping of beam position monitor for medium energy beam transport section of RAON heavy ion accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jang, Hyojae, E-mail: lkcom@ibs.re.kr; Jin, Hyunchang; Jang, Ji-Ho

2016-02-15

A heavy ion accelerator, RAON is going to be built by Rare Isotope Science Project in Korea. Its target is to accelerate various stable ions such as uranium, proton, and xenon from electron cyclotron resonance ion source and some rare isotopes from isotope separation on-line. The beam shaping, charge selection, and modulation should be applied to the ions from these ion sources because RAON adopts a superconducting linear accelerator structure for beam acceleration. For such treatment, low energy beam transport, radio frequency quadrupole, and medium energy beam transport (MEBT) will be installed in injector part of RAON accelerator. Recently, developmentmore » of a prototype of stripline beam position monitor (BPM) to measure the position of ion beams in MEBT section is under way. In this presentation, design of stripline, electromagnetic (EM) simulation results, and RF measurement test results obtained from the prototyped BPM will be described.« less

Arrays of suspended silicon nanowires defined by ion beam implantation: mechanical coupling and combination with CMOS technology.

PubMed

Llobet, J; Rius, G; Chuquitarqui, A; Borrisé, X; Koops, R; van Veghel, M; Perez-Murano, F

2018-04-02

We present the fabrication, operation, and CMOS integration of arrays of suspended silicon nanowires (SiNWs). The functional structures are obtained by a top-down fabrication approach consisting in a resistless process based on focused ion beam irradiation, causing local gallium implantation and silicon amorphization, plus selective silicon etching by tetramethylammonium hydroxide, and a thermal annealing process in a boron rich atmosphere. The last step enables the electrical functionality of the irradiated material. Doubly clamped silicon beams are fabricated by this method. The electrical readout of their mechanical response can be addressed by a frequency down-mixing detection technique thanks to an enhanced piezoresistive transduction mechanism. Three specific aspects are discussed: (i) the engineering of mechanically coupled SiNWs, by making use of the nanometer scale overhang that it is inherently-generated with this fabrication process, (ii) the statistical distribution of patterned lateral dimensions when fabricating large arrays of identical devices, and (iii) the compatibility of the patterning methodology with CMOS circuits. Our results suggest that the application of this method to the integration of large arrays of suspended SiNWs with CMOS circuitry is interesting in view of applications such as advanced radio frequency band pass filters and ultra-high-sensitivity mass sensors.

Arrays of suspended silicon nanowires defined by ion beam implantation: mechanical coupling and combination with CMOS technology

NASA Astrophysics Data System (ADS)

Llobet, J.; Rius, G.; Chuquitarqui, A.; Borrisé, X.; Koops, R.; van Veghel, M.; Perez-Murano, F.

2018-04-01

We present the fabrication, operation, and CMOS integration of arrays of suspended silicon nanowires (SiNWs). The functional structures are obtained by a top-down fabrication approach consisting in a resistless process based on focused ion beam irradiation, causing local gallium implantation and silicon amorphization, plus selective silicon etching by tetramethylammonium hydroxide, and a thermal annealing process in a boron rich atmosphere. The last step enables the electrical functionality of the irradiated material. Doubly clamped silicon beams are fabricated by this method. The electrical readout of their mechanical response can be addressed by a frequency down-mixing detection technique thanks to an enhanced piezoresistive transduction mechanism. Three specific aspects are discussed: (i) the engineering of mechanically coupled SiNWs, by making use of the nanometer scale overhang that it is inherently-generated with this fabrication process, (ii) the statistical distribution of patterned lateral dimensions when fabricating large arrays of identical devices, and (iii) the compatibility of the patterning methodology with CMOS circuits. Our results suggest that the application of this method to the integration of large arrays of suspended SiNWs with CMOS circuitry is interesting in view of applications such as advanced radio frequency band pass filters and ultra-high-sensitivity mass sensors.

Transportation of high-current ion and electron beams in the accelerator drift gap in the presence of an additional electron background

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karas’, V. I., E-mail: karas@kipt.kharkov.ua; Kornilov, E. A.; Manuilenko, O. V.

2015-12-15

The dynamics of a high-current ion beam propagating in the drift gap of a linear induction accelerator with collective focusing is studied using 3D numerical simulations in the framework of the full system of the Vlasov–Maxwell equations (code KARAT). The ion beam is neutralized by a comoving electron beam in the current density and, partially, in space charge, since the velocities of electrons and ions differ substantially. The dynamics of the high-current ion beam is investigated for different versions of additional neutralization of its space charge. It is established that, for a given configuration of the magnetic field and inmore » the presence of a specially programmed injection of additional electrons from the boundary opposite to the ion injection boundary, the angular divergence of the ion beam almost vanishes, whereas the current of the ion beam at the exit from the accelerator drift gap changes insignificantly and the beam remains almost monoenergetic.« less

Ion-beam apparatus and method for analyzing and controlling integrated circuits

DOEpatents

Campbell, A.N.; Soden, J.M.

1998-12-01

An ion-beam apparatus and method for analyzing and controlling integrated circuits are disclosed. The ion-beam apparatus comprises a stage for holding one or more integrated circuits (ICs); a source means for producing a focused ion beam; and a beam-directing means for directing the focused ion beam to irradiate a predetermined portion of the IC for sufficient time to provide an ion-beam-generated electrical input signal to a predetermined element of the IC. The apparatus and method have applications to failure analysis and developmental analysis of ICs and permit an alteration, control, or programming of logic states or device parameters within the IC either separate from or in combination with applied electrical stimulus to the IC for analysis thereof. Preferred embodiments of the present invention including a secondary particle detector and an electron floodgun further permit imaging of the IC by secondary ions or electrons, and allow at least a partial removal or erasure of the ion-beam-generated electrical input signal. 4 figs.

Transportation of high-current ion and electron beams in the accelerator drift gap in the presence of an additional electron background

NASA Astrophysics Data System (ADS)

Karas', V. I.; Kornilov, E. A.; Manuilenko, O. V.; Tarakanov, V. P.; Fedorovskaya, O. V.

2015-12-01

The dynamics of a high-current ion beam propagating in the drift gap of a linear induction accelerator with collective focusing is studied using 3D numerical simulations in the framework of the full system of the Vlasov-Maxwell equations (code KARAT). The ion beam is neutralized by a comoving electron beam in the current density and, partially, in space charge, since the velocities of electrons and ions differ substantially. The dynamics of the high-current ion beam is investigated for different versions of additional neutralization of its space charge. It is established that, for a given configuration of the magnetic field and in the presence of a specially programmed injection of additional electrons from the boundary opposite to the ion injection boundary, the angular divergence of the ion beam almost vanishes, whereas the current of the ion beam at the exit from the accelerator drift gap changes insignificantly and the beam remains almost monoenergetic.

Ion-beam apparatus and method for analyzing and controlling integrated circuits

DOEpatents

Campbell, Ann N.; Soden, Jerry M.

1998-01-01

An ion-beam apparatus and method for analyzing and controlling integrated circuits. The ion-beam apparatus comprises a stage for holding one or more integrated circuits (ICs); a source means for producing a focused ion beam; and a beam-directing means for directing the focused ion beam to irradiate a predetermined portion of the IC for sufficient time to provide an ion-beam-generated electrical input signal to a predetermined element of the IC. The apparatus and method have applications to failure analysis and developmental analysis of ICs and permit an alteration, control, or programming of logic states or device parameters within the IC either separate from or in combination with applied electrical stimulus to the IC for analysis thereof. Preferred embodiments of the present invention including a secondary particle detector and an electron floodgun further permit imaging of the IC by secondary ions or electrons, and allow at least a partial removal or erasure of the ion-beam-generated electrical input signal.

Simulation of electrostatic turbulence in the plasma sheet boundary layer with electron currents and bean-shaped ion beams

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Frank, L. A.; Huang, C. Y.

1988-01-01

Plasma data from ISEE-1 show the presence of electron currents as well as energetic ion beams in the plasma sheet boundary layer. Broadband electrostatic noise and low-frequency electromagnetic bursts are detected in the plasma sheet boundary layer, especially in the presence of strong ion flows, currents, and steep spacial gradients in the fluxes of few-keV electrons and ions. Particle simulations have been performed to investigate electrostatic turbulence driven by a cold electron beam and/or ion beams with a bean-shaped velocity distribution. The simulation results show that the counterstreaming ion beams as well as the counterstreaming of the cold electron beam and the ion beam excite ion acoustic waves with a given Doppler-shifted real frequency. However, the effect of the bean-shaped ion velocity distributions reduces the growth rates of ion acoustic instability. The simulation results also show that the slowing down of the ion bean is larger at the larger perpendicular velocity. The wave spectra of the electric fields at some points of the simulations show turbulence generated by growing waves.

Production of intense negative hydrogen beams with polarized nuclei by selective neutralization of negative ions

DOEpatents

Hershcovitch, Ady

1987-01-01

A process for selectively neutralizing H.sup.- ions in a magnetic field to produce an intense negative hydrogen ion beam with spin polarized protons. Characteristic features of the process include providing a multi-ampere beam of H.sup.- ions that are intersected by a beam of laser light. Photodetachment is effected in a uniform magnetic field that is provided around the beam of H.sup.- ions to spin polarize the H.sup.- ions and produce first and second populations or groups of ions, having their respective proton spin aligned either with the magnetic field or opposite to it. The intersecting beam of laser light is directed to selectively neutralize a majority of the ions in only one population, or given spin polarized group of H.sup.- ions, without neutralizing the ions in the other group thereby forming a population of H.sup.- ions each of which has its proton spin down, and a second group or population of H.sup.o atoms having proton spin up. Finally, the two groups of ions are separated from each other by magnetically bending the group of H.sup.- ions away from the group of neutralized ions, thereby to form an intense H.sup.- ion beam that is directed toward a predetermined objective.

Nickel nanowires mesh fabricated by ion beam irradiation-induced nanoscale welding for transparent conducting electrodes

NASA Astrophysics Data System (ADS)

Honey, S.; Ahmad, I.; Madhuku, M.; Naseem, S.; Maaza, M.; Kennedy, J. V.

2017-07-01

In this report, random nickel nanowires (Ni-NWs) meshes are fabricated by ions beam irradiation-induced nanoscale welding of NWs on intersecting positions. Ni-NWs are exposed to beam of 50 KeV Argon (Ar+) ions at various fluencies in the range ~1015 ions cm-2 to 1016 ions cm-2 at room temperature. Ni-NWs are welded due to accumulation of Ar+ ions beam irradiation-induced sputtered atoms on crossing positions. Ar+ ions irradiated Ni-NWs meshes are optically transparent and optical transparency is enhanced with increase in beam fluence of Ar+ ions. Ar+ ions beam irradiation-induced welded and optically transparent mesh is then exposed to 2.75 MeV hydrogen (H+) ions at fluencies 1  ×  1015 ions cm-2, 3  ×  1015 ions cm-2 and 1  ×  1016 ions cm-2 at room temperature. MeV H+ ions irradiation-induced local heat cause melting and fusion of NWs on intersecting points and eventually lead to reduce contact resistance between Ni-NWs. Electrical conductivity is enhanced with increase in beam fluence of H+ ions. These welded highly transparent and electrically conductive Ni-NWs meshes can be employed as transparent conducting electrodes in optoelectronic devices.

Laser scattering induced holograms in lithium niobate. [observation of diffraction cones

NASA Technical Reports Server (NTRS)

Magnusson, R.; Gaylord, T. K.

1974-01-01

A 3.0-mm thick poled single crystal of lithium niobate doped with 0.1 mole% iron was exposed to a single beam and then to two intersecting beams of an argon ion laser operating at 515-nm wavelength. Laser scattering induced holograms were thus written and analyzed. The presence of diffraction cones was observed and is shown to result from the internally recorded interference pattern resulting from the interference of the original incident laser beam with light scattered from material inhomogeneities. This phenomenon is analyzed using Ewald sphere construction techniques which reveal the geometrical relationships existing for the diffraction cones.

A new multidimensional diagnostic method for measuring the properties of intense ion beams

NASA Astrophysics Data System (ADS)

Yasuike, Kazuhito; Miyamoto, Shuji; Nakai, Sadao

1996-02-01

A new arrayed pinhole camera (APC) diagnostic method for intense ion beams has been developed. The APC diagnostic technique permits the acquisition of the angular divergences and the ion fluxes of high intensity ion beams, in one shot, with a spatial resolution on the source of better than 1 mm and an effective angular divergence resolution of better than 10 mrad. A prototype time integrated APC has been designed and evaluated. The demonstration experiments have been performed on a Reiden-IV, 1 MV and 1 Ω pulsed power machine [1 T W (tera-watt or trillion watts)]. Proton beams of 0.7 MeV, with a pulse duration of ˜50 ns and an ion current density of about 100 A/cm2, were generated in an applied-Br type ion diode source using paraffin-filled grooves. These experimental results show that the APC can measure nonuniformities in the ion beam intensity generated from the ion source and the dependence of beam angular divergence on ion beam intensity.

Targets used in the production of radioactive ion beams at the HRIBF

NASA Astrophysics Data System (ADS)

Stracener, D. W.; Alton, G. D.; Auble, R. L.; Beene, J. R.; Mueller, P. E.; Bilheux, J. C.

2004-03-01

Radioactive ion beams are produced at the Holifield Radioactive Ion Beam Facility using the Isotope Separation On-Line (ISOL) technique where the atoms are produced in a thick target, transported to an ion source, ionized, and extracted from the ion source to form an ion beam. These radioactive ion beams are then accelerated to energies of a few MeV per nucleon and delivered to experimental stations for use in nuclear physics and nuclear astrophysics experiments. At the heart of this facility is the RIB production target, where the radioactive nuclei are produced using beams of light ions (p, d, 3He, α) to induce nuclear reactions in the target nuclei. Several target materials have been developed and used successfully, including Al 2O 3, HfO 2, SiC, CeS, liquid Ge, liquid Ni, and a low-density matrix of uranium carbide. The details of these targets and some of the target developments that led to the delivery of high-quality radioactive ion beams are discussed in this paper.

On the limits of uniaxial magnetic anisotropy tuning by a ripple surface pattern

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arranz, Miguel A.; Colino, Jose M., E-mail: josemiguel.colino@uclm.es; Palomares, Francisco J.

Ion beam patterning of a nanoscale ripple surface has emerged as a versatile method of imprinting uniaxial magnetic anisotropy (UMA) on a desired in-plane direction in magnetic films. In the case of ripple patterned thick films, dipolar interactions around the top and/or bottom interfaces are generally assumed to drive this effect following Schlömann's calculations for demagnetizing fields of an ideally sinusoidal surface [E. Schlömann, J. Appl. Phys. 41, 1617 (1970)]. We have explored the validity of his predictions and the limits of ion beam sputtering to induce UMA in a ferromagnetic system where other relevant sources of magnetic anisotropy aremore » neglected: ripple films not displaying any evidence of volume uniaxial anisotropy and where magnetocrystalline contributions average out in a fine grain polycrystal structure. To this purpose, the surface of 100 nm cobalt films grown on flat substrates has been irradiated at fixed ion energy, fixed ion fluency but different ion densities to make the ripple pattern at the top surface with wavelength Λ and selected, large amplitudes (ω) up to 20 nm so that stray dipolar fields are enhanced, while the residual film thickness t = 35–50 nm is sufficiently large to preserve the continuous morphology in most cases. The film-substrate interface has been studied with X-ray photoemission spectroscopy depth profiles and is found that there is a graded silicon-rich cobalt silicide, presumably formed during the film growth. This graded interface is of uncertain small thickness but the range of compositions clearly makes it a magnetically dead layer. On the other hand, the ripple surface rules both the magnetic coercivity and the uniaxial anisotropy as these are found to correlate with the pattern dimensions. Remarkably, the saturation fields in the hard axis of uniaxial continuous films are measured up to values as high as 0.80 kG and obey a linear dependence on the parameter ω{sup 2}/Λ/t in quantitative agreement with Schlömann's prediction for a surface anisotropy entirely ruled by dipolar interaction. The limits of UMA tuning by a ripple pattern are discussed in terms of the surface local angle with respect to the mean surface and of the onset of ripple detachment.« less

Effects of fixture rotation on coating uniformity for high-performance optical filter fabrication

NASA Astrophysics Data System (ADS)

Rubin, Binyamin; George, Jason; Singhal, Riju

2018-04-01

Coating uniformity is critical in fabricating high-performance optical filters by various vacuum deposition methods. Simple and planetary rotation systems with shadow masks are used to achieve the required uniformity [J. B. Oliver and D. Talbot, Appl. Optics 45, 13, 3097 (2006); O. Lyngnes, K. Kraus, A. Ode and T. Erguder, in `Method for Designing Coating Thickness Uniformity Shadow Masks for Deposition Systems with a Planetary Fixture', 2014 Technical Conference Proceedings, Optical Coatings, August 13, 2014, DOI: 10.14332/svc14.proc.1817.]. In this work, we discuss the effect of rotation pattern and speed on thickness uniformity in an ion beam sputter deposition system. Numerical modeling is used to determine statistical distribution of random thickness errors in coating layers. The relationship between thickness tolerance and production yield are simulated theoretically and demonstrated experimentally. Production yields for different optical filters produced in an ion beam deposition system with planetary rotation are presented. Single-wavelength and broadband optical monitoring systems were used for endpoint monitoring during filter deposition. Limitations of thickness tolerances that can be achieved in systems with planetary rotation are shown. Paths for improving production yield in an ion beam deposition system are described.

Detectors for low energy electron cooling in RHIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlier, F. S.

Low-energy operation of RHIC is of particular interest to study the location of a possible critical point in the QCD phase diagram. The performance of RHIC at energies equal to or lower than 10 GV/nucleon is limited by nonlinearities, Intra-BeamScattering (IBS) processes and space-charge effects. To successfully address the luminosity and ion store lifetime limitations imposed by IBS, the method of electron cooling has been envisaged. During electron cooling processes electrons are injected along with the ion beam at the nominal ion bunch velocities. The velocity spread of the ion beam is reduced in all planes through Coulomb interactions betweenmore » the cold electron beam and the ion beam. The electron cooling system proposed for RHIC will be the first of its kind to use bunched beams for the delivery of the electron bunches, and will therefore be accompanied by the necessary challenges. The designed electron cooler will be located in IP2. The electron bunches will be accelerated by a linac before being injected along side the ion beams. Thirty consecutive electron bunches will be injected to overlap with a single ion bunch. They will first cool the yellow beam before being extracted, turned by 180-degrees, and reinjected into the blue beam for cooling. As such, both the yellow and blue beams will be cooled by the same ion bunches. This will pose considerable challenges to ensure proper electron beam quality to cool the second ion beam. Furthermore, no ondulator will be used in the electron cooler so radiative recombination between the ions and the electrons will occur.« less

CALUTRON RECEIVERS

DOEpatents

Schmidt, F.H.; Stone, K.F.

1958-09-01

S>This patent relates to improvements in calutron devices and, more specifically, describes a receiver fer collecting the ion curreot after it is formed into a beam of non-homogeneous isotropic cross-section. The invention embodies a calutron receiver having an ion receiving pocket for separately collecting and retaining ions traveling in a selected portion of the ion beam and anelectrode for intercepting ions traveling in another selected pontion of the ion beam. The electrode is disposed so as to fix the limit of one side of the pontion of the ion beam admitted iato the ion receiving pocket.

Collective acceleration of ions in picosecond pinched electron beams

NASA Astrophysics Data System (ADS)

Baryshnikov, V. I.; Paperny, V. L.; Shipayev, I. V.

2017-10-01

Сharacteristics of intense electron-ion beams emitted by a high-voltage (280 kV) electron accelerator with a pulse duration of 200 ps and current 5 kA are studied. The capture phenomena and the subsequent collective acceleration of multi charged ions of the cathode material by the electric field of the electron beam are observed. It is shown that the electron-ion beam diameter does not exceed 30 µm therein in the case of lighter ions, and the decay of the pinched beam occurs at a shorter distance from the cathode. It is established that the ions of the cathode material Tin+ captured by the electron beam are accelerated up to an energy of  ⩽10 MeV, and the ion fluence reaches 1017 ion cm-2 in the pulse. These ions are effectively embedded into the lattice sites of the irradiated substrate (sapphire crystal), forming the luminescent areas of the micron scale.

Ion Beam Facilities at the National Centre for Accelerator based Research using a 3 MV Pelletron Accelerator

NASA Astrophysics Data System (ADS)

Trivedi, T.; Patel, Shiv P.; Chandra, P.; Bajpai, P. K.

A 3.0 MV (Pelletron 9 SDH 4, NEC, USA) low energy ion accelerator has been recently installed as the National Centre for Accelerator based Research (NCAR) at the Department of Pure & Applied Physics, Guru Ghasidas Vishwavidyalaya, Bilaspur, India. The facility is aimed to carried out interdisciplinary researches using ion beams with high current TORVIS (for H, He ions) and SNICS (for heavy ions) ion sources. The facility includes two dedicated beam lines, one for ion beam analysis (IBA) and other for ion implantation/ irradiation corresponding to switching magnet at +20 and -10 degree, respectively. Ions with 60 kV energy are injected into the accelerator tank where after stripping positively charged ions are accelerated up to 29 MeV for Au. The installed ion beam analysis techniques include RBS, PIXE, ERDA and channelling.

Large area ion beam sputtered YBa2Cu3O(7-delta) films for novel device structures

NASA Astrophysics Data System (ADS)

Gauzzi, A.; Lucia, M. L.; Kellett, B. J.; James, J. H.; Pavuna, D.

1992-03-01

A simple single-target ion-beam system is employed to manufacture large areas of uniformly superconducting YBa2Cu3O(7-delta) films which can be reproduced. The required '123' stoichiometry is transferred from the target to the substrate when ion-beam power, target/ion-beam angle, and target temperature are adequately controlled. Ion-beam sputtering is experimentally demonstrated to be an effective technique for producing homogeneous YBa2Cu3O(7-delta) films.

Studies on ion scattering and sputtering processes relevant to ion beam sputter deposition of multicomponent thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auciello, O.; Ameen, M.S.; Kingon, A.I.

1989-01-01

Results from computer simulation and experiments on ion scattering and sputtering processes in ion beam sputter deposition of high Tc superconducting and ferroelectric thin films are presented. It is demonstrated that scattering of neutralized ions from the targets can result in undesirable erosion of, and inert gas incorporation in, the growing films, depending on the ion/target atom ass ratio and ion beam angle of incidence/target/substrate geometry. The studies indicate that sputtering Kr{sup +} or Xe{sup +} ions is preferable to the most commonly used Ar{sup +} ions, since the undesirable phenomena mentioned above are minimized for the first two ions.more » These results are used to determine optimum sputter deposition geometry and ion beam parameters for growing multicomponent oxide thin films by ion beam sputter-deposition. 10 refs., 5 figs.« less

High-energy accelerator for beams of heavy ions

DOEpatents

Martin, Ronald L.; Arnold, Richard C.

1978-01-01

An apparatus for accelerating heavy ions to high energies and directing the accelerated ions at a target comprises a source of singly ionized heavy ions of an element or compound of greater than 100 atomic mass units, means for accelerating the heavy ions, a storage ring for accumulating the accelerated heavy ions and switching means for switching the heavy ions from the storage ring to strike a target substantially simultaneously from a plurality of directions. In a particular embodiment the heavy ion that is accelerated is singly ionized hydrogen iodide. After acceleration, if the beam is of molecular ions, the ions are dissociated to leave an accelerated singly ionized atomic ion in a beam. Extraction of the beam may be accomplished by stripping all the electrons from the atomic ion to switch the beam from the storage ring by bending it in magnetic field of the storage ring.

Scintillation screen applications in a vacuum arc ion source with composite hydride cathode

NASA Astrophysics Data System (ADS)

Wang, X. H.; Tuo, X. G.; Yang, Z.; Peng, Y. F.; Li, J.; Lv, H. Y.; Li, J. H.; Long, J. D.

2018-05-01

Vacuum arc ion source with composite hydride cathode was developed to produce intense ion beams which can be applied in particle accelerator injections. Beam profile and beam composition are two fundamental parameters of the beam for the vacuum arc ion source in such specific applications. An aluminum-coated scintillation screen with an ICCD camera readout was used to show the space-time distribution of the beam directly. A simple magnetic analysis assembly with the scintillation screen shows the beam composition information of this kind ion source. Some physical and technical issues are discussed and analyzed in the text.

Metformin enhances the radiosensitivity of human liver cancer cells to γ–rays and carbon ion beams

PubMed Central

Kim, Eun Ho; Kim, Mi-Sook; Furusawa, Yoshiya; Uzawa, Akiko; Han, Soorim; Jung, Won-Gyun; Sai, Sei

2016-01-01

The purpose of this study was to investigate the effect of metformin on the responses of hepatocellular carcinoma (HCC) cells to γ–rays (low-linear energy transfer (LET) radiation) and carbon-ion beams (high-LET radiation). HCC cells were pretreated with metformin and exposed to a single dose of γ–rays or carbon ion beams. Metformin treatment increased radiation-induced clonogenic cell death, DNA damage, and apoptosis. Carbon ion beams combined with metformin were more effective than carbon ion beams or γ-rays alone at inducing subG1 and decreasing G2/M arrest, reducing the expression of vimentin, enhancing phospho-AMPK expression, and suppressing phospho-mTOR and phospho-Akt. Thus, metformin effectively enhanced the therapeutic effect of radiation with a wide range of LET, in particular carbon ion beams and it may be useful for increasing the clinical efficacy of carbon ion beams. PMID:27802188

Ion beam sputtering of fluoropolymers. [etching polymer films and target surfaces

NASA Technical Reports Server (NTRS)

Sovey, J. S.

1978-01-01

Ion beam sputter processing rates as well as pertinent characteristics of etched targets and films are described. An argon ion beam source was used to sputter etch and deposit the fluoropolymers PTFE, FEP, and CTFE. Ion beam energy, current density, and target temperature were varied to examine effects on etch and deposition rates. The ion etched fluoropolymers yield cone or spire-like surface structures which vary depending upon the type of polymer, ion beam power density, etch time, and target temperature. Sputter target and film characteristics documented by spectral transmittance measurements, X-ray diffraction, ESCA, and SEM photomicrographs are included.

Experiments on Ion Beam Deflection Using Ion Optics with Slit Apertures

NASA Astrophysics Data System (ADS)

Okawa, Yasushi; Hayakawa, Yukio; Kitamura, Shoji

2004-03-01

An experimental investigation on ion beam deflection by grid translation was performed. The ion beam deflection in ion optics is a desired technology for ion thrusters because thrust vector control utilizing this technique can eliminate the need for conventional gimbaling devices and thus reduce propulsion system mass. A grid translation mechanism consisting of a piezoelectric motor, a ceramic lever, and carbon-based grids with slit apertures was fabricated and high repeatability in beam deflection characteristics was obtained using this mechanism. Results showed that the beam deflection angle was proportional to the grid translation distance and independent of slit width and grid voltage. A numerical simulation successfully reproduced the beam deflection characteristics in a qualitative and quantitative sense. A maximum beam deflection angle of approximately plus or minus 6 degrees, which was comparable to that of the ordinary gimbaling devices used in space, was obtained without a severe drain current. Therefore, the beam deflection by grid translation is promising as a thrust vectoring method in ion thrusters.

Development of textured magnesium oxide templates and bicrystals using ion beam assisted deposition

NASA Astrophysics Data System (ADS)

Vallejo, Ronald N.

Recently, there has been an increased research effort in the deposition of near-single-crystal thin films on substrates that do not provide a template for epitaxial crystalline film growth. Ion beam assisted deposition (IBAD) has been demonstrated as one of the most promising methods to artificially control the texture in thin films. Biaxially textured MgO templates of 10 nm thickness were successfully fabricated on glass and silicon substrates without any buffer layers using IBAD. This work has shed insights on several issues. First, surface morphology ˜ 1 nm or better is only a necessary condition for textured IBAD-MgO, but not a sufficient condition. Additional surface preparation must be provided for nucleation and subsequent formation of the textured IBAD-MgO templates. Second, the role of buffer layer on IBAD-MgO texturing. It was found that the ion beam pre-exposure of the substrates prior to IBAD processing provided a sufficient condition for the nucleation and subsequent texture formation of the IBAD grown films. The ion pre-exposure replaced the need for buffer layers in silicon and glass substrates. Finally, by pre-exposing the substrates to Ar + ions, it was found that the ion beam modified the surface and improved the surface roughness of the glass substrates. Textured MgO epi templates were demonstrated for the first time on polymer based substrates (polyimide). This is a crucial step in the realization of epitaxial suspended devices. To achieve an epitaxial film on a sacrificial layer, an epitaxial template film must first be grown prior to subsequent film growth. The role of ion pre-exposure and buffer layer on texture formation was investigated in this part of the work. This thesis also presents groundbreaking results on the fabrication of bicrystal MgO films and bicrystal networks using ion beam assisted deposition. Highly oriented bicrystals, with a common (100) out-of-plane orientation and (110) in-plane orientations having a tilt angle of 45° and 20° have been successfully fabricated. This method has also been used to fabricate two dimensional bicrystal MgO networks in the micrometer scale. The same strategy can be applied to generate nanometer scale bicrystal networks of desired patterns.

Ion-optical studies for a range adaptation method in ion beam therapy using a static wedge degrader combined with magnetic beam deflection.

PubMed

Chaudhri, Naved; Saito, Nami; Bert, Christoph; Franczak, Bernhard; Steidl, Peter; Durante, Marco; Rietzel, Eike; Schardt, Dieter

2010-06-21

Fast radiological range adaptation of the ion beam is essential when target motion is mitigated by beam tracking using scanned ion beams for dose delivery. Electromagnetically controlled deflection of a well-focused ion beam on a small static wedge degrader positioned between two dipole magnets, inside the beam delivery system, has been considered as a fast range adaptation method. The principle of the range adaptation method was tested in experiments and Monte Carlo simulations for the therapy beam line at the GSI Helmholtz Centre for Heavy Ions Research. Based on the simulations, ion optical settings of beam deflection and realignment of the adapted beam were experimentally applied to the beam line, and additional tuning was manually performed. Different degrader shapes were employed for the energy adaptation. Measured and simulated beam profiles, i.e. lateral distribution and range in water at isocentre, were analysed and compared with the therapy beam values for beam scanning. Deflected beam positions of up to +/-28 mm on degrader were performed which resulted in a range adaptation of up to +/-15 mm water equivalence (WE). The maximum deviation between the measured adapted range from the nominal range adaptation was below 0.4 mm WE. In experiments, the width of the adapted beam at the isocentre was adjustable between 5 and 11 mm full width at half maximum. The results demonstrate the feasibility/proof of the proposed range adaptation method for beam tracking from the beam quality point of view.

High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region.

PubMed

Hirano, Y; Kiyama, S; Fujiwara, Y; Koguchi, H; Sakakita, H

2015-11-01

A high current density (≈3 mA/cm(2)) hydrogen ion beam source operating in an extremely low-energy region (E(ib) ≈ 150-200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E(ib) is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

Ion beam technology applications study. [ion impact, implantation, and surface finishing

NASA Technical Reports Server (NTRS)

Sellen, J. M., Jr.; Zafran, S.; Komatsu, G. K.

1978-01-01

Specific perceptions and possible ion beam technology applications were obtained as a result of a literature search and contact interviews with various institutions and individuals which took place over a 5-month period. The use of broad beam electron bombardment ion sources is assessed for materials deposition, removal, and alteration. Special techniques examined include: (1) cleaning, cutting, and texturing for surface treatment; (2) crosslinking of polymers, stress relief in deposited layers, and the creation of defect states in crystalline material by ion impact; and (3) ion implantation during epitaxial growth and the deposition of neutral materials sputtered by the ion beam. The aspects, advantages, and disadvantages of ion beam technology and the competitive role of alternative technologies are discussed.

Rotating field mass and velocity analyzer

NASA Technical Reports Server (NTRS)

Smith, Steven Joel (Inventor); Chutjian, Ara (Inventor)

1998-01-01

A rotating field mass and velocity analyzer having a cell with four walls, time dependent RF potentials that are applied to each wall, and a detector. The time dependent RF potentials create an RF field in the cell which effectively rotates within the cell. An ion beam is accelerated into the cell and the rotating RF field disperses the incident ion beam according to the mass-to-charge (m/e) ratio and velocity distribution present in the ion beam. The ions of the beam either collide with the ion detector or deflect away from the ion detector, depending on the m/e, RF amplitude, and RF frequency. The detector counts the incident ions to determine the m/e and velocity distribution in the ion beam.

Combination of carbon ion beam and gemcitabine causes irreparable DNA damage and death of radioresistant pancreatic cancer stem-like cells in vitro and in vivo

PubMed Central

Sai, Sei; Wakai, Toshifumi; Vares, Guillaume; Yamada, Shigeru; Kamijo, Takehiko; Kamada, Tadashi; Shirai, Toshiyuki

2015-01-01

We try to elucidate whether a carbon ion beam alone or in combination with gemcitabine has advantages over X-ray in targeting putative pancreatic cancer stem-like cells (CSCs) in vitro and in vivo. Colony, spheroid formation and tumorigenicity assays confirmed that CD44+/ESA+ cells sorted from PANC1 and PK45 cells have more CSC properties than CD44−/ESA− cells. The number of colonies and spheroids formed from CSCs after carbon ion beam irradiation was significantly reduced compared to after X-ray irradiation, and they were extremely highly suppressed when carbon ion beam combined with gemcitabine. The relative biological effectiveness (RBE) values for the carbon ion beam relative to X-ray at the D10 levels for CSCs were 2.23-2.66. Expressions of multiple cell death-related genes were remarkably highly induced, and large numbers of γH2AX foci in CSCs were formed after carbon ion beam combined with gemcitabine. The highly expressed CSC markers were significantly inhibited after 30 Gy of carbon ion beam and almost lost after 25 Gy carbon ion beam combined with 50 mg/kg gemcitabine. In conclusion, a carbon ion beam combined with gemcitabine has superior potential to kill pancreatic CSCs via irreparable clustered DSB compared to a carbon ion alone or X-rays combined with gemcitabine. PMID:25849939

Electron cyclotron resonance ion sources in use for heavy ion cancer therapy.

PubMed

Tinschert, K; Iannucci, R; Lang, R

2008-02-01

The use of electron cyclotron resonance (ECR) ion sources for producing ion beams for heavy ion cancer therapy has been established for more than ten years. After the Heavy Ion Medical Accelerator (HIMAC) at Chiba, Japan started therapy of patients with carbon ions in 1994 the first carbon ion beam for patient treatment at the accelerator facility of GSI was delivered in 1997. ECR ion sources are the perfect tool for providing the required ion beams with good stability, high reliability, and easy maintenance after long operating periods. Various investigations were performed at GSI with different combinations of working gas and auxiliary gas to define the optimal beam conditions for an extended use of further ion species for the dedicated Heidelberg Ion Beam Therapy (HIT) facility installed at the Radiological University Hospital Heidelberg, Germany. Commercially available compact all permanent magnet ECR ion sources operated at 14.5 GHz were chosen for this facility. Besides for (12)C(4+) these ion sources are used to provide beams of (1)H(3)(1+), (3)He(1+), and (16)O(6+). The final commissioning at the HIT facility could be finished at the end of 2006.

Ion beam sputtering of Ag - Angular and energetic distributions of sputtered and scattered particles

NASA Astrophysics Data System (ADS)

Feder, René; Bundesmann, Carsten; Neumann, Horst; Rauschenbach, Bernd

2013-12-01

Ion beam sputter deposition (IBD) provides intrinsic features which influence the properties of the growing film, because ion properties and geometrical process conditions generate different energy and spatial distribution of the sputtered and scattered particles. A vacuum deposition chamber is set up to measure the energy and spatial distribution of secondary particles produced by ion beam sputtering of different target materials under variation of geometrical parameters (incidence angle of primary ions and emission angle of secondary particles) and of primary ion beam parameters (ion species and energies).

High responsivity secondary ion energy analyzer

NASA Astrophysics Data System (ADS)

Belov, A. S.; Chermoshentsev, D. A.; Gavrilov, S. A.; Frolov, O. T.; Netchaeva, L. P.; Nikulin, E. S.; Zubets, V. N.

2018-05-01

The degree of space charge compensation of a 70 mA, 400 keV pulsed hydrogen ion beam has been measured with the use of an electrostatic energy analyzer of secondary ions. The large azimuthal angle of the analyzer enables a high responsivity, defined as the ratio of the slow secondary ion current emerging from the partially-compensated ion beam to the fast ion beam current. We measured 84% space charge compensation of the ion beam. The current from the slow ions and the rise time from the degree of space charge compensation were measured and compared with expected values.

Sub-micron resolution of localized ion beam induced charge reduction in silicon detectors damaged by heavy ions

DOE PAGES

Auden, Elizabeth C.; Pacheco, Jose L.; Bielejec, Edward; ...

