[en] The H^- beam extraction from the multicusp ion source for the Spallation Neutron Source (SNS) is being simulated utilizing the 3D ion optics code KOBRA and the 3D magnet code TOSCA. Design of the extraction system for the SNS project requires proper simulation of the extraction of both electrons and H^- ions. The goal is to optimize the magnetic field of the extraction system so that the electrons are completely deflected and captured at the plasma electrode

[en] The low-energy beam transport system (LEBT) for the Spallation Neutron Source (SNS) is required to transport 35 mA of a 65 keV H^- ion beam from the ion source to the RFQ accelerator entrance with a normalized rms emittance of less than 0.15 π mm mrad. A radio frequency driven, magnetically filtered multicusp ion source is under development at LBNL. The H^- beam extraction from this ion source is being simulated utilizing the 2D-computer code IGUN [Rev. Sci. Instr. 63 (1992) 2756]. An H^- ion extraction model is discussed. Computational results are presented for the H^- ion beam emittance of a single aperture two electrode extraction system and for the tuning range of the low-energy beam transport system

[en] A design study for the extraction system of the 3rd Generation super conducting ECR ion source at LBNL is presented. The magnetic design of the ion source has a mirror field of 4 T at the injection and 3 T at the extraction side and a radial field of 2.4 T at the plasma chamber wall. Therefore, the ion beam formation takes place in a strong axial magnetic field. Furthermore the axial field drops from 3 T to 0.4 T within the first 30 cm. The influence of the high magnetic field on the ion beam extraction and matching to the beam line is investigated. The extraction system is first simulated with the 2D ion trajectory code IGUN with an estimated mean charge state of the extracted ion beam. These results are then compared with the 2D code AXCEL-INP, which can simulate the extraction of ions with different charge states. Finally, the influence of the strong magnetic hexapole field is studied with the three dimensional ion optics code KOBRA. The introduced tool set can be used to optimize the extraction system of the super conducting ECR ion source

[en] The Virtual National Laboratory for Heavy-Ion Fusion Science is developing a physics design for NDCX-II, an experiment to study warm dense matter heated by ions near the Bragg-peak energy. Present plans call for using about thirty induction cells to accelerate 30 nC of Li+ ions to more than 3 MeV, followed by neutralized drift-compression. To heat targets to useful temperatures, the beam must be compressed to a sub-millimeter radius and a duration of about 1 ns. An interactive 1-D particle-in-cell simulation with an electrostatic field solver, acceleation-gap fringe fields, and a library of realizable analytic waveforms has been used for developing NDCX-II acceleration schedules. Axisymmetric simulations with WARP have validated this 1-D model and have been used both to design transverse focusing and to compensate for injection non-uniformities and radial variation of the fields. Highlights of this work are presented here.

[en] Over the next three years the research program of the Heavy Ion Fusion Virtual National Laboratory (HIF-VNL), a collaboration among LBNL, LLNL, and PPPL, is focused on separate scientific experiments in the injection, transport and focusing of intense heavy ion beams at currents from 100 mA to 1 A. As a next major step in the HIF-VNL program, we aim for a complete ''source-to-target'' experiment, the Integrated Beam Experiment (IBX). By combining the experience gained in the current separate beam experiments IBX would allow the integrated scientific study of the evolution of a single heavy ion beam at high current (∼1 A) through all sections of a possible heavy ion fusion accelerator: the injection, acceleration, compression, and beam focusing. This paper describes the main parameters and technology choices of the planned IBX experiment. IBX will accelerate singly charged potassium or argon ion beams up to 10 MeV final energy and a longitudinal beam compression ratio of 10, resulting in a beam current at target of more than 10 Amperes. Different accelerator cell design options are described in detail: Induction cores incorporating either room temperature pulsed focusing-magnets or superconducting magnets

[en] The Virtual National Laboratory for Heavy-Ion Fusion Science is developing a physics design for NDCX-II, an experiment to study warm dense matter heated by ions near the Bragg-peak energy. Present plans call for using about thirty induction cells to accelerate 30 nC of Li+ ions to more than 3 MeV, followed by neutralized drift-compression. To heat targets to useful temperatures, the beam must be compressed to a millimeter-scale radius and a duration of about 1 ns. An interactive 1-D particle-in-cell simulation with an electrostatic field solver, acceleration-gap fringe fields, and a library of realizable analytic waveforms has been used for developing NDCX-II acceleration schedules. Axisymmetric simulations with WARP have validated this 1-D model and have been used both to design transverse focusing and to compensate for injection non-uniformities and radial variation of the fields. Highlights of this work are presented here

[en] The Virtual National Laboratory for Heavy-Ion Fusion Science is developing a physics design for NDCX-II, an experiment to study warm dense matter heated by ions. Present plans call for using 34 induction cells to accelerate 45 nC of Li⁺ ions to more than 3 MeV, followed by neutralized drift-compression. To heat targets to the desired temperatures, the beam must be compressed to a millimeter-scale radius and a duration of about 1 ns. A novel NDCX-II acceleration schedule has been developed using an interactive one-dimensional particle-in-cell simulation ASP to model the longitudinal physics and axisymmetric WARP simulations to validate the 1-D model and add transverse focusing. Three-dimensional Warp runs have been used recently to study the sensitivity to misalignments in the focusing solenoids

[en] In order to investigate the ion-optical parameters of the AECR-U injection line into the 88-Inch Cyclotron, an electrostatic-deflection-type emittance scanner has been designed and constructed. It allows fast on-line measurements, while tuning the ion beam through the cyclotron. Emittance measurements have been performed for various high charge state ions. First results indicate a strong mass dependence of the normalized beam emittance. For example the normalized rms emittance for protons (0.24π.mm.mrad) is four times higher than for O⁶⁺ (0.06π.mm.mrad) and about 8 times higher than Kr¹⁹⁺ (0.03π.mm.mrad). Furthermore it was found, that the emittance values are approximately independent of the current at the medium ion beam intensities. The predominant factor on the beam emittance is shown to be the plasma stability. The emittance measurements and the results are discussed in the paper. (orig.)

[en] Over the next three years the research program of the Heavy Ion Fusion Virtual National Laboratory (HIF-VNL), a collaboration among LBNL, LLNL, and PPPL, is focused on separate scientific experiments in the injection, transport and focusing of intense heavy ion beams at currents from 100 mA to 1 A. As a next major step in the HIF-VNL program, they aim for a complete ''source-to-target'' experiment, the Integrated Beam Experiment (IBX). By combining the experience gained in the current separate beam experiments IBX would allow the integrated scientific study of the evolution of a high current (∼1 A) single heavy ion beam through all sections of a possible heavy ion fusion accelerator: the injection, acceleration, compression, and beam focusing. This paper describes the main parameters and technology choices of the proposed IBX experiment. IBX will accelerate singly charged potassium or argon ion beams up to 10 MeV final energy and a longitudinal beam compression ratio of 10, resulting in a beam current at the target of more than 10 Amperes. The different accelerator cell design options are described in detail, in particular the induction core modules incorporating either room temperature pulsed focusing-magnets or superconducting magnets

[en] The construction of VENUS, an Electron