Download or read book Charge and Current Neutralization Physics of a Heavy Ion Beam During Final Transport written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Heavy ion fusion requires high power to be focussed onto a small pellet. If the reactor chamber pressure is below 10−4 to 10−5 Torr, beam compression will be limited by space charge unless neutralized by co-moving electrons. If higher chamber pressures are used, the heavy ion beam will create a significant number of background electrons during its propagation and will undergo stripping. The background electrons could provide the neutralization required for high beam intensities. In this paper we will focus on the physics associated with propagation through a fully ionized hydrogen plasma, so background electron generation is not included. One-dimensional electrostatic and two-dimensional fully electromagnetic particle-in-cell simulations are presented. If a background plasma is present, we find that coinjected electrons whose purpose is to charge and current neutralize the ion beam become two-stream unstable and no longer provide the thermally cool neutralization required. Further, we find that the ion induced background electron temperature is very sensitive to the ion beam to background electron charge density ratio.
Download or read book Comparison of Experimental Data and 3D Simulations of Ion Beam Neutralization from the Neutralized Transport Experiment written by and published by . This book was released on 2004 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Neutralized Transport Experiment (NTX) at Lawrence Berkeley National Laboratory has been designed to study the final focus and neutralization of high perveance ion beams for applications in heavy ion fusion (HIF) and high energy density physics (HEDP) experiments. Pre-formed plasmas in the last meter before the target of the scaled experiment provide a source of electrons which neutralize the ion current and prevent the space-charge induced spreading of the beam spot. NTX physics issues are discussed and experimental data is analyzed and compared with 3D particle-in-cell simulations. Along with detailed target images, 4D phase-space data of the NTX at the entrance of the neutralization region has been acquired. This data is used to provide a more accurate beam distribution with which to initialize the simulation. Previous treatments have used various idealized beam distributions which lack the detailed features of the experimental ion beam images. Simulation results are compared with NTX experimental measurements for 250 keV K ion beams with dimensionless perveance of 1-7 x 10−4. In both simulation and experiment, the deduced beam charge neutralization is close to the predicted maximum value.
Download or read book Physics of Neutralization of Intense High Energy Ion Beam Pulses by Electrons written by and published by . This book was released on 2010 with total page 567 pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutralization and focusing of intense charged particle beam pulses by electrons forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self- magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating through the background plasma. If controlled, this physical effect can be used for optimized beam transport over long distances.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Download or read book Fusion Energy Update written by and published by . This book was released on 1986 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma written by and published by . This book was released on 2009 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutralization and focusing of intense charged particle beam pulses by a background plasma forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating through the background plasma. If controlled, this physical effect can be used for optimized beam transport over long distances.