2015-12-01

In this study, displacement damage reduces ion beam induced charge (IBIC) through Shockley-Read-Hall recombination. Closely spaced pulses of 200 keV Si ++ ions focused in a 40 nm beam spot are used to create damage cascades within 0.25 μm 2 areas. Damaged areas are detected through contrast in IBIC signals generated with focused ion beams of 200 keV Si ++ ions and 60 keV Li + ions. IBIC signal reduction can be resolved over sub-micron regions of a silicon detector damaged by as few as 1000 heavy ions.

Sub-micron resolution of localized ion beam induced charge reduction in silicon detectors damaged by heavy ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auden, Elizabeth C.; Pacheco, Jose L.; Bielejec, Edward

In this study, displacement damage reduces ion beam induced charge (IBIC) through Shockley-Read-Hall recombination. Closely spaced pulses of 200 keV Si ++ ions focused in a 40 nm beam spot are used to create damage cascades within 0.25 μm 2 areas. Damaged areas are detected through contrast in IBIC signals generated with focused ion beams of 200 keV Si ++ ions and 60 keV Li + ions. IBIC signal reduction can be resolved over sub-micron regions of a silicon detector damaged by as few as 1000 heavy ions.

Direct-write three-dimensional nanofabrication of nanopyramids and nanocones on Si by nanotumefaction using a helium ion microscope

NASA Astrophysics Data System (ADS)

Zhang, L.; Heinig, N. F.; Bazargan, S.; Abd-Ellah, M.; Moghimi, N.; Leung, K. T.

2015-06-01

The recently commercialized helium ion microscope (HIM) has already demonstrated its outstanding imaging capabilities in terms of resolution, surface sensitivity, depth of field and ease of charge compensation. Here, we show its exceptional patterning capabilities by fabricating dense lines and three-dimensional (3D) nanostructures on a Si substrate. Small focusing spot size and confined ion-Si interaction volume of a high-energy helium ion beam account for the high resolution in HIM patterning. We demonstrate that a set of resolvable parallel lines with a half pitch as small as 3.5 nm can be achieved. During helium ion bombardment of the Si surface, implantation outperforms milling due to the small mass of the helium ions, which produces tumefaction instead of depression in the Si surface. The Si surface tumefaction is the result of different kinetic processes including diffusion, coalescence and nanobubble formation of the implanted ions, and is found to be very stable structurally at room temperature. Under appropriate conditions, a linear dependence of the surface swollen height on the ion doses can be observed. This relation has enabled us to fabricate nanopyramids and nanocones, thus demonstrating that HIM patterning provides a new ‘bottom-up’ approach to fabricate 3D nanostructures. This surface tumefaction method is direct, both positioning and height accurate, and free of resist, etch, mode and precursor, and it promises new applications in nanoimprint mold fabrication and photomask clear defect reparation.

Development of long-lived thick carbon stripper foils for high energy heavy ion accelerators by a heavy ion beam sputtering method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muto, Hideshi; Ohshiro, Yukimitsu; Kawasaki, Katsunori

2013-04-19

In the past decade, we have developed extremely long-lived carbon stripper foils of 1-50 {mu}g/cm{sup 2} thickness prepared by a heavy ion beam sputtering method. These foils were mainly used for low energy heavy ion beams. Recently, high energy negative Hydrogen and heavy ion accelerators have started to use carbon stripper foils of over 100 {mu}g/cm{sup 2} in thickness. However, the heavy ion beam sputtering method was unsuccessful in production of foils thicker than about 50 {mu}g/cm{sup 2} because of the collapse of carbon particle build-up from substrates during the sputtering process. The reproduction probability of the foils was lessmore » than 25%, and most of them had surface defects. However, these defects were successfully eliminated by introducing higher beam energies of sputtering ions and a substrate heater during the sputtering process. In this report we describe a highly reproducible method for making thick carbon stripper foils by a heavy ion beam sputtering with a Krypton ion beam.« less

Application and development of ion-source technology for radiation-effects testing of electronics

NASA Astrophysics Data System (ADS)

Kalvas, T.; Javanainen, A.; Kettunen, H.; Koivisto, H.; Tarvainen, O.; Virtanen, A.

2017-09-01

Studies of heavy-ion induced single event effect (SEE) on space electronics are necessary to verify the operation of the components in the harsh radiation environment. These studies are conducted by using high-energy heavy-ion beams to simulate the radiation effects in space. The ion beams are accelerated as so-called ion cocktails, containing several ion beam species with similar mass-to-charge ratio, covering a wide range of linear energy transfer (LET) values also present in space. The use of cocktails enables fast switching between beam species during testing. Production of these high-energy ion cocktails poses challenging requirements to the ion sources because in most laboratories reaching the necessary beam energies requires very high charge state ions. There are two main technologies producing these beams: The electron beam ion source EBIS and the electron cyclotron resonance ion source ECRIS. The EBIS is most suitable for pulsed accelerators, while ECRIS is most suitable for use with cyclotrons, which are the most common accelerators used in these applications. At the Accelerator Laboratory of the University of Jyväskylä (JYFL), radiation effects testing is currently performed using a K130 cyclotron and a 14 GHz ECRIS at a beam energy of 9.3 MeV/u. A new 18 GHz ECRIS, pushing the limits of the normal conducting ECR technology is under development at JYFL. The performances of existing 18 GHz ion sources have been compared, and based on this analysis, a 16.2 MeV/u beam cocktail with 1999 MeV 126Xe44+ being the most challenging component to has been chosen for development at JYFL. The properties of the suggested beam cocktail are introduced and discussed.

Laser-assisted focused He + ion beam induced etching with and without XeF 2 gas assist

DOE PAGES

Stanford, Michael G.; Mahady, Kyle; Lewis, Brett B.; ...

2016-10-04

Focused helium ion (He +) milling has been demonstrated as a high-resolution nanopatterning technique; however, it can be limited by its low sputter yield as well as the introduction of undesired subsurface damage. Here, we introduce pulsed laser- and gas-assisted processes to enhance the material removal rate and patterning fidelity. A pulsed laser-assisted He+ milling process is shown to enable high-resolution milling of titanium while reducing subsurface damage in situ. Gas-assisted focused ion beam induced etching (FIBIE) of Ti is also demonstrated in which the XeF 2 precursor provides a chemical assist for enhanced material removal rate. In conclusion, amore » pulsed laser-assisted and gas-assisted FIBIE process is shown to increase the etch yield by ~9× relative to the pure He+ sputtering process. These He + induced nanopatterning techniques improve material removal rate, in comparison to standard He + sputtering, while simultaneously decreasing subsurface damage, thus extending the applicability of the He + probe as a nanopattering tool.« less

Laser-assisted focused He + ion beam induced etching with and without XeF 2 gas assist

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stanford, Michael G.; Mahady, Kyle; Lewis, Brett B.

Focused helium ion (He +) milling has been demonstrated as a high-resolution nanopatterning technique; however, it can be limited by its low sputter yield as well as the introduction of undesired subsurface damage. Here, we introduce pulsed laser- and gas-assisted processes to enhance the material removal rate and patterning fidelity. A pulsed laser-assisted He+ milling process is shown to enable high-resolution milling of titanium while reducing subsurface damage in situ. Gas-assisted focused ion beam induced etching (FIBIE) of Ti is also demonstrated in which the XeF 2 precursor provides a chemical assist for enhanced material removal rate. In conclusion, amore » pulsed laser-assisted and gas-assisted FIBIE process is shown to increase the etch yield by ~9× relative to the pure He+ sputtering process. These He + induced nanopatterning techniques improve material removal rate, in comparison to standard He + sputtering, while simultaneously decreasing subsurface damage, thus extending the applicability of the He + probe as a nanopattering tool.« less

Optics of ion beams for the neutral beam injection system on HL-2A Tokamak.

PubMed

Zou, G Q; Lei, G J; Cao, J Y; Duan, X R

2012-07-01

The ion beam optics for the neutral beam injection system on HL-2A Tokomak is studied by two- dimensional numerical simulation program firstly, where the emitting surface is taken at 100 Debye lengths from the plasma electrode. The mathematical formulation, computation techniques are described. Typical ion orbits, equipotential contours, and emittance diagram are shown. For a fixed geometry electrode, the effect of plasma density, plasma potential and plasma electron temperature on ion beam optics is examined, and the calculation reliability is confirmed by experimental results. In order to improve ion beam optics, the application of a small pre-acceleration voltage (∼100 V) between the plasma electrode and the arc discharge anode is reasonable, and a lower plasma electron temperature is desired. The results allow optimization of the ion beam optics in the neutral beam injection system on HL-2A Tokomak and provide guidelines for designing future neutral beam injection system on HL-2M Tokomak.

Neutral particle beam intensity controller

DOEpatents

Dagenhart, William K.

1986-01-01

A neutral beam intensity controller is provided for a neutral beam generator in which a neutral beam is established by accelerating ions from an ion source into a gas neutralizer. An amplitude modulated, rotating magnetic field is applied to the accelerated ion beam in the gas neutralizer to defocus the resultant neutral beam in a controlled manner to achieve intensity control of the neutral beam along the beam axis at constant beam energy. The rotating magnetic field alters the orbits of ions in the gas neutralizer before they are neutralized, thereby controlling the fraction of neutral particles transmitted out of the neutralizer along the central beam axis to a fusion device or the like. The altered path or defocused neutral particles are sprayed onto an actively cooled beam dump disposed perpendicular to the neutral beam axis and having a central open for passage of the focused beam at the central axis of the beamline. Virtually zero therough 100% intensity control is achieved by varying the magnetic field strength without altering the ion source beam intensity or its species yield.

Ion beam modification of biological materials in nanoscale

NASA Astrophysics Data System (ADS)

Yu, L. D.; Anuntalabhochai, S.

2012-07-01

Ion interaction with biological objects in nanoscale is a novel research area stemming from applications of low-energy ion beams in biotechnology and biomedicine. Although the ion beam applications in biotechnology and biomedicine have achieved great successes, many mechanisms remain unclear and many new applications are to be explored. We have carried out some research on exploring the mechanisms and new applications besides attaining ion beam induction of mutation breeding and gene transformation. In the studies on the mechanisms, we focused our investigations on the direct interaction in nanoscale between ions and biological living materials. Our research topics have included the low-energy ion range in DNA, low-energy ion or neutral beam bombardment effect on DNA topological form change and mutation, low-energy ion or neutral beam bombardment effect on the cell envelope and gene transformation, and molecular dynamics simulation of ultra-low-energy ion irradiation of DNA. In the exploration of new applications, we have started experiments on ion irradiation or bombardment, in the nanoscaled depth or area, of human cells for biomedical research. This paper introduces our experiments and reports interesting results.

Plasma formed ion beam projection lithography system

DOEpatents

Leung, Ka-Ngo; Lee, Yung-Hee Yvette; Ngo, Vinh; Zahir, Nastaran

2002-01-01

A plasma-formed ion-beam projection lithography (IPL) system eliminates the acceleration stage between the ion source and stencil mask of a conventional IPL system. Instead a much thicker mask is used as a beam forming or extraction electrode, positioned next to the plasma in the ion source. Thus the entire beam forming electrode or mask is illuminated uniformly with the source plasma. The extracted beam passes through an acceleration and reduction stage onto the resist coated wafer. Low energy ions, about 30 eV, pass through the mask, minimizing heating, scattering, and sputtering.

A Study of Single Pass Ion Effects at the ALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byrd, J.M.; Thomson, J.; /LBL, Berkeley

2011-09-13

We report the results of experiments on a 'fast beam-ion instability' at the Advanced Light Source (ALS). This ion instability, which can arise even when the ions are not trapped over multiple beam passages, will likely be important for many future accelerators. In our experiments, we filled the ALS storage ring with helium gas, raising the pressure approximately two orders of magnitude above the nominal pressure. With gaps in the bunch train large enough to avoid conventional (multi-turn) ion trapping, we observed a factor of 2-3 increase in the vertical beam size along with coherent beam oscillations which increased alongmore » the bunch train. Ion trapping has long been recognized as a potential limitation in electron storage rings. The ions, generated by beam-gas collisions, become trapped in the negative potential of the beam and accumulate over multiple beam passages. The trapped ions are then observed to cause a number of deleterious effects such as an increasing beam phase space, a broadening and shifting of the beam transverse oscillation frequencies (tunes), collective beam instabilities, and beam lifetime reductions. All of these effects are of concern for the next generation of accelerators, such as the B-factories or damping rings for future linear colliders, which will store high beam currents with closely spaced bunches and ultra-low beam emittances. One of the standard solutions used to prevent ion trapping is to include a gap in the bunch train which is long compared to the bunch spacing. In this case, the ions are first strongly-focused by the passing electron bunches and then over-focused in the gap. With a sufficiently large gap, the ions can be driven to large amplitudes where they form a diffuse halo and do not affect the beam. In this paper, we describe experiments that study a new regime of transient ion instabilities predicted to arise in future electron storage rings, and linacs with bunch trains. These future rings and linacs, which will be operated with higher beam currents, small transverse beam emittances, and long bunch trains, will use ion clearing gaps to prevent conventional ion trapping. But, while the ion clearing gap may suppress the conventional ion instabilities, it will not suppress a transient beam-ion instability where ions generated and trapped during the passage of a single train lead to a fast instability. While both conventional and transient ion instabilities have the same origin, namely ions produced by the beam, they have different manifestations and, more importantly, the new transient instability can arise even after the conventional ion instability is cured. This new instability is called the 'Fast Beam-Ion Instability' (FBII). In many future rings, the FBII is predicted to have very fast growth rates, much faster than the damping rates of existing and proposed transverse feedback systems, and thus is a potential limitation. To study the FBII, we performed experiments at the ALS, a 1.5 GeV electron storage ring. At the nominal ALS pressure of about 0.24 nTorr, the FBII is not evident. To study the instability, we intentionally added helium gas to the storage-ring vacuum system until the residual gas pressure was increased about 80 nTorr. This brought the predicted growth rate of the instability at least an order of magnitude above the growth rate of conventional multibunch instabilities driven by the RF cavities and above the damping rate of the transverse feedback system (TFB) in the ALS and, thereby, established conditions very similar to those in a future storage ring. We then filled the ring with a relatively short train of bunches, suppressing conventional ion instabilities. In the following, we will first briefly describe This paper describes the experiment and results in more detail.« less

Simulation of electrostatic turbulence in the plasma sheet boundary layer with electron currents and bean-shaped ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishikawa, K.; Frank, L.A.; Huang, C.Y.

Plasma data from ISEE 1 show the presence of electron currents as well as energetic ion beams in the plasma sheet boundary layer. Broadband electrostatic noise and low-frequency electromagnetic bursts are detected in the plasma sheet boundary layer, especially in the presence of strong ion flows, currents, and steep spacial gradients in the fluxes of few-keV electrons and ions. Particle simulations have been performed to investigate electrostatic turbulence driven by a cold electron beam and/or ion beams with a bean-shaped velocity distribution. The simulation results show that the counterstreaming ion beams as well as the counterstreaming of the cold electronmore » beam and the ion beam excite ion acoustic waves with the Doppler-shifted real frequency ..omega..approx. = +- k/sub parallel/(c/sub s/-V/sub i//sub //sub parallel/). However, the effect of the bean-shaped ion velocity distributions reduces the growth rates of ion acoustic instability. The simulation results also show that the slowing down of the ion beam is larger at the larger perpendicular velocity. The wave spectra of the electric fields at some points for simulations show turbulence generated by growing waves. The frequency of these spectra ranges from ..cap omega../sub i/ to ..omega../sub p//sub e/, which is in qualitative agreement with the satellite data. copyright American Geophysical Union 1988« less

First Results From A Multi-Ion Beam Lithography And Processing System At The University Of Florida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gila, Brent; Appleton, Bill R.; Fridmann, Joel

2011-06-01

The University of Florida (UF) have collaborated with Raith to develop a version of the Raith ionLiNE IBL system that has the capability to deliver multi-ion species in addition to the Ga ions normally available. The UF system is currently equipped with a AuSi liquid metal alloy ion source (LMAIS) and ExB filter making it capable of delivering Au and Si ions and ion clusters for ion beam processing. Other LMAIS systems could be developed in the future to deliver other ion species. This system is capable of high performance ion beam lithography, sputter profiling, maskless ion implantation, ion beammore » mixing, and spatial and temporal ion beam assisted writing and processing over large areas (100 mm2)--all with selected ion species at voltages from 15-40 kV and nanometer precision. We discuss the performance of the system with the AuSi LMAIS source and ExB mass separator. We report on initial results from the basic system characterization, ion beam lithography, as well as for basic ion-solid interactions.« less

A lithium niobate electro-optic tunable Bragg filter fabricated by electron beam lithography

NASA Astrophysics Data System (ADS)

Pierno, L.; Dispenza, M.; Secchi, A.; Fiorello, A.; Foglietti, V.

2008-06-01

We have designed and fabricated a lithium niobate tunable Bragg filter patterned by electron beam lithography and etched by reactive ion etching. Devices with 1 mm, 2 mm and 4 mm length and 360 and 1080 nm Bragg period, with 5 pm V-1 tuning efficiency, have been characterized. Some applications were identified. Optical simulation based on finite element model (FEM) software showing the optical filtering curve and the coupling factor dependence on the manufacturing parameter is reported. The tuning of the filter window position is electro-optically controlled.

Production of high current proton beams using complex H-rich molecules at GSI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adonin, A., E-mail: a.adonin@gsi.de; Barth, W.; Heymach, F.

2016-02-15

In this contribution, the concept of production of intense proton beams using molecular heavy ion beams from an ion source is described, as well as the indisputable advantages of this technique for operation of the GSI linear accelerator. The results of experimental investigations, including mass-spectra analysis and beam emittance measurements, with different ion beams (CH{sub 3}{sup +},C{sub 2}H{sub 4}{sup +},C{sub 3}H{sub 7}{sup +}) using various gaseous and liquid substances (methane, ethane, propane, isobutane, and iodoethane) at the ion source are summarized. Further steps to improve the ion source and injector performance with molecular beams are depicted.

Controlling and patterning the effective magnetization in Y3Fe5O12 thin films using ion irradiation

NASA Astrophysics Data System (ADS)

Ruane, W. T.; White, S. P.; Brangham, J. T.; Meng, K. Y.; Pelekhov, D. V.; Yang, F. Y.; Hammel, P. C.

2018-05-01

We report an approach to controlling the effective magnetization (Meff), a combination of the saturation magnetization and uniaxial anisotropy, of the ferrimagnet Y3Fe5O12 (YIG) using different species of ions: He+ and Ga+. The effective magnetization can be tuned as a function of the fluence, with He + providing the largest effect. We quantified the change in effective magnetization through an angular dependence of the ferromagnetic resonance before and after irradiation. Increases in 4πMeff were observed to be as much as 400 G with only a 15% increase in Gilbert damping, α (from 8.2e-4 to 9.4e-4). This result was combined with a method for accurate ion pattering, a focused ion beam, providing a mechanism for shaping the magnetic environment with submicron precision. We observe resonance modes localized by ion patterning of micron-sized dots, whose resonances match well with micromagnetic simulations. This technique offers a flexible tool for precision nanoscale control and characterization of the magnetic properties of YIG.

Development of an energy analyzer as diagnostic of beam-generated plasma in negative ion beam systems

NASA Astrophysics Data System (ADS)

Sartori, E.; Carozzi, G.; Veltri, P.; Spolaore, M.; Cavazzana, R.; Antoni, V.; Serianni, G.

2017-08-01

The measurement of the plasma potential and the energy spectrum of secondary particles in the drift region of a negative ion beam offers an insight into beam-induced plasma formation and beam transport in low pressure gasses. Plasma formation in negative-ion beam systems, and the characteristics of such a plasma are of interest especially for space charge compensation, plasma formation in neutralizers, and the development of improved schemes of beam-induced plasma neutralisers for future fusion devices. All these aspects have direct implications in the ITER Heating Neutral Beam and the operation of the prototypes, SPIDER and MITICA, and also have important role in the conceptual studies for NBI systems of DEMO, while at present experimental data are lacking. In this paper we present the design and development of an ion energy analyzer to measure the beam plasma formation and space charge compensation in negative ion beams. The diagnostic is a retarding field energy analyzer (RFEA), and will measure the transverse energy spectra of plasma molecular ions. The calculations that supported the design are reported, and a method to interpret the measurements in negative ion beam systems is also proposed. Finally, the experimental results of the first test in a magnetron plasma are presented.

Ion beam enhancement in magnetically insulated ion diodes for high-intensity pulsed ion beam generation in non-relativistic mode

NASA Astrophysics Data System (ADS)

Zhu, X. P.; Zhang, Z. C.; Pushkarev, A. I.; Lei, M. K.

2016-01-01

High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200-300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.

An overview of the facilities, activities, and developments at the University of North Texas Ion Beam Modification and Analysis Laboratory (IBMAL)

NASA Astrophysics Data System (ADS)

Rout, Bibhudutta; Dhoubhadel, Mangal S.; Poudel, Prakash R.; Kummari, Venkata C.; Pandey, Bimal; Deoli, Naresh T.; Lakshantha, Wickramaarachchige J.; Mulware, Stephen J.; Baxley, Jacob; Manuel, Jack E.; Pacheco, Jose L.; Szilasi, Szabolcs; Weathers, Duncan L.; Reinert, Tilo; Glass, Gary A.; Duggan, Jerry L.; McDaniel, Floyd D.

2013-07-01

The Ion Beam Modification and Analysis Laboratory (IBMAL) at the University of North Texas includes several accelerator facilities with capabilities of producing a variety of ion beams from tens of keV to several MeV in energy. The four accelerators are used for research, graduate and undergraduate education, and industrial applications. The NEC 3MV Pelletron tandem accelerator has three ion sources for negative ions: He Alphatross and two different SNICS-type sputter ion sources. Presently, the tandem accelerator has four high-energy beam transport lines and one low-energy beam transport line directly taken from the negative ion sources for different research experiments. For the low-energy beam line, the ion energy can be varied from ˜20 to 80 keV for ion implantation/modification of materials. The four post-acceleration beam lines include a heavy-ion nuclear microprobe; multi-purpose PIXE, RBS, ERD, NRA, and broad-beam single-event upset; high-energy ion implantation line; and trace-element accelerator mass spectrometry. The NEC 3MV single-ended Pelletron accelerator has an RF ion source mainly for hydrogen, helium and heavier inert gases. We recently installed a capacitive liner to the terminal potential stabilization system for high terminal voltage stability and high-resolution microprobe analysis. The accelerator serves a beam line for standard RBS and RBS/C. Another beamline for high energy focused ion beam application using a magnetic quadrupole lens system is currently under construction. This beam line will also serve for developmental work on an electrostatic lens system. The third accelerator is a 200 kV Cockcroft-Walton accelerator with an RF ion source. The fourth accelerator is a 2.5 MV Van de Graaff accelerator, which was in operation for last several decades is currently planned to be used mainly for educational purpose. Research projects that will be briefly discussed include materials synthesis/modification for photonic, electronic, and magnetic applications, surface sputtering and micro-fabrication of materials, development of high-energy ion microprobe systems, and educational and outreach activities.

An overview of the facilities, activities, and developments at the University of North Texas Ion Beam Modification and Analysis Laboratory (IBMAL)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rout, Bibhudutta; Dhoubhadel, Mangal S.; Poudel, Prakash R.

2013-07-03

The Ion Beam Modification and Analysis Laboratory (IBMAL) at the University of North Texas includes several accelerator facilities with capabilities of producing a variety of ion beams from tens of keV to several MeV in energy. The four accelerators are used for research, graduate and undergraduate education, and industrial applications. The NEC 3MV Pelletron tandem accelerator has three ion sources for negative ions: He Alphatross and two different SNICS-type sputter ion sources. Presently, the tandem accelerator has four high-energy beam transport lines and one low-energy beam transport line directly taken from the negative ion sources for different research experiments. Formore » the low-energy beam line, the ion energy can be varied from {approx}20 to 80 keV for ion implantation/modification of materials. The four post-acceleration beam lines include a heavy-ion nuclear microprobe; multi-purpose PIXE, RBS, ERD, NRA, and broad-beam single-event upset; high-energy ion implantation line; and trace-element accelerator mass spectrometry. The NEC 3MV single-ended Pelletron accelerator has an RF ion source mainly for hydrogen, helium and heavier inert gases. We recently installed a capacitive liner to the terminal potential stabilization system for high terminal voltage stability and high-resolution microprobe analysis. The accelerator serves a beam line for standard RBS and RBS/C. Another beamline for high energy focused ion beam application using a magnetic quadrupole lens system is currently under construction. This beam line will also serve for developmental work on an electrostatic lens system. The third accelerator is a 200 kV Cockcroft-Walton accelerator with an RF ion source. The fourth accelerator is a 2.5 MV Van de Graaff accelerator, which was in operation for last several decades is currently planned to be used mainly for educational purpose. Research projects that will be briefly discussed include materials synthesis/modification for photonic, electronic, and magnetic applications, surface sputtering and micro-fabrication of materials, development of high-energy ion microprobe systems, and educational and outreach activities.« less

Preliminary result of rapid solenoid for controlling heavy-ion beam parameters of laser ion source

DOE PAGES

Okamura, M.; Sekine, M.; Ikeda, S.; ...

2015-03-13

To realize a heavy ion inertial fusion driver, we have studied a possibility of laser ion source (LIS). A LIS can provide high current high brightness heavy ion beams, however it was difficult to manipulate the beam parameters. To overcome the issue, we employed a pulsed solenoid in the plasma drift section and investigated the effect of the solenoid field on singly charged iron beams. The rapid ramping magnetic field could enhance limited time slice of the current and simultaneously the beam emittance changed accordingly. This approach may also useful to realize an ion source for HIF power plant.

Charge amplifier with bias compensation

DOEpatents

Johnson, Gary W.

2002-01-01

An ion beam uniformity monitor for very low beam currents using a high-sensitivity charge amplifier with bias compensation. The ion beam monitor is used to assess the uniformity of a raster-scanned ion beam, such as used in an ion implanter, and utilizes four Faraday cups placed in the geometric corners of the target area. Current from each cup is integrated with respect to time, thus measuring accumulated dose, or charge, in Coulombs. By comparing the dose at each corner, a qualitative assessment of ion beam uniformity is made possible. With knowledge of the relative area of the Faraday cups, the ion flux and areal dose can also be obtained.

Pseudo ribbon metal ion beam source.

PubMed

Stepanov, Igor B; Ryabchikov, Alexander I; Sivin, Denis O; Verigin, Dan A

2014-02-01

The paper describes high broad metal ion source based on dc macroparticle filtered vacuum arc plasma generation with the dc ion-beam extraction. The possibility of formation of pseudo ribbon beam of metal ions with the parameters: ion beam length 0.6 m, ion current up to 0.2 A, accelerating voltage 40 kV, and ion energy up to 160 kV has been demonstrated. The pseudo ribbon ion beam is formed from dc vacuum arc plasma. The results of investigation of the vacuum arc evaporator ion-emission properties are presented. The influence of magnetic field strength near the cathode surface on the arc spot movement and ion-emission properties of vacuum-arc discharge for different cathode materials are determined. It was shown that vacuum-arc discharge stability can be reached when the magnetic field strength ranges from 40 to 70 G on the cathode surface.

Photodetachment process for beam neutralization

DOEpatents

Fink, Joel H. [Livermore, CA; Frank, Alan M. [Livermore, CA

1979-02-20

A process for neutralization of accelerated ions employing photo-induced charge detachment. The process involves directing a laser beam across the path of a negative ion beam such as to effect photodetachment of electrons from the beam ions. The frequency of the laser beam employed is selected to provide the maximum cross-section for the photodetachment process.

Ion beams in multi-species plasmas

NASA Astrophysics Data System (ADS)

Aguirre, E. M.; Scime, E. E.; Good, T. N.

2018-04-01

Argon and xenon ion velocity distribution functions are measured in Ar-He, Ar-Xe, and Xe-He expanding helicon plasmas to determine if ion beam velocity is enhanced by the presence of lighter ions. Contrary to observations in mixed gas sheath experiments, we find that adding a lighter ion does not increase the ion beam speed. The predominant effect is a reduction of ion beam velocity consistent with increased drag arising from increased gas pressure under all conditions: constant total gas pressure, equal plasma densities of different ions, and very different plasma densities of different ions. These results suggest that the physics responsible for the acceleration of multiple ion species in simple sheaths is not responsible for the ion acceleration observed in expanding helicon plasmas.

SU-D-BRB-02: Investigations of Secondary Ion Distributions in Carbon Ion Therapy Using the Timepix Detector.

PubMed

Gwosch, K; Hartmann, B; Jakubek, J; Granja, C; Soukup, P; Jaekel, O; Martisikova, M

2012-06-01

Due to the high conformity of carbon ion therapy, unpredictable changes in the patient's geometry or deviations from the planned beam properties can result in changes of the dose distribution. PET has been used successfully to monitor the actual dose distribution in the patient. However, it suffers from biological washout processes and low detection efficiency. The purpose of this contribution is to investigate the potential of beam monitoring by detection of prompt secondary ions emerging from a homogeneous phantom, simulating a patient's head. Measurements were performed at the Heidelberg Ion-Beam Therapy Center (Germany) using a carbon ion pencil beam irradiated on a cylindrical PMMA phantom (16cm diameter). For registration of the secondary ions, the Timepix detector was used. This pixelated silicon detector allows position-resolved measurements of individual ions (256×256 pixels, 55μm pitch). To track the secondary ions we used several parallel detectors (3D voxel detector). For monitoring of the beam in the phantom, we analyzed the directional distribution of the registered ions. This distribution shows a clear dependence on the initial beam energy, width and position. Detectable were range differences of 1.7mm, as well as vertical and horizontal shifts of the beam position by 1mm. To estimate the clinical potential of this method, we measured the yield of secondary ions emerging from the phantom for a beam energy of 226MeV/u. The differential distribution of secondary ions as a function of the angle from the beam axis for angles between 0 and 90° will be presented. In this setup the total yield in the forward hemisphere was found to be in the order of 10 -1 secondary ions per primary carbon ion. The presented measurements show that tracking of secondary ions provides a promising method for non-invasive monitoring of ion beam parameters for clinical relevant carbon ion fluences. Research with the pixel detectors was carried out in frame of the Medipix Collaboration. © 2012 American Association of Physicists in Medicine.

Development of procedures for programmable proximity aperture lithography

NASA Astrophysics Data System (ADS)

Whitlow, H. J.; Gorelick, S.; Puttaraksa, N.; Napari, M.; Hokkanen, M. J.; Norarat, R.

2013-07-01

Programmable proximity aperture lithography (PPAL) with MeV ions has been used in Jyväskylä and Chiang Mai universities for a number of years. Here we describe a number of innovations and procedures that have been incorporated into the LabView-based software. The basic operation involves the coordination of the beam blanker and five motor-actuated translators with high accuracy, close to the minimum step size with proper anti-collision algorithms. By using special approaches, such writing calibration patterns, linearisation of position and careful backlash correction the absolute accuracy of the aperture size and position, can be improved beyond the standard afforded by the repeatability of the translator end-point switches. Another area of consideration has been the fluence control procedures. These involve control of the uniformity of the beam where different approaches for fluence measurement such as simultaneous aperture current and the ion current passing through the aperture using a Faraday cup are used. Microfluidic patterns may contain many elements that make-up mixing sections, reaction chambers, separation columns and fluid reservoirs. To facilitate conception and planning we have implemented a .svg file interpreter, that allows the use of scalable vector graphics files produced by standard drawing software for generation of patterns made up of rectangular elements.

Generating High-Brightness Ion Beams for Inertial Confinement Fusion

NASA Astrophysics Data System (ADS)

Cuneo, M. E.

1997-11-01

The generation of high current density ion beams with applied-B ion diodes showed promise in the late-1980's as an efficient, rep-rate, focusable driver for inertial confinement fusion. These devices use several Tesla insulating magnetic fields to restrict electron motion across anode-cathode gaps of order 1-2 cm, while accelerating ions to generate ≈ 1 kA/cm^2, 5 - 15 MeV beams. These beams have been used to heat hohlraums to about 65 eV. However, meeting the ICF driver requirements for low-divergence and high-brightness lithium ion beams has been more technically challenging than initially thought. Experimental and theoretical work over the last 5 years shows that high-brightness beams meeting the requirements for inertial confinement fusion are possible. The production of these beams requires the simultaneous integration of at least four conditions: 1) rigorous vacuum cleaning techniques for control of undesired anode, cathode, ion source and limiter plasma formation from electrode contaminants to control impurity ions and impedance collapse; 2) carefully tailored insulating magnetic field geometry for uniform beam generation; 3) high magnetic fields (V_crit/V > 2) and other techniques to control the electron sheath and the onset of a high divergence electromagnetic instability that couples strongly to the ion beam; and 4) an active, pre-formed, uniform lithium plasma for low source divergence which is compatible with the above electron-sheath control techniques. These four conditions have never been simultaneously present in any lithium beam experiment, but simulations and experimental tests of individual conditions have been done. The integration of these conditions is a goal of the present ion beam generation program at Sandia. This talk will focus on the vacuum cleaning techniques for ion diodes and pulsed power devices in general, including experimental results obtained on the SABRE and PBFA-II accelerators over the last 3 years. The current status of integration of the other key physics and technologies required to demonstrate high-brightness ion beams will also be presented.

Deuteron Beam Source Based on Mather Type Plasma Focus

NASA Astrophysics Data System (ADS)

Lim, L. K.; Yap, S. L.; Wong, C. S.; Zakaullah, M.

2013-04-01

A 3 kJ Mather type plasma focus system filled with deuterium gas is operated at pressure lower than 1 mbar. Operating the plasma focus in a low pressure regime gives a consistent ion beam which can make the plasma focus a reliable ion beam source. In our case, this makes a good deuteron beam source, which can be utilized for neutron generation by coupling a suitable target. This paper reports ion beam measurements obtained at the filling pressure of 0.05-0.5 mbar. Deuteron beam energy is measured by time of flight technique using three biased ion collectors. The ion beam energy variation with the filling pressure is investigated. Deuteron beam of up to 170 keV are obtained with the strongest deuteron beam measured at 0.1 mbar, with an average energy of 80 keV. The total number of deuterons per shot is in the order of 1018 cm-2.

Detection and clearing of trapped ions in the high current Cornell photoinjector

DOE PAGES

Full, S.; Bartnik, A.; Bazarov, I. V.; ...

2016-03-03

Here, we have recently performed experiments to test the effectiveness of three ion-clearing strategies in the Cornell high intensity photoinjector: DC clearing electrodes, bunch gaps, and beam shaking. The photoinjector reaches a new regime of linac beam parameters where high continuous wave beam currents lead to ion trapping. Therefore ion mitigation strategies must be evaluated for this machine and other similar future high current linacs. We have developed several techniques to directly measure the residual trapped ions. Our two primary indicators of successful clearing are the amount of ion current removed by a DC clearing electrode, and the absence ofmore » bremsstrahlung radiation generated by beam-ion interactions. Measurements were taken for an electron beam with an energy of 5 MeV and continuous wave beam currents in the range of 1–20 mA. Several theoretical models have been developed to explain our data. Using them, we are able to estimate the clearing electrode voltage required for maximum ion clearing, the creation and clearing rates of the ions while employing bunch gaps, and the sinusoidal shaking frequency necessary for clearing via beam shaking. In all cases, we achieve a maximum ion clearing of at least 70% or higher, and in some cases our data is consistent with full ion clearing.« less

High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirano, Y., E-mail: y.hirano@aist.go.jp, E-mail: hirano.yoichi@phys.cst.nihon-u.ac.jp; College of Science and Technologies, Nihon University, Chiyodaku, Tokyo 101-0897; Kiyama, S.

2015-11-15

A high current density (≈3 mA/cm{sup 2}) hydrogen ion beam source operating in an extremely low-energy region (E{sub ib} ≈ 150–200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E{sub ib} is being reduced. The radial profiles of the ion beam current density and the low temperature ion current densitymore » can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.« less

Pattern transition from nanohoneycomb to nanograss on germanium by gallium ion bombardment

NASA Astrophysics Data System (ADS)

Zheng Xiao-Hu郑, 晓虎; Zhang Miao张, 苗; Huang An-Ping黄, 安平; Xiao Zhi-Song肖, 志松; Paul, K. Chu朱 剑 豪; Wang Xi王, 曦; Di Zeng-Feng狄, 增峰

2015-05-01

During the irradiation of Ge surface with Ga+ ions up to 1017 ions·cm-2, various patterns from ordered honeycomb to nanograss structure appear to be decided by the ion beam energy. The resulting surface morphologies have been studied by scanning electron microscopy and atomic force microscopy. For high energy Ga+ irradiation (16-30 keV), by controlling the ion fluence, we have captured that the equilibrium nanograss morphology also originates from the ordered honeycomb structure. When honeycomb holes are formed by ion erosion, heterogeneous distribution of the deposited energy along the holes leads to viscous flow from the bottom to the plateau. Redistribution of target atoms results in the growth of protuberances on the plateau, and finally the pattern evolution from honeycomb to nanograss with an equilibrium condition. Project supported by the National Natural Science Funds for Excellent Young Scholar, China (Grant No. 51222211), the National Natural Science Foundation of China (Grant Nos. 61176001 and 61006088), the National Basic Research Program of China (Grant No. 2010CB832906), the Pujiang Talent Project of Shanghai, China (Grant No. 11PJ1411700), the Hong Kong Research Grants Council (RGC) General Research Funds (GRF), China (Grant No. 112212), the City University of Hong Kong of Hong Kong Applied Research Grant (ARG), China (Grant No. 9667066), and the International Collaboration and Innovation Program on High Mobility Materials Engineering of Chinese Academy of Sciences.

