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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
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
Author: D. V. Rose Publisher: ISBN: Category : Languages : en Pages :
Book Description
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
Author: Publisher: ISBN: Category : Languages : en Pages : 44
Book Description
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.
Author: J. M. Sellen Publisher: ISBN: Category : Languages : en Pages : 65
Book Description
A series of experiments are described which relate to the charge neutralization of a broad cesium ion beam under circumstances which simulate the conditions of space. This was accomplished by the use of pulsed beams and by the control of the boundary conditions in such a manner as to reduce to an extremely low level the electric fields between these boundaries and the ejected plasma. The period of ion turn-around was reduced to values below the present limits of measurement (approx. 1 micro-sec). The ejected plasma was found to possess a high degree of overall neutrality. The fraction of ions which were matched by the presence of an electron equaled or exceeded 0.998. The plasma was well neutralized on a point-by-point basis. It was also demonstrated that for fixed ion source perveance the neutralization is independent of the acceleration voltage.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The Argonne National Laboratory Ion Beam Fusion group is presently studying the transport and charge neutralization of beams of heavy ions using a small PDPE (Penning Discharge Pierce Extraction) ion source. This source is a scaled down version of the high current high brightness source of the 1.5 MeV Heavy Ion Preaccelerator. Both sources were developed by Hughes Research Laboratories. This report gives results obtained with a low vacuum system (up to 5 x 10−7 torr static vacuum) and an 80 keV dc Xe/sup +1/ beam. The emphasis of these measurements was on neutralization times and space charge blow up of the beam.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The Argonne National Laboratory Ion Beam Fusion group is presently studying the transport and charge neutralization of beams of heavy ions using a small PDPE (Penning Discharge Pierce Extraction) ion source. This source is a scaled down version of the high current high brightness source of the 1.5 MeV Heavy Ion Preaccelerator. Both sources were developed by Hughes Research Laboratories. This report gives results obtained with a low vacuum system (up to 5 x 10/sup -7/ torr static vacuum) and an 80 keV dc Xe/sup +1/ beam. The emphasis of these measurements was on neutralization times and space charge blow up of the beam.
Author: National Research Council Publisher: National Academies Press ISBN: 030908637X Category : Science Languages : en Pages : 177
Book Description
Recent scientific and technical advances have made it possible to create matter in the laboratory under conditions relevant to astrophysical systems such as supernovae and black holes. These advances will also benefit inertial confinement fusion research and the nation's nuclear weapon's program. The report describes the major research facilities on which such high energy density conditions can be achieved and lists a number of key scientific questions about high energy density physics that can be addressed by this research. Several recommendations are presented that would facilitate the development of a comprehensive strategy for realizing these research opportunities.
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Author: D. V. Rose
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Author: J. M. Sellen
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Author: Ronald C. Davidson
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Author: National Research Council