Download or read book Physics of Gas Breakdown for Ion Beam Transport in Gas written by and published by . This book was released on 1993 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Publications of Los Alamos Research written by Los Alamos National Laboratory and published by . This book was released on 1986 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heavy Ion Fusion Science written by R. C. Davidson and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past two years noteworthy experimental and theoretical progress has been made towards the top-level scientific question for the U.S. program in Heavy Ion Fusion Science and High Energy Density Physics: ''How can heavy ion beams be compressed to the high intensity required to create high energy density matter and fusion conditions''? [1]. New results in transverse and longitudinal beam compression, beam-target interaction, high-brightness transport, beam production, as well as a new scheme in beam acceleration will be reported. Longitudinal and Transverse Beam Compression: The Neutralized Transport Experiment (NTX) demonstrated transverse beam density enhancement by a factor greater than 100 when an otherwise space-charge dominated ion beam was neutralized by a plasma source [2]. This experiment was followed by the Neutralized Drift Compression Experiment (NDCX) in which an ion beam was longitudinally compressed by a factor of 50 [3]. This was accomplished by applying a linear head-to-tail velocity ''tilt'' to the beam, and then allowing the beam to drift through a meter-long neutralizing plasma. In both the transverse and longitudinal experiments, extensive 3-D simulations, using LSP, were carried out, and the agreement with experiments was excellent [4]. A three-dimensional kinetic model for longitudinal compression was developed, and it was shown that the Vlasov equation possesses a class of exact solutions for the problem [5]. Beam-Target Interaction: We have also made significant progress in identifying the unique role ion beams can play in heating material to warm dense matter (WDM) conditions. We have identified promising accelerator, beam, and target configurations, as well as new experiments on material properties. It is shown that the target temperature uniformity can be maximized if the ion energy at target corresponds to the maximum in the energy loss rate dE/dX [6]. Ions of moderate energy (a few to tens of MeV) may be used. The energy must be deposited in times much shorter than the hydrodynamic expansion time (ns for metallic foams at 0.01 to 0.1 times solid density). Hydrodynamic simulations [7] have confirmed that uniform conditions with temperature variations of less than a few per cent can be achieved. High-Brightness Transport: Unwanted electrons can lead to deleterious effects for high-brightness ion beam transport. We are studying electron accumulation in quadrupole and solenoid beam transport systems. Electrons can originate from background gas ionization, from beam-tubes struck by ions near grazing incidence, and from end-walls struck by ions near normal incidence [8]. In parallel with the experimental campaign, we have developed and implemented in WARP 3D a new approach to large time-step advancement of electron orbits, as well as a comprehensive suite of models for electrons, gas, and wall interactions [9]. If sufficient electrons are accumulated within the beam, severe distortion of the beam phase space can result. Simulations of this effect have reproduced the key features observed in the experiments. Beam Production: The merging-beamlet injector experiment recently completed demonstrates the feasibility of a compact, high-current injector for heavy ion fusion drivers. In our experiment, 119 argon ion beamlets at 400 keV beam energy were merged into an electrostatic quadrupole channel to form a single beam of 70 mA. The measured unnormalized transverse emittance (phase space area) of 200-250 mm-mrad for the merged beam met fusion driver requirement. These measurements are in good agreement with our particle-in-cell simulations using WARP3D [10]. We have also completed the physics design of a short-pulse injector suitable for WDM studies. Beam Acceleration: A new concept for acceleration, the Pulse Line Ion Accelerator PLIA [11], offers the potential of a very low cost accelerator for WDM studies. It is based on a traveling wave structure, using a simple geometry with a helical conductor. We have obtained experimental verification of the predicted PLIA beam dynamics. Measured energy gain, longitudinal phase space, and beam bunching are in good agreement with WARP3D simulations. Computational Models and Simulator Experiments: The pioneering merger of Adaptive Mesh Refinement and particle-in-cell methods [12] underlies much of the recent success of WARP3D. BEST, the Beam Equilibrium Stability and Transport code was optimized for massively parallel computers and applied to studies of the collective effects of 3D bunched beams [13] and the temperature-anisotropy instability [14]. Space-charge-dominated beam physics experiments relevant to long-path accelerators were carried out on the recently completed University of Maryland Electron Ring, and on the Paul Trap Simulator Experiment at PPPL.