Polarized negative ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haeberli, W.

1981-04-01

This paper presents a survey of methods, commonly in use or under development, to produce beams of polarized negative ions for injection into accelerators. A short summary recalls how the hyperfine interaction is used to obtain nuclear polarization in beams of atoms. Atomic-beam sources for light ions are discussed. If the best presently known techniques are incorporated in all stages of the source, polarized H/sup -/ and D/sup -/ beams in excess of 10 ..mu..A can probably be achieved. Production of polarized ions from fast (keV) beams of polarized atoms is treated separately for atoms in the H(25) excited statemore » (Lamb-Shift source) and atoms in the H(1S) ground state. The negative ion beam from Lamb-Shift sources has reached a plateau just above 1 ..mu..A, but this beam current is adequate for many applications and the somewhat lower beam current is compensated by other desirable characteristics. Sources using fast polarized ground state atoms are in a stage of intense development. The next sections summarize production of polarized heavy ions by the atomic beam method, which is well established, and by optical pumping, which has recently been demonstrated to yield very large nuclear polarization. A short discussion of proposed ion sources for polarized /sup 3/He/sup -/ ions is followed by some concluding remarks.« less

Improvements for extending the time between maintenance periods for the Heidelberg ion beam therapy center (HIT) ion sources.

PubMed

Winkelmann, Tim; Cee, Rainer; Haberer, Thomas; Naas, Bernd; Peters, Andreas; Schreiner, Jochen

2014-02-01

The clinical operation at the Heidelberg Ion Beam Therapy Center (HIT) started in November 2009; since then more than 1600 patients have been treated. In a 24/7 operation scheme two 14.5 GHz electron cyclotron resonance ion sources are routinely used to produce protons and carbon ions. The modification of the low energy beam transport line and the integration of a third ion source into the therapy facility will be shown. In the last year we implemented a new extraction system at all three sources to enhance the lifetime of extraction parts and reduce preventive and corrective maintenance. The new four-electrode-design provides electron suppression as well as lower beam emittance. Unwanted beam sputtering effects which typically lead to contamination of the insulator ceramics and subsequent high-voltage break-downs are minimized by the beam guidance of the new extraction system. By this measure the service interval can be increased significantly. As a side effect, the beam emittance can be reduced allowing a less challenging working point for the ion sources without reducing the effective beam performance. This paper gives also an outlook to further enhancements at the HIT ion source testbench.

Numerical simulation of ion charge breeding in electron beam ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, L., E-mail: zhao@far-tech.com; Kim, Jin-Soo

2014-02-15

The Electron Beam Ion Source particle-in-cell code (EBIS-PIC) tracks ions in an EBIS electron beam while updating electric potential self-consistently and atomic processes by the Monte Carlo method. Recent improvements to the code are reported in this paper. The ionization module has been improved by using experimental ionization energies and shell effects. The acceptance of injected ions and the emittance of extracted ion beam are calculated by extending EBIS-PIC to the beam line transport region. An EBIS-PIC simulation is performed for a Cs charge-breeding experiment at BNL. The charge state distribution agrees well with experiments, and additional simulation results ofmore » radial profiles and velocity space distributions of the trapped ions are presented.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ast, D.G.

Research focused on control of misfit dislocations in strained epitaxial layers of GaAs through prepatterning of the substrate. Patterning and etching trenches into GaAs substrates before epitaxial growth results in nonplanar wafer surface, which makes device fabrication more difficult. Selective ion damaging the substrate prior to growth was investigated. The question of whether the overlayer must or must not be discontinuous was addressed. The third research direction was to extend results from molecular beam epitaxially grown material to organometallic chemical vapor deposition. Effort was increased to study the patterning processes and the damage it introduces into the substrate. The researchmore » program was initiated after the discovery that 500-eV dry etching in GaAs damages the substrate much deeper than the ion range.« less

Investigation of ion-beam machining methods for replicated x-ray optics

NASA Technical Reports Server (NTRS)

Drueding, Thomas W.

1996-01-01

The final figuring step in the fabrication of an optical component involves imparting a specified contour onto the surface. This can be expensive and time consuming step. The recent development of ion beam figuring provides a method for performing the figuring process with advantages over standard mechanical methods. Ion figuring has proven effective in figuring large optical components. The process of ion beam figuring removes material by transferring kinetic energy from impinging neutral particles. The process utilizes a Kaufman type ion source, where a plasma is generated in a discharge chamber by controlled electric potentials. Charged grids extract and accelerate ions from the chamber. The accelerated ions form a directional beam. A neutralizer outside the accelerator grids supplies electrons to the positive ion beam. It is necessary to neutralize the beam to prevent charging workpieces and to avoid bending the beam with extraneous electro-magnetic fields. When the directed beam strikes the workpiece, material sputters in a predicable manner. The amount and distribution of material sputtered is a function of the energy of the beam, material of the component, distance from the workpiece, and angle of incidence of the beam. The figuring method described here assumes a constant beam removal, so that the process can be represented by a convolution operation. A fixed beam energy maintains a constant sputtering rate. This temporally and spatially stable beam is held perpendicular to the workpiece at a fixed distance. For non-constant removal, corrections would be required to model the process as a convolution operation. Specific figures (contours) are achieved by rastering the beam over the workpiece at varying velocities. A unique deconvolution is performed, using series-derivative solution developed for the system, to determine these velocities.

Sub-Optical Lithography With Nanometer Definition Masks

NASA Technical Reports Server (NTRS)

Hartley, Frank T.; Malek, Chantal Khan; Neogi, Jayant

2000-01-01

Nanometer feature size lithography represents a major paradigm shift for the electronics and micro-electro-mechanical industries. In this paper, we discuss the capacity of dynamic focused reactive ion beam (FIB) etching systems to undertake direct and highly anisotropic erosion of thick evaporated gold coatings on boron-doped silicon X-ray mask membranes. FIB offers a new level of flexibility in micro fabrication, allowing for fast fabrication of X-ray masks, where pattern definition and surface alteration are combined in the same step which eliminates the whole lithographic process, in particular resist, resist development, electro-deposition and resist removal. Focused ion beam diameters as small as 7 nm can be obtained enabling fabrication well into the sub-20 nm regime. In preliminary demonstrations of this X-ray mask fabrication technique 22 nm width lines were milled directly through 0.9 microns of gold and a miniature mass spectrometer pattern was milled through over 0.5 microns of gold. Also presented are the results of the shadow printing, using the large depth of field of synchrotron high energy parallel X-ray beam, of these and other sub-optical defined patterns in photoresist conformally coated over surfaces of extreme topographical variation. Assuming that electronic circuits and/or micro devices scale proportionally, the surface area of devices processed with X-ray lithography and 20 nm critical dimension X-ray masks would be 0.5% that of contemporary devices (350 nm CD). The 20 CD mask fabrication represents an initial effort - a further factor of three reduction is anticipated which represents a further order-of-magnitude reduction in die area.

Surface modification using low energy ground state ion beams

NASA Technical Reports Server (NTRS)

Chutjian, Ara (Inventor); Hecht, Michael H. (Inventor); Orient, Otto J. (Inventor)

1990-01-01

A method of effecting modifications at the surfaces of materials using low energy ion beams of known quantum state, purity, flux, and energy is presented. The ion beam is obtained by bombarding ion-generating molecules with electrons which are also at low energy. The electrons used to bombard the ion generating molecules are separated from the ions thus obtained and the ion beam is directed at the material surface to be modified. Depending on the type of ion generating molecules used, different ions can be obtained for different types of surface modifications such as oxidation and diamond film formation. One area of application is in the manufacture of semiconductor devices from semiconductor wafers.

Note: A well-confined pulsed low-energy ion beam: Test experiments of Ar+

NASA Astrophysics Data System (ADS)

Hu, Jie; Wu, Chun-Xiao; Tian, Shan Xi

2018-06-01

Here we report a pulsed low-energy ion beam source for ion-molecule reaction study, in which the ions produced by the pulsed electron impact are confined well in the spatial size of each bunch. In contrast to the ion focusing method to reduce the transverse section of the beam, the longitudinal section in the translational direction is compressed by introducing a second pulse in the ion time-of-flight system. The test experiments for the low-energy argon ions are performed. The present beam source is ready for applications in the ion-molecule reaction dynamics experiments, in particular, in combination with the ion velocity map imaging technique.

Long-pulse beam acceleration of MeV-class H(-) ion beams for ITER NB accelerator.

PubMed

Umeda, N; Kashiwagi, M; Taniguchi, M; Tobari, H; Watanabe, K; Dairaku, M; Yamanaka, H; Inoue, T; Kojima, A; Hanada, M

2014-02-01

In order to realize neutral beam systems in International Thermonuclear Experimental Reactor whose target is to produce a 1 MeV, 200 A/m(2) during 3600 s D(-) ion beam, the electrostatic five-stages negative ion accelerator so-called "MeV accelerator" has been developed at Japan Atomic Energy Agency. To extend pulse length, heat load of the acceleration grids was reduced by controlling the ion beam trajectory. Namely, the beam deflection due to the residual magnetic field of filter magnet was suppressed with the newly developed extractor with a 0.5 mm off-set aperture displacement. The new extractor improved the deflection angle from 6 mrad to 1 mrad, resulting in the reduction of direct interception of negative ions from 23% to 15% of the total acceleration power, respectively. As a result, the pulse length of 130 A/m(2), 881 keV H(-) ion beam has been successfully extended from a previous value of 0.4 s to 8.7 s. This is the first long pulse negative ion beam acceleration over 100 MW/m(2).

Upgrade of the beam extraction system of the GTS-LHC electron cyclotron resonance ion source at CERN.

PubMed

Toivanen, V; Bellodi, G; Dimov, V; Küchler, D; Lombardi, A M; Maintrot, M

2016-02-01

Linac3 is the first accelerator in the heavy ion injector chain of the Large Hadron Collider (LHC), providing multiply charged heavy ion beams for the CERN experimental program. The ion beams are produced with GTS-LHC, a 14.5 GHz electron cyclotron resonance ion source, operated in afterglow mode. Improvement of the GTS-LHC beam formation and beam transport along Linac3 is part of the upgrade program of the injector chain in preparation for the future high luminosity LHC. A mismatch between the ion beam properties in the ion source extraction region and the acceptance of the following Low Energy Beam Transport (LEBT) section has been identified as one of the factors limiting the Linac3 performance. The installation of a new focusing element, an einzel lens, into the GTS-LHC extraction region is foreseen as a part of the Linac3 upgrade, as well as a redesign of the first section of the LEBT. Details of the upgrade and results of a beam dynamics study of the extraction region and LEBT modifications will be presented.

Study on the coloration response of a radiochromic film to MeV cluster ion beams

NASA Astrophysics Data System (ADS)

Yuri, Yosuke; Narumi, Kazumasa; Chiba, Atsuya; Hirano, Yoshimi; Saitoh, Yuichi

2017-11-01

A radiochromic film, Gafchromic HD-V2, is applied to a possible method of measuring a two-dimensional (2D) spatial profile of MeV cluster ion beams. The coloration responses of the HD-V2 film to MeV carbon and gold cluster ion beams are experimentally investigated since some cluster effect may appear. The degree of the film coloration is quantified as a change in optical density (OD) by reading the films with an image scanner for high-resolution measurement of the 2D beam profile. The OD response of HD-V2 is characterized as a function of the ion and atom fluence for comparison. The dependences of the OD response on the cluster size, kinetic energy, and ion species are discussed. It is found that the sensitivity of the OD change is reduced when the cluster size is large. The beam profile of MeV cluster ion beams delivered from the tandem accelerator in TIARA is characterized from the measurement result using HD-V2 films. The present results show that the use of the Gafchromic HD-V2 film is suitable for the detail beam profile measurement of MeV cluster ions, especially C60 ions, whose available intensity is rather low in comparison with that of monatomic ion beams.

Ion beam applications research. A summary of Lewis Research Center Programs

NASA Technical Reports Server (NTRS)

Banks, B. A.

1981-01-01

A summary of the ion beam applications research (IBAR) program organized to enable the development of materials, products, and processes through the nonpropulsive application of ion thruster technology is given. Specific application efforts utilizing ion beam sputter etching, deposition, and texturing are discussed as well as ion source and component technology applications.

Development of Bipolar Pulse Accelerator for Pulsed Ion Beam Implantation to Semiconductor

NASA Astrophysics Data System (ADS)

Masugata, Katsumi; Kawahara, Yoshihiro; Mitsui, Chihiro; Kitamura, Iwao; Takahashi, Takakazu; Tanaka, Yasunori; Tanoue, Hisao; Arai, Kazuo

2002-12-01

To improve the purity of the ion beams new type of pulsed power ion accelerator named "bipolar pulse accelerator" was proposed. The accelerator consists of two acceleration gaps (an ion source gap and a post acceleration gap) and a drift tube, and a bipolar pulse is applied to the drift tube to accelerate the beam. In the accelerator intended ions are selectively accelerated and the purity of the ion beam is enhanced. As the first step of the development of the accelerator, a Br-type magnetically insulated acceleration gap is developed. The gap has an ion source of coaxial gas puff plasma gun on the grounded anode and a negative pulse is applied to the cathode to accelerate the ion beam. By using the plasma gun, ion source plasma (nitrogen) of current density around 100 A/cm2 is obtained. In the paper, the experimental results of the evaluation of the ion beam and the characteristics of the gap are shown with the principle and the design concept of the proposed accelerator.

Plasma effects of active ion beam injections in the ionosphere at rocket altitudes

NASA Technical Reports Server (NTRS)

Arnoldy, R. L.; Cahill, L. J., Jr.; Kintner, P. M.; Moore, T. E.; Pollock, C. J.

1992-01-01

Data from ARCS rocket ion beam injection experiments are primarily discussed. There are three results from this series of active experiments that are of particular interest in space plasma physics. These are the transverse acceleration of ambient ions in the large beam volume, the scattering of beam ions near the release payload, and the possible acceleration of electrons very close to the plasma generator which produce intense high frequency waves. The ability of 100 ma ion beam injections into the upper E and F regions of the ionosphere to produce these phenomena appear to be related solely to the process by which the plasma release payload and the ion beam are neutralized. Since the electrons in the plasma release do not convect with the plasma ions, the neutralization of both the payload and beam must be accomplished by large field-aligned currents (milliamperes/square meter) which are very unstable to wave growth of various modes.

A high brightness proton injector for the Tandetron accelerator at Jožef Stefan Institute

NASA Astrophysics Data System (ADS)

Pelicon, Primož; Podaru, Nicolae C.; Vavpetič, Primož; Jeromel, Luka; Ogrinc Potocnik, Nina; Ondračka, Simon; Gottdang, Andreas; Mous, Dirk J. M.

2014-08-01

Jožef Stefan Institute recently commissioned a high brightness H- ion beam injection system for its existing tandem accelerator facility. Custom developed by High Voltage Engineering Europa, the multicusp ion source has been tuned to deliver at the entrance of the Tandetron™ accelerator H- ion beams with a measured brightness of 17.1 A m-2 rad-2 eV-1 at 170 μA, equivalent to an energy normalized beam emittance of 0.767 π mm mrad MeV1/2. Upgrading the accelerator facility with the new injection system provides two main advantages. First, the high brightness of the new ion source enables the reduction of object slit aperture and the reduction of acceptance angle at the nuclear microprobe, resulting in a reduced beam size at selected beam intensity, which significantly improves the probe resolution for micro-PIXE applications. Secondly, the upgrade strongly enhances the accelerator up-time since H and He beams are produced by independent ion sources, introducing a constant availability of 3He beam for fusion-related research with NRA. The ion beam particle losses and ion beam emittance growth imply that the aforementioned beam brightness is reduced by transport through the ion optical system. To obtain quantitative information on the available brightness at the high-energy side of the accelerator, the proton beam brightness is determined in the nuclear microprobe beamline. Based on the experience obtained during the first months of operation for micro-PIXE applications, further necessary steps are indicated to obtain optimal coupling of the new ion source with the accelerator to increase the normalized high-energy proton beam brightness at the JSI microprobe, currently at 14 A m-2 rad-2 eV-1, with the output current at 18% of its available maximum.

Computer simulations of electromagnetic cool ion beam instabilities. [in near earth space

NASA Technical Reports Server (NTRS)

Gary, S. P.; Madland, C. D.; Schriver, D.; Winske, D.

1986-01-01

Electromagnetic ion beam instabilities driven by cool ion beams at propagation parallel or antiparallel to a uniform magnetic field are studied using computer simulations. The elements of linear theory applicable to electromagnetic ion beam instabilities and the simulations derived from a one-dimensional hybrid computer code are described. The quasi-linear regime of the right-hand resonant ion beam instability, and the gyrophase bunching of the nonlinear regime of the right-hand resonant and nonresonant instabilities are examined. It is detected that in the quasi-linear regime the instability saturation is due to a reduction in the beam core relative drift speed and an increase in the perpendicular-to-parallel beam temperature; in the nonlinear regime the instabilities saturate when half the initial beam drift kinetic energy density is converted to fluctuating magnetic field energy density.

The effects of ion gun beam voltage on the electrical characteristics of NbCN/PbBi edge junctions

NASA Technical Reports Server (NTRS)

Lichtenberger, A. W.; Feldman, M. J.; Mattauch, R. J.; Cukauskas, E. J.

1989-01-01

The authors have succeeded in fabricating high-quality submicron NbCN edge junctions using a technique which is commonly used to make Nb edge junctions. A modified commercial ion gun was used to cut an edge in SiO2/NbCN films partially covered with photoresist. An insulating barrier was then formed on the exposed edge by reactive ion beam oxidation, and a counterelectrode of PbBi was deposited. The electrical quality of the resulting junctions was found to be strongly influenced by the ion beam acceleration voltages used to cut the edge and to oxidize it. For low ion beam voltages, the junction quality parameter was as high as Vm = 55 mV (measured at 3 mV), but higher ion beam voltages yielded strikingly poorer quality junctions. In light of the small coherence length of NbN, the dependence of the electrical characteristics on ion beam voltage is presumably due to mechanical damage of the NbCN surface. In contrast, for similar ion beam voltages, no such dependence was found for Nb edge junctions.

Ion related problems for the XLS ring

NASA Astrophysics Data System (ADS)

Bozoki, Eva S.; Halama, Henry

1991-10-01

The electron beam in a storage ring collides with the residual gas in the vacuum chamber. As a consequence, low velocity positive ions are produced and trapped in the potential well of the electron beam. They perform stable or unstable oscillations around the beam under the repetitive Coulomb force of the bunches. If not cleared, the captured ions can lead to partial or total neutralization of the beam, causing both a decrease of lifetime and a change in the vertical tunes as well as an increase in the tune spread. It can also cause coherent and incoherent transverse instabilities. An electrostatic clearing electrodes system was designed to keep the neutralization below a desired limit. The location and the geometry of the clearing electrodes as well as the applied clearing voltage is based on the study of the ion production rate, longitudinal velocity of ions in field-free regions and in the dipoles, beam self-electric field, beam potential, critical mass for ion capture in the bunched beam and the bounce frequencies of the ions, tune shift and pressure rise due to trapped ions.

Ion beam neutralization using three-dimensional electron confinement by surface modification of magnetic poles

NASA Astrophysics Data System (ADS)

Nicolaescu, Dan; Sakai, Shigeki; Gotoh, Yasuhito; Ishikawa, Junzo

2011-07-01

Advanced implantation systems used for semiconductor processing require transportation of quasi-parallel ion beams, which have low energy (11B+, 31P+,75As+, Eion=200-1000 eV). Divergence of the ion beam due to space charge effects can be compensated through injection of electrons into different regions of the ion beam. The present study shows that electron confinement takes place in regions of strong magnetic field such as collimator magnet provided with surface mirror magnetic fields and that divergence of the ion beam passing through such regions is largely reduced. Modeling results have been obtained using Opera3D/Tosca/Scala. Electrons may be provided by collision between ions and residual gas molecules or may be injected by field emitter arrays. The size of surface magnets is chosen such as not to disturb ion beam collimation, making the approach compatible with ion beam systems. Surface magnets may form thin magnetic layers with thickness h=0.5 mm or less. Conditions for spacing of surface magnet arrays for optimal electron confinement are outlined.

A Versatile Ion Injector at KACST

NASA Astrophysics Data System (ADS)

El Ghazaly, M. O. A.; Behery, S. A.; Almuqhim, A. A.; Papash, A. I.; Welsch, C. P.

2011-10-01

A versatile ion-beam injector is presently being constructed at the National Centre for Mathematics and Physics (NCMP) at the King Abdul-Aziz City for Science and Technology (KACST), Saudi Arabia. This versatile injector will provide an electrostatic storage ring with high-quality ion beams of energies up to 30 keV per charge q. It will also allow for crossed-beams experiments in single-pass setups. The injector has been designed to include beams from two different ion sources, switched by a 90° deflection setup, and to allow for matching of the beam parameters to the Twiss parameters of the ring. The injector is equipped with two crossed beam-lines (inlets), with duplicated beam extraction and acceleration systems. As part of the initial setup, a simple electric discharge ion source has been developed for commissioning of the whole injector. In this paper, we report on the ion optics layout and the design parameters of the injector.

Monte Carlo simulations of nanoscale focused neon ion beam sputtering.

PubMed

Timilsina, Rajendra; Rack, Philip D

2013-12-13

A Monte Carlo simulation is developed to model the physical sputtering of aluminum and tungsten emulating nanoscale focused helium and neon ion beam etching from the gas field ion microscope. Neon beams with different beam energies (0.5-30 keV) and a constant beam diameter (Gaussian with full-width-at-half-maximum of 1 nm) were simulated to elucidate the nanostructure evolution during the physical sputtering of nanoscale high aspect ratio features. The aspect ratio and sputter yield vary with the ion species and beam energy for a constant beam diameter and are related to the distribution of the nuclear energy loss. Neon ions have a larger sputter yield than the helium ions due to their larger mass and consequently larger nuclear energy loss relative to helium. Quantitative information such as the sputtering yields, the energy-dependent aspect ratios and resolution-limiting effects are discussed.

Perspective on the Role of Negative Ions and Ion-Ion Plasmas in Heavy Ion Fusion Science, Magnetic Fusion Energy,and Related Fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grisham, L. R.; Kwan, J. W.

2008-08-01

Some years ago it was suggested that halogen negative ions could offer a feasible alternative path to positive ions as a heavy ion fusion driver beam which would not suffer degradation due to electron accumulation in the accelerator and beam transport system, and which could be converted to a neutral beam by photodetachment near the chamber entrance if desired. Since then, experiments have demonstrated that negative halogen beams can be extracted and accelerated away from the gas plume near the source with a surviving current density close to what could be achieved with a positive ion of similar mass, andmore » with comparable optical quality. In demonstrating the feasibility of halogen negative ions as heavy ion driver beams, ion - ion plasmas, an interesting and somewhat novel state of matter, were produced. These plasmas, produced near the extractor plane of the sources, appear, based upon many lines of experimental evidence, to consist of almost equal densities of positive and negative chlorine ions, with only a small component of free electrons. Serendipitously, the need to extract beams from this plasma for driver development provides a unique diagnostic tool to investigate the plasma, since each component - positive ions, negative ions, and electrons - can be extracted and measured separately. We discuss the relevance of these observations to understanding negative ion beam extraction from electronegative plasmas such as halogens, or the more familiar hydrogen of magnetic fusion ion sources. We suggest a concept which might improve negative hydrogen extraction by the addition of a halogen. The possibility and challenges of producing ion - ion plasmas with thin targets of halogens or, perhaps, salt, is briefly addressed.« less

Electron density profile measurements at a self-focusing ion beam with high current density and low energy extracted through concave electrodes.

PubMed

Fujiwara, Y; Hirano, Y; Kiyama, S; Nakamiya, A; Koguchi, H; Sakakita, H

2014-02-01

The self-focusing phenomenon has been observed in a high current density and low energy ion beam. In order to study the mechanism of this phenomenon, a special designed double probe to measure the electron density and temperature is installed into the chamber where the high current density ion beam is injected. Electron density profile is successfully measured without the influence of the ion beam components. Estimated electron temperature and density are ∼0.9 eV and ∼8 × 10(8) cm(-3) at the center of ion beam cross section, respectively. It was found that a large amount of electrons are spontaneously accumulated in the ion beam line in the case of self-forcing state.

Invited review article: the electrostatic plasma lens.

PubMed

Goncharov, Alexey

2013-02-01

The fundamental principles, experimental results, and potential applications of the electrostatic plasma lens for focusing and manipulating high-current, energetic, heavy ion beams are reviewed. First described almost 50 years ago, this optical beam device provides space charge neutralization of the ion beam within the lens volume, and thus provides an effective and unique tool for focusing high current beams where a high degree of neutralization is essential to prevent beam blow-up. Short and long lenses have been explored, and a lens in which the magnetic field is provided by rare-earth permanent magnets has been demonstrated. Applications include the use of this kind of optical tool for laboratory ion beam manipulation, high dose ion implantation, heavy ion accelerator injection, in heavy ion fusion, and other high technology.

Ion Beam Characterization of a NEXT Multi-Thruster Array Plume

NASA Technical Reports Server (NTRS)

Pencil, Eric J.; Foster, John E.; Patterson, Michael J.; Diaz, Esther M.; Van Noord, Jonathan L.; McEwen, Heather K.

2006-01-01

Three operational, engineering model, 7-kW ion thrusters and one instrumented, dormant thruster were installed in a cluster array in a large vacuum facility at NASA Glenn Research Center. A series of engineering demonstration tests were performed to evaluate the system performance impacts of operating various multiple-thruster configurations in an array. A suite of diagnostics was installed to investigate multiple-thruster operation impact on thruster performance and life, thermal interactions, and alternative system modes and architectures. The ion beam characterization included measuring ion current density profiles and ion energy distribution with Faraday probes and retarding potential analyzers, respectively. This report focuses on the ion beam characterization during single thruster operation, multiple thruster operation, various neutralizer configurations, and thruster gimbal articulation. Comparison of beam profiles collected during single and multiple thruster operation demonstrated the utility of superimposing single engine beam profiles to predict multi-thruster beam profiles. High energy ions were detected in the region 45 off the thruster axis, independent of thruster power, number of operating thrusters, and facility background pressure, which indicated that the most probable ion energy was not effected by multiple-thruster operation. There were no significant changes to the beam profiles collected during alternate thruster-neutralizer configurations, therefore supporting the viability of alternative system configuration options. Articulation of one thruster shifted its beam profile, whereas the beam profile of a stationary thruster nearby did not change, indicating there were no beam interactions which was consistent with the behavior of a collisionless beam expansion.

ITEP MEVVA ion beam for rhenium silicide production.

PubMed

Kulevoy, T; Gerasimenko, N; Seleznev, D; Kropachev, G; Kozlov, A; Kuibeda, R; Yakushin, P; Petrenko, S; Medetov, N; Zaporozhan, O

2010-02-01

The rhenium silicides are very attractive materials for semiconductor industry. In the Institute for Theoretical and Experimental Physics (ITEP) at the ion source test bench the research program of rhenium silicide production by ion beam implantation are going on. The investigation of silicon wafer after implantation of rhenium ion beam with different energy and with different total dose were carried out by secondary ions mass spectrometry, energy-dispersive x-ray microanalysis, and x-ray diffraction analysis. The first promising results of rhenium silicide film production by high intensity ion beam implantation are presented.

Photodetachment process for beam neutralization

DOEpatents

Fink, J.H.; Frank, A.M.

1979-02-20

A process for neutralization of accelerated ions employing photo-induced charge detachment is disclosed. The process involves directing a laser beam across the path of a negative ion beam such as to effect photodetachment of electrons from the beam ions. The frequency of the laser beam employed is selected to provide the maximum cross-section for the photodetachment process. 2 figs.

Approach to high quality GaN lateral nanowires and planar cavities fabricated by focused ion beam and metal-organic vapor phase epitaxy.

PubMed

Pozina, Galia; Gubaydullin, Azat R; Mitrofanov, Maxim I; Kaliteevski, Mikhail A; Levitskii, Iaroslav V; Voznyuk, Gleb V; Tatarinov, Evgeniy E; Evtikhiev, Vadim P; Rodin, Sergey N; Kaliteevskiy, Vasily N; Chechurin, Leonid S

2018-05-08

We have developed a method to fabricate GaN planar nanowires and cavities by combination of Focused Ion Beam (FIB) patterning of the substrate followed by Metal Organic Vapor Phase Epitaxy (MOVPE). The method includes depositing a silicon nitride mask on a sapphire substrate, etching of the trenches in the mask by FIB with a diameter of 40 nm with subsequent MOVPE growth of GaN within trenches. It was observed that the growth rate of GaN is substantially increased due to enhanced bulk diffusion of the growth precursor therefore the model for analysis of the growth rate was developed. The GaN strips fabricated by this method demonstrate effective luminescence properties. The structures demonstrate enhancement of spontaneous emission via formation of Fabry-Perot modes.

Ion energy distribution near a plasma meniscus with beam extraction for multi element focused ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathew, Jose V.; Paul, Samit; Bhattacharjee, Sudeep

2010-05-15

An earlier study of the axial ion energy distribution in the extraction region (plasma meniscus) of a compact microwave plasma ion source showed that the axial ion energy spread near the meniscus is small ({approx}5 eV) and comparable to that of a liquid metal ion source, making it a promising candidate for focused ion beam (FIB) applications [J. V. Mathew and S. Bhattacharjee, J. Appl. Phys. 105, 96101 (2009)]. In the present work we have investigated the radial ion energy distribution (IED) under the influence of beam extraction. Initially a single Einzel lens system has been used for beam extractionmore » with potentials up to -6 kV for obtaining parallel beams. In situ measurements of IED with extraction voltages upto -5 kV indicates that beam extraction has a weak influence on the energy spread ({+-}0.5 eV) which is of significance from the point of view of FIB applications. It is found that by reducing the geometrical acceptance angle at the ion energy analyzer probe, close to unidirectional distribution can be obtained with a spread that is smaller by at least 1 eV.« less

First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE.

PubMed

Schmidt, H T; Thomas, R D; Gatchell, M; Rosén, S; Reinhed, P; Löfgren, P; Brännholm, L; Blom, M; Björkhage, M; Bäckström, E; Alexander, J D; Leontein, S; Hanstorp, D; Zettergren, H; Liljeby, L; Källberg, A; Simonsson, A; Hellberg, F; Mannervik, S; Larsson, M; Geppert, W D; Rensfelt, K G; Danared, H; Paál, A; Masuda, M; Halldén, P; Andler, G; Stockett, M H; Chen, T; Källersjö, G; Weimer, J; Hansen, K; Hartman, H; Cederquist, H

2013-05-01

We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (C(n)(-), n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C2 (-) molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s ± 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10(-14) mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.

Selective Isobar Suppression for Accelerator Mass Spectrometry and Radioactive Ion Beam Science

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galindo-Uribarri, Alfredo; Havener, Charles C; Lewis, Thomas L.

2010-01-01

Several applications of AMS will benefit from pushing further the detection limits of AMS isotopes. A new method of selective isobar suppression by photodetachment in a radio-frequency quadrupole ion cooler is being developed at HRIBF with a two-fold purpose: (1) increasing the AMS sensitivity for certain isotopes of interest and (2) purifying radioactive ion beams for nuclear science. The potential of suppressing the 36S contaminants in a 36Cl beam using this method has been explored with stable S- and Cl- ions and a Nd:YLF laser. In the study, the laser beam was directed along the experiment's beam line and throughmore » a RF quadrupole ion cooler. Negative 32S and 35Cl ions produced by a Cs sputter ion source were focused into the ion cooler where they were slowed by collisions with He buffer gas; this increased the interaction time between the negative ion beam and the laser beam. As a result, suppression of S- by a factor of 3000 was obtained with about 2.5 W average laser power in the cooler while no reduction in Cl- current was observed.« less

An all permanent magnet electron cyclotron resonance ion source for heavy ion therapy.

PubMed

Cao, Yun; Li, Jia Qing; Sun, Liang Ting; Zhang, Xue Zhen; Feng, Yu Cheng; Wang, Hui; Ma, Bao Hua; Li, Xi Xia

2014-02-01

A high charge state all permanent Electron Cyclotron Resonance ion source, Lanzhou All Permanent ECR ion source no. 3-LAPECR3, has been successfully built at IMP in 2012, which will serve as the ion injector of the Heavy Ion Medical Machine (HIMM) project. As a commercial device, LAPECR3 features a compact structure, small size, and low cost. According to HIMM scenario more than 100 eμA of C(5+) ion beam should be extracted from the ion source, and the beam emittance better than 75 π*mm*mrad. In recent commissioning, about 120 eμA of C(5+) ion beam was got when work gas was CH4 while about 262 eμA of C(5+) ion beam was obtained when work gas was C2H2 gas. The design and construction of the ion source and its low-energy transportation beam line, and the preliminary commissioning results will be presented in detail in this paper.

Status of the Beam Thermalization Area at the NSCL

NASA Astrophysics Data System (ADS)

Cooper, Kortney; Barquest, Bradley; Morrissey, David; Rodriguez, Jose Alberto; Schwarz, Stefan; Sumithrarachchi, Chandana; Kwarsick, Jeff; Savard, Guy

2013-10-01

Beam thermalization is a necessary process for the production of low-energy ion beams at projectile fragmentation facilities. Present beam thermalization techniques rely on passing high-energy ion beams through solid degraders followed by a gas cell where the remaining kinetic energy is dissipated through collisions with buffer gas atoms. Recently, the National Superconducting Cyclotron Laboratory (NSCL) upgraded its thermalization area with the implementation of new large acceptance beam lines and a large RF-gas catcher constructed by Argonne National Lab (ANL). Two high-energy beam lines were commissioned along with the installation and commissioning of this new device in late 2012. Low-energy radioactive ion beams have been successfully delivered to the Electron Beam Ion Trap (EBIT) charge breeder for the ReA3 reaccelerator, the SuN detector, the Low Energy Beam Ion Trap (LEBIT) penning trap, and the Beam Cooler and Laser Spectroscopy (BeCoLa) collinear laser beamline. Construction of a gas-filled reverse cyclotron dubbed the CycStopper is also underway. The status of the beam thermalization area will be presented and the overall efficiency of the system will be discussed.

Design study of primary ion provider for relativistic heavy ion collider electron beam ion source.

PubMed

Kondo, K; Kanesue, T; Tamura, J; Okamura, M

2010-02-01

Brookhaven National Laboratory has developed the new preinjector system, electron beam ion source (EBIS) for relativistic heavy ion collider (RHIC) and National Aeronautics and Space Administration Space Radiation Laboratory. Design of primary ion provider is an essential problem since it is required to supply beams with different ion species to multiple users simultaneously. The laser ion source with a defocused laser can provide a low charge state and low emittance ion beam, and is a candidate for the primary ion source for RHIC-EBIS. We show a suitable design with appropriate drift length and solenoid, which helps to keep sufficient total charge number with longer pulse length. The whole design of primary ion source, as well as optics arrangement, solid targets configuration and heating about target, is presented.

Process For Patterning Dispenser-Cathode Surfaces

NASA Technical Reports Server (NTRS)

Garner, Charles E.; Deininger, William D.

1989-01-01

Several microfabrication techniques combined into process cutting slots 100 micrometer long and 1 to 5 micrometer wide into tungsten dispenser cathodes for traveling-wave tubes. Patterned photoresist serves as mask for etching underlying aluminum. Chemically-assisted ion-beam etching with chlorine removes exposed parts of aluminum layer. Etching with fluorine or chlorine trifluoride removes tungsten not masked by aluminum layer. Slots enable more-uniform low-work function coating dispensed to electron-emitting surface. Emission of electrons therefore becomes more uniform over cathode surface.

Amplification due to two-stream instability of self-electric and magnetic fields of an ion beam propagating in background plasma

NASA Astrophysics Data System (ADS)

Tokluoglu, Erinc K.; Kaganovich, Igor D.; Carlsson, Johan A.; Hara, Kentaro; Startsev, Edward A.

2018-05-01

Propagation of charged particle beams in background plasma as a method of space charge neutralization has been shown to achieve a high degree of charge and current neutralization and therefore enables nearly ballistic propagation and focusing of charged particle beams. Correspondingly, the use of plasmas for propagation of charged particle beams has important applications for transport and focusing of intense particle beams in inertial fusion and high energy density laboratory plasma physics. However, the streaming of beam ions through a background plasma can lead to the development of two-stream instability between the beam ions and the plasma electrons. The beam electric and magnetic fields enhanced by the two-stream instability can lead to defocusing of the ion beam. Using particle-in-cell simulations, we study the scaling of the instability-driven self-electromagnetic fields and consequent defocusing forces with the background plasma density and beam ion mass. We identify plasma parameters where the defocusing forces can be reduced.

SU-E-T-562: Scanned Percent Depth Dose Curve Discrepancy for Photon Beams with Physical Wedge in Place (Varian IX) Using Different Sensitive Volume Ion Chambers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, H; Sarkar, V; Rassiah-Szegedi, P

2014-06-01

Purpose: To investigate and report the discrepancy of scanned percent depth dose (PDD) for photon beams with physical wedge in place when using ion chambers with different sensitive volumes. Methods/Materials: PDD curves of open fields and physical wedged fields (15, 30, 45, and 60 degree wedge) were scanned for photon beams (6MV and 10MV, Varian iX) with field size of 5x5 and 10x10 cm using three common scanning chambers with different sensitive volumes - PTW30013 (0.6cm3), PTW23323 (0.1cm3) and Exradin A16 (0.007cm3). The scanning system software used was OmniPro version 6.2, and the scanning water tank was the Scanditronix Wellhoffermore » RFA 300.The PDD curves from the three chambers were compared. Results: Scanned PDD curves of the same energy beams for open fields were almost identical between three chambers, but the wedged fields showed non-trivial differences. The largest differences were observed between chamber PTW30013 and Exradin A16. The differences increased as physical wedge angle increased. The differences also increased with depth, and were more pronounced for 6MV beam. Similar patterns were shown for both 5x5 and 10x10 cm field sizes. For open fields, all PDD values agreed with each other within 1% at 10cm depth and within 1.62% at 20 cm depth. For wedged fields, the difference of PDD values between PTW30013 and A16 reached 4.09% at 10cm depth, and 5.97% at 20 cm depth for 6MV with 60 degree physical wedge. Conclusion: We observed a significant difference in scanned PDD curves of photon beams with physical wedge in place obtained when using different sensitive volume ion chambers. The PDD curves scanned with the smallest sensitive volume ion chamber showed significant difference from larger chamber results, beyond 10cm depth. We believe this to be caused by varying response to beam hardening by the wedges.« less

The fate of b-ions in the two worlds of collision-induced dissociation.

PubMed

Waldera-Lupa, Daniel M; Stefanski, Anja; Meyer, Helmut E; Stühler, Kai

2013-12-01

Fragment analysis of proteins and peptides by mass spectrometry using collision-induced dissociation (CID) revealed that the pairwise generated N-terminal b- and C-terminal y-ions have different stabilities resulting in underrepresentation of b-ions. Detailed analyses of large-scale spectra databases and synthetic peptides underlined these observations and additionally showed that the fragmentation pattern depends on utilized CID regime. To investigate this underrepresentation further we systematically compared resonant excitation energy and beam-type CID facilitated on different mass spectrometer platforms: (i) quadrupole time-of-flight, (ii) linear ion trap and (iii) three-dimensional ion trap. Detailed analysis of MS/MS data from a standard tryptic protein digest revealed that b-ions are significantly underrepresented on all investigated mass spectrometers. By N-terminal acetylation of tryptic peptides we show for the first time that b-ion cyclization reaction significantly contributes to b-ion underrepresentation even on ion trap instruments and accounts for at most 16% of b-ion loss. © 2013.

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

PubMed

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

2010-04-01

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

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

NASA Astrophysics Data System (ADS)

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

2010-04-01

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

Prize for Industrial Applications of Physics Talk: Low energy spread Ion source for focused ion beam systems-Search for the holy grail

NASA Astrophysics Data System (ADS)

Ward, Bill

2011-03-01

In this talk I will cover my personal experiences as a serial entrepreneur and founder of a succession of focused ion beam companies (1). Ion Beam Technology, which developed a 200kv (FIB) direct ion implanter (2). Micrion, where the FIB found a market in circuit edit and mask repair, which eventually merged with FEI corporation. and (3). ALIS Corporation which develop the Orion system, the first commercially successful sub-nanometer helium ion microscope, that was ultimately acquired by Carl Zeiss corporation. I will share this adventure beginning with my experiences in the early days of ion beam implantation and e-beam lithography which lead up to the final breakthrough understanding of the mechanisms that govern the successful creation and operation of a single atom ion source.

Spatial structure of ion beams in an expanding plasma

NASA Astrophysics Data System (ADS)

Aguirre, E. M.; Scime, E. E.; Thompson, D. S.; Good, T. N.

2017-12-01

We report spatially resolved perpendicular and parallel, to the magnetic field, ion velocity distribution function (IVDF) measurements in an expanding argon helicon plasma. The parallel IVDFs, obtained through laser induced fluorescence (LIF), show an ion beam with v ≈ 8000 m/s flowing downstream and confined to the center of the discharge. The ion beam is measurable for tens of centimeters along the expansion axis before the LIF signal fades, likely a result of metastable quenching of the beam ions. The parallel ion beam velocity slows in agreement with expectations for the measured parallel electric field. The perpendicular IVDFs show an ion population with a radially outward flow that increases with distance from the plasma axis. Structures aligned to the expanding magnetic field appear in the DC electric field, the electron temperature, and the plasma density in the plasma plume. These measurements demonstrate that at least two-dimensional and perhaps fully three-dimensional models are needed to accurately describe the spontaneous acceleration of ion beams in expanding plasmas.

Ion recombination correction in carbon ion beams.

PubMed

Rossomme, S; Hopfgartner, J; Lee, N D; Delor, A; Thomas, R A S; Romano, F; Fukumura, A; Vynckier, S; Palmans, H

2016-07-01

In this work, ion recombination is studied as a function of energy and depth in carbon ion beams. Measurements were performed in three different passively scattered carbon ion beams with energies of 62 MeV/n, 135 MeV/n, and 290 MeV/n using various types of plane-parallel ionization chambers. Experimental results were compared with two analytical models for initial recombination. One model is generally used for photon beams and the other model, developed by Jaffé, takes into account the ionization density along the ion track. An investigation was carried out to ascertain the effect on the ion recombination correction with varying ionization chamber orientation with respect to the direction of the ion tracks. The variation of the ion recombination correction factors as a function of depth was studied for a Markus ionization chamber in the 62 MeV/n nonmodulated carbon ion beam. This variation can be related to the depth distribution of linear energy transfer. Results show that the theory for photon beams is not applicable to carbon ion beams. On the other hand, by optimizing the value of the ionization density and the initial mean-square radius, good agreement is found between Jaffé's theory and the experimental results. As predicted by Jaffé's theory, the results confirm that ion recombination corrections strongly decrease with an increasing angle between the ion tracks and the electric field lines. For the Markus ionization chamber, the variation of the ion recombination correction factor with depth was modeled adequately by a sigmoid function, which is approximately constant in the plateau and strongly increasing in the Bragg peak region to values of up to 1.06. Except in the distal edge region, all experimental results are accurately described by Jaffé's theory. Experimental results confirm that ion recombination in the investigated carbon ion beams is dominated by initial recombination. Ion recombination corrections are found to be significant and cannot be neglected for reference dosimetry and for the determination of depth dose curves in carbon ion beams.

First heavy ion beam tests with a superconducting multigap CH cavity

NASA Astrophysics Data System (ADS)

Barth, W.; Aulenbacher, K.; Basten, M.; Busch, M.; Dziuba, F.; Gettmann, V.; Heilmann, M.; Kürzeder, T.; Miski-Oglu, M.; Podlech, H.; Rubin, A.; Schnase, A.; Schwarz, M.; Yaramyshev, S.

2018-02-01

Very compact accelerating-focusing structures, as well as short focusing periods, high accelerating gradients and short drift spaces are strongly required for superconducting (sc) accelerator sections operating at low and medium energies for continuous wave (cw) heavy ion beams. To keep the GSI-super heavy element (SHE) program competitive on a high level and even beyond, a standalone sc cw linac (Helmholtz linear accelerator) in combination with the GSI high charge state injector (HLI), upgraded for cw operation, is envisaged. Recently the first linac section (financed by Helmholtz Institute Mainz (HIM) and GSI) as a demonstration of the capability of 217 MHz multigap crossbar H-mode structures (CH) has been commissioned and extensively tested with heavy ion beam from the HLI. The demonstrator setup reached acceleration of heavy ions up to the design beam energy. The required acceleration gain was achieved with heavy ion beams even above the design mass to charge ratio at high beam intensity and full beam transmission. This paper presents systematic beam measurements with varying rf amplitudes and phases of the CH cavity, as well as phase space measurements for heavy ion beams with different mass to charge ratio. The worldwide first and successful beam test with a superconducting multigap CH cavity is a milestone of the R&D work of HIM and GSI in collaboration with IAP in preparation of the HELIAC project and other cw-ion beam applications.

Self-pinched transport for ion-driven inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Welch, D.R.; Olson, C.L.

Efficient transport of intense ion beams is necessary for ion-driven inertial confinement fusion (ICF). The self-pinched transport scheme involves the focusing of an ion beam to a radius of about 1 cm or less. At this radius, using the beam`s self-magnetic field for confinement, the ion beam propagates through the reactor chamber to an ICF target. A promising regime for self-pinched transport involves the injection of a high current beam into an initially neutral gas at about 200 mTorr less. A simple equilibrium theory of a beam with a temporally pinching radial envelope predicts that large confining magnetic fields aremore » possible with net currents of more than 50% of the beam current. The magnitude of these fields is strongly dependent on the rate of ionization of the given ion species. The authors have simulated ion-beam propagation, using the hybrid code IPROP, which self-consistently calculates the gas breakdown and electromagnetic fields. In agreement, with the theory, a propagation window of 20-200 mTorr of argon is calculated for a 50 kA, 5 MeV proton beam similar to the parameters of the SABRE accelerator at Sandia National Laboratories. The authors present simulations of the focusing and propagation of the SABRE beam, with the purpose of designing a self-pinch experiment.« less

Controllability in Multi-Stage Laser Ion Acceleration

NASA Astrophysics Data System (ADS)

Kawata, S.; Kamiyama, D.; Ohtake, Y.; Barada, D.; Ma, Y. Y.; Kong, Q.; Wang, P. X.; Gu, Y. J.; Li, X. F.; Yu, Q.

2015-11-01

The present paper shows a concept for a future laser ion accelerator, which should have an ion source, ion collimators, ion beam bunchers and ion post acceleration devices. Based on the laser ion accelerator components, the ion particle energy and the ion energy spectrum are controlled, and a future compact laser ion accelerator would be designed for ion cancer therapy or for ion material treatment. In this study each component is designed to control the ion beam quality. The energy efficiency from the laser to ions is improved by using a solid target with a fine sub-wavelength structure or a near-critical density gas plasma. The ion beam collimation is performed by holes behind the solid target or a multi-layered solid target. The control of the ion energy spectrum and the ion particle energy, and the ion beam bunching are successfully realized by a multi-stage laser-target interaction. A combination of each component provides a high controllability of the ion beam quality to meet variable requirements in various purposes in the laser ion accelerator. The work was partly supported by MEXT, JSPS, ASHULA project/ ILE, Osaka University, CORE (Center for Optical Research and Education, Utsunomiya University, Japan), Fudan University and CDI (Creative Dept. for Innovation) in CCRD, Utsunomiya University.

Non-invasive monitoring of therapeutic carbon ion beams in a homogeneous phantom by tracking of secondary ions.

PubMed

Gwosch, K; Hartmann, B; Jakubek, J; Granja, C; Soukup, P; Jäkel, O; Martišíková, M

2013-06-07

Radiotherapy with narrow scanned carbon ion beams enables a highly accurate treatment of tumours while sparing the surrounding healthy tissue. Changes in the patient's geometry can alter the actual ion range in tissue and result in unfavourable changes in the dose distribution. Consequently, it is desired to verify the actual beam delivery within the patient. Real-time and non-invasive measurement methods are preferable. Currently, the only technically feasible method to monitor the delivered dose distribution within the patient is based on tissue activation measurements by means of positron emission tomography (PET). An alternative monitoring method based on tracking of prompt secondary ions leaving a patient irradiated with carbon ion beams has been previously suggested. It is expected to help in overcoming the limitations of the PET-based technique like physiological washout of the beam induced activity, low signal and to allow for real-time measurements. In this paper, measurements of secondary charged particle tracks around a head-sized homogeneous PMMA phantom irradiated with pencil-like carbon ion beams are presented. The investigated energies and beam widths are within the therapeutically used range. The aim of the study is to deduce properties of the primary beam from the distribution of the secondary charged particles. Experiments were performed at the Heidelberg Ion Beam Therapy Center, Germany. The directions of secondary charged particles emerging from the PMMA phantom were measured using an arrangement of two parallel pixelated silicon detectors (Timepix). The distribution of the registered particle tracks was analysed to deduce its dependence on clinically important beam parameters: beam range, width and position. Distinct dependencies of the secondary particle tracks on the properties of the primary carbon ion beam were observed. In the particular experimental set-up used, beam range differences of 1.3 mm were detectable. In addition, variations in the beam width could be measured with a precision of 0.9 mm. Furthermore, shifts of the lateral beam position could be monitored with a sub-millimetre precision. The presented investigations demonstrate experimentally that the non-invasive measurement and analysis of secondary ion distributions around head-sized homogeneous objects provide information on the actual beam delivery. Beam range, width and position could be monitored with a precision attractive for therapeutic situations.

Selective area growth of InAs nanowires from SiO2/Si(1 1 1) templates direct-written by focused helium ion beam technology

NASA Astrophysics Data System (ADS)

Yang, Che-Wei; Chen, Wei-Chieh; Chou, Chieh; Lin, Hao-Hsiung

2018-02-01

We report on the selective area growth of InAs nanowires on patterned SiO2/Si (1 1 1) nano-holes, prepared by focused helium ion beam technology. We used a single spot mode, in which the focused helium ion beam was fixed on a single point with a He+-ion dosage, ranging from 1.5 pC to 8 pC, to drill the nano-holes. The smallest hole diameter achieved is ∼8 nm. We found that low He+-ion dosage is able to facilitate the nucleation of (1 1 1)B InAs on the highly mismatched Si, leading to the vertical growth of InAs nanowires (NWs). High He-ion dosage, on the contrary, severely damaged Si surface, resulting in tilted and stripe-like NWs. In addition to titled NW grown from (1 1 1)A InAs domain, a new titled growth direction due to defect induced twinning was observed. Cross-sectional TEM images of vertical NWs show mixed wurtizite (WZ) and zincblende (ZB) phases, while WZ phase dominants. The stacking faults resulting from the phase change is proportional to NW diameter, suggesting that the critical diameter of phase turning is larger than 110 nm, the maximum diameter of our NWs. Period of misfit dislocation at the InAs/Si interface of vertical NW is also found larger than the theoretical value when the diameter of heterointerface is smaller than 50 nm, indicating that the small contact area is able to accommodate the large lattice and thermal mismatch between InAs and Si.

Negative ion source with low temperature transverse divergence optical system

DOEpatents

Whealton, John H.; Stirling, William L.

1986-01-01

A negative ion source is provided which has extremely low transverse divergence as a result of a unique ion focusing system in which the focal line of an ion beam emanating from an elongated, concave converter surface is outside of the ion exit slit of the source and the path of the exiting ions. The beam source operates with a minimum ion temperature which makes possible a sharply focused (extremely low transverse divergence) ribbon like negative ion beam.

Negative ion source with low temperature transverse divergence optical system

DOEpatents

Whealton, J.H.; Stirling, W.L.

1985-03-04

A negative ion source is provided which has extremely low transverse divergence as a result of a unique ion focusing system in which the focal line of an ion beam emanating from an elongated, concave converter surface is outside of the ion exit slit of the source and the path of the exiting ions. The beam source operates with a minimum ion temperature which makes possible a sharply focused (extremely low transverse divergence) ribbon like negative ion beam.

Acceleration and stability of a high-current ion beam in induction fields

NASA Astrophysics Data System (ADS)

Karas', V. I.; Manuilenko, O. V.; Tarakanov, V. P.; Federovskaya, O. V.

2013-03-01

A one-dimensional nonlinear analytic theory of the filamentation instability of a high-current ion beam is formulated. The results of 2.5-dimensional numerical particle-in-cell simulations of acceleration and stability of an annular compensated ion beam (CIB) in a linear induction particle accelerator are presented. It is shown that additional transverse injection of electron beams in magnetically insulated gaps (cusps) improves the quality of the ion-beam distribution function and provides uniform beam acceleration along the accelerator. The CIB filamentation instability in both the presence and the absence of an external magnetic field is considered.

Beam production of a laser ion source with a rotating hollow cylinder target for low energy positive and negative ions

NASA Astrophysics Data System (ADS)

Saquilayan, G. Q.; Wada, M.

2017-08-01

A laser ion source that utilizes a hollow cylinder target is being developed for the production of positive and negative ions. Continuous operation of the laser ion source is possible through the design of a rotating target. Ion extraction through a grounded circular aperture was tested for positive and negative ions up to 1 kV. Time-of-flight measurements for the mass separation of ions were made by placing a Faraday cup at locations 0 and 15 mm from the beam extraction axis. Signals corresponding to slow and massive ions were detected with mass at least 380 amu. Investigation on the beam profile suggests a geometrical optimization of the beam forming system is necessary.

Ion traps for precision experiments at rare-isotope-beam facilities

NASA Astrophysics Data System (ADS)

Kwiatkowski, Anna

2016-09-01

Ion traps first entered experimental nuclear physics when the ISOLTRAP team demonstrated Penning trap mass spectrometry of radionuclides. From then on, the demand for ion traps has grown at radioactive-ion-beam (RIB) facilities since beams can be tailored for the desired experiment. Ion traps have been deployed for beam preparation, from bunching (thereby allowing time coincidences) to beam purification. Isomerically pure beams needed for nuclear-structure investigations can be prepared for trap-assisted or in-trap decay spectroscopy. The latter permits studies of highly charged ions for stellar evolution, which would be impossible with traditional experimental nuclear-physics methods. Moreover, the textbook-like conditions and advanced ion manipulation - even of a single ion - permit high-precision experiments. Consequently, the most accurate and precise mass measurements are now performed in Penning traps. After a brief introduction to ion trapping, I will focus on examples which showcase the versatility and utility of the technique at RIB facilities. I will demonstrate how this atomic-physics technique has been integrated into nuclear science, accelerator physics, and chemistry. DOE.

A Penning sputter ion source with very low energy spread

NASA Astrophysics Data System (ADS)

Nouri, Z.; Li, R.; Holt, R. A.; Rosner, S. D.

2010-03-01

We have developed a version of the Frankfurt Penning ion source that produces ion beams with very low energy spreads of ˜3 eV, while operating in a new discharge mode characterized by very high pressure, low voltage, and high current. The extracted ions also comprise substantial metastable and doubly charged species. Detailed studies of the operating parameters of the source showed that careful adjustment of the magnetic field and gas pressure is critical to achieving optimum performance. We used a laser-fluorescence method of energy analysis to characterize the properties of the extracted ion beam with a resolving power of 1×10 4, and to measure the absolute ion beam energy to an accuracy of 4 eV in order to provide some insight into the distribution of plasma potential within the ion source. This characterization method is widely applicable to accelerator beams, though not universal. The low energy spread, coupled with the ability to produce intense ion beams from almost any gas or conducting solid, make this source very useful for high-resolution spectroscopic measurements on fast-ion beams.

Ion Beam And Plasma Jet Generated By A 3 kJ Plasma Focus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, L. K.; Ngoi, S. K.; Yap, S. L.

The plasma focus device is well known as a copious source of X-ray, neutrons, ion and electron beams. In this work, the characteristics of energetic ion beam emission in a 3 kJ Mather-type plasma focus is studied. The plasma focus system is operated at low pressure with argon as the working gas. The objective of the project is to obtain the argon ion beam and the plasma jet. The ion beam and plasma jet are used for material processing. In order to investigate the effect of the ion beam and plasma jet, crystalline silicon substrates are placed above the anode.more » Samples obtained after irradiation with the plasma focus discharge are analyzed by using the Scanning electron microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX).« less

Ion related problems for the XLS ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bozoki, E.; Halama, H.

1989-07-11

The electron beam in the XLS will collide with the residual gas in the vacuum chamber. The positive ions will be trapped in the potential well of the electron beam. They will perform stable or unstable oscillations around the beam under the repetitive Coulomb force of the bunches. If not cleared, the captured ions will lead to partial or total neutralization of the beam, causing both, a decrease of life-time and a change in the vertical tunes as well as an increase in the tune-spread. They can also cause coherent transverse instabilities. The degree of neutralization {theta} that one canmore » tolerate, is primarily determined by the allowable tune shift, which of the XLS is between 1 and 5 10{sup {minus}3}. Electrostatic clearing electrodes will be used to keep the neutralization below the desired limit. In order to determine their location and the necessary clearing-rate and voltage, we examine the ion production rate, longitudinal velocity of ions in field-free regions and in the dipoles to see what distance the ions can travel without clearing before the neutralization of the beam reaches the prescribed limit, beam potential to see the locations of the potential wells, voltage requirements for ion clearing, critical mass for ion capture in the bunched beam, tune shift caused by neutralization of the beam, pressure rise due to the trapped ions and power dissipation due to beam image current. 13 refs., 3 figs., 4 tabs.« less

Design of free patterns of nanocrystals with ad hoc features via templated dewetting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aouassa, M.; Berbezier, I.; Favre, L.

Design of monodisperse ultra-small nanocrystals (NCs) into large scale patterns with ad hoc features is demonstrated. The process makes use of solid state dewetting of a thin film templated through alloy liquid metal ion source focused ion beam (LMIS-FIB) nanopatterning. The solid state dewetting initiated at the edges of the patterns controllably creates the ordering of NCs with ad hoc placement and periodicity. The NC size is tuned by varying the nominal thickness of the film while their position results from the association of film retraction from the edges of the lay out and Rayleigh-like instability. The use of ultra-highmore » resolution LMIS-FIB enables to produce monocrystalline NCs with size, periodicity, and placement tunable as well. It provides routes for the free design of nanostructures for generic applications in nanoelectronics.« less

Beam property measurement of a 300-kV ion source test stand for a 1-MV electrostatic accelerator

NASA Astrophysics Data System (ADS)

Park, Sae-Hoon; Kim, Dae-Il; Kim, Yu-Seok

2016-09-01

The KOMAC (Korea Multi-purpose Accelerator Complex) has been developing a 300-kV ion source test stand for a 1-MV electrostatic accelerator for industrial purposes. A RF ion source was operated at 200 MHz with its matching circuit. The beam profile and emittance were measured behind an accelerating column to confirm the beam property from the RF ion source. The beam profile was measured at the end of the accelerating tube and at the beam dump by using a beam profile monitor (BPM) and wire scanner. An Allison-type emittance scanner was installed behind the beam profile monitor (BPM) to measure the beam density in phase space. The measurement results for the beam profile and emittance are presented in this paper.

Tandem-Mirror Ion Source

NASA Technical Reports Server (NTRS)

Biddle, A.; Stone, N.; Reasoner, D.; Chisholm, W.; Reynolds, J.

1986-01-01

Improved ion source produces beam of ions at any kinetic energy from 1 to 1,000 eV, with little spread in energy or angle. Such ion beams useful in studies of surface properties of materials, surface etching, deposition, and development of plasma-diagnostic instrumentation. Tandemmirror ion source uses electrostatic and magnetic fields to keep electrons in ionization chamber and assure uniform output ion beam having low divergence in energy and angle.

Methods and apparatus for altering material using ion beams

DOEpatents

Bloomquist, Douglas D.; Buchheit, Rudy; Greenly, John B.; McIntyre, Dale C.; Neau, Eugene L.; Stinnett, Regan W.

1996-01-01

A method and apparatus for treating material surfaces using a repetitively pulsed ion beam. In particular, a method of treating magnetic material surfaces in order to reduce surface defects, and produce amorphous fine grained magnetic material with properties that can be tailored by adjusting treatment parameters of a pulsed ion beam. In addition to a method of surface treating materials for wear and corrosion resistance using pulsed particle ion beams.

Meniscus and beam halo formation in a tandem-type negative ion source with surface production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyamoto, K.; Okuda, S.; Hatayama, A.

2012-06-04

A meniscus of plasma-beam boundary in H{sup -} ion sources largely affects the extracted H{sup -} ion beam optics. Although it is hypothesized that the shape of the meniscus is one of the main reasons for the beam halo observed in experiments, a physical mechanism of the beam halo formation is not yet fully understood. In this letter, it is first shown by the 2D particle in cell simulation that the H{sup -} ions extracted from the periphery of the meniscus cause a beam halo since the surface produced H{sup -} ions penetrate into the bulk plasma, and, thus, themore » resultant meniscus has a relatively large curvature.« less

Effect of ion beam irradiation on the structure of ZnO films deposited by a dc arc plasmatron.

PubMed

Penkov, Oleksiy V; Lee, Heon-Ju; Plaksin, Vadim Yu; Ko, Min Gook; Joa, Sang Beom; Yim, Chan Joo

2008-02-01

The deposition of polycrystalline ZnO film on a cold substrate was performed by using a plasmatron in rough vacuum condition. Low energy oxygen ion beam generated by a cold cathode ion source was introduced during the deposition process. The change of film property on the ion beam energy was checked. It is shown that irradiation by 200 eV ions improves crystalline structure of the film. Increasing of ion beam energy up to 400 eV leads to the degradation of a crystalline structure and decreases the deposition rate.

Electron beam ion source and electron beam ion trap (invited).

PubMed

Becker, Reinard; Kester, Oliver

2010-02-01

The electron beam ion source (EBIS) and its trap variant [electron beam ion trap (EBIT)] celebrated their 40th and 20th anniversary, respectively, at the EBIS/T Symposium 2007 in Heidelberg. These technologically challenging sources of highly charged ions have seen a broad development in many countries over the last decades. In contrast to most other ion sources the recipe of improvement was not "sorcery" but a clear understanding of the physical laws and obeying the technological constraints. This review will report important achievements of the past as well as promising developments in the future.

Highly charged ion beams and their applications

NASA Astrophysics Data System (ADS)

Marler, Joan

2018-01-01

While much previous work with highly charged ions has been performed with the ions in the plasma state in which they were formed, beams of highly charged ions hold promise for exciting new experiments. Specifically low energy beams with a high degree of charge state purity are a prerequisite for momentum resolved cross section measurements and for efficient loading of highly charged ions into UHV traps for spectroscopy. The Clemson University facility is optimized for the delivery of such beams of highly charged ions with low kinetic energies. Near term experiments include energy resolved charge exchange with neutral targets.

Production of intense negative hydrogen beams with polarized nuclei by selective neutralization of cold negative ions

DOEpatents

Hershcovitch, A.

1984-02-13

A process for selectively neutralizing H/sup -/ ions in a magnetic field to produce an intense negative hydrogen ion beam with spin polarized protons. Characteristic features of the process include providing a multi-ampere beam of H/sup -/ ions that are

Inductively generated streaming plasma ion source

DOEpatents

Glidden, Steven C.; Sanders, Howard D.; Greenly, John B.

2006-07-25

A novel pulsed, neutralized ion beam source is provided. The source uses pulsed inductive breakdown of neutral gas, and magnetic acceleration and control of the resulting plasma, to form a beam. The beam supplies ions for applications requiring excellent control of ion species, low remittance, high current density, and spatial uniformity.

Development of a high current 60 keV neutral lithium beam injector for beam emission spectroscopy measurements on fusion experiments.

PubMed

Anda, G; Dunai, D; Lampert, M; Krizsanóczi, T; Németh, J; Bató, S; Nam, Y U; Hu, G H; Zoletnik, S

2018-01-01

A 60 keV neutral lithium beam system was designed and built up for beam emission spectroscopy measurement of edge plasma on the KSTAR and EAST tokamaks. The electron density profile and its fluctuation can be measured using the accelerated lithium beam-based emission spectroscopy system. A thermionic ion source was developed with a SiC heater to emit around 4-5 mA ion current from a 14 mm diameter surface. The ion optic is following the 2 step design used on other devices with small modifications to reach about 2-3 cm beam diameter in the plasma at about 4 m from the ion source. A newly developed recirculating sodium vapour neutralizer neutralizes the accelerated ion beam at around 260-280 °C even during long (<20 s) discharges. A set of new beam diagnostic and manipulation techniques are applied to allow optimization, aiming, cleaning, and beam modulation. The maximum 60 keV beam energy with 4 mA ion current was successfully reached at KSTAR and at EAST. Combined with an efficient observation system, the Li-beam diagnostic enables the measurement of the density profile and fluctuations on the plasma turbulence time scale.

Development of a high current 60 keV neutral lithium beam injector for beam emission spectroscopy measurements on fusion experiments

NASA Astrophysics Data System (ADS)

Anda, G.; Dunai, D.; Lampert, M.; Krizsanóczi, T.; Németh, J.; Bató, S.; Nam, Y. U.; Hu, G. H.; Zoletnik, S.

2018-01-01

A 60 keV neutral lithium beam system was designed and built up for beam emission spectroscopy measurement of edge plasma on the KSTAR and EAST tokamaks. The electron density profile and its fluctuation can be measured using the accelerated lithium beam-based emission spectroscopy system. A thermionic ion source was developed with a SiC heater to emit around 4-5 mA ion current from a 14 mm diameter surface. The ion optic is following the 2 step design used on other devices with small modifications to reach about 2-3 cm beam diameter in the plasma at about 4 m from the ion source. A newly developed recirculating sodium vapour neutralizer neutralizes the accelerated ion beam at around 260-280 °C even during long (<20 s) discharges. A set of new beam diagnostic and manipulation techniques are applied to allow optimization, aiming, cleaning, and beam modulation. The maximum 60 keV beam energy with 4 mA ion current was successfully reached at KSTAR and at EAST. Combined with an efficient observation system, the Li-beam diagnostic enables the measurement of the density profile and fluctuations on the plasma turbulence time scale.

Performance of the K+ ion diode in the 2 MV injector for heavy ion fusion

NASA Astrophysics Data System (ADS)

Bieniosek, F. M.; Henestroza, E.; Kwan, J. W.

2002-02-01

Heavy ion beam inertial fusion driver concepts depend on the availability and performance of high-brightness high-current ion sources. Surface ionization sources have relatively low current density but high brightness because of the low temperature of the emitted ions. We have measured the beam profiles at the exit of the injector diode, and compared the measured profiles with EGUN and WARP-3D predictions. Spherical aberrations are significant in this large aspect ratio diode. We discuss the measured and calculated beam size and beam profiles, the effect of aberrations, quality of vacuum, and secondary electron distributions on the beam profile.

Ion beam enhancement in magnetically insulated ion diodes for high-intensity pulsed ion beam generation in non-relativistic mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, X. P.; Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024; Zhang, Z. C.

High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, takingmore » into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200–300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.« less

Performance Evaluation of Titanium Ion Optics for the NASA 30 cm Ion Thruster

NASA Technical Reports Server (NTRS)

Soulas, George C.

2001-01-01

The results of performance tests with titanium ion optics were presented and compared to those of molybdenum ion optics. Both titanium and molybdenum ion optics were initially operated until ion optics performance parameters achieved steady state values. Afterwards, performance characterizations were conducted. This permitted proper performance comparisons of titanium and molybdenum ion optics. Ion optics' performance A,as characterized over a broad thruster input power range of 0.5 to 3.0 kW. All performance parameters for titanium ion optics of achieved steady state values after processing 1200 gm of propellant. Molybdenum ion optics exhibited no burn-in. Impingement-limited total voltages for titanium ion optics where up to 55 V greater than those for molybdenum ion optics. Comparisons of electron backstreaming limits as a function of peak beam current density for molybdenum and titanium ion optics demonstrated that titanium ion optics operated with a higher electron backstreaming limit than molybdenum ion optics for a given peak beam current density. Screen grid ion transparencies for titanium ion optics were as much as 3.8 percent lower than those for molybdenum ion optics. Beam divergence half-angles that enclosed 95 percent of the total beam current for titanium ion optics were within 1 to 3 deg. of those for molybdenum ion optics. All beam divergence thrust correction factors for titanium ion optics were within 1 percent of those with molybdenum ion optics.

Upgrade of the beam extraction system of the GTS-LHC electron cyclotron resonance ion source at CERN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toivanen, V., E-mail: ville.aleksi.toivanen@cern.ch; Bellodi, G.; Dimov, V.

2016-02-15

Linac3 is the first accelerator in the heavy ion injector chain of the Large Hadron Collider (LHC), providing multiply charged heavy ion beams for the CERN experimental program. The ion beams are produced with GTS-LHC, a 14.5 GHz electron cyclotron resonance ion source, operated in afterglow mode. Improvement of the GTS-LHC beam formation and beam transport along Linac3 is part of the upgrade program of the injector chain in preparation for the future high luminosity LHC. A mismatch between the ion beam properties in the ion source extraction region and the acceptance of the following Low Energy Beam Transport (LEBT)more » section has been identified as one of the factors limiting the Linac3 performance. The installation of a new focusing element, an einzel lens, into the GTS-LHC extraction region is foreseen as a part of the Linac3 upgrade, as well as a redesign of the first section of the LEBT. Details of the upgrade and results of a beam dynamics study of the extraction region and LEBT modifications will be presented.« less

Ion beam machining error control and correction for small scale optics.

PubMed

Xie, Xuhui; Zhou, Lin; Dai, Yifan; Li, Shengyi

2011-09-20

Ion beam figuring (IBF) technology for small scale optical components is discussed. Since the small removal function can be obtained in IBF, it makes computer-controlled optical surfacing technology possible to machine precision centimeter- or millimeter-scale optical components deterministically. Using a small ion beam to machine small optical components, there are some key problems, such as small ion beam positioning on the optical surface, material removal rate, ion beam scanning pitch control on the optical surface, and so on, that must be seriously considered. The main reasons for the problems are that it is more sensitive to the above problems than a big ion beam because of its small beam diameter and lower material ratio. In this paper, we discuss these problems and their influences in machining small optical components in detail. Based on the identification-compensation principle, an iterative machining compensation method is deduced for correcting the positioning error of an ion beam with the material removal rate estimated by a selected optimal scanning pitch. Experiments on ϕ10 mm Zerodur planar and spherical samples are made, and the final surface errors are both smaller than λ/100 measured by a Zygo GPI interferometer.

Development of a negative ion-based neutral beam injector in Novosibirsk.

PubMed

Ivanov, A A; Abdrashitov, G F; Anashin, V V; Belchenko, Yu I; Burdakov, A V; Davydenko, V I; Deichuli, P P; Dimov, G I; Dranichnikov, A N; Kapitonov, V A; Kolmogorov, V V; Kondakov, A A; Sanin, A L; Shikhovtsev, I V; Stupishin, N V; Sorokin, A V; Popov, S S; Tiunov, M A; Belov, V P; Gorbovsky, A I; Kobets, V V; Binderbauer, M; Putvinski, S; Smirnov, A; Sevier, L

2014-02-01

A 1000 keV, 5 MW, 1000 s neutral beam injector based on negative ions is being developed in the Budker Institute of Nuclear Physics, Novosibirsk in collaboration with Tri Alpha Energy, Inc. The innovative design of the injector features the spatially separated ion source and an electrostatic accelerator. Plasma or photon neutralizer and energy recuperation of the remaining ion species is employed in the injector to provide an overall energy efficiency of the system as high as 80%. A test stand for the beam acceleration is now under construction. A prototype of the negative ion beam source has been fabricated and installed at the test stand. The prototype ion source is designed to produce 120 keV, 1.5 A beam.

Ion beam collimating grid to reduce added defects

DOEpatents

Lindquist, Walter B.; Kearney, Patrick A.

2003-01-01

A collimating grid for an ion source located after the exit grid. The collimating grid collimates the ion beamlets and disallows beam spread and limits the beam divergence during transients and steady state operation. The additional exit or collimating grid prevents beam divergence during turn-on and turn-off and prevents ions from hitting the periphery of the target where there is re-deposited material or from missing the target and hitting the wall of the vessel where there is deposited material, thereby preventing defects from being deposited on a substrate to be coated. Thus, the addition of a collimating grid to an ion source ensures that the ion beam will hit and be confined to a specific target area.

Ion beam sputtering of fluoropolymers

NASA Technical Reports Server (NTRS)

Sovey, J. S.

1978-01-01

Etching and deposition of fluoropolymers are of considerable industrial interest for applications dealing with adhesion, chemical inertness, hydrophobicity, and dielectric properties. This paper describes ion beam sputter processing rates as well as pertinent characteristics of etched targets and films. An argon ion beam source was used to sputter etch and deposit the fluoropolymers PTFE, FEP, and CTFE. Ion beam energy, current density, and target temperature were varied to examine effects on etch and deposition rates. The ion etched fluoropolymers yield cone or spire-like surface structures which vary depending upon the type of polymer, ion beam power density, etch time, and target temperature. Also presented are sputter target and film characteristics which were documented by spectral transmittance measurements, X-ray diffraction, ESCA, and SEM photomicrographs.