Download or read book Simulations of Ion Beam Neutralization in Support of Theneutralized Transport Experiment written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Heavy ion fusion (HIF) requires the acceleration, transport, and focusing of many individual ion beams. Drift compression and beam combining prior to focusing result in [approx]100 individual ion beams with line-charge densities of order 10[sup -5] C/m. A focusing force is applied to the individual ion beams outside of the chamber. For neutralized ballistic chamber transport (NBT), these beams enter the chamber with a large radius (relative to the target spot size) and must overlap inside the chamber at small radius (roughly 3-mm radius) prior to striking the target. The physics of NBT, in particular the feasibility of achieving the required small spot size, is being examined in the Neutralized Transport Experiment (NTX) at Lawrence Berkeley National Laboratory. Interpreted by detailed particle-in-cell simulations of beam neutralization, experimental results are being used to validate theoretical and simulation models for driver scale beam transport. In the NTX experiment, a low-emittance 300-keV, 25-mA K[sup +] beam is focused 1 m downstream into a 4-cm radius pipe containing one or more plasma regions. The beam passes through the first 10-cm-long plasma, produced by an Al plasma arc source, just after the final focus magnet and propagates with the entrained electrons. A second, 10-cm-long plasma (produced with a cyclotron resonance plasma source) is created near focus to simulate the effects of a photo-ionized plasma created by the heated target in a fusion chamber. Given a 0.1-[pi]-mm-mrad beam emittance, two and three-dimensional particle-in-cell (PIC) LSP simulations of the beam neutralization predict a
Download or read book Simulations of Ion Beam Neutralization in Support of Theneutralized Transport Experiment written by D. V. Rose and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Heavy ion fusion (HIF) requires the acceleration, transport, and focusing of many individual ion beams. Drift compression and beam combining prior to focusing result in {approx}100 individual ion beams with line-charge densities of order 10{sup -5} C/m. A focusing force is applied to the individual ion beams outside of the chamber. For neutralized ballistic chamber transport (NBT), these beams enter the chamber with a large radius (relative to the target spot size) and must overlap inside the chamber at small radius (roughly 3-mm radius) prior to striking the target. The physics of NBT, in particular the feasibility of achieving the required small spot size, is being examined in the Neutralized Transport Experiment (NTX) at Lawrence Berkeley National Laboratory. Interpreted by detailed particle-in-cell simulations of beam neutralization, experimental results are being used to validate theoretical and simulation models for driver scale beam transport. In the NTX experiment, a low-emittance 300-keV, 25-mA K{sup +} beam is focused 1 m downstream into a 4-cm radius pipe containing one or more plasma regions. The beam passes through the first 10-cm-long plasma, produced by an Al plasma arc source, just after the final focus magnet and propagates with the entrained electrons. A second, 10-cm-long plasma (produced with a cyclotron resonance plasma source) is created near focus to simulate the effects of a photo-ionized plasma created by the heated target in a fusion chamber. Given a 0.1-{pi}-mm-mrad beam emittance, two and three-dimensional particle-in-cell (PIC) LSP simulations of the beam neutralization predict a
Download or read book Overview of Theory and Modeling in the Heavy Ion Fusion Virtual National Laboratory written by Ronald C. Davidson and published by . This book was released on 2002* with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1989 with total page 1384 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Intense Pulsed Ion Beams for Fusion Applications written by Stanley Humphries (Jr.) and published by . This book was released on 1980 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: The subject of this review paper is the field of intense pulsed ion beam generation and the potential application of the beams to fusion research. Considerable progress has been made over the past six years. The ion injectors discussed utilize the introduction of electrons into vacuum acceleration gaps in conjunction with high voltage pulsed power technology to achieve high output current. Power levels from injectors exceeding 1000 MW/cm2 have been obtained for pulse lengths on the order of 10−7 sec. The first part of the paper treats the physics and technology of intense ion beams. The second part is devoted to applications of intense ion beams in fusion research. A number of potential uses in magnetic confinement systems have been proposed.
Download or read book Transport of a Partially neutralized Ion Beam in a Heavy ion Fusion Reactor Chamber written by and published by . This book was released on 1995 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a heavy-ion driven, inertial confinement fusion power plant, a space-charge dominated beam of heavy ions must be transported through a reactor chamber and focused on a 2-3 mm spot at the target. The spot size at the target is determined by the beam emittance and space charge, plus chromatic aberrations in the focusing lens system and errors in aiming the beam. The gain of the ICF capsule depends on the focal spot size. We are investigating low density, nearly-ballistic transport using an electromagnetic, r-z particle-in-cell code. Even at low density (n (almost equal to) 5 x 1013 cm−3), beam stripping may be important. To offset the effects of stripping and reduce the space charge, the beam is partially charge neutralized via a pre-formed plasma near the chamber entrance. Additional electrons for charge neutralization come from ionization of the background gas by the beam. Simulations have shown that stripping can greatly increase the spot size; however, partial neutralization can offset most of this increase.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1988 with total page 908 pages. Available in PDF, EPUB and Kindle. Book excerpt: Includes all works deriving from DOE, other related government-sponsored information and foreign nonnuclear information.