Characterization and Performance of a High-Current-Density Ion Implanter with Magnetized Hollow-Cathode Plasma Source

NASA Astrophysics Data System (ADS)

Falkenstein, Zoran; Rej, Donald; Gavrilov, Nikolai

1998-10-01

In a collaboration between the Institute of Electrophysics (IEP) and the Los Alamos National Laboratory (LANL), the IEP has developed an industrial scalable, high-power, large-area ion source for the surface modification of materials. The plasma source of the ion beam source can be described as a pulsed glow discharge with a cold, hollow-cathode in a weak magnetic field. Extraction and focusing of positive ions by an acceleration and ion-optical plate system renders the generation of a homogeneous, large-area ion beam with an averaged total ion current of up to 50 mA at acceleration voltages of up to 50 kV. The principle set-up of the ion beam source as well as some electrical characteristics (gas discharge current and the extracted ion beam current) are presented for a lab-scale prototype. Measurements of the radial ion current density profiles within the ion beam for various discharge parameters, as well as results on surface modification by ion implantation of nitrogen into aluminum and chromium are presented. Finally, a comparison of the applied ion dose with the retained ion doses is given.

Enabling High Fidelity Measurements of Energy and Pitch Angle for Escaping Energetic Ions with a Fast Ion Loss Detector

NASA Astrophysics Data System (ADS)

Chaban, R.; Pace, D. C.; Marcy, G. R.; Taussig, D.

2016-10-01

Energetic ion losses must be minimized in burning plasmas to maintain fusion power, and existing tokamaks provide access to energetic ion parameter regimes that are relevant to burning machines. A new Fast Ion Loss Detector (FILD) probe on the DIII-D tokamak has been optimized to resolve beam ion losses across a range of 30 - 90 keV in energy and 40° to 80° in pitch angle, thereby providing valuable measurements during many different experiments. The FILD is a magnetic spectrometer; once inserted into the tokamak, the magnetic field allows energetic ions to pass through a collimating aperture and strike a scintillator plate that is imaged by a wide view camera and narrow view photomultiplier tubes (PMTs). The design involves calculating scintillator strike patterns while varying probe geometry. Calculated scintillator patterns are then used to design an optical system that allows adjustment of the focus regions for the 1 MS/s resolved PMTs. A synthetic diagnostic will be used to determine the energy and pitch angle resolution that can be attained in DIII-D experiments. Work supported in part by US DOE under the Science Undergraduate Laboratory Internship (SULI) program and under DE-FC02-04ER54698.

Uniform deposition of size-selected clusters using Lissajous scanning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beniya, Atsushi; Watanabe, Yoshihide, E-mail: e0827@mosk.tytlabs.co.jp; Hirata, Hirohito

2016-05-15

Size-selected clusters can be deposited on the surface using size-selected cluster ion beams. However, because of the cross-sectional intensity distribution of the ion beam, it is difficult to define the coverage of the deposited clusters. The aggregation probability of the cluster depends on coverage, whereas cluster size on the surface depends on the position, despite the size-selected clusters are deposited. It is crucial, therefore, to deposit clusters uniformly on the surface. In this study, size-selected clusters were deposited uniformly on surfaces by scanning the cluster ions in the form of Lissajous pattern. Two sets of deflector electrodes set in orthogonalmore » directions were placed in front of the sample surface. Triangular waves were applied to the electrodes with an irrational frequency ratio to ensure that the ion trajectory filled the sample surface. The advantages of this method are simplicity and low cost of setup compared with raster scanning method. The authors further investigated CO adsorption on size-selected Pt{sub n} (n = 7, 15, 20) clusters uniformly deposited on the Al{sub 2}O{sub 3}/NiAl(110) surface and demonstrated the importance of uniform deposition.« less

Focused ion beam source method and apparatus

DOEpatents

Pellin, Michael J.; Lykke, Keith R.; Lill, Thorsten B.

2000-01-01

A focused ion beam having a cross section of submicron diameter, a high ion current, and a narrow energy range is generated from a target comprised of particle source material by laser ablation. The method involves directing a laser beam having a cross section of critical diameter onto the target, producing a cloud of laser ablated particles having unique characteristics, and extracting and focusing a charged particle beam from the laser ablated cloud. The method is especially suited for producing focused ion beams for semiconductor device analysis and modification.

Electrical shielding box measurement of the negative hydrogen beam from Penning ion gauge ion source.

PubMed

Wang, T; Yang, Z; Dong, P; long, J D; He, X Z; Wang, X; Zhang, K Z; Zhang, L W

2012-06-01

The cold-cathode Penning ion gauge (PIG) type ion source has been used for generation of negative hydrogen (H(-)) ions as the internal ion source of a compact cyclotron. A novel method called electrical shielding box dc beam measurement is described in this paper, and the beam intensity was measured under dc extraction inside an electrical shielding box. The results of the trajectory simulation and dc H(-) beam extraction measurement were presented. The effect of gas flow rate, magnetic field strength, arc current, and extraction voltage were also discussed. In conclusion, the dc H(-) beam current of about 4 mA from the PIG ion source with the puller voltage of 40 kV and arc current of 1.31 A was extrapolated from the measurement at low extraction dc voltages.

Modern applications of high energy ion beams: From "single-event burnout" to human eye cancer treatment

NASA Astrophysics Data System (ADS)

Homeyer, H.; Mahnke, H.-E.

1996-12-01

Energetic ion beams, originally the domain of nuclear physics, become increasingly important tools in many other fields of research and development. The choice of ion species and ion energy allows an enormously wide variation of the penetration depth and of the amount of the electronic stopping power. These features are utilized to modify or damage materials and living tissues in a specific way. Materials modification with energetic ion beams is one of the central aims of research and development at the ion beam laboratory, ISL-Berlin, a center for ion-beam applications at the Hahn-Meitner-Institut Berlin. In particular, energetic protons will be used for eye cancer treatment. Selected topics such as the "single-event burnout" of high power diodes and the eye cancer therapy setup will be presented in detail.

Planned Experiments on the Princeton Advanced Test Stand

NASA Astrophysics Data System (ADS)

Stepanov, A.; Gilson, E. P.; Grisham, L.; Kaganovich, I.; Davidson, R. C.

2010-11-01

The Princeton Advanced Test Stand (PATS) device is an experimental facility based on the STS-100 high voltage test stand transferred from LBNL. It consists of a multicusp RF ion source, a pulsed extraction system capable of forming high-perveance 100keV ion beams, and a large six-foot-long vacuum with convenient access for beam diagnostics. This results in a flexible system for studying high perveance ion beams relevant to NDCX-I/II, including experiments on beam neutralization by ferroelectric plasma sources (FEPS) being developed at PPPL. Research on PATS will concern the basic physics of beam-plasma interactions, such as the effects of volume neutralization on beam emittance, as well as optimizing technology of the FEPS. PATS combines the advantage of an ion beam source and a large-volume plasma source in a chamber with ample access for diagnostics, resulting in a robust setup for investigating and improving relevant aspects of neutralized drift. There are also plans for running the ion source with strongly electro-negative gases such as chlorine, making it possible to extract positive or negative ion beams.

Modeling the biophysical effects in a carbon beam delivery line by using Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Cho, Ilsung; Yoo, SeungHoon; Cho, Sungho; Kim, Eun Ho; Song, Yongkeun; Shin, Jae-ik; Jung, Won-Gyun

2016-09-01

The Relative biological effectiveness (RBE) plays an important role in designing a uniform dose response for ion-beam therapy. In this study, the biological effectiveness of a carbon-ion beam delivery system was investigated using Monte Carlo simulations. A carbon-ion beam delivery line was designed for the Korea Heavy Ion Medical Accelerator (KHIMA) project. The GEANT4 simulation tool kit was used to simulate carbon-ion beam transport into media. An incident energy carbon-ion beam with energy in the range between 220 MeV/u and 290 MeV/u was chosen to generate secondary particles. The microdosimetric-kinetic (MK) model was applied to describe the RBE of 10% survival in human salivary-gland (HSG) cells. The RBE weighted dose was estimated as a function of the penetration depth in the water phantom along the incident beam's direction. A biologically photon-equivalent Spread Out Bragg Peak (SOBP) was designed using the RBE-weighted absorbed dose. Finally, the RBE of mixed beams was predicted as a function of the depth in the water phantom.

Molecular Dynamics Simulation of the Three-Dimensional Ordered State in Laser-Cooled Heavy-Ion Beams

NASA Astrophysics Data System (ADS)

Yuri, Yosuke

A molecular dynamics simulation is performed to study the formation of three-dimensional ordered beams by laser cooling in a cooler storage ring. Ultralow-temperature heavy-ion beams are generated by transverse cooling with displaced Gaussian lasers and resonant coupling. A three-dimensional ordered state of the ion beam is attained at a high line density. The ordered beam exhibits several unique characteristics different from those of an ideal crystalline beam.

Neutral beam monitoring

DOEpatents

Fink, Joel H.

1981-08-18

Method and apparatus for monitoring characteristics of a high energy neutral beam. A neutral beam is generated by passing accelerated ions through a walled cell containing a low energy neutral gas, such that charge exchange neutralizes the high energy ion beam. The neutral beam is monitored by detecting the current flowing through the cell wall produced by low energy ions which drift to the wall after the charge exchange. By segmenting the wall into radial and longitudinal segments various beam conditions are further identified.

Towards ion beam therapy based on laser plasma accelerators.

PubMed

Karsch, Leonhard; Beyreuther, Elke; Enghardt, Wolfgang; Gotz, Malte; Masood, Umar; Schramm, Ulrich; Zeil, Karl; Pawelke, Jörg

2017-11-01

Only few ten radiotherapy facilities worldwide provide ion beams, in spite of their physical advantage of better achievable tumor conformity of the dose compared to conventional photon beams. Since, mainly the large size and high costs hinder their wider spread, great efforts are ongoing to develop more compact ion therapy facilities. One promising approach for smaller facilities is the acceleration of ions on micrometre scale by high intensity lasers. Laser accelerators deliver pulsed beams with a low pulse repetition rate, but a high number of ions per pulse, broad energy spectra and high divergences. A clinical use of a laser based ion beam facility requires not only a laser accelerator providing beams of therapeutic quality, but also new approaches for beam transport, dosimetric control and tumor conformal dose delivery procedure together with the knowledge of the radiobiological effectiveness of laser-driven beams. Over the last decade research was mainly focused on protons and progress was achieved in all important challenges. Although currently the maximum proton energy is not yet high enough for patient irradiation, suggestions and solutions have been reported for compact beam transport and dose delivery procedures, respectively, as well as for precise dosimetric control. Radiobiological in vitro and in vivo studies show no indications of an altered biological effectiveness of laser-driven beams. Laser based facilities will hardly improve the availability of ion beams for patient treatment in the next decade. Nevertheless, there are possibilities for a need of laser based therapy facilities in future.

Advances in Heavy Ion Beam Probe Technology and Operation on MST

NASA Astrophysics Data System (ADS)

Demers, D. R.; Connor, K. A.; Schoch, P. M.; Radke, R. J.; Anderson, J. K.; Craig, D.; den Hartog, D. J.

2003-10-01

A technique to map the magnetic field of a plasma via spectral imaging is being developed with the Heavy Ion Beam Probe on the Madison Symmetric Torus. The technique will utilize two-dimensional images of the ion beam in the plasma, acquired by two CCD cameras, to generate a three-dimensional reconstruction of the beam trajectory. This trajectory, and the known beam ion mass, energy and charge-state, will be used to determine the magnetic field of the plasma. A suitable emission line has not yet been observed since radiation from the MST plasma is both broadband and intense. An effort to raise the emission intensity from the ion beam by increasing beam focus and current has been undertaken. Simulations of the accelerator ion optics and beam characteristics led to a technique, confirmed by experiment, that achieves a narrower beam and marked increase in ion current near the plasma surface. The improvements arising from these simulations will be discussed. Realization of the magnetic field mapping technique is contingent upon accurate reconstruction of the beam trajectory from the camera images. Simulations of two camera CCD images, including the interior of MST, its various landmarks and beam trajectories have been developed. These simulations accept user input such as camera locations, resolution via pixellization and noise. The quality of the images simulated with these and other variables will help guide the selection of viewing port pairs, image size and camera specifications. The results of these simulations will be presented.

Monte Carlo simulations of secondary electron emission due to ion beam milling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahady, Kyle; Tan, Shida; Greenzweig, Yuval

We present a Monte Carlo simulation study of secondary electron emission resulting from focused ion beam milling of a copper target. The basis of this study is a simulation code which simulates ion induced excitation and emission of secondary electrons, in addition to simulating focused ion beam sputtering and milling. This combination of features permits the simulation of the interaction between secondary electron emission, and the evolving target geometry as the ion beam sputters material. Previous ion induced SE Monte Carlo simulation methods have been restricted to predefined target geometries, while the dynamic target in the presented simulations makes thismore » study relevant to image formation in ion microscopy, and chemically assisted ion beam etching, where the relationship between sputtering, and its effects on secondary electron emission, is important. We focus on a copper target, and validate our simulation against experimental data for a range of: noble gas ions, ion energies, ion/substrate angles and the energy distribution of the secondary electrons. We then provide a detailed account of the emission of secondary electrons resulting from ion beam milling; we quantify both the evolution of the yield as high aspect ratio valleys are milled, as well as the emission of electrons within these valleys that do not escape the target, but which are important to the secondary electron contribution to chemically assisted ion induced etching.« less

Development of a pepper pot emittance probe and its application for ECR ion beam studies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kondrashev, S.; Barcikowski, A.; Mustapha, B.

2009-07-21

A pepper pot-scintillator screen system has been developed and used to measure the emittance of DC ion beams extracted from a high-intensity permanent magnet ECR ion source. The system includes a fast beam shutter with a minimum dwell time of 18 ms to reduce the degradation of the CsI(Tl) scintillator by DC ion beam irradiation and a CCD camera with a variable shutter speed in the range of 1 {micro}s-65 s. On-line emittance measurements are performed by an application code developed on a LabVIEW platform. The sensitivity of the device is sufficient to measure the emittance of DC ion beamsmore » with current densities down to about 100 nA/cm{sup 2}. The emittance of all ion species extracted from the ECR ion source and post-accelerated to an energy of 75-90 keV/charge have been measured downstream of the LEBT. As the mass-to-charge ratio of ion species increases, the normalized RMS emittances in both transverse phase planes decrease from 0.5-1.0 {pi} mm mrad for light ions to 0.05-0.09 {pi} mm mrad for highly charged {sup 209}Bi ions. The dependence of the emittance on ion's mass-to-charge ratio follows very well the dependence expected from beam rotation induced by decreasing ECR axial magnetic field. The measured emittance values cannot be explained by only ion beam rotation for all ion species and the contribution to emittance of ion temperature in plasma, non-linear electric fields and non-linear space charge is comparable or even higher than the contribution of ion beam rotation.« less

An all permanent magnet electron cyclotron resonance ion source for heavy ion therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Yun, E-mail: caoyun@impcas.ac.cn; Li, Jia Qing; Sun, Liang Ting

2014-02-15

A high charge state all permanent Electron Cyclotron Resonance ion source, Lanzhou All Permanent ECR ion source no. 3-LAPECR3, has been successfully built at IMP in 2012, which will serve as the ion injector of the Heavy Ion Medical Machine (HIMM) project. As a commercial device, LAPECR3 features a compact structure, small size, and low cost. According to HIMM scenario more than 100 eμA of C{sup 5+} ion beam should be extracted from the ion source, and the beam emittance better than 75 π*mm*mrad. In recent commissioning, about 120 eμA of C{sup 5+} ion beam was got when work gasmore » was CH{sub 4} while about 262 eμA of C{sup 5+} ion beam was obtained when work gas was C{sub 2}H{sub 2} gas. The design and construction of the ion source and its low-energy transportation beam line, and the preliminary commissioning results will be presented in detail in this paper.« less

Charged particle measurements on a 30-CM diameter mercury ion engine thrust beam

NASA Technical Reports Server (NTRS)

Sellen, J. M., Jr.; Komatsu, G. K.; Hoffmaster, D. K.; Kemp, R. F.

1974-01-01

Measurements of both thrust ions and charge exchange ions were made in the beam of a 30 centimeter diameter electron bombardment mercury ion thruster. A qualitative model is presented which describes magnitudes of charge exchange ion formation and motions of these ions in the weak electric field structure of the neutralized thrust beam plasma. Areas of agreement and discrepancy between observed and modeled charge exchange properties are discussed.

An ion source module for the Beijing Radioactive Ion-beam Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cui, B., E-mail: cui@ciae.ac.cn; Huang, Q.; Tang, B.

2014-02-15

An ion source module is developed for Beijing Radioactive Ion-beam Facility. The ion source module is designed to meet the requirements of remote handling. The connection and disconnection of the electricity, cooling and vacuum between the module and peripheral units can be executed without on-site manual work. The primary test of the target ion source has been carried out and a Li{sup +} beam has been extracted. Details of the ion source module and its primary test results are described.

Ion beams extraction and measurements of plasma parameters on a multi-frequencies microwaves large bore ECRIS with permanent magnets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nozaki, Dai; Kiriyama, Ryutaro; Takenaka, Tomoya

2012-11-06

We have developed an all-permanent magnet large bore electron cyclotron resonance ion source (ECRIS) for broad ion beam processing. The cylindrically comb-shaped magnetic field configuration is adopted for efficient plasma production and good magnetic confinement. To compensate for disadvantages of fixed magnetic configuration, a traveling wave tube amplifier (TWTA) is used. In the comb-shaped ECRIS, it is difficult to achieve controlling ion beam profiles in the whole inside the chamber by using even single frequency-controllable TWTA (11-13GHz), because of large bore size with all-magnets. We have tried controlling profiles of plasma parameters and then those of extracted ion beams bymore » launching two largely different frequencies simultaneously, i.e., multi-frequencies microwaves. Here we report ion beam profiles and corresponding plasma parameters under various experimental conditions, dependence of ion beams against extraction voltages, and influence of different electrode positions on the electron density profile.« less

Computers and the design of ion beam optical systems

NASA Astrophysics Data System (ADS)

White, Nicholas R.

Advances in microcomputers have made it possible to maintain a library of advanced ion optical programs which can be used on inexpensive computer hardware, which are suitable for the design of a variety of ion beam systems including ion implanters, giving excellent results. This paper describes in outline the steps typically involved in designing a complete ion beam system for materials modification applications. Two computer programs are described which, although based largely on algorithms which have been in use for many years, make possible detailed beam optical calculations using microcomputers, specifically the IBM PC. OPTICIAN is an interactive first-order program for tracing beam envelopes through complex optical systems. SORCERY is a versatile program for solving Laplace's and Poisson's equations by finite difference methods using successive over-relaxation. Ion and electron trajectories can be traced through these potential fields, and plots of beam emittance obtained.

Correlation of ion and beam current densities in Kaufman thrusters.

NASA Technical Reports Server (NTRS)

Wilbur, P. J.

1973-01-01

In the absence of direct impingement erosion, electrostatic thruster accelerator grid lifetime is defined by the charge exchange erosion that occurs at peak values of the ion beam current density. In order to maximize the thrust from an engine with a specified grid lifetime, the ion beam current density profile should therefore be as flat as possible. Knauer (1970) has suggested this can be achieved by establishing a radial plasma uniformity within the thruster discharge chamber; his tests with the radial field thruster provide an example of uniform plasma properties within the chamber and a flat ion beam profile occurring together. It is shown that, in particular, the ion density profile within the chamber determines the beam current density profile, and that a uniform ion density profile at the screen grid end of the discharge chamber should lead to a flat beam current density profile.

Negative ion beam injection apparatus with magnetic shield and electron removal means

DOEpatents

Anderson, Oscar A.; Chan, Chun F.; Leung, Ka-Ngo

1994-01-01

A negative ion source is constructed to produce H.sup.- ions without using Cesium. A high percentage of secondary electrons that typically accompany the extracted H.sup.- are trapped and eliminated from the beam by permanent magnets in the initial stage of acceleration. Penetration of the magnetic field from the permanent magnets into the ion source is minimized. This reduces the destructive effect the magnetic field could have on negative ion production and extraction from the source. A beam expansion section in the extractor results in a strongly converged final beam.

Patterning of Spiral Structure on Optical Fiber by Focused-Ion-Beam Etching

NASA Astrophysics Data System (ADS)

Mekaru, Harutaka; Yano, Takayuki

2012-06-01

We produce patterns on minute and curved surfaces of optical fibers, and develop a processing technology for fabricating sensors, antennas, electrical circuits, and other devices on such patterned surfaces by metallization. A three-dimensional processing technology can be used to fabricate a spiral coil on the surface of cylindrical quartz materials, and then the microcoils can also be applied to capillaries of micro-fluid devices, as well as to receiver coils connected to a catheter and an endoscope of nuclear magnetic resonance imaging (MRI) systems used in imaging blood vessels. To create a spiral line pattern with a small linewidth on a full-circumference surface of an optical fiber, focused-ion-beam (FIB) etching was employed. Here, a simple rotation stage comprising a dc motor and an LR3 battery was built. However, during the development of a prototype rotation stage before finalizing a large-scale remodelling of our FIB etching system, a technical problem was encountered where a spiral line could not be processed without running into breaks and notches in the features. It turned out that the problem was caused by axis blur resulting from an eccentric spinning (or wobbling) of the axis of the fiber caused by its unrestrained free end. The problem was solved by installing a rotation guide and an axis suppression device onto the rotation stage. Using this improved rotation stage. we succeeded in the seamless patterning of 1-µm-wide features on the full-circumference surface of a 250-µm-diameter quartz optical fiber (QOF) by FIB etching.

Suppression of energetic particle driven instabilities with HHFW heating

DOE PAGES

Fredrickson, E. D.; Taylor, G.; Bertelli, N.; ...

2015-01-01

In plasmas in the National Spherical Torus Experiment (NSTX) [Ono et al., Nucl. Fusion 40 (2000) 557] heated with neutral beams, the beam ions typically excite Energetic Particle Modes (EPMs or fishbones), and Toroidal, Global or Compressional Alfvén Eigenmodes (TAE, GAE, CAE). These modes can redistribute the energetic beam ions, altering the beam driven current profile and the plasma heating profile, or they may affect electron thermal transport or cause losses of the beam ions. In this paper we present experimental results where these instabilities, driven by the super-thermal beam ions, are suppressed with the application of High Harmonic Fastmore » Wave heating.« less

Ion beam modification of the structure and properties of hexagonal boron nitride: An infrared and X-ray diffraction study

NASA Astrophysics Data System (ADS)

Aradi, E.; Naidoo, S. R.; Billing, D. G.; Wamwangi, D.; Motochi, I.; Derry, T. E.

2014-07-01

The vibrational mode for the cubic symmetry of boron nitride (BN) has been produced by boron ion implantation of hexagonal boron nitride (h-BN). The optimum fluence at 150 keV was found to be 5 × 1014 ions/cm2. The presence of the c-BN phase was inferred using glancing incidence XRD (GIXRD) and Fourier Transform Infrared Spectroscopy (FTIR). After implantation, Fourier Transform Infrared Spectroscopy indicated a peak at 1092 cm-1 which corresponds to the vibrational mode for nanocrystalline BN (nc-BN). The glancing angle XRD pattern after implantation exhibited c-BN diffraction peaks relative to the implantation depth of 0.4 μm.

Numerical study of neutron beam divergence in a beam-fusion scenario employing laser driven ions

NASA Astrophysics Data System (ADS)

Alejo, A.; Green, A.; Ahmed, H.; Robinson, A. P. L.; Cerchez, M.; Clarke, R.; Doria, D.; Dorkings, S.; Fernandez, J.; McKenna, P.; Mirfayzi, S. R.; Naughton, K.; Neely, D.; Norreys, P.; Peth, C.; Powell, H.; Ruiz, J. A.; Swain, J.; Willi, O.; Borghesi, M.; Kar, S.

2016-09-01

The most established route to create a laser-based neutron source is by employing laser accelerated, low atomic-number ions in fusion reactions. In addition to the high reaction cross-sections at moderate energies of the projectile ions, the anisotropy in neutron emission is another important feature of beam-fusion reactions. Using a simple numerical model based on neutron generation in a pitcher-catcher scenario, anisotropy in neutron emission was studied for the deuterium-deuterium fusion reaction. Simulation results are consistent with the narrow-divergence (∼ 70 ° full width at half maximum) neutron beam recently served in an experiment employing multi-MeV deuteron beams of narrow divergence (up to 30° FWHM, depending on the ion energy) accelerated by a sub-petawatt laser pulse from thin deuterated plastic foils via the Target Normal Sheath Acceleration mechanism. By varying the input ion beam parameters, simulations show that a further improvement in the neutron beam directionality (i.e. reduction in the beam divergence) can be obtained by increasing the projectile ion beam temperature and cut-off energy, as expected from interactions employing higher power lasers at upcoming facilities.

Focused-ion-beam overlay-patterning of three-dimensional diamond structures for advanced single-photon properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Qianqing; Liu, Dongqi; Liu, Gangqin

2014-07-28

Sources of single photons are of fundamental importance in many applications as to provide quantum states for quantum communication and quantum information processing. Color centers in diamond are prominent candidates to generate and manipulate quantum states of light, even at room temperature. However, the efficiency of photon collection of the color centers in bulk diamond is greatly reduced by refraction at the diamond/air interface. To address this issue, diamond structuring has been investigated by various methods. Among them, focused-ion-beam (FIB) direct patterning has been recognized as the most favorable technique. But it has been noted that diamond tends to presentmore » significant challenges in FIB milling, e.g., the susceptibility of forming charging related artifacts and topographical features. In this work, periodically-positioned-rings and overlay patterning with stagger-superimposed-rings were proposed to alleviate some problems encountered in FIB milling of diamond, for improved surface morphology and shape control. Cross-scale network and uniform nanostructure arrays have been achieved in single crystalline diamond substrates. High quality diamond solid immersion lens and nanopillars were sculptured with a nitrogen-vacancy center buried at the desired position. Compared with the film counterpart, an enhancement of about ten folds in single photon collection efficiency was achieved with greatly improved signal to noise ratio. All these results indicate that FIB milling through over-lay patterning could be an effective approach to fabricate diamond structures, potentially for quantum information studies.« less

Synthesis and characterizations of nanoscale single crystal GaN grown by ion assisted gas source MBE

NASA Astrophysics Data System (ADS)

Cui, Bentao; Cohen, P. I.

2004-03-01

Nanoscale patterns could be induced by ion bombardment [1, 2]. In this study, an in-situ real time light scattering technique, combined with Reflection High Energy Electron Diffraction (RHEED), were used to study the surface morphology evolution during the ion beam assisted growth of GaN in a gas source MBE system. Ga was provided by a thermal effusion cell. Ammonia was used as the nitrogen source. A hot-filament Kaufman ion source was used to supply sub-KeV ion beams. Sapphire and MOCVD GaN templates were used as the substrates. A custom-designed Desorption Mass Spectrometer (DMS) was used to calibrate the growth temperature and determine the growth rate. Before growing GaN, the sapphire substrates were pretreated in an ion flux and then annealed for cleaning. The sapphire surface was then nitrided in ammonia at 1100K for about 10 min. After nitridation, a thin GaN buffer layer was prepared by a sequence of adsorption and annealing steps. During the growth, the short-range surface morphology and film quality were monitored in situ by RHEED. In a real-time way, the long-range surface morphology was monitored in-situ by light scattering technique. Photodiode array detector and CCD camera were used to record the reflected light scattering intensity and spectra profile respectively. Periodical patterns, such as ripple, have been observed during ion bombardment on GaN with or without growth. A linear theory (from Bradley and Harper 1988 [3]) has been modified to explain the dependence of ripple wavelength on ion species and ion energy. Partially supported by the National Science Foundation and the Air Force Office of Scientific Research. [1]. J. Erlebacher, M. J. Aziz, E. Chason, M. B. Sinclair, and J. A. Floro, Phys. Rev. Lett. 82, 2330 (1998); J. Erlebacher, M. J. Aziz, E. Chason, M. B. Sinclair, and J. A. Floro, Phys. Rev. Lett. 84, 5800 (2000). [2]. S. Facsko, T. Dekorsy, C. Koerdt, C. Trappe, H. Kurz, A. Vogt et al.. Science 285, 1551 (1999). [3]. R. M. Bradley and J. M. E. Harper, J. Vac. Sci. Technol. A 6, 2390 (1988).

Technical use of compact micro-onde devicesa)

NASA Astrophysics Data System (ADS)

Sortais, P.; Lamy, T.; Médard, J.; Angot, J.; Sudraud, P.; Salord, O.; Homri, S.

2012-02-01

Due to the very small size of a COMIC (Compact MIcrowave and Coaxial) device [P. Sortais, T. Lamy, J. Médard, J. Angot, L. Latrasse, and T. Thuillier, Rev. Sci. Instrum. 81, 02B31 (2010), 10.1063/1.3272878] it is possible to install such plasma or ion source inside very different technical environments. New applications of such a device are presented, mainly for industrial applications. We have now designed ion sources for highly focused ion beam devices, ion beam machining ion guns, or thin film deposition machines. We will mainly present new capabilities opened by the use of a multi-beam system for thin film deposition based on sputtering by medium energy ion beams. With the new concept of multi-beam sputtering (MBS), it is possible to open new possibilities concerning the ion beam sputtering (IBS) technology, especially for large size deposition of high uniformity thin films. By the use of multi-spots of evaporation, each one corresponding to an independent tuning of an individual COMIC ion source, it will be very easy to co-evaporate different components.

New ion source for KSTAR neutral beam injection system.

PubMed

Kim, Tae-Seong; Jeong, Seung Ho; In, Sang-Ryul

2012-02-01

The neutral beam injection system (NBI-1) of the KSTAR tokamak can accommodate three ion sources; however, it is currently equipped with only one prototype ion source. In the 2010 and 2011 KSTAR campaigns, this ion source supplied deuterium neutral beam power of 0.7-1.6 MW to the KSTAR plasma with a beam energy of 70-100 keV. A new ion source will be prepared for the 2012 KSTAR campaign with a much advanced performance compared with the previous one. The newly designed ion source has a very large transparency (∼56%) without deteriorating the beam optics, which is designed to deliver a 2 MW injection power of deuterium beams at 100 keV. The plasma generator of the ion source is of a horizontally cusped bucket type, and the whole inner wall, except the cathode filaments and plasma grid side, functions as an anode. The accelerator assembly consists of four multi-circular aperture grids made of copper and four electrode flanges made of aluminum alloy. The electrodes are insulated using PEEK. The ion source will be completed and tested in 2011.

Transport of a high brightness proton beam through the Munich tandem accelerator

NASA Astrophysics Data System (ADS)

Moser, M.; Greubel, C.; Carli, W.; Peeper, K.; Reichart, P.; Urban, B.; Vallentin, T.; Dollinger, G.

2015-04-01

Basic requirement for ion microprobes with sub-μm beam focus is a high brightness beam to fill the small phase space usually accepted by the ion microprobe with enough ion current for the desired application. We performed beam transport simulations to optimize beam brightness transported through the Munich tandem accelerator. This was done under the constraint of a maximum ion current of 10 μA that is allowed to be injected due to radiation safety regulations and beam power constrains. The main influence of the stripper foil in conjunction with intrinsic astigmatism in the beam transport on beam brightness is discussed. The calculations show possibilities for brightness enhancement by using astigmatism corrections and asymmetric filling of the phase space volume in the x- and y-direction.

Large scale silver nanowires network fabricated by MeV hydrogen (H+) ion beam irradiation

NASA Astrophysics Data System (ADS)

Honey, S.; Naseem, S.; Ishaq, A.; Maaza, M.; Bhatti, M. T.; Wan, D.

2016-04-01

A random two-dimensional large scale nano-network of silver nanowires (Ag-NWs) is fabricated by MeV hydrogen (H+) ion beam irradiation. Ag-NWs are irradiated under H+ ion beam at different ion fluences at room temperature. The Ag-NW network is fabricated by H+ ion beam-induced welding of Ag-NWs at intersecting positions. H+ ion beam induced welding is confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Moreover, the structure of Ag NWs remains stable under H+ ion beam, and networks are optically transparent. Morphology also remains stable under H+ ion beam irradiation. No slicings or cuttings of Ag-NWs are observed under MeV H+ ion beam irradiation. The results exhibit that the formation of Ag-NW network proceeds through three steps: ion beam induced thermal spikes lead to the local heating of Ag-NWs, the formation of simple junctions on small scale, and the formation of a large scale network. This observation is useful for using Ag-NWs based devices in upper space where protons are abandoned in an energy range from MeV to GeV. This high-quality Ag-NW network can also be used as a transparent electrode for optoelectronics devices. Project supported by the National Research Foundation of South Africa (NRF), the French Centre National pour la Recherche Scientifique, iThemba-LABS, the UNESCO-UNISA Africa Chair in Nanosciences & Nanotechnology, the Third World Academy of Science (TWAS), Organization of Women in Science for the Developing World (OWSDW), the Abdus Salam ICTP via the Nanosciences African Network (NANOAFNET), and the Higher Education Commission (HEC) of Pakistan.

Self-focusing of a high current density ion beam extracted with concave electrodes in a low energy region around 150 eV.

PubMed

Hirano, Y; Kiyama, S; Koguchi, H; Sakakita, H

2014-02-01

Spontaneous self-focusing of ion beam with high current density (Jc ∼ 2 mA/cm(2), Ib ∼ 65 mA) in low energy region (∼150 eV) is observed in a hydrogen ion beam extracted from an ordinary bucket type ion source with three electrodes having concave shape (acceleration, deceleration, and grounded electrodes). The focusing appears abruptly in the beam energy region over ∼135-150 eV, and the Jc jumps up from 0.7 to 2 mA/cm(2). Simultaneously a strong electron flow also appears in the beam region. The electron flow has almost the same current density. Probably these electrons compensate the ion space charge and suppress the beam divergence.

Radio frequency source of a weakly expanding wedge-shaped xenon ion beam for contactless removal of large-sized space debris objects.

PubMed

Balashov, Victor; Cherkasova, Maria; Kruglov, Kirill; Kudriavtsev, Arseny; Masherov, Pavel; Mogulkin, Andrey; Obukhov, Vladimir; Riaby, Valentin; Svotina, Victoria

2017-08-01

A theoretical-experimental research has been carried out to determine the characteristics of a radio frequency (RF) ion source for the generation of a weakly expanding wedge-shaped xenon ion beam. Such ion beam geometry is of interest as a prototype of an on-board ion injector for contactless "ion shepherding" by service spacecraft to remove large space debris objects from geostationary orbits. The wedge shape of the ion beam increases its range. The device described herein comprises an inductive gas discharge chamber and a slit-type three-electrode ion extraction grid (IEG) unit. Calculations of accelerating cell geometries and ion trajectories determined the dependence of beam expansion half-angle on normalized perveance based on the measurements of the spatial distributions of the xenon plasma parameters at the IEG entrance for a xenon flow rate q ≈ 0.2 mg/s and an incident RF power P in ≤ 250 W at a driving frequency f = 2 MHz. Experimental studies showed that the ion beam, circular at the IEG exit, accepted the elliptical form at the distance of 580 mm with half-angle of beam expansion across IEG slits about 2°-3° and close to 0° along them. Thus, the obtained result proved the possibility of creating a new-generation on-board ion injector that could be used in spacecrafts for removal of debris.

Measurements of Classical Transport of Fast Ions in the LAPD

NASA Astrophysics Data System (ADS)

Zhao, L.; Boehmer, H.; Edrich, D.; Heidbrink, W. W.; McWilliams, R.; Zimmerman, D.; Lenenman, D.; Vincena, S.

2004-11-01

To study fast ion transport in a well controlled background plasma, a 3cm diameter RF ion gun launches a pulsed, 400 eV ribbon shape argon ion beam in the LArge Plasma Device (LAPD) at UCLA. The beam velocity distribution is calibrated by Laser Induced Fluorescence (LIF) on the Mirror of UCI and the beam energy is also measured by a two-grid energy analyzer at different axial locations (z=0.3-6.0 m) from the source on LAPD. Slowing down of the ion beam is observed when the beam is launched parallel or at 15 degrees to the 0.85 kG magnetic field. Using Langmuir probe measurements of the plasma parameters, the observed energy deceleration rate is consistent with classical Coulomb scattering theory. The radial beam profile is also measured by the energy analyzer when the beam is launched at 15 degrees to the magnetic field. The beam follows the expected helical trajectory and its contour has the shape predicted by Monte Carlo simulations. The diffusion measurements are performed at different axial locations where the ion beam has the same gyro-phase to eliminate the peristaltic effect. The spatial spreading of the beam is compared with classical scattering and neutral scattering theory.

Electron cooling of a bunched ion beam in a storage ring

NASA Astrophysics Data System (ADS)

Zhao, He; Mao, Lijun; Yang, Jiancheng; Xia, Jiawen; Yang, Xiaodong; Li, Jie; Tang, Meitang; Shen, Guodong; Ma, Xiaoming; Wu, Bo; Wang, Geng; Ruan, Shuang; Wang, Kedong; Dong, Ziqiang

2018-02-01

A combination of electron cooling and rf system is an effective method to compress the beam bunch length in storage rings. A simulation code based on multiparticle tracking was developed to calculate the bunched ion beam cooling process, in which the electron cooling, intrabeam scattering (IBS), ion beam space-charge field, transverse and synchrotron motion are considered. Meanwhile, bunched ion beam cooling experiments have been carried out in the main cooling storage ring (CSRm) of the Heavy Ion Research Facility in Lanzhou, to investigate the minimum bunch length obtained by the cooling method, and study the dependence of the minimum bunch length on beam and machine parameters. The experiments show comparable results to those from simulation. Based on these simulations and experiments, we established an analytical model to describe the limitation of the bunch length of the cooled ion beam. It is observed that the IBS effect is dominant for low intensity beams, and the space-charge effect is much more important for high intensity beams. Moreover, the particles will not be bunched for much higher intensity beam. The experimental results in CSRm show a good agreement with the analytical model in the IBS dominated regime. The simulation work offers us comparable results to those from the analytical model both in IBS dominated and space-charge dominated regimes.

Superconductivity in the system Mo{sub x}C{sub y}Ga{sub z}O{sub δ} prepared by focused ion beam induced deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weirich, P. M., E-mail: p.weirich@Physik.uni-frankfurt.de; Schwalb, C. H.; Winhold, M.

2014-05-07

We have prepared the new amorphous superconductor Mo{sub x}C{sub y}Ga{sub z}O{sub δ} with a maximum critical temperature T{sub c} of 3.8 K by the direct-write nano-patterning technique of focused (gallium) ion beam induced deposition (FIBID) using Mo(CO){sub 6} as precursor gas. From a detailed analysis of the temperature-dependent resistivity and the upper critical field, we found clear evidence for proximity of the samples to a disorder-induced metal-insulator transition. We observed a strong dependence of T{sub c} on the deposition parameters and identified clear correlations between T{sub c}, the localization tendency visible in the resistance data and the sample composition. By anmore » in-situ feedback-controlled optimization process in the FIB-induced growth, we were able to identify the beam parameters which lead to samples with the largest T{sub c}-value and sharpest transition into the superconducting state.« less

Excitation of Ion Cyclotron Waves by Ion and Electron Beams in Compensated-current System

NASA Astrophysics Data System (ADS)

Xiang, L.; Wu, D. J.; Chen, L.

2018-04-01

Ion cyclotron waves (ICWs) can play important roles in the energization of plasma particles. Charged particle beams are ubiquitous in space, and astrophysical plasmas and can effectively lead to the generation of ICWs. Based on linear kinetic theory, we consider the excitation of ICWs by ion and electron beams in a compensated-current system. We also investigate the competition between reactive and kinetic instabilities. The results show that ion and electron beams both are capable of generating ICWs. For ICWs driven by ion beams, there is a critical beam velocity, v bi c , and critical wavenumber, k z c , for a fixed beam density; the reactive instability dominates the growth of ICWs when the ion-beam velocity {v}{bi}> {v}{bi}c and the wavenumber {k}z< {k}zc, and the maximal growth rate is reached at {k}z≃ 2{k}zc/3 for a given {v}{bi}> {v}{bi}c. For the slow ion beams with {v}{bi}< {v}{bi}c, the kinetic instability can provide important growth rates of ICWs. On the other hand, ICWs driven by electron beams are excited only by the reactive instability, but require a critical velocity, {v}{be}c\\gg {v}{{A}} (the Alfvén velocity). In addition, the comparison between the approximate analytical results based on the kinetic theory and the exact numerical calculation based on the fluid model demonstrates that the reactive instabilities can well agree quantitatively with the numerical results by the fluid model. Finally, some possible applications of the present results to ICWs observed in the solar wind are briefly discussed.

The characteristics of a new negative metal ion beam source and its applications

NASA Astrophysics Data System (ADS)

Paik, Namwoong

2001-10-01

Numerous efforts at energetic thin film deposition processes using ion beams have been made to meet the demands of today's thin film industry. As one of these efforts, a new Magnetron Sputter Negative Ion Source (MSNIS) was developed. In this study, the development and the characterization of the MSNIS were investigated. Amorphous carbon films were used as a sample coating medium to evaluate the ion beam energy effect. A review of energetic Physical Vapor Deposition (PVD) techniques is presented in Chapter 1. The energetic PVD methods can be classified into two major categories: the indirect ion beam method Ion Beam Assisted Deposition (IBAD), and the direct ion beam method-Direct Ion Beam Deposition (DIBD). In this chapter, currently available DIBD processes such as Cathodic Arc, Laser Ablation, Ionized Physical Vapor Deposition (I-PVD) and Magnetron Sputter Negative Ion Source (MSNIS) are individually reviewed. The design and construction of the MSNIS is presented in chapter 2. The MSNIS is a hybrid of the conventional magnetron sputter configuration and the cesium surface ionizer. The negative sputtered ions are produced directly from the sputter target by surface ionization. In chapter 3, the ion beam and plasma characteristics of an 8″ diameter MSNIS are investigated using a retarding field analyzer and a cylindrical Langmuir Probe. The measured electron temperature is approximately 2-5 eV, while the plasma density and plasma potential were of the order of 10 11-1012 cm3 and 5-20 V, respectively, depending on the pressure and power. In chapter 4, in order to evaluate the effect of the ion beam on the resultant films, amorphous carbon films were deposited under various conditions. The structure of carbon films was investigated using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The result suggests the fraction of spa bonding is more than 70% in some samples prepared by MSNIS while magnetron sputtered samples showed less than 30%. (Abstract shortened by UMI.)

Design of a compact all-permanent magnet ECR ion source injector for ReA at the MSU NSCL

NASA Astrophysics Data System (ADS)

Pham, Alfonse N.; Leitner, Daniela; Glennon, Patrick; Ottarson, Jack; Lawton, Don; Portillo, Mauricio; Machicoane, Guillaume; Wenstrom, John; Lajoie, Andrew

2016-06-01

The design of a compact all-permanent magnet electron cyclotron resonance (ECR) ion source injector for the ReAccelerator Facility (ReA) at the Michigan State University (MSU) National Superconducting Cyclotron Laboratory (NSCL) is currently being carried out. The ECR ion source injector will complement the electron beam ion trap (EBIT) charge breeder as an off-line stable ion beam injector for the ReA linac. The objective of the ECR ion source injector is to provide continuous-wave beams of heavy ions from hydrogen to masses up to 136Xe within the ReA charge-to-mass ratio (Q / A) operational range from 0.2 to 0.5. The ECR ion source will be mounted on a high-voltage platform that can be adjusted to obtain the required 12 keV/u injection energy into a room temperature radio-frequency quadrupole (RFQ) for further acceleration. The beam line consists of a 30 kV tetrode extraction system, mass analyzing section, and optical matching section for injection into the existing ReA low energy beam transport (LEBT) line. The design of the ECR ion source and the associated beam line are discussed.

Intense Pulsed Heavy Ion Beam Technology

NASA Astrophysics Data System (ADS)

Masugata, Katsumi; Ito, Hiroaki

Development of intense pulsed heavy ion beam accelerator technology is described for the application of materials processing. Gas puff plasma gun and vacuum arc discharge plasma gun were developed as an active ion source for magnetically insulated pulsed ion diode. Source plasma of nitrogen and aluminum were successfully produced with the gas puff plasma gun and the vacuum arc plasma gun, respectively. The ion diode was successfully operated with gas puff plasma gun at diode voltage 190 kV, diode current 2.2 kA and nitrogen ion beam of ion current density 27 A/cm2 was obtained. The ion composition was evaluated by a Thomson parabola spectrometer and the purity of the nitrogen ion beam was estimated to be 86%. The diode also operated with aluminum ion source of vacuum arc plasma gun. The ion diode was operated at 200 kV, 12 kA, and aluminum ion beam of current density 230 A/cm2 was obtained. The beam consists of aluminum ions (Al(1-3)+) of energy 60-400 keV, and protons (90-130 keV), and the purity was estimated to be 89 %. The development of the bipolar pulse accelerator (BPA) was reported. A double coaxial type bipolar pulse generator was developed as the power supply of the BPA. The generator was tested with dummy load of 7.5 ohm, bipolar pulses of -138 kV, 72 ns (1st pulse) and +130 kV, 70 ns (2nd pulse) were succesively generated. By applying the bipolar pulse to the drift tube of the BPA, nitrogen ion beam of 2 A/cm2 was observed in the cathode, which suggests the bipolar pulse acceleration.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drueding, T.W.

The final figuring step in the fabrication of an optical component involves imparting a specified contour onto the surface. This can be expensive and time consuming step. The recent development of ion beam figuring provides a method for performing the figuring process with advantages over standard mechanical methods. Ion figuring has proven effective in figuring large optical components. The process of ion beam figuring removes material by transferring kinetic energy from impinging neutral particles. The process utilizes a Kaufman type ion source, where a plasma is generated in a discharge chamber by controlled electric potentials. Charged grids extract and acceleratemore » ions from the chamber. The accelerated ions form a directional beam. A neutralizer outside the accelerator grids supplies electrons to the positive ion beam. It is necessary to neutralize the beam to prevent charging workpieces and to avoid bending the beam with extraneous electro-magnetic fields. When the directed beam strikes the workpiece, material sputters in a predicable manner. The amount and distribution of material sputtered is a function of the energy of the beam, material of the component, distance from the workpiece, and angle of incidence of the beam. The figuring method described here assumes a constant beam removal, so that the process can be represented by a convolution operation. A fixed beam energy maintains a constant sputtering rate. This temporally and spatially stable beam is held perpendicular to the workpiece at a fixed distance. For non-constant removal, corrections would be required to model the process as a convolution operation. Specific figures (contours) are achieved by rastering the beam over the workpiece at varying velocities. A unique deconvolution is performed, using series-derivative solution developed for the system, to determine these velocities.« less

Axial energy spread measurements of an accelerated positive ion beam

NASA Astrophysics Data System (ADS)

Lee, Y.; Gough, R. A.; Kunkel, W. B.; Leung, K. N.; Perkins, L. T.; Pickard, D. S.; Sun, L.; Vujic, J.; Williams, M. D.; Wutte, D.; Mondelli, Alfred A.; Stengl, Gerhard

1997-01-01

A multicusp ion source has been designed for use in ion projection lithography. Longitudinal energy spreads of the extracted positive hydrogen ion beam have been studied using a retarding field energy analyzer. It has been found that the filament-discharge multicusp ion source can deliver a beam with an energy spread less than 3 eV which is required for the ALG-1000 machine. The multicusp ion source can also deliver the current required for the application.

Simulation and optimization of a 10 A electron gun with electrostatic compression for the electron beam ion source.

PubMed

Pikin, A; Beebe, E N; Raparia, D

2013-03-01

Increasing the current density of the electron beam in the ion trap of the Electron Beam Ion Source (EBIS) in BNL's Relativistic Heavy Ion Collider facility would confer several essential benefits. They include increasing the ions' charge states, and therefore, the ions' energy out of the Booster for NASA applications, reducing the influx of residual ions in the ion trap, lowering the average power load on the electron collector, and possibly also reducing the emittance of the extracted ion beam. Here, we discuss our findings from a computer simulation of an electron gun with electrostatic compression for electron current up to 10 A that can deliver a high-current-density electron beam for EBIS. The magnetic field in the cathode-anode gap is formed with a magnetic shield surrounding the gun electrodes and the residual magnetic field on the cathode is (5 ÷ 6) Gs. It was demonstrated that for optimized gun geometry within the electron beam current range of (0.5 ÷ 10) A the amplitude of radial beam oscillations can be maintained close to 4% of the beam radius by adjusting the injection magnetic field generated by a separate magnetic coil. Simulating the performance of the gun by varying geometrical parameters indicated that the original gun model is close to optimum and the requirements to the precision of positioning the gun elements can be easily met with conventional technology.

Simulation and optimization of a 10 A electron gun with electrostatic compression for the electron beam ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pikin, A.; Beebe, E. N.; Raparia, D.

Increasing the current density of the electron beam in the ion trap of the Electron Beam Ion Source (EBIS) in BNL's Relativistic Heavy Ion Collider facility would confer several essential benefits. They include increasing the ions' charge states, and therefore, the ions' energy out of the Booster for NASA applications, reducing the influx of residual ions in the ion trap, lowering the average power load on the electron collector, and possibly also reducing the emittance of the extracted ion beam. Here, we discuss our findings from a computer simulation of an electron gun with electrostatic compression for electron current upmore » to 10 A that can deliver a high-current-density electron beam for EBIS. The magnetic field in the cathode-anode gap is formed with a magnetic shield surrounding the gun electrodes and the residual magnetic field on the cathode is (5 Division-Sign 6) Gs. It was demonstrated that for optimized gun geometry within the electron beam current range of (0.5 Division-Sign 10) A the amplitude of radial beam oscillations can be maintained close to 4% of the beam radius by adjusting the injection magnetic field generated by a separate magnetic coil. Simulating the performance of the gun by varying geometrical parameters indicated that the original gun model is close to optimum and the requirements to the precision of positioning the gun elements can be easily met with conventional technology.« less

Surface periodicity of Ir(110) from time-of-flight scattering and recoiling spectrometry (TOF-SARS)

NASA Astrophysics Data System (ADS)

Bu, H.; Shi, M.; Rabalais, J. W.

1991-03-01

The surface periodicity of the Ir(110) surface in both the clean reconstructed (1×3) and oxygen stabilized unreconstructed (1×1) phases have been investigated using time-of-flight scattering and recoiling spectrometry (TOF-SARS). A pulsed 4 keV Ar + ion beam is directed at a grazing incident angle to the surface and the scattered neutral plus ion flux is monitored as a function of beam exit angle and crystal azimuthal angle. It is demonstrated that either maxima or minima are obtained in the scattered flux along the low-index crystallographic directions depending on whether near-specular or off-specular scattering conditions, respectively, are used. These scattering intensity patterns as a function of crystal azimuthal angle provide a direct measure of the surface periodicity. These intensity variations are explained in terms of the Lindhard critical angle, semichannel focusing effects, and trajectory simulations.

High-resolution fluence verification for treatment plan specific QA in ion beam radiotherapy

NASA Astrophysics Data System (ADS)

Martišíková, Mária; Brons, Stephan; Hesse, Bernd M.; Jäkel, Oliver

2013-03-01

Ion beam radiotherapy exploits the finite range of ion beams and the increased dose deposition of ions toward the end of their range in material. This results in high dose conformation to the target region, which can be further increased using scanning ion beams. The standard method for patient-plan verification in ion beam therapy is ionization chamber dosimetry. The spatial resolution of this method is given by the distance between the chambers (typically 1 cm). However, steep dose gradients created by scanning ion beams call for more information and improved spatial resolution. Here we propose a clinically applicable method, supplementary to standard patient-plan verification. It is based on ion fluence measurements in the entrance region with high spatial resolution in the plane perpendicular to the beam, separately for each energy slice. In this paper the usability of the RID256 L amorphous silicon flat-panel detector for the measurements proposed is demonstrated for carbon ion beams. The detector provides sufficient spatial resolution for this kind of measurement (pixel pitch 0.8 mm). The experiments were performed at the Heidelberg Ion-Beam Therapy Center in Germany. This facility is equipped with a synchrotron capable of accelerating ions from protons up to oxygen to energies between 48 and 430 MeV u-1. Beam application is based on beam scanning technology. The measured signal corresponding to single energy slices was translated to ion fluence on a pixel-by-pixel basis, using calibration, which is dependent on energy and ion type. To quantify the agreement of the fluence distributions measured with those planned, a gamma-index criterion was used. In the patient field investigated excellent agreement was found between the two distributions. At least 95% of the slices contained more than 96% of points agreeing with our criteria. Due to the high spatial resolution, this method is especially valuable for measurements of strongly inhomogeneous fluence distributions like those in intensity-modulated treatment plans or plans including dose painting. Since no water phantom is needed to perform measurements, the flat-panel detector investigated has high potential for use with gantries. Before the method can be used in the clinical routine, it has to be sufficiently tested for each detector-facility combination.

Development of a simple, low cost, indirect ion beam fluence measurement system for ion implanters, accelerators

NASA Astrophysics Data System (ADS)

Suresh, K.; Balaji, S.; Saravanan, K.; Navas, J.; David, C.; Panigrahi, B. K.

2018-02-01

We developed a simple, low cost user-friendly automated indirect ion beam fluence measurement system for ion irradiation and analysis experiments requiring indirect beam fluence measurements unperturbed by sample conditions like low temperature, high temperature, sample biasing as well as in regular ion implantation experiments in the ion implanters and electrostatic accelerators with continuous beam. The system, which uses simple, low cost, off-the-shelf components/systems and two distinct layers of in-house built softwarenot only eliminates the need for costly data acquisition systems but also overcomes difficulties in using properietry software. The hardware of the system is centered around a personal computer, a PIC16F887 based embedded system, a Faraday cup drive cum monitor circuit, a pair of Faraday Cups and a beam current integrator and the in-house developed software include C based microcontroller firmware and LABVIEW based virtual instrument automation software. The automatic fluence measurement involves two important phases, a current sampling phase lasting over 20-30 seconds during which the ion beam current is continuously measured by intercepting the ion beam and the averaged beam current value is computed. A subsequent charge computation phase lasting 700-900 seconds is executed making the ion beam to irradiate the samples and the incremental fluence received by the sampleis estimated usingthe latest averaged beam current value from the ion beam current sampling phase. The cycle of current sampling-charge computation is repeated till the required fluence is reached. Besides simplicity and cost-effectiveness, other important advantages of the developed system include easy reconfiguration of the system to suit customisation of experiments, scalability, easy debug and maintenance of the hardware/software, ability to work as a standalone system. The system was tested with different set of samples and ion fluences and the results were verified using Rutherford backscattering technique which showed the satisfactory functioning of the system. The accuracy of the fluence measurements is found to be less than 2% which meets the demands of the irradiation experiments undertaken using the developed set up. The system was incorporated for regular use at the existing ultra high vacuum (UHV) ion irradiation chamber of 1.7 MV Tandem accelerator and several ion implantation experiments on a variety of samples like SS304, D9, ODS alloys have been successfully carried out.

Very-low-energy-spread ion sources

NASA Astrophysics Data System (ADS)

Lee, Y.

1997-05-01

Ion beams with low axial energy spread are required in many applications such as ion projection lithography, isobaric separation in radioactive ion beam experiments, and ion beam deposition processes. In an ion source, the spread of the axial ion energy is caused by the nonuniformity of the plasma potential distribution along the source axis. Multicusp ion sources are capable of production positive and negative ions with good beam quality and relatively low energy spread. By intorducing a magnetic filter inside the multicusp source chamber, the axial plasma potential distribution is modified and the energy spread of positive hydrogen ions can be reduced to as low as 1 eV. The energy spread measurements of multicusp sources have been conducted by employing three different techniques: an electrostatic energy analyzer at the source exit; a magnetic deflection spectrometer; and a retarding-field energy analyzer for the accelerated beam. These different measurements confirmed tha! t ! the axial energy spread of positive and negative ions generated in the filter-equipped multicusp sources are small. New ion source configurations are now being investigated at LBNL with the purpose of achieving enen lower energy spread (<1eV) and of maximizing source performance such as reliability and lifetime.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu Haijun; Zhu Jun; Chen Nan

2010-04-15

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

Pressure dependence of an ion beam accelerating structure in an expanding helicon plasma

NASA Astrophysics Data System (ADS)

Zhang, Xiao; Aguirre, Evan; Thompson, Derek S.; McKee, John; Henriquez, Miguel; Scime, Earl E.

2018-02-01

We present measurements of the parallel ion velocity distribution function and electric field in an expanding helicon source plasma plume as a function of downstream gas pressure and radial and axial positions. The ion beam that appears spontaneously in the plume persists for all downstream pressures investigated, with the largest parallel ion beam velocities obtained for the lowest downstream pressures. However, the change in ion beam velocity exceeds what would be expected simply for a change in the collisionality of the system. Electric field measurements confirm that it is the magnitude of the potential structure responsible for accelerating the ion beam that changes with downstream pressure. Interestingly, the ion density radial profile is hollow close to the end of the plasma source for all pressures, but it is hollow at downstream distances far from the source only at the highest downstream neutral pressures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prost, L.; Carneiro, J.-P.; Shemyakin, A.

In a Low Energy Beam Transport line (LEBT), the emittance growth due to the beam’s space charge is typically suppressed by way of neutralization from either electrons or ions, which originate from ionization of the background gas. In cases where the beam is chopped, the neutralization pattern usually changes throughout the beginning of the pulse, causing the Twiss parameters to differ significantly from their steady state values, which, in turn, may result in beam losses downstream. For a modest beam perveance, there is an alternative solution, in which the beam is kept un-neutralized in the portion of the LEBT thatmore » contains the chopper. The emittance can be nearly preserved if the transition to the un-neutralized section occurs where the beam exhibits low transverse tails. This report introduces the rationale for the proposed scheme and formulates the physical arguments for it as well as its limitations. An experimental realization of the scheme was carried out at Fermilab’s PIP2IT where low beam emittance dilution was demonstrated for a 5 mA, 30 keV H- beam.« less

Photonic guiding structures in lithium niobate crystals produced by energetic ion beams

NASA Astrophysics Data System (ADS)

Chen, Feng

2009-10-01

A range of ion beam techniques have been used to fabricate a variety of photonic guiding structures in the well-known lithium niobate (LiNbO3 or LN) crystals that are of great importance in integrated photonics/optics. This paper reviews the up-to-date research progress of ion-beam-processed LiNbO3 photonic structures and reports on their fabrication, characterization, and applications. Ion beams are being used with this material in a wide range of techniques, as exemplified by the following examples. Ion beam milling/etching can remove the selected surface regions of LiNbO3 crystals via the sputtering effects. Ion implantation and swift ion irradiation can form optical waveguide structures by modifying the surface refractive indices of the LiNbO3 wafers. Crystal ion slicing has been used to obtain bulk-quality LiNbO3 single-crystalline thin films or membranes by exfoliating the implanted layer from the original substrate. Focused ion beams can either generate small structures of micron or submicron dimensions, to realize photonic bandgap crystals in LiNbO3, or directly write surface waveguides or other guiding devices in the crystal. Ion beam-enhanced etching has been extensively applied for micro- or nanostructuring of LiNbO3 surfaces. Methods developed to fabricate a range of photonic guiding structures in LiNbO3 are introduced. Modifications of LiNbO3 through the use of various energetic ion beams, including changes in refractive index and properties related to the photonic guiding structures as well as to the materials (i.e., electro-optic, nonlinear optic, luminescent, and photorefractive features), are overviewed in detail. The application of these LiNbO3 photonic guiding structures in both micro- and nanophotonics are briefly summarized.

Junction size dependence of ferroelectric properties in e-beam patterned BaTiO{sub 3} ferroelectric tunnel junctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, A. V.; Gupta, A.; Althammer, M.

We investigate the switching characteristics in BaTiO{sub 3}-based ferroelectric tunnel junctions patterned in a capacitive geometry with circular Ru top electrode with diameters ranging from ∼430 to 2300 nm. Two different patterning schemes, viz., lift-off and ion-milling, have been employed to examine the variations in the ferroelectric polarization, switching, and tunnel electro-resistance resulting from differences in the pattering processes. The values of polarization switching field are measured and compared for junctions of different diameter in the samples fabricated using both patterning schemes. We do not find any specific dependence of polarization switching bias on the size of junctions in both samplemore » stacks. The junctions in the ion-milled sample show up to three orders of resistance change by polarization switching and the polarization retention is found to improve with increasing junction diameter. However, similar switching is absent in the lift-off sample, highlighting the effect of patterning scheme on the polarization retention.« less

High resolution energy analyzer for broad ion beam characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanarov, V.; Hayes, A.; Yevtukhov, R.

2008-09-15

Characterization of the ion energy distribution function (IEDF) of low energy high current density ion beams by conventional retarding field and deflection type energy analyzers is limited due to finite ion beam emittance and beam space charge spreading inside the analyzer. These deficiencies are, to a large extent, overcome with the recent development of the variable-focusing retarding field energy analyzer (RFEA), which has a cylindrical focusing electrode preceding the planar retarding grid. The principal concept of this analyzer is conversion of a divergent charged particle beam into a quasiparallel beam before analyzing it by the planar retarding field. This allowsmore » analysis of the beam particle total kinetic energy distribution with greatly improved energy resolution. Whereas this concept was first applied to analyze 5-10 keV pulsed electron beams, the present authors have adapted it to analyze the energy distribution of a low energy ({<=}1 KeV) broad ion beam. In this paper we describe the RFEA design, which was modified from the original, mainly as required by the specifics of broad ion beam energy analysis, and the device experimental characterization and modeling results. Among the modifications, an orifice electrode placed in front of the RFEA provides better spatial resolution of the broad ion beam ion optics emission region and reduces the beam plasma density in the vicinity of analyzer entry. An electron repeller grid placed in front of the RFEA collector was found critical for suppressing secondary electrons, both those incoming to the collector and those released from its surface, and improved energy spectrum measurement repeatability and accuracy. The use of finer mesh single- and double-grid retarding structures reduces the retarding grid lens effect and improves the analyzer energy resolution and accuracy of the measured spectrum mean energy. However, additional analyzer component and configuration improvements did not further change the analyzed IEDF shape or mean energy value. This led us to conclude that the optimized analyzer construction provides an energy resolution considerably narrower than the investigated ion beam energy spectrum full width at half maximum, and the derived energy spectrum is an objective and accurate representation of the analyzed broad ion beam energy distribution characteristics. A quantitative study of the focusing voltage and retarding grid field effects based on the experimental data and modeling results have supported this conclusion.« less

Laser ion source for high brightness heavy ion beam

DOE PAGES

Okamura, M.

2016-09-01

A laser ion source is known as a high current high charge state heavy ion source. But, we place great emphasis on the capability to realize a high brightness ion source. A laser ion source has a pinpoint small volume where materials are ionized and can achieve quite uniform low temperature ion beam. Those features may enable us to realize very small emittance beams. Furthermore, a low charge state high brightness laser ion source was successfully commissioned in Brookhaven National Laboratory in 2014. Now most of all the solid based heavy ions are being provided from the laser ion sourcemore » for regular operation.« less

Comparison of gridded energy analyzer and laser induced fluorescence measurements of a two-component ion distribution.

PubMed

Harvey, Z; Thakur, S Chakraborty; Hansen, A; Hardin, R; Przybysz, W S; Scime, E E

2008-10-01

We present ion velocity distribution function (IVDF) measurements obtained with a five grid retarding field energy analyzer (RFEA) and IVDF measurements obtained with laser induced fluorescence (LIF) for an expanding helicon plasma. The ion population consists of a background population and an energetic ion beam. When the RFEA measurements are corrected for acceleration due to the electric potential difference across the plasma sheath, we find that the RFEA measurements indicate a smaller background to beam density ratio and a much larger parallel ion temperature than the LIF. The energy of the ion beam is the same in both measurements. These results suggest that ion heating occurs during the transit of the background ions through the sheath and that LIF cannot detect the fraction of the ion beam whose metastable population has been eliminated by collisions.

Intense ion beam generator

DOEpatents

Humphries, Jr., Stanley; Sudan, Ravindra N.

1977-08-30

Methods and apparatus for producing intense megavolt ion beams are disclosed. In one embodiment, a reflex triode-type pulsed ion accelerator is described which produces ion pulses of more than 5 kiloamperes current with a peak energy of 3 MeV. In other embodiments, the device is constructed so as to focus the beam of ions for high concentration and ease of extraction, and magnetic insulation is provided to increase the efficiency of operation.

Spectroscopic investigations of beam-plasma interactions in an ion plume

NASA Technical Reports Server (NTRS)

Ruyten, W. M.; Friedly, V. J.; Peng, X.; Celenza, J. A.; Keefer, D.

1993-01-01

We report the results of spectroscopic investigations of beam-plasma interactions in the plume from a 3 cm ion source operated on argon. Ion-electron, ion-neutral, and electron-neutral scattering are identified by studying the dependence of neutral and ion emission intensities on chamber pressure and mass flow rate, and by analyzing the emission lineshapes at a non-orthogonal angle to the plume axis. Through the Doppler shift, we are able to separate contributions from fast beam ions and fast charge-exchange neutrals on the one hand, and of slow neutrals and slow ions on the other. We discuss the application of this new technique to the characterization of beam plasma interactions in the downstream region of ion thruster engines, and its potential for identifying the processes which lead to grid erosion.

The role of tortuosity on ion conduction in block copolymer electrolyte thin films

NASA Astrophysics Data System (ADS)

Kambe, Yu; Arges, Christopher G.; Nealey, Paul F.

This talk discusses the role of grain tortuosity on ion conductivity in block copolymer electrolyte (BCE) thin films. In particular, we studied lamellae forming BCEs with both domains oriented perpendicular to the substrate surface and connected directly from one electrode to another - i.e., tortuosity of one. The BCE is composed of ion-conducting, poly(2-vinyl n-methylpyridinium) blocks and non-ionic polystyrene blocks. Prior to creating the BCE, the pristine block copolymer, poly(styrene- b-2-vinyl pyridine), was directly self-assembled (DSA) on topographical or chemical patterns via graphoepitaxy and chemoepitaxy. A chemical vapor infiltration reaction modified the P2VP block into positively charged, fixed quaternary ammonium groups paired with mobile counteranions. The graphoepitaxy process utilized topographical interdigitated gold nanoelectrodes (100s of nanometers spacing between electrodes) created via e-beam lithography. Alternatively, chemical patterns had gold electrodes incorporated into them with 10s to 100s of microns spacing using conventional optical lithography. The interdigitated gold electrodes enabled in-plane ion conductivity measurements of the DSA BCEs to study the role of grain tortuosity on ion conductivity. U.S. Department of Energy Office of Science: Contract No. DE-AC02-06CH11357.

Diagnostic evaluations of a beam-shielded 8-cm mercury ion thruster

NASA Technical Reports Server (NTRS)

Nakanishi, S.

1978-01-01

An engineering model thruster fitted with a remotely actuated graphite fiber polyimide composite beam shield was tested in a 3- by 6.5-meter vacuum facility for in-situ assessment of beam shield effects on thruster performance. Accelerator drain current neutralizer floating potential and ion beam floating potential increased slightly when the shield was moved into position. A target exposed to the low density regions of the ion beam was used to map the boundaries of energetic fringe ions capable of sputtering. The particle efflux was evaluated by measurement of film deposits on cold, heated, bare, and enclosed glass slides.

Spectroscopic properties and radiation damage investigation of a diamond based Schottky diode for ion-beam therapy microdosimetry

NASA Astrophysics Data System (ADS)

Verona, C.; Magrin, G.; Solevi, P.; Grilj, V.; Jakšić, M.; Mayer, R.; Marinelli, Marco; Verona-Rinati, G.

2015-11-01

In this work, a detailed analysis of the properties of a novel microdosimeter based on a synthetic single crystal diamond is reported. Focused ion microbeams were used to investigate the device spectropscopic properties as well as the induced radiation damage effects. A diamond based Schottky diode was fabricated by chemical vapor deposition with a very thin detecting region, about 400 nm thick (approximately 1.4 μm water equivalent thickness), corresponding to the typical size in microdosimetric measurements. A 200 × 200 μm2 square metallic contact was patterned on the diamond surface by standard photolithography to define the sensitive area. Experimental measurements were carried out at the Ruder Bo\\vskovic' Institute microbeam facility using 4 MeV carbon and 5 MeV silicon ions. Ion beam induced charge maps were employed to characterize the microdosimeter response in terms of its charge collection properties. A stable response with no evidence of polarization or memory effects was observed up to the maximum investigated ion beam flux of about 1.7 × 109 ions.cm-2.s-1. A homogeneity of the response about 6% was found over the sensitive region with a well-defined confinement of the response within the active area. Tests of the radiation damage effect were performed by selectively irradiating small areas of the device with different ion fluences, up to about 1012 ions/cm2. An exponential decrease of the charge collection efficiency was observed with a characteristic decay constant of about 4.8 MGy and 1 MGy for C and Si ions, respectively. The experimental data were analyzed by means of GEANT4 Monte Carlo simulations. A direct correlation between the diamond damaging effect and the Non Ionizing Energy Loss (NIEL) fraction was found. In particular, an exponential decay of the charge collection efficiency with an exponential decay as a function of NIEL is observed, with a characteristic constant of about 9.3 kGy-NIEL for both carbon and silicon ions.

Back-streaming ion emission and beam focusing on high power linear induction accelerator

NASA Astrophysics Data System (ADS)

Zhu, Jun; Chen, Nan; Yu, Haijun; Jiang, Xiaoguo; Wang, Yuan; Dai, Wenhua; Gao, Feng; Wang, Minhong; Li, Jin; Shi, Jinshui

2011-08-01

Ions released from target surfaces by impact of a high intensity and current electron beam can be accelerated and trapped in the beam potential, and further destroy the beam focus. By solving the 2D Poisson equation, we found that the charge neutralization factor of the ions to the beam under space charge limited condition is 1/3, which is large enough to disrupt the spot size. Therefore, the ion emission at the target in a single-pulse beam/target system must be source limited. Experimental results on the time-resolved beam profile measurement have also proven that. A new focus scheme is proposed in this paper to focus the beam to a small spot size with the existence of back-streaming ions. We found that the focal spot will move upstream as the charge neutralization factor increases. By comparing the theoretical and experimental focal length of the Dragon-I accelerator (20 MeV, 2.5 kA, 60 ns flattop), we found that the average neutralization factor is about 5% in the beam/target system.

Maskless Lithography and in situ Visualization of Conductivity of Graphene using Helium Ion Microscopy

DOE PAGES

Iberi, Vighter O.; Vlassiouk, Ivan V.; Zhang, X. -G.; ...

2015-07-07

The remarkable mechanical and electronic properties of graphene make it an ideal candidate for next generation nanoelectronics. With the recent development of commercial-level single-crystal graphene layers, the potential for manufacturing household graphene-based devices has improved, but significant challenges still remain with regards to patterning the graphene into devices. In the case of graphene supported on a substrate, traditional nanofabrication techniques such as e-beam lithography (EBL) are often used in fabricating graphene nanoribbons but the multi-step processes they require can result in contamination of the graphene with resists and solvents. In this letter, we report the utility of scanning helium ionmore » lithography for fabricating functional graphene nanoconductors that are supported directly on a silicon dioxide layer, and we measure the minimum feature size achievable due to limitations imposed by thermal fluctuations and ion scattering during the milling process. Further we demonstrate that ion beams, due to their positive charging nature, may be used to observe and test the conductivity of graphene-based nanoelectronic devices in situ.« less

Experimental observation of ion beams in the Madison Helicon eXperiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiebold, Matt; Sung, Yung-Ta; Scharer, John E.

2011-06-15

Argon ion beams up to E{sub b} = 165 eV at P{sub rf} = 500 W are observed in the Madison Helicon eXperiment (MadHeX) helicon source with a magnetic nozzle. A two-grid retarding potential analyzer (RPA) is used to measure the ion energy distribution, and emissive and rf-filtered Langmuir probes measure the plasma potential, electron density, and temperature. The supersonic ion beam (M = v{sub i}/c{sub s} up to 5) forms over tens of Debye lengths and extends spatially for a few ion-neutral charge-exchange mean free paths. The parametric variation of the ion beam energy is explored, including flow rate,more » rf power, and magnetic field dependence. The beam energy is equal to the difference in plasma potentials in the Pyrex chamber and the grounded expansion chamber. The plasma potential in the expansion chamber remains near the predicted eV{sub p} {approx} 5kT{sub e} for argon, but the upstream potential is much higher, likely due to wall charging, resulting in accelerated ion beam energies E{sub b} = e[V{sub beam} - V{sub plasma}] > 10kT{sub e}.« less

Mutation breeding of ornamental plants using ion beams.

PubMed

Yamaguchi, Hiroyasu

2018-01-01

Ornamental plants that have a rich variety of flower colors and shapes are highly prized in the commercial flower market, and therefore, mutant cultivars that produce different types of flowers while retaining their growth habits are in demand. Furthermore, mutation breeding is well suited for ornamental plants because many species can be easily vegetatively propagated, facilitating the production of spontaneous and induced mutants. The use of ion beams in mutation breeding has rapidly expanded since the 1990s in Japan, with the prospect that more ion beam-specific mutants will be generated. There are currently four irradiation facilities in Japan that provide ion beam irradiation for plant materials. The development of mutant cultivars using ion beams has been attempted on many ornamental plants thus far, and some species have been used to investigate the process of mutagenesis. In addition, progress is being made in clarifying the genetic mechanism for expressing important traits, which will probably result in the development of more efficient mutation breeding methods for ornamental plants. This review not only provides examples of successful mutation breeding results using ion beams, but it also describes research on mutagenesis and compares results of ion beam and gamma ray breeding using ornamental plants.

High spatial resolution and high brightness ion beam probe for in-situ elemental and isotopic analysis

NASA Astrophysics Data System (ADS)

Long, Tao; Clement, Stephen W. J.; Bao, Zemin; Wang, Peizhi; Tian, Di; Liu, Dunyi

2018-03-01

A high spatial resolution and high brightness ion beam from a cold cathode duoplasmatron source and primary ion optics are presented and applied to in-situ analysis of micro-scale geological material with complex structural and chemical features. The magnetic field in the source as well as the influence of relative permeability of magnetic materials on source performance was simulated using COMSOL to confirm the magnetic field strength of the source. Based on SIMION simulation, a high brightness and high spatial resolution negative ion optical system has been developed to achieve Critical (Gaussian) illumination mode. The ion source and primary column are installed on a new Time-of-Flight secondary ion mass spectrometer for analysis of geological samples. The diameter of the ion beam was measured by the knife-edge method and a scanning electron microscope (SEM). Results show that an O2- beam of ca. 5 μm diameter with a beam intensity of ∼5 nA and an O- beam of ca. 5 μm diameter with a beam intensity of ∼50 nA were obtained, respectively. This design will open new possibilities for in-situ elemental and isotopic analysis in geological studies.

Mutation breeding of ornamental plants using ion beams

PubMed Central

Yamaguchi, Hiroyasu

2018-01-01

Ornamental plants that have a rich variety of flower colors and shapes are highly prized in the commercial flower market, and therefore, mutant cultivars that produce different types of flowers while retaining their growth habits are in demand. Furthermore, mutation breeding is well suited for ornamental plants because many species can be easily vegetatively propagated, facilitating the production of spontaneous and induced mutants. The use of ion beams in mutation breeding has rapidly expanded since the 1990s in Japan, with the prospect that more ion beam-specific mutants will be generated. There are currently four irradiation facilities in Japan that provide ion beam irradiation for plant materials. The development of mutant cultivars using ion beams has been attempted on many ornamental plants thus far, and some species have been used to investigate the process of mutagenesis. In addition, progress is being made in clarifying the genetic mechanism for expressing important traits, which will probably result in the development of more efficient mutation breeding methods for ornamental plants. This review not only provides examples of successful mutation breeding results using ion beams, but it also describes research on mutagenesis and compares results of ion beam and gamma ray breeding using ornamental plants. PMID:29681749

Ion collector design for an energy recovery test proposal with the negative ion source NIO1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Variale, V., E-mail: vincenzo.variale@ba.infn.it; Cavenago, M.; Agostinetti, P.

2016-02-15

Commercial viability of thermonuclear fusion power plants depends also on minimizing the recirculation power used to operate the reactor. The neutral beam injector (NBI) remains one of the most important method for plasma heating and control. For the future fusion power plant project DEMO, a NBI wall plug efficiency at least of 0.45 is required, while efficiency of present NBI project is about 0.25. The D{sup −} beam from a negative ion source is partially neutralized by a gas cell, which leaves more than 40% of energy in residual beams (D{sup −} and D{sup +}), so that an ion beammore » energy recovery system can significantly contribute to optimize efficiency. Recently, the test negative ion source NIO1 (60 keV, 9 beamlets with 15 mA H{sup −} each) has been designed and built at RFX (Padua) for negative ion production efficiency and the beam quality optimization. In this paper, a study proposal to use the NIO1 source also for a beam energy recovery test experiment is presented and a preliminary design of a negative ion beam collector with simulations of beam energy recovery is discussed.« less

Development of C⁶⁺ laser ion source and RFQ linac for carbon ion radiotherapy.

PubMed

Sako, T; Yamaguchi, A; Sato, K; Goto, A; Iwai, T; Nayuki, T; Nemoto, K; Kayama, T; Takeuchi, T

2016-02-01

A prototype C(6+) injector using a laser ion source has been developed for a compact synchrotron dedicated to carbon ion radiotherapy. The injector consists of a laser ion source and a 4-vane radio-frequency quadrupole (RFQ) linac. Ion beams are extracted from plasma and directly injected into the RFQ. A solenoid guides the low-energy beams into the RFQ. The RFQ is designed to accelerate high-intensity pulsed beams. A structure of monolithic vanes and cavities is adopted to reduce its power consumption. In beam acceleration tests, a solenoidal magnetic field set between the laser ion source and the RFQ helped increase both the peak currents before and after the RFQ by a factor of 4.

Development of C6+ laser ion source and RFQ linac for carbon ion radiotherapy

NASA Astrophysics Data System (ADS)

Sako, T.; Yamaguchi, A.; Sato, K.; Goto, A.; Iwai, T.; Nayuki, T.; Nemoto, K.; Kayama, T.; Takeuchi, T.

2016-02-01

A prototype C6+ injector using a laser ion source has been developed for a compact synchrotron dedicated to carbon ion radiotherapy. The injector consists of a laser ion source and a 4-vane radio-frequency quadrupole (RFQ) linac. Ion beams are extracted from plasma and directly injected into the RFQ. A solenoid guides the low-energy beams into the RFQ. The RFQ is designed to accelerate high-intensity pulsed beams. A structure of monolithic vanes and cavities is adopted to reduce its power consumption. In beam acceleration tests, a solenoidal magnetic field set between the laser ion source and the RFQ helped increase both the peak currents before and after the RFQ by a factor of 4.

Performance on the low charge state laser ion source in BNL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okamura, M.; Alessi, J.; Beebe, E.

On March 2014, a Laser Ion Source (LIS) was commissioned which delivers high-brightness, low-charge-state heavy ions for the hadron accelerator complex in Brookhaven National Laboratory (BNL). Since then, the LIS has provided many heavy ion species successfully. The low-charge-state (mostly singly charged) beams are injected to the Electron Beam Ion Source (EBIS), where ions are then highly ionized to fit to the following accelerator’s Q/M acceptance, like Au 32+. Recently we upgraded the LIS to be able to provide two different beams into EBIS on a pulse-to-pulse basis. Now the LIS is simultaneously providing beams for both the Relativistic Heavymore » Ion Collider (RHIC) and NASA Space Radiation Laboratory (NSRL).« less

Improved ion containment using a ring-cusp ion thruster

NASA Technical Reports Server (NTRS)

Sovey, J. S.

1982-01-01

A 30-centimeter diameter ring-cusp ion thruster is described which operates at inert gas ion beam currents up to about 7 ampere, with significant improvements in discharge chamber performance over conventional divergent-field thrusters. The thruster has strong boundary ring-cusp magnetic fields, a diverging field on the cathode region, and a nearly field-free volume upstream of the ion extraction system. Minimum ion beam production costs of 90 to 100 watts per beam ampere (W/A) were obtained for argon, krypton and xenon. Propellant efficiencies in excess of 0.90 were achieved at 100 to 120 W/A for the three inert gases. The ion beam charge-state was documented with a collimating mass spectrometer probe to allow evaluation of overall thruster efficiencies.

Generation of multicomponent ion beams by a vacuum arc ion source with compound cathode.

PubMed

Savkin, K P; Yushkov, Yu G; Nikolaev, A G; Oks, E M; Yushkov, G Yu

2010-02-01

This paper presents the results of time-of-flight mass spectrometry studies of the elemental and mass-to-charge state compositions of metal ion beams produced by a vacuum arc ion source with compound cathode (WC-Co(0.5), Cu-Cr(0.25), Ti-Cu(0.1)). We found that the ion beam composition agrees well with the stoichiometric composition of the cathode material from which the beam is derived, and the maximum ion charge state of the different plasma components is determined by the ionization capability of electrons within the cathode spot plasma, which is common to all components. The beam mass-to-charge state spectrum from a compound cathode features a greater fraction of multiply charged ions for those materials with lower electron temperature in the vacuum arc cathode spot, and a smaller fraction for those with higher electron temperature within the spot. We propose a potential diagram method for determination of attainable ion charge states for all components of the compound cathodes.

Transverse field focused system

DOEpatents

Anderson, O.A.

1983-06-01

It is an object of the invention to provide a transport apparatus for a high current negative-ion beam which will bend the beam around corners through a baffled path in a differential pump or a neutron trap. It is another object of the invention to provide a transport apparatus for a high current negative-ion beam which will allow gas molecules in the beam to exit outwardly from the transport apparatus. A further object of the invention is to provide a multi-stage accelerator for a high current negative-ion beam which will enable acceleration of the beam to very high energy levels with a minimum loss of current carrying capacity. A still further object of the invention is to provide an apparatus for transport or accelertion of a sheet beam of negative ions which is shaped to confine the beam against divergence or expansion.

Isotope separation by selective charge conversion and field deflection

DOEpatents

Hickman, Robert G.

1978-01-01

A deuterium-tritium separation system wherein a source beam comprised of positively ionized deuterium (D.sup.+) and tritium (T.sup.+) is converted at different charge-exchange cell sections of the system to negatively ionized deuterium (D.sup.-) and tritium (T.sup.-). First, energy is added to the beam to accelerate the D.sup.+ ions to the velocity that is optimum for conversion of the D.sup.+ ions to D.sup.- ions in a charge-exchange cell. The T.sup.+ ions are accelerated at the same time, but not to the optimum velocity since they are heavier than the D.sup.+ ions. The T.sup.+ ions are, therefore, not converted to T.sup.- ions when the D.sup.+ ions are converted to D.sup.- ions. This enables effective separation of the beam by deflection of the isotopes with an electrostatic field, the D.sup.- ions being deflected in one direction and the T.sup.+ ions being deflected in the opposite direction. Next, more energy is added to the deflected beam of T.sup.+ ions to bring the T.sup.+ ions to the optimum velocity for their conversion to T.sup.- ions. In a particular use of the invention, the beams of D.sup.- and T.sup.- ions are separately further accelerated and then converted to energetic neutral particles for injection as fuel into a thermonuclear reactor. The reactor exhaust of D.sup.+ and T.sup.+ and the D.sup.+ and T.sup.+ that was not converted in the respective sections is combined with the source beam and recycled through the system to increase the efficiency of the system.

Aberration of a negative ion beam caused by space charge effect.

PubMed

Miyamoto, K; Wada, S; Hatayama, A

2010-02-01

Aberrations are inevitable when the charged particle beams are extracted, accelerated, transmitted, and focused with electrostatic and magnetic fields. In this study, we investigate the aberration of a negative ion accelerator for a neutral beam injector theoretically, especially the spherical aberration caused by the negative ion beam expansion due to the space charge effect. The negative ion current density profiles with the spherical aberration are compared with those without the spherical aberration. It is found that the negative ion current density profiles in a log scale are tailed due to the spherical aberration.

Plasma waves produced by the xenon ion beam experiment on the Porcupine sounding rocket

NASA Technical Reports Server (NTRS)

Kintner, P. M.; Kelley, M.

1982-01-01

The production of electrostatic ion cyclotron waves by a perpendicular ion beam in the F-region ionosphere is described. The ion beam experiment was part of the Porcupine program and produced electrostatic hydrogen cyclotron waves just above harmonics of the hydrogen cyclotron frequency. The plasma process may be thought of as a magnetized background ionosphere through which an unmagnetized beam is flowing. The dispersion equation for this hypothesis is constructed and solved. Preliminary solutions agree well with the observed plasma waves.

Control of secondary electrons from ion beam impact using a positive potential electrode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowley, T. P., E-mail: tpcrowley@xanthotechnologies.com; Demers, D. R.; Fimognari, P. J.

2016-11-15

Secondary electrons emitted when an ion beam impacts a detector can amplify the ion beam signal, but also introduce errors if electrons from one detector propagate to another. A potassium ion beam and a detector comprised of ten impact wires, four split-plates, and a pair of biased electrodes were used to demonstrate that a low-voltage, positive electrode can be used to maintain the beneficial amplification effect while greatly reducing the error introduced from the electrons traveling between detector elements.

Fast neutral beam ion source coupled to a Fourier transform ion cyclotron resonance mass spectrometer

NASA Astrophysics Data System (ADS)

Hill, Nicholas C.; Limbach, Patrick A.; Shomo, Ronald E., II; Marshall, Alan G.; Appelhans, Anthony D.; Delmore, James E.

1991-11-01

The coupling of an autoneutralizing SF-6 fast ion-beam gun to a Fourier transform ion cyclotron resonance (FT/ICR) mass spectrometer is described. The fast neutral beam provides for secondary-ion-type FT/ICR mass analysis [e.g., production of abundant pseudomolecular (M+H)+ ions] of involatile samples without the need for external ion injection, since ions are formed at the entrance to the ICR ion trap. The design, construction, and testing of the hybrid instrument are described. The feasibility of the experiment (for both broadband and high-resolution FT/ICR positive-ion mass spectra) is demonstrated with tetra-butylammonium bromide and a Tylenol■ sample. The ability to analyze high molecular weight polymers with high mass resolution is demonstrated for Teflon■. All of the advantages of the fast neutral beam ion source previously demonstrated with quadrupole mass analysis are preserved, and the additional advantages of FT/ICR mass analysis (e.g., high mass resolving power, ion trapping) are retained.

Highly charged ion secondary ion mass spectroscopy

DOEpatents

Hamza, Alex V.; Schenkel, Thomas; Barnes, Alan V.; Schneider, Dieter H.

2001-01-01

A secondary ion mass spectrometer using slow, highly charged ions produced in an electron beam ion trap permits ultra-sensitive surface analysis and high spatial resolution simultaneously. The spectrometer comprises an ion source producing a primary ion beam of highly charged ions that are directed at a target surface, a mass analyzer, and a microchannel plate detector of secondary ions that are sputtered from the target surface after interaction with the primary beam. The unusually high secondary ion yield permits the use of coincidence counting, in which the secondary ion stops are detected in coincidence with a particular secondary ion. The association of specific molecular species can be correlated. The unique multiple secondary nature of the highly charged ion interaction enables this new analytical technique.

Analysis of Neutron Production in Passively Scattered Ion-Beam Therapy.

PubMed

Heo, Seunguk; Yoo, Seunghoon; Song, Yongkeun; Kim, Eunho; Shin, Jaeik; Han, Soorim; Jung, Wongyun; Nam, Sanghee; Lee, Rena; Lee, Kitae; Cho, Sungho

2017-07-01

A new treatment facility for heavy ion therapy since 2010 was constructed. In the broad beam, a range shifter, ridge filter and multi leaf collimator (MLC) for the generation of the spread-out Bragg peak is used. In this case, secondary neutrons produced by the interactions of the ion field with beam-modifying devices (e.g. double-scattering system, beam shaping collimators and range compensators) are very important for patient safety. Therefore, these components must be carefully examined in the context of secondary neutron yield and associated secondary cancer risk. In this article, Monte Carlo simulation has been carried out with the FLUktuierende KAskade particle transport code, the fluence and distribution of neutron generation and the neutron dose equivalent from the broad beam components are compared using carbon and proton beams. As a result, it is confirmed that the yield of neutron production using a carbon beam from all components of the broad beam was higher than using a proton beam. The ambient dose by neutrons per heavy ion and proton ion from the MLC surface was 0.12-0.18 and 0.0067-0.0087 pSv, respectively, which shows that heavy ions generate more neutrons than protons. However, ambient dose per treatment 2 Gy, which means physical dose during treatment by ion beam, is higher than carbon beam because proton therapy needs more beam flux to make 2-Gy prescription dose. Therefore, the neutron production from the MLC, which is closed to the patient, is a very important parameter for patient safety. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Storage-ring Electron Cooler for Relativistic Ion Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Fanglei; Derbenev, Yaroslav; Douglas, David R.

Application of electron cooling at ion energies above a few GeV has been limited due to reduction of electron cooling efficiency with energy and difficulty in producing and accelerating a high-current high-quality electron beam. A high-current storage-ring electron cooler offers a solution to both of these problems by maintaining high cooling beam quality through naturally-occurring synchrotron radiation damping of the electron beam. However, the range of ion energies where storage-ring electron cooling can be used has been limited by low electron beam damping rates at low ion energies and high equilibrium electron energy spread at high ion energies. This papermore » reports a development of a storage ring based cooler consisting of two sections with significantly different energies: the cooling and damping sections. The electron energy and other parameters in the cooling section are adjusted for optimum cooling of a stored ion beam. The beam parameters in the damping section are adjusted for optimum damping of the electron beam. The necessary energy difference is provided by an energy recovering SRF structure. A prototype linear optics of such storage-ring cooler is presented.« less

Studies of extraction and transport system for highly charged ion beam of 18 GHz superconducting electron cyclotron resonance ion source at Research Center for Nuclear Physics.

PubMed

Yorita, T; Hatanaka, K; Fukuda, M; Ueda, H; Yasuda, Y; Morinobu, S; Tamii, A; Kamakura, K

2014-02-01

An 18 GHz superconducting electron cyclotron resonance ion source is installed to increase beam currents and to extend the variety of ions especially for highly charged heavy ions which can be accelerated by cyclotrons of Research Center for Nuclear Physics (RCNP), Osaka University. The beam production developments of several ions from B to Xe have been already done [T. Yorita, K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, H.Okamura, and A. Tamii, Rev. Sci. Instrum. 79, 02A311 (2008) and T. Yorita, K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, H.Okamura, and A. Tamii, Rev. Sci. Instrum. 81, 02A332 (2010)] and the further studies for those beam extraction and its transport have been done in order to increase the beam current more. The plasma electrode, extraction electrode, and einzel lens are modified. Especially extraction electrode can be applied minus voltage for the beam extraction and it works well to improve the extracted beam current. The extraction voltage dependences of transmission and emittance also have been studied for beam current improvement which is injected into azimuthally varying field cyclotron at RCNP.

Materials science education: ion beam modification and analysis of materials

NASA Astrophysics Data System (ADS)

Zimmerman, Robert; Muntele, Claudiu; Ila, Daryush

2012-08-01

The Center for Irradiation of Materials (CIM) at Alabama A&M University (http://cim.aamu.edu) was established in 1990 to serve the University in its research, education and services to the need of the local community and industry. CIM irradiation capabilities are oriented around two tandem-type ion accelerators with seven beam lines providing high-resolution Rutherford backscattering spectrometry, MeV focus ion beam, high-energy ion implantation and irradiation damage studies, particle-induced X-ray emission, particle-induced gamma emission and ion-induced nuclear reaction analysis in addition to fully automated ion channeling. One of the two tandem ion accelerators is designed to produce high-flux ion beam for MeV ion implantation and ion irradiation damage studies. The facility is well equipped with a variety of surface analysis systems, such as SEM, ESCA, as well as scanning micro-Raman analysis, UV-VIS Spectrometry, luminescence spectroscopy, thermal conductivity, electrical conductivity, IV/CV systems, mechanical test systems, AFM, FTIR, voltammetry analysis as well as low-energy implanters, ion beam-assisted deposition and MBE systems. In this presentation, we will demonstrate how the facility is used in material science education, as well as providing services to university, government and industry researches.

Characterization of a Gafchromic film for the two-dimensional profile measurement of low-energy heavy-ion beams

NASA Astrophysics Data System (ADS)

Yuri, Yosuke; Narumi, Kazumasa; Yuyama, Takahiro

2016-08-01

The feasibility of the transverse intensity distribution measurement of low-energy (keV/u range) heavy-ion beams using radiochromic films is experimentally explored. We employ a Gafchromic radiochromic film, HD-V2, whose active layer is not laminated by a surface-protection layer. The coloration response of films irradiated with several ion beams is characterized in terms of optical density (OD) by reading the films with a general-purpose scanner. To explore the energy dependence of the film response widely, the kinetic energy of the beams is varied from 1.5 keV/u to 27 MeV/u. We have found that the coloration of HD-V2 films is induced by irradiation with low-energy ion beams of the order of 10 keV/u. The range of the beams is considerably shorter than the thickness of the film's active layer. The dependence of OD response on ion species is also discussed. We demonstrate that the Gafchromic film used here is useful for measuring the intensity distribution of such low-energy ion beams.

Optimization of ion-atomic beam source for deposition of GaN ultrathin films.

PubMed

Mach, Jindřich; Šamořil, Tomáš; Kolíbal, Miroslav; Zlámal, Jakub; Voborny, Stanislav; Bartošík, Miroslav; Šikola, Tomáš

2014-08-01

We describe the optimization and application of an ion-atomic beam source for ion-beam-assisted deposition of ultrathin films in ultrahigh vacuum. The device combines an effusion cell and electron-impact ion beam source to produce ultra-low energy (20-200 eV) ion beams and thermal atomic beams simultaneously. The source was equipped with a focusing system of electrostatic electrodes increasing the maximum nitrogen ion current density in the beam of a diameter of ≈15 mm by one order of magnitude (j ≈ 1000 nA/cm(2)). Hence, a successful growth of GaN ultrathin films on Si(111) 7 × 7 substrate surfaces at reasonable times and temperatures significantly lower (RT, 300 °C) than in conventional metalorganic chemical vapor deposition technologies (≈1000 °C) was achieved. The chemical composition of these films was characterized in situ by X-ray Photoelectron Spectroscopy and morphology ex situ using Scanning Electron Microscopy. It has been shown that the morphology of GaN layers strongly depends on the relative Ga-N bond concentration in the layers.

Optical and electrical properties of ion beam textured Kapton and Teflon

NASA Technical Reports Server (NTRS)

Mirtich, M. J.; Sovey, J. S.

1977-01-01

Results are given for ion beam texturing of polyimide (Kapton) and fluorinated ethylene propylene (Teflon) by means of a 30-cm diam electron bombardment argon ion source. Ion beam-textured Kapton and Teflon surfaces are evaluated for various beam energies, current densities, and exposure times. The optical properties and sheet resistance are measured after each exposure. Provided in the paper are optical spectral data, resistivity measurements, calculated absorptance and emittance measurements, and surface structure SEM micrographs for various exposures to argon ions. It is found that Kapton becomes conducting and Teflon nonconducting when ion beam-textured. Textured Kapton exhibits large changes in the transmittance and solar absorptance, but only slight changes in reflectance. Surface texturing of Teflon may allow better adherence of subsequent sputtered metallic films for a high absorptance value. The results are valuable in spacecraft charging applications.

Research in pulsed power plasma physics

NASA Astrophysics Data System (ADS)

Hinshelwood, David; Rose, David

1993-11-01

The research was conducted in support of light-ion-driven inertial confinement fusion (ICF) for the Department of Energy (DOE), and nuclear weapon effects simulation (NWES) for the Defense Nuclear Agency (DNA). Accomplishments related to ion beams include: development of a practical backup approach to ion beam transport; the first studies of ion-beam interaction with a neutral gas; initial investigations of a promising industrial application of ion beam technology; and detailed theoretical evaluation of several different ion beam transport schemes. Major accomplishments relating to opening switches include: the first direct measurement of the electron density in an opening switch; detailed studies of switch conduction-time scaling; evaluation of several different switch plasma sources; and extensive studies of switch performance into diode loads, leading to the development of a new (and now generally accepted) model of switch behavior.

Progress in Electron Beam Mastering of 100 Gbit/inch2 Density Disc

NASA Astrophysics Data System (ADS)

Takeda, Minoru; Furuki, Motohiro; Yamamoto, Masanobu; Shinoda, Masataka; Saito, Kimihiro; Aki, Yuichi; Kawase, Hiroshi; Koizumi, Mitsuru; Miyokawa, Toshiaki; Mutou, Masao; Handa, Nobuo

2004-07-01

We developed an electron beam recorder (EBR) capable of recording master discs under atmospheric conditions using a novel differential pumping head. Using the EBR and optimized fabrication process for Si-etched discs with reactive ion etching (RIE), a bottom signal jitter of 9.6% was obtained from a 36 Gbit/inch2 density disc, readout using a near-field optical pickup with an effective numerical aperture (NA) of 1.85 and a wavelength of 405 nm. We also obtained the eye patterns from a 70 Gbit/inch2 density disc readout using an optical pickup with a 2.05 NA and the same wavelength, and showed almost the same modulation ratio as the simulation value. Moreover, the capability of producing pit patterns corresponding to a 104 Gbit/inch2 density is demonstrated.

Production, formation, and transport of high-brightness atomic hydrogen beam studies for the relativistic heavy ion collider polarized source upgrade.

PubMed

Kolmogorov, A; Atoian, G; Davydenko, V; Ivanov, A; Ritter, J; Stupishin, N; Zelenski, A

2014-02-01

The RHIC polarized H(-) ion source had been successfully upgraded to higher intensity and polarization by using a very high brightness fast atomic beam source developed at BINP, Novosibirsk. In this source the proton beam is extracted by a four-grid multi-aperture ion optical system and neutralized in the H2 gas cell downstream from the grids. The proton beam is extracted from plasma emitter with a low transverse ion temperature of ∼0.2 eV which is formed by plasma jet expansion from the arc plasma generator. The multi-hole grids are spherically shaped to produce "geometrical" beam focusing. Proton beam formation and transport of atomic beam were experimentally studied at test bench.

Intense highly charged ion beam production and operation with a superconducting electron cyclotron resonance ion source

NASA Astrophysics Data System (ADS)

Zhao, H. W.; Sun, L. T.; Guo, J. W.; Lu, W.; Xie, D. Z.; Hitz, D.; Zhang, X. Z.; Yang, Y.

2017-09-01

The superconducting electron cyclotron resonance ion source with advanced design in Lanzhou (SECRAL) is a superconducting-magnet-based electron cyclotron resonance ion source (ECRIS) for the production of intense highly charged heavy ion beams. It is one of the best performing ECRISs worldwide and the first superconducting ECRIS built with an innovative magnet to generate a high strength minimum-B field for operation with heating microwaves up to 24-28 GHz. Since its commissioning in 2005, SECRAL has so far produced a good number of continuous wave intensity records of highly charged ion beams, in which recently the beam intensities of 40Ar+ and 129Xe26+ have, for the first time, exceeded 1 emA produced by an ion source. Routine operations commenced in 2007 with the Heavy Ion accelerator Research Facility in Lanzhou (HIRFL), China. Up to June 2017, SECRAL has been providing more than 28,000 hours of highly charged heavy ion beams to the accelerator demonstrating its great capability and reliability. The great achievement of SECRAL is accumulation of numerous technical advancements, such as an innovative magnetic system and an efficient double-frequency (24 +18 GHz ) heating with improved plasma stability. This article reviews the development of SECRAL and production of intense highly charged ion beams by SECRAL focusing on its unique magnet design, source commissioning, performance studies and enhancements, beam quality and long-term operation. SECRAL development and its performance studies representatively reflect the achievements and status of the present ECR ion source, as well as the ECRIS impacts on HIRFL.

Noise reduction in negative-ion quadrupole mass spectrometry

DOEpatents

Chastagner, P.

1993-04-20

A quadrupole mass spectrometer (QMS) system is described having an ion source, quadrupole mass filter, and ion collector/recorder system. A weak, transverse magnetic field and an electron collector are disposed between the quadrupole and ion collector. When operated in negative ion mode, the ion source produces a beam of primarily negatively-charged particles from a sample, including electrons as well as ions. The beam passes through the quadrupole and enters the magnetic field, where the electrons are deflected away from the beam path to the electron collector. The negative ions pass undeflected to the ion collector where they are detected and recorded as a mass spectrum.

Noise reduction in negative-ion quadrupole mass spectrometry

DOEpatents

Chastagner, Philippe

1993-01-01

A quadrupole mass spectrometer (QMS) system having an ion source, quadrupole mass filter, and ion collector/recorder system. A weak, transverse magnetic field and an electron collector are disposed between the quadrupole and ion collector. When operated in negative ion mode, the ion source produces a beam of primarily negatively-charged particles from a sample, including electrons as well as ions. The beam passes through the quadrupole and enters the magnetic field, where the electrons are deflected away from the beam path to the electron collector. The negative ions pass undeflected to the ion collector where they are detected and recorded as a mass spectrum.

Space processing applications of ion beam technology. [surface finishing, welding, milling and film deposition

NASA Technical Reports Server (NTRS)

Grodzka, P. G.

1977-01-01

Ion thruster engines for spacecraft propulsion can serve as ion beam sources for potential space processing applications. The advantages of space vacuum environments and the possible gravity effects on thruster ion beam materials operations such as thin film growth, ion milling, and surface texturing were investigated. The direct gravity effect on sputter deposition and vapor deposition processes are discussed as well as techniques for cold and warm welding.

Industrial ion source technology. [for ion beam etching, surface texturing, and deposition

NASA Technical Reports Server (NTRS)

Kaufman, H. R.

1977-01-01

Plasma probe surveys were conducted in a 30-cm source to verify that the uniformity in the ion beam is the result of a corresponding uniformity in the discharge-chamber plasma. A 15 cm permanent magnet multipole ion source was designed, fabricated, and demonstrated. Procedures were investigated for texturing a variety of seed and surface materials for controlling secondary electron emission, increasing electron absorption of light, and improved attachment of biological tissue for medical implants using argon and tetrafluoromethane as the working gases. The cross section for argon-argon elastic collisions in the ion-beam energy range was calculated from interaction potentials and permits calculation of beam interaction effects that can determine system pumping requirements. The data also indicate that different optimizations of ion-beam machines will be advantageous for long and short runs, with 1 mA-hr/cm being the rough dividing line for run length. The capacity to simultaneously optimize components in an ion-beam machine for a single application, a capacity that is not evident in competitive approaches such as diode sputtering is emphasized.

Large area multiarc ion beam source {open_quote}MAIS{close_quote}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engelko, V.; Giese, H.; Schalk, S.

1996-12-31

A pulsed large area intense ion beam source is described, in which the ion emitting plasma is built up by an array of individual discharge units, homogeneously distributed over the surface of a common discharge electrode. A particularly advantageous feature of the source is that for plasma generation and subsequent acceleration of the ions only one common energy supply is necessary. This allows to simplify the source design and provides inherent synchronization of plasma production and ion extraction. The homogeneity of the plasma density was found to be superior to plasma sources using plasma expanders. Originally conceived for the productionmore » of proton beams, the source can easily be modified for the production of beams composed of carbon and metal ions or mixed ion species. Results of investigations of the source performance for the production of a proton beam are presented. The maximum beam current achieved to date is of the order of 100 A, with a particle kinetic energy of 15 - 30 keV and a pulse length in the range of 10 {mu}s.« less

Drag of ballistic electrons by an ion beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gurevich, V. L.; Muradov, M. I., E-mail: mag.muradov@mail.ioffe.ru

2015-12-15

Drag of electrons of a one-dimensional ballistic nanowire by a nearby one-dimensional beam of ions is considered. We assume that the ion beam is represented by an ensemble of heavy ions of the same velocity V. The ratio of the drag current to the primary current carried by the ion beam is calculated. The drag current turns out to be a nonmonotonic function of velocity V. It has a sharp maximum for V near v{sub nF}/2, where n is the number of the uppermost electron miniband (channel) taking part in conduction and v{sub nF} is the corresponding Fermi velocity. Thismore » means that the phenomenon of ion beam drag can be used for investigation of the electron spectra of ballistic nanostructures. We note that whereas observation of the Coulomb drag between two parallel quantum wires may in general be complicated by phenomena such as tunneling and phonon drag, the Coulomb drag of electrons of a one-dimensional ballistic nanowire by an ion beam is free of such spurious effects.« less

Self-organized broadband light trapping in thin film amorphous silicon solar cells.

PubMed

Martella, C; Chiappe, D; Delli Veneri, P; Mercaldo, L V; Usatii, I; Buatier de Mongeot, F

2013-06-07

Nanostructured glass substrates endowed with high aspect ratio one-dimensional corrugations are prepared by defocused ion beam erosion through a self-organized gold (Au) stencil mask. The shielding action of the stencil mask is amplified by co-deposition of gold atoms during ion bombardment. The resulting glass nanostructures enable broadband anti-reflection functionality and at the same time ensure a high efficiency for diffuse light scattering (Haze). It is demonstrated that the patterned glass substrates exhibit a better photon harvesting than the flat glass substrate in p-i-n type thin film a-Si:H solar cells.

Laser-driven ion acceleration: methods, challenges and prospects

NASA Astrophysics Data System (ADS)

Badziak, J.

2018-01-01

The recent development of laser technology has resulted in the construction of short-pulse lasers capable of generating fs light pulses with PW powers and intensities exceeding 1021 W/cm2, and has laid the basis for the multi-PW lasers, just being built in Europe, that will produce fs pulses of ultra-relativistic intensities ~ 1023 - 1024 W/cm2. The interaction of such an intense laser pulse with a dense target can result in the generation of collimated beams of ions of multi-MeV to GeV energies of sub-ps time durations and of extremely high beam intensities and ion fluencies, barely attainable with conventional RF-driven accelerators. Ion beams with such unique features have the potential for application in various fields of scientific research as well as in medical and technological developments. This paper provides a brief review of state-of-the art in laser-driven ion acceleration, with a focus on basic ion acceleration mechanisms and the production of ultra-intense ion beams. The challenges facing laser-driven ion acceleration studies, in particular those connected with potential applications of laser-accelerated ion beams, are also discussed.

Charge breeding simulations for radioactive ion beam production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Variale, V.; Raino, A. C.; Clauser, T.

2012-02-15

The charge breeding technique is used for radioactive ion beam (RIB) production in order of optimizing the re-acceleration of the radioactive element ions produced by a primary beam in a thick target. Charge breeding is achieved by means of a device capable of increasing the ion charge state from 1+ to a desired value n+. In order to get high intensity RIB, experiments with charge breeding of very high efficiency could be required. To reach this goal, the charge breeding simulation could help to optimize the high charge state production efficiency by finding more proper parameters for the radioactive 1+more » ions. In this paper a device based on an electron beam ion source (EBIS) is considered. In order to study that problem, a code already developed for studying the ion selective containment in an EBIS with RF quadrupoles, BRICTEST, has been modified to simulate the ion charge state breeding rate for different 1+ ion injection conditions. Particularly, the charge breeding simulations for an EBIS with a hollow electron beam have been studied.« less

Boron ion beam generation utilizing lanthanum hexaboride cathodes: Comparison of vacuum arc and planar magnetron glow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikolaev, A. G.; Vizir, A. V.; Yushkov, G. Yu., E-mail: gyushkov@mail.ru

Boron ion beams are widely used for semiconductor ion implantation and for surface modification for improving the operating parameters and increasing the lifetime of machine parts and tools. For the latter application, the purity requirements of boron ion beams are not as stringent as for semiconductor technology, and a composite cathode of lanthanum hexaboride may be suitable for the production of boron ions. We have explored the use of two different approaches to boron plasma production: vacuum arc and planar high power impulse magnetron in self-sputtering mode. For the arc discharge, the boron plasma is generated at cathode spots, whereasmore » for the magnetron discharge, the main process is sputtering of cathode material. We present here the results of comparative test experiments for both kinds of discharge, aimed at determining the optimal discharge parameters for maximum yield of boron ions. For both discharges, the extracted ion beam current reaches hundreds of milliamps and the fraction of boron ions in the total extracted ion beam is as high as 80%.« less

Characteristics of solitary waves in a relativistic degenerate ion beam driven magneto plasma

NASA Astrophysics Data System (ADS)

Deka, Manoj Kr.; Dev, Apul N.; Misra, Amar P.; Adhikary, Nirab C.

2018-01-01

The nonlinear propagation of a small amplitude ion acoustic solitary wave in a relativistic degenerate magneto plasma in the presence of an ion beam is investigated in detail. The nonlinear equations describing the evolution of a solitary wave in the presence of relativistic non-degenerate magnetized positive ions and ion beams including magnetized degenerate relativistic electrons are derived in terms of Zakharov-Kuznetsov (Z-K) equation for such plasma systems. The ion beams which are a ubiquitous ingredient in such plasma systems are found to have a decisive role in the propagation of a solitary wave in such a highly dense plasma system. The conditions of a wave, propagating with typical solitonic characteristics, are examined and discussed in detail under suitable conditions of different physical parameters. Both a subsonic and supersonic wave can propagate in such plasmas bearing different characteristics under different physical situations. A detailed analysis of waves propagating in subsonic and/or supersonic regime is carried out. The ion beam concentrations, magnetic field, as well as ion beam streaming velocity are found to play a momentous role on the control of the amplitude and width of small amplitude perturbation in both weakly (or non-relativistic) and relativistic plasmas.

[Clinical experience of carbon ion radiotherapy for malignant tumors].

PubMed

Ishikawa, Hitoshi; Tsuji, Hiroshi; Tsujii, Hirohiko

2006-04-01

The carbon ion (C-ion) beams provide unique advantageous biological and physical properties in radiotherapy (RT) for malignant tumors. C-ion beams have a high relative biological effectiveness (RBE) resulting from the high linear energy transfer (LET). In terms of their physical characteristics, C-ion beams exhibit a spread-out Bragg peak (SOBP) and make for a better dose distribution of the target volume by specified beam modulations. Between June 1994 and August 2005, a total of 2,371 patients with malignant tumors were registered in phase I/II dose-escalation studies and clinical phase II trials using C-ion beams generated at Heavy Ion Medical Accelerator in Chiba (HIMAC). In the initial dose-escalation studies, grade 3 or more late rectal complications had developed in some patients. However, the adverse effects were resolved because of the use of appropriate dose levels and modification of the radiation technique. C-ion beams can carry out hypofractionated radiotherapy with a large fraction dose and reduce the overall treatment times compared with conventional radiotherapy. They can also achieve better local tumor control even for radio-resistant tumors such as malignant melanoma, hepatocellular carcinoma and bone and soft tissue sarcomas with minimal morbidity to the normal surrounding tissues.

Use of a Gafchromic film HD-V2 for the profile measurement of energetic ion beams

NASA Astrophysics Data System (ADS)

Yuri, Yosuke; Ishizaka, Tomohisa; Agematsu, Takashi; Yuyama, Takahiro; Seito, Hajime; Okumura, Susumu

2017-09-01

The coloration response of a radiochromic film, Gafchromic HD-V2, to ion beams was investigated to apply the film to measuring the transverse intensity distribution of large-area ion beams. HD-V2 films were, therefore, irradiated with proton (10 MeV) and several heavy-ion (4.1-27 MeV/u) beams in a wide fluence range at the azimuthally-varying-field cyclotron facility in National Institutes for Quantum and Radiological Science and Technology, and read with an image scanner to analyze changes in the optical density. It was shown that the available fluence range (106-1011 ions/cm2) of HD-V2 depends strongly on ion species, i.e., linear energy transfer (LET). In addition, the reduction of the sensitivity to dose was shown over a wide LET range. The transverse intensity distribution of a large-area ion beam was measured using a response function determined from the measured data. We have demonstrated that the Gafchromic film HD-V2 is useful for measuring the intensity distribution at a low fluence and thus evaluating the characteristics of various ion beams.

The Development of High-Intensity Negative Ion Sources and Beams in the USSR

DTIC Science & Technology

1981-09-01

ion beams as the basis for creating neutral beams for injection into mirror traps and tokamaks, for inertial confinement fusion, and possibly for...create intense neutral beams for injection systems for mirror traps and tokamaks and for inertial confinement fusion. These applications require high...Scient. Instr., Vol. 44, 1973, p. 145. 46. Gabovich, M. D., Yu. N. Kozyrev , A. P. Nayda, L. S. Simonenko, I. A. Soloshenko, "H- Ion Beam Limit from a

A combined thermal dissociation and electron impact ionization source for radioactive ion beam generation{sup a}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alton, G.D.; Williams, C.

1996-04-01

The probability for simultaneously dissociating and efficiently ionizing the individual atomic constituents of molecular feed materials with conventional, hot-cathode, electron-impact ion sources is low and consequently, the ion beams from these sources often appear as mixtures of several molecular sideband beams. This fragmentation process leads to dilution of the intensity of the species of interest for radioactive ion beam (RIB) applications where beam intensity is at a premium. We have conceived an ion source that combines the excellent molecular dissociation properties of a thermal dissociator and the high ionization efficiency characteristics of an electron impact ionization source that will, inmore » principle, overcome this handicap. The source concept will be evaluated as a potential candidate for use for RIB generation at the Holifield Radioactive Ion Beam Facility, now under construction at the Oak Ridge National Laboratory. The design features and principles of operation of the source are described in this article. {copyright} {ital 1996 American Institute of Physics.}« less

A combined thermal dissociation and electron impact ionization source for radioactive ion beam generation (abstract){sup a}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alton, G.D.; Williams, C.

1996-03-01

The probability for simultaneously dissociating and efficiently ionizing the individual atomic constituents of molecular feed materials with conventional, hot-cathode, electron-impact ion sources is low and consequently, the ion beams from these sources often appear as mixtures of several molecular sideband beams. This fragmentation process leads to dilution of the intensity of the species of interest for radioactive ion beam (RIB) applications where beam intensity is at a premium. We have conceived an ion source that combines the excellent molecular dissociation properties of a thermal dissociator and the high ionization efficiency characteristics of an electron impact ionization source that will, inmore » principle, overcome this handicap. The source concept will be evaluated as a potential candidate for use for RIB generation at the Holifield Radioactive Ion Beam Facility, now under construction at the Oak Ridge National Laboratory. The design features and principles of operation of the source are described in this article. {copyright} {ital 1996 American Institute of Physics.}« less

Optimization, Characterization and Commissioning of a Novel Uniform Scanning Proton Beam Delivery System

NASA Astrophysics Data System (ADS)

Mascia, Anthony Edward

Purpose: To develop and characterize the required detectors for uniform scanning optimization and characterization, and to develop the methodology and assess their efficacy for optimizing, characterizing and commissioning a novel proton beam uniform scanning system. Methods and Materials: The Multi Layer Ion Chamber (MLIC), a 1D array of vented parallel plate ion chambers, was developed in-house for measurement of longitudinal profiles. The Matrixx detector (IBA Dosimetry, Germany) and XOmat V film (Kodak, USA) were characterized for measurement of transverse profiles. The architecture of the uniform scanning system was developed and then optimized and characterized for clinical proton radiotherapy. Results: The MLIC detector significantly increased data collection efficiency without sacrificing data quality. The MLIC was capable of integrating an entire scanned and layer stacked proton field with one measurement, producing results with the equivalent spatial sampling of 1.0mm. The Matrixx detector and modified 1D water phantom jig improved data acquisition efficiency and complemented the film measurements. The proximal, central and distal proton field planes were measured using these methods, yielding better than 3% uniformity. The binary range modulator was programmed, optimized and characterized such that the proton field ranges were separated by approximately 5.0mm modulation width and delivered with an accuracy of 1.0mm in water. Several wobbling magnet scan patterns were evaluated and the raster pattern, spot spacing, scan amplitude and overscan margin were optimized for clinical use. Conclusion: Novel detectors and methods are required for clinically efficient optimization and characterization of proton beam scanning systems. Uniform scanning produces proton beam fields that are suited for clinical proton radiotherapy.

Energetic ion losses caused by magnetohydrodynamic activity resonant and non-resonant with energetic ions in Large Helical Device

NASA Astrophysics Data System (ADS)

Ogawa, Kunihiro; Isobe, Mitsutaka; Toi, Kazuo; Shimizu, Akihiro; Spong, Donald A.; Osakabe, Masaki; Yamamoto, Satoshi; the LHD Experiment Group

2014-09-01

Experiments to reveal energetic ion dynamics associated with magnetohydrodynamic activity are ongoing in the Large Helical Device (LHD). Interactions between beam-driven toroidal Alfvén eigenmodes (TAEs) and energetic ions have been investigated. Energetic ion losses induced by beam-driven burst TAEs have been observed using a scintillator-based lost fast-ion probe (SLIP) in neutral beam-heated high β plasmas. The loss flux of co-going beam ions increases as the TAE amplitude increases. In addition to this, the expulsion of beam ions associated with edge-localized modes (ELMs) has been also recognized in LHD. The SLIP has indicated that beam ions having co-going and barely co-going orbits are affected by ELMs. The relation between ELM amplitude and ELM-induced loss has a dispersed structure. To understand the energetic ion loss process, a numerical simulation based on an orbit-following model, DELTA5D, that incorporates magnetic fluctuations is performed. The calculation result shows that energetic ions confined in the interior region are lost due to TAE instability, with a diffusive process characterizing their loss. For the ELM, energetic ions existing near the confinement/loss boundary are lost through a convective process. We found that the ELM-induced loss flux measured by SLIP changes with the ELM phase. This relation between the ELM amplitude and measured ELM-induced loss results in a more dispersed loss structure.

Neoplastic transformation of hamster embryo cells by heavy ions

NASA Astrophysics Data System (ADS)

Han, Z.; Suzuki, H.; Suzuki, F.; Suzuki, M.; Furusawa, Y.; Kato, T.; Ikenaga, M.

1998-11-01

We have studied the induction of morphological transformation of Syrian hamster embryo cells by low doses of heavy ions with different linear energy transfer (LET), ranging from 13 to 400 keV/μm. Exponentially growing cells were irradiated with 12C or 28Si ion beams generated by the Heavy Ion Medical Accelerator in Chiba (HIMAC), inoculated to culture dishes, and transformed colonies were identified when the cells were densely stacked and showed a crisscross pattern. Over the LET range examined, the frequency of transformation induced by the heavy ions increased sharply at very low doses no greater than 5 cGy. The relative biological effectiveness (RBE) of the heavy ions relative to 250 kVp X-rays showed an initial increase with LET, reaching a maximum value of about 7 at 100 keV/μm, and then decreased with the further increase in LET. Thus, we confirmed that high LET heavy ions are significantly more effective than X-rays for the induction of in vitro cell transformation.

Neoplastic transformation of hamster embyro cells by heavy ions.

PubMed

Han, Z; Suzuki, H; Suzuki, F; Suzuki, M; Furusawa, Y; Kato, T; Ikenaga, M

1998-01-01

We have studied the induction of morphological transformation of Syrian hamster embryo cells by low doses of heavy ions with different linear energy transfer (LET), ranging from 13 to 400 keV/micrometer. Exponentially growing cells were irradiated with 12C or 28Si ion beams generated by the Heavy Ion Medical Accelerator in Chiba (HIMAC), inoculated to culture dishes, and transformed colonies were identified when the cells were densely stacked and showed a crisscross pattern. Over the LET range examined, the frequency of transformation induced by the heavy ions increased sharply at very low doses no greater than 5 cGy. The relative biological effectiveness (RBE) of the heavy ions relative to 250 kVp X-rays showed an initial increase with LET, reaching a maximum value of about 7 at 100 keV/micrometer, and then decreased with the further increase in LET. Thus, we confirmed that high LET heavy ions are significantly more effective than X-rays for the induction of in vitro cell transformation.

Modeling of negative ion extraction from a magnetized plasma source: Derivation of scaling laws and description of the origins of aberrations in the ion beam

NASA Astrophysics Data System (ADS)

Fubiani, G.; Garrigues, L.; Boeuf, J. P.

2018-02-01

We model the extraction of negative ions from a high brightness high power magnetized negative ion source. The model is a Particle-In-Cell (PIC) algorithm with Monte-Carlo Collisions. The negative ions are generated only on the plasma grid surface (which separates the plasma from the electrostatic accelerator downstream). The scope of this work is to derive scaling laws for the negative ion beam properties versus the extraction voltage (potential of the first grid of the accelerator) and plasma density and investigate the origins of aberrations on the ion beam. We show that a given value of the negative ion beam perveance correlates rather well with the beam profile on the extraction grid independent of the simulated plasma density. Furthermore, the extracted beam current may be scaled to any value of the plasma density. The scaling factor must be derived numerically but the overall gain of computational cost compared to performing a PIC simulation at the real plasma density is significant. Aberrations appear for a meniscus curvature radius of the order of the radius of the grid aperture. These aberrations cannot be cancelled out by switching to a chamfered grid aperture (as in the case of positive ions).

Rectangular beam (5 X 40 cm multipole ion source). M.S. Thesis - Nov. 1979; [applications to electron bombardment in materials processing

NASA Technical Reports Server (NTRS)

Haynes, C. M.

1980-01-01

A 5 x 40 cm rectangular-beam ion source was designed and fabricated. A multipole field configuration was used to facilitate design of the modular rectangular chamber, while a three-grid ion optics system was used for increased ion current densities. For the multipole chamber, a magnetic integral of 0.000056 Tesla-m was used to contain the primary electrons. This integral value was reduced from the initial design value, with the reduction found necessary for discharge stability. The final value of magnetic integral resulted in discharge losses at typical operating conditions which ranged from 600 to 1000 eV/ion, in good agreement with the design value of 800 eV/ion. The beam current density at the ion optics was limited to about 3.2 mA/sq cm at 500 eV and to about 3.5 mA/sq cm at 1000 ev. The effects of nonuniform ion current, dimension tolerance, and grid thermal warping were considered. The use of multiple rectangular-beam ion sources to process wider areas than would be possible with a single source (approx. 40 cm) was also studied. Beam profiles were surveyed at a variety of operating conditions and the results of various amounts of beam overlap calculated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meusel, O., E-mail: o.meusel@iap.uni-frankfurt.de; Droba, M.; Noll, D.

The transport of intense ion beams is affected by the collective behavior of this kind of multi-particle and multi-species system. The space charge expressed by the generalized perveance dominates the dynamical process of thermalisation, which leads to emittance growth. To prevent changes of intrinsic beam properties and to reduce the intensity dependent focusing forces, space charge compensation seems to be an adequate solution. In the case of positively charged ion beams, electrons produced by residual gas ionization and secondary electrons provide the space charge compensation. The influence of the compensation particles on the beam transport and the local degree ofmore » space charge compensation is given by different beam properties as well as the ion beam optics. Especially for highly charged ion beams, space charge compensation in combination with poor vacuum conditions leads to recombination processes and therefore increased beam losses. Strategies for providing a compensation-electron reservoir at very low residual gas pressures will be discussed.« less

Harmonic plasma waves excitation and structure evolution of intense ion beams in background plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Zhang-Hu, E-mail: zhanghu@dlut.edu.cn; Wang, You-Nian

2016-08-15

The long-term dynamic evolutions of intense ion beams in plasmas have been investigated with two-dimensional electromagnetic particle simulations, taking into account the effect of the two-stream instability between beam ions and plasma electrons. Depending on the initial beam radial density profile and velocity distribution, ring structures may be formed in the beam edge regions. At the later stage of beam-plasma interactions, the ion beams are strongly modulated by the two-stream instability and multiple density spikes are formed in the longitudinal direction. The formation of these density spikes is shown to result from the excitation of harmonic plasma waves when themore » instability gets saturated. Comparisons between the beam cases with initial flat-top and Gaussian radial density profiles are made, and a higher instability growth rate is observed for the flat-top profile case.« less

Optimization of a charge-state analyzer for electron cyclotron resonance ion source beams.

PubMed

Saminathan, S; Beijers, J P M; Kremers, H R; Mironov, V; Mulder, J; Brandenburg, S

2012-07-01

A detailed experimental and simulation study of the extraction of a 24 keV He(+) beam from an ECR ion source and the subsequent beam transport through an analyzing magnet is presented. We find that such a slow ion beam is very sensitive to space-charge forces, but also that the neutralization of the beam's space charge by secondary electrons is virtually complete for beam currents up to at least 0.5 mA. The beam emittance directly behind the extraction system is 65 π mm mrad and is determined by the fact that the ion beam is extracted in the strong magnetic fringe field of the ion source. The relatively large emittance of the beam and its non-paraxiality lead, in combination with a relatively small magnet gap, to significant beam losses and a five-fold increase of the effective beam emittance during its transport through the analyzing magnet. The calculated beam profile and phase-space distributions in the image plane of the analyzing magnet agree well with measurements. The kinematic and magnet aberrations have been studied using the calculated second-order transfer map of the analyzing magnet, with which we can reproduce the phase-space distributions of the ion beam behind the analyzing magnet. Using the transfer map and trajectory calculations we have worked out an aberration compensation scheme based on the addition of compensating hexapole components to the main dipole field by modifying the shape of the poles. The simulations predict that by compensating the kinematic and geometric aberrations in this way and enlarging the pole gap the overall beam transport efficiency can be increased from 16% to 45%.

High brilliance negative ion and neutral beam source

DOEpatents

Compton, Robert N.

1991-01-01

A high brilliance mass selected (Z-selected) negative ion and neutral beam source having good energy resolution. The source is based upon laser resonance ionization of atoms or molecules in a small gaseous medium followed by charge exchange through an alkali oven. The source is capable of producing microampere beams of an extremely wide variety of negative ions, and milliampere beams when operated in the pulsed mode.

ARCS 3 ionospheric artificial argon ion beam injections - Waves near the heavy ion gyrofrequencies

NASA Technical Reports Server (NTRS)

Erlandson, R. E.; Cahill, L. J., Jr.; Kaufmann, R. L.; Arnoldy, R. L.; Pollock, C. J.

1989-01-01

Low-frequency electric field data below the proton gyrofrequency are presented for the duration of the argon ion beam experiment conducted as part of the Argon Release for Controlled Studies (ARCS) program. An argon ion beam was injected from the subpayload antiparallel or perpendicular to the magnetic field at altitudes from 250 to 405 km. During the injections, the wave spectra were broadband near the subpayload and narrow-band near heavy ion gyrofrequencies at perpendicular separation distances between 42 and 254 m. It is suggested that the narrow-band waves are associated with both the perpendicular argon ion beam and an unexpected flux of low-energy ions which peaked in energy near 15 eV and pitch angle near 90 deg with respect to the magnetic field.

Production of N[sup +] ions from a multicusp ion beam apparatus

DOEpatents

Kango Leung; Kunkel, W.B.; Walther, S.R.

1993-03-30

A method of generating a high purity (at least 98%) N[sup +] ion beam using a multicusp ion source having a chamber formed by a cylindrical chamber wall surrounded by a plurality of magnets, a filament centrally disposed in said chamber, a plasma electrode having an extraction orifice at one end of the chamber, a magnetic filter having two parallel magnets spaced from said plasma electrode and dividing the chamber into arc discharge and extraction regions. The method includes ionizing nitrogen gas in the arc discharge region of the chamber, maintaining the chamber wall at a positive voltage relative to the filament and at a magnitude for an optimum percentage of N[sup +] ions in the extracted ion beams, disposing a hot liner within the chamber and near the chamber wall to limit recombination of N[sup +] ions into the N[sub 2][sup +] ions, spacing the magnets of the magnetic filter from each other for optimum percentage of N[sup 3] ions in the extracted ion beams, and maintaining a relatively low pressure downstream of the extraction orifice and of a magnitude (preferably within the range of 3-8[times]10[sup [minus]4] torr) for an optimum percentage of N[sup +] ions in the extracted ion beam.

A pepper-pot emittance meter for low-energy heavy-ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kremers, H. R.; Beijers, J. P. M.; Brandenburg, S.

2013-02-15

A novel emittance meter has been developed to measure the four-dimensional, transverse phase-space distribution of a low-energy ion beam using the pepper-pot technique. A characteristic feature of this instrument is that the pepper-pot plate, which has a linear array of holes in the vertical direction, is scanned horizontally through the ion beam. This has the advantage that the emittance can also be measured at locations along the beam line where the beam has a large horizontal divergence. A set of multi-channel plates, scintillation screen, and ccd camera is used as a position-sensitive ion detector allowing a large range of beammore » intensities that can be handled. This paper describes the design, construction, and operation of the instrument as well as the data analysis used to reconstruct the four-dimensional phase-space distribution of an ion beam. Measurements on a 15 keV He{sup +} beam are used as an example.« less

An ion beam facility based on a 3 MV tandetron accelerator in Sichuan University, China

NASA Astrophysics Data System (ADS)

Han, Jifeng; An, Zhu; Zheng, Gaoqun; Bai, Fan; Li, Zhihui; Wang, Peng; Liao, Xiaodong; Liu, Mantian; Chen, Shunli; Song, Mingjiang; Zhang, Jun

2018-03-01

A new ion beam facility based on a 3 MV tandetron accelerator system has been installed in Sichuan University, China. The facility was developed by High Voltage Engineering Europa and consists of three high-energy beam lines including the ion beam analysis, ion implantation and nuclear physics experiment end stations, respectively. The terminal voltage stability of the accelerator is better than ±30 V, and the brightness of the proton beam is approximately 5.06 A/rad2/m2/eV. The system demonstrates a great application potential in fields such as nuclear, material and environmental studies.

Intense beams from gases generated by a permanent magnet ECR ion source at PKU.

PubMed

Ren, H T; Peng, S X; Lu, P N; Yan, S; Zhou, Q F; Zhao, J; Yuan, Z X; Guo, Z Y; Chen, J E

2012-02-01

An electron cyclotron resonance (ECR) ion source is designed for the production of high-current ion beams of various gaseous elements. At the Peking University (PKU), the primary study is focused on developing suitable permanent magnet ECR ion sources (PMECRs) for separated function radio frequency quadrupole (SFRFQ) accelerator and for Peking University Neutron Imaging Facility. Recently, other kinds of high-intensity ion beams are required for new acceleration structure demonstration, simulation of fusion reactor material irradiation, aviation bearing modification, and other applications. So we expanded the ion beam category from O(+), H(+), and D(+) to N(+), Ar(+), and He(+). Up to now, about 120 mA of H(+), 83 mA of D(+), 50 mA of O(+), 63 mA of N(+), 70 mA of Ar(+), and 65 mA of He(+) extracted at 50 kV through a φ 6 mm aperture were produced by the PMECRs at PKU. Their rms emittances are less than 0.2 π mm mrad. Tungsten samples were irradiated by H(+) or He(+) beam extracted from this ion source and H∕He holes and bubbles have been observed on the samples. A method to produce a high intensity H∕He mixed beam to study synergistic effect is developed for nuclear material irradiation. To design a He(+) beam injector for coupled radio frequency quadruple and SFRFQ cavity, He(+) beam transmission experiments were carried out on PKU low energy beam transport test bench and the transmission was less than 50%. It indicated that some electrode modifications must be done to decrease the divergence of He(+) beam.

High efficiency ion beam accelerator system

NASA Technical Reports Server (NTRS)

Aston, G.

1981-01-01

An ion accelerator system that successfully combines geometrical and electrostatic focusing principles is presented. This accelerator system uses thin, concave, multiple-hole, closely spaced graphite screen and focusing grids which are coupled to single slot accelerator and decelerator grids to provide high ion extraction efficiency and good focusing. Tests with the system showed a substantial improvement in ion beam current density and collimation as compared with a Pierce electrode configuration. Durability of the thin graphite screen and focusing grids has been proven, and tests are being performed to determine the minimum screen and focusing grid spacing and thickness required to extract the maximum reliable beam current density. Compared with present neutral beam injector accelerator systems, this one has more efficient ion extraction, easier grid alignment, easier fabrication, a less cumbersome design, and the capacity to be constructed in a modular fashion. Conceptual neutral beam injector designs using this modular approach have electrostatic beam deflection plates downstream of each module.

Investigations on the structure of the extracted ion beam from an electron cyclotron resonance ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spaedtke, P.; Lang, R.; Maeder, J.

2012-02-15

Using improved beam diagnostic tools, the structure of an ion beam extracted from an electron cyclotron resonance ion source (ECRIS) becomes visible. Especially viewing targets to display the beam profile and pepper pot devices for emittance measurements turned out to be very useful. On the contrary, diagnostic tools integrating over one space coordinate like wire harps for profile measurements or slit-slit devices, respectively slit-grid devices to measure the emittance might be applicable for beam transport investigations in a quadrupole channel, but are not very meaningful for investigations regarding the given ECRIS symmetry. Here we try to reproduce the experimentally foundmore » structure on the ion beam by simulation. For the simulation, a certain model has to be used to reproduce the experimental results. The model is also described in this paper.« less

On the generation of cnoidal waves in ion beam-dusty plasma containing superthermal electrons and ions

NASA Astrophysics Data System (ADS)

El-Bedwehy, N. A.

2016-07-01

The reductive perturbation technique is used for investigating an ion beam-dusty plasma system consisting of two opposite polarity dusty grains, and superthermal electrons and ions in addition to ion beam. A two-dimensional Kadomtsev-Petviashvili equation is derived. The solution of this equation, employing Painlevé analysis, leads to cnoidal waves. The dependence of the structural features of these waves on the physical plasma parameters is investigated.

On the generation of cnoidal waves in ion beam-dusty plasma containing superthermal electrons and ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Bedwehy, N. A., E-mail: nab-elbedwehy@yahoo.com

2016-07-15

The reductive perturbation technique is used for investigating an ion beam-dusty plasma system consisting of two opposite polarity dusty grains, and superthermal electrons and ions in addition to ion beam. A two-dimensional Kadomtsev–Petviashvili equation is derived. The solution of this equation, employing Painlevé analysis, leads to cnoidal waves. The dependence of the structural features of these waves on the physical plasma parameters is investigated.

Ion beam development for the needs of the JYFL nuclear physics programme.

PubMed

Koivisto, H; Suominen, P; Ropponen, T; Ropponen, J; Koponen, T; Savonen, M; Toivanen, V; Wu, X; Machicoane, G; Stetson, J; Zavodszky, P; Doleans, M; Spädtke, P; Vondrasek, R; Tarvainen, O

2008-02-01

The increased requirements towards the use of higher ion beam intensities motivated us to initiate the project to improve the overall transmission of the K130 cyclotron facility. With the facility the transport efficiency decreases rapidly as a function of total beam intensity extracted from the JYFL ECR ion sources. According to statistics, the total transmission efficiency is of the order of 10% for low beam intensities (I(total)< or =0.7 mA) and only about 2% for high beam intensities (I(total)>1.5 mA). Requirements towards the use of new metal ion beams for the nuclear physics experiments have also increased. The miniature oven used for the production of metal ion beams at the JYFL is not able to reach the temperature needed for the requested metal ion beams. In order to fulfill these requirements intensive development work has been performed. An inductively and a resistively heated oven has successfully been developed and both are capable of reaching temperatures of about 2000 degrees C. In addition, sputtering technique has been tested. GEANT4 simulations have been started in order to better understand the processes involved with the bremsstrahlung, which gives an extra heat load to cryostat in the case of superconducting ECR ion source. Parallel with this work, a new advanced ECR heating simulation program has been developed. In this article we present the latest results of the above-mentioned projects.

Focused helium-ion-beam-induced deposition

NASA Astrophysics Data System (ADS)

Alkemade, P. F. A.; Miro, H.

2014-12-01

The recent introduction of the helium ion microscope (HIM) offers new possibilities for materials modification and fabrication with spatial resolution below 10 nm. In particular, the specific interaction of He+ ions in the tens of keV energy range with materials—i.e., minimal deflection and mainly energy loss via electronic excitations—renders the HIM a special tool for ion-beam-induced deposition. In this work, an overview is given of all studies of helium-ion-beam-induced deposition (He-IBID) that appeared in the literature before summer 2014. Continuum models that describe the deposition processes are presented in detail, with emphasis on precursor depletion and replenishment. In addition, a Monte Carlo model is discussed. Basic experimental He-IBID studies are critically examined. They show deposition rates of up to 0.1 nm3/ion. Analysis by means of a continuum model yields the precursor diffusion constant and the cross sections for beam-induced precursor decomposition and beam-induced desorption. Moreover, it is shown that deposition takes place only in a small zone around the beam impact point. Furthermore, the characterization of deposited materials is discussed in terms of microstructure and resistivity. It is shown that He-IBID material resembles more electron-beam-induced-deposition (EBID) material than Ga-ion-beam-induced-deposition (Ga-IBID) material. Nevertheless, the spatial resolution for He-IBID is in general better than for EBID and Ga-IBID; in particular, proximity effects are minimal.

Production of multicharged metal ion beams on the first stage of tandem-type ECRIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagino, Shogo, E-mail: hagino@nf.eie.eng.osaka-u.ac.jp; Nagaya, Tomoki; Nishiokada, Takuya

2016-02-15

Multicharged metal ion beams are required to be applied in a wide range of fields. We aim at synthesizing iron-endohedral fullerene by transporting iron ion beams from the first stage into the fullerene plasma in the second stage of the tandem-type electron cyclotron resonance ion source (ECRIS). We developed new evaporators by using a direct ohmic heating method and a radiation heating method from solid state pure metal materials. We investigate their properties in the test chamber and produce iron ions on the first stage of the tandem-type ECRIS. As a result, we were successful in extracting Fe{sup +} ionmore » beams from the first stage and introducing Fe{sup +} ion beams to the second stage. We will try synthesizing iron-endohedral fullerene on the tandem-type ECRIS by using these evaporators.« less

Monoatomic and cluster beam effect on ToF-SIMS spectra of self-assembled monolayers on gold

NASA Astrophysics Data System (ADS)

Tuccitto, N.; Torrisi, V.; Delfanti, I.; Licciardello, A.

2008-12-01

Self-assembled monolayers represent well-defined systems that is a good model surface to study the effect of primary ion beams used in secondary ion mass spectrometry. The effect of polyatomic primary beams on both aliphatic and aromatic self-assembled monolayers has been studied. In particular, we analysed the variation of the relative secondary ion yield of both substrate metal-cluster (Au n-) in comparison with the molecular ions (M -) and clusters (M xAu y-) by using Bi +, Bi 3+, Bi 5+ beams. Moreover, the differences in the secondary ion generation efficiency are discussed. The main effect of the cluster beams is related to an increased formation of low-mass fragments and to the enhancement of the substrate related gold-clusters. The results show that, at variance of many other cases, the static SIMS of self-assembled monolayers does not benefit of the use of polyatomic primary ions.

Status of the SPIRAL2 injector commissioning

NASA Astrophysics Data System (ADS)

Thuillier, T.; Angot, J.; Barué, C.; Bertrand, P.; Biarrotte, J. L.; Canet, C.; Denis, J.-F.; Ferdinand, R.; Flambard, J.-L.; Jacob, J.; Jardin, P.; Lamy, T.; Lemagnen, F.; Maunoury, L.; Osmond, B.; Peaucelle, C.; Roger, A.; Sole, P.; Touzery, R.; Tuske, O.; Uriot, D.

2016-02-01

The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3 aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ˜50. A status of its assembly is proposed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thuillier, T., E-mail: thuillier@lpsc.in2p3.fr; Angot, J.; Jacob, J.

The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3more » aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ∼50. A status of its assembly is proposed.« less

Status of the SPIRAL2 injector commissioning.

PubMed

Thuillier, T; Angot, J; Barué, C; Bertrand, P; Biarrotte, J L; Canet, C; Denis, J-F; Ferdinand, R; Flambard, J-L; Jacob, J; Jardin, P; Lamy, T; Lemagnen, F; Maunoury, L; Osmond, B; Peaucelle, C; Roger, A; Sole, P; Touzery, R; Tuske, O; Uriot, D

2016-02-01

The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3 aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ∼50. A status of its assembly is proposed.

Uniform heating of materials into the warm dense matter regime with laser-driven quasimonoenergetic ion beams

DOE PAGES

Bang, W.; Albright, B. J.; Bradley, P. A.; ...

2015-12-01

In a recent experiment at the Trident laser facility, a laser-driven beam of quasimonoenergetic aluminum ions was used to heat solid gold and diamond foils isochorically to 5.5 and 1.7 eV, respectively. Here theoretical calculations are presented that suggest the gold and diamond were heated uniformly by these laser-driven ion beams. According to calculations and SESAME equation-of-state tables, laser-driven aluminum ion beams achievable at Trident, with a finite energy spread of ΔE/E~20%, are expected to heat the targets more uniformly than a beam of 140-MeV aluminum ions with zero energy spread. As a result, the robustness of the expected heatingmore » uniformity relative to the changes in the incident ion energy spectra is evaluated, and expected plasma temperatures of various target materials achievable with the current experimental platform are presented.« less

Neutron interrogation systems using pyroelectric crystals and methods of preparation thereof

DOEpatents

Tang, Vincent; Meyer, Glenn A.; Falabella, Steven; Guethlein, Gary; Rusnak, Brian; Sampayan, Stephen; Spadaccini, Christopher M.; Wang, Li-Fang; Harris, John; Morse, Jeff

2017-08-01

According to one embodiment, an apparatus includes a pyroelectric crystal, a deuterated or tritiated target, an ion source, and a common support coupled to the pyroelectric crystal, the deuterated or tritiated target, and the ion source. In another embodiment, a method includes producing a voltage of negative polarity on a surface of a deuterated or tritiated target in response to a temperature change of a pyroelectric crystal, pulsing a deuterium ion source to produce a deuterium ion beam, accelerating the deuterium ion beam to the deuterated or tritiated target to produce a neutron beam, and directing the ion beam onto the deuterated or tritiated target to make neutrons using a voltage of the pyroelectric crystal and/or an HGI surrounding the pyroelectric crystal. The directionality of the neutron beam is controlled by changing the accelerating voltage of the system. Other apparatuses and methods are presented as well.

Uniform heating of materials into the warm dense matter regime with laser-driven quasimonoenergetic ion beams

NASA Astrophysics Data System (ADS)

Bang, W.; Albright, B. J.; Bradley, P. A.; Vold, E. L.; Boettger, J. C.; Fernández, J. C.

2015-12-01

In a recent experiment at the Trident laser facility, a laser-driven beam of quasimonoenergetic aluminum ions was used to heat solid gold and diamond foils isochorically to 5.5 and 1.7 eV, respectively. Here theoretical calculations are presented that suggest the gold and diamond were heated uniformly by these laser-driven ion beams. According to calculations and SESAME equation-of-state tables, laser-driven aluminum ion beams achievable at Trident, with a finite energy spread of ΔE /E ˜20 %, are expected to heat the targets more uniformly than a beam of 140-MeV aluminum ions with zero energy spread. The robustness of the expected heating uniformity relative to the changes in the incident ion energy spectra is evaluated, and expected plasma temperatures of various target materials achievable with the current experimental platform are presented.

Ion beam accelerator system

NASA Technical Reports Server (NTRS)

Aston, G. (Inventor)

1981-01-01

A system is described that combines geometrical and electrostatic focusing to provide high ion extraction efficiency and good focusing of an accelerated ion beam. The apparatus includes a pair of curved extraction grids with multiple pairs of aligned holes positioned to direct a group of beamlets along converging paths. The extraction grids are closely spaced and maintained at a moderate potential to efficiently extract beamlets of ions and allow them to combine into a single beam. An accelerator electrode device downstream from the extraction grids is at a much lower potential than the grids to accelerate the combined beam. The application of the system to ion implantation is mentioned.

Liquid metal ion source assembly for external ion injection into an electron string ion source (ESIS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Segal, M. J., E-mail: mattiti@gmail.com; University of Cape Town, Rondebosch, Cape Town 7700; Bark, R. A.

An assembly for a commercial Ga{sup +} liquid metal ion source in combination with an ion transportation and focusing system, a pulse high-voltage quadrupole deflector, and a beam diagnostics system has been constructed in the framework of the iThemba LABS (Cape Town, South Africa)—JINR (Dubna, Russia) collaboration. First, results on Ga{sup +} ion beam commissioning will be presented. Outlook of further experiments for measurements of charge breeding efficiency in the electron string ion source with the use of external injection of Ga{sup +} and Au{sup +} ion beams will be reported as well.

Large Area Microcorrals and Cavity Formation on Cantilevers using a Focused Ion Beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saraf, Laxmikant V.; Britt, David W.

2011-09-14

We utilize focused ion beam (FIB) to explore various sputtering parameters to form large area microcorrals and cavities on cantilevers. Microcorrals were rapidly created by modifying ion beam blur and overlaps. Modification in FIB sputtering parameters affects the periodicity and shape of corral microstructure. Cantilever deflections show ion beam amorphization effects as a function of sputtered area and cantilever base cavities with or without side walls. The FIB sputtering parameters address a method for rapid creation of a cantilever tensiometer with integrated fluid storage and delivery.

Ion beam synthesis of Au nanoparticles embedded nano-composite glass

NASA Astrophysics Data System (ADS)

Varma, Ranjana S.; Kothari, D. C.; Kumar, Ravi; Kumar, P.; Santra, S. S.; Thomas, R. G.

2013-02-01

Ion beam mixing using low energy (LE) ion beams (100 keV Ar+) has been used to form Au nanoparticles in the near-surface region of fused silica glasses. Effect of swift heavy ion (SHI) irradiation (with 120 MeV Ag9+), on the nanoparticles has been studied. Diffusion length of Au after the beam mixing and the irradiation has been found to be 14nm. SHI irradiation causes the increase in the size of the nanoparticles, reduction in size-distribution and increase in number density.

Stripline fast faraday cup for measuring GHz structure of ion beams

DOEpatents

Bogaty, John M.

1992-01-01

The Stripline Fast Faraday Cup is a device which is used to quantitatively and qualitatively measure gigahertz time structure characteristics of ion beams with energies up to at least 30 Mev per nucleon. A stripline geometry is employed in conjunction with an electrostatic screen and a Faraday cup to provide for analysis of the structural characteristics of an ion beam. The stripline geometry allows for a large reduction in the size of the instrument while the electrostatic screen permits measurements of the properties associated with low speed ion beams.

Focused ion beam system

DOEpatents

Leung, Ka-Ngo; Gough, Richard A.; Ji, Qing; Lee, Yung-Hee Yvette

1999-01-01

A focused ion beam (FIB) system produces a final beam spot size down to 0.1 .mu.m or less and an ion beam output current on the order of microamps. The FIB system increases ion source brightness by properly configuring the first (plasma) and second (extraction) electrodes. The first electrode is configured to have a high aperture diameter to electrode thickness aspect ratio. Additional accelerator and focusing electrodes are used to produce the final beam. As few as five electrodes can be used, providing a very compact FIB system with a length down to only 20 mm. Multibeamlet arrangements with a single ion source can be produced to increase throughput. The FIB system can be used for nanolithography and doping applications for fabrication of semiconductor devices with minimum feature sizes of 0.1 .mu.m or less.

Focused ion beam system

DOEpatents

Leung, K.; Gough, R.A.; Ji, Q.; Lee, Y.Y.

1999-08-31

A focused ion beam (FIB) system produces a final beam spot size down to 0.1 {mu}m or less and an ion beam output current on the order of microamps. The FIB system increases ion source brightness by properly configuring the first (plasma) and second (extraction) electrodes. The first electrode is configured to have a high aperture diameter to electrode thickness aspect ratio. Additional accelerator and focusing electrodes are used to produce the final beam. As few as five electrodes can be used, providing a very compact FIB system with a length down to only 20 mm. Multibeamlet arrangements with a single ion source can be produced to increase throughput. The FIB system can be used for nanolithography and doping applications for fabrication of semiconductor devices with minimum feature sizes of 0.1 m or less. 13 figs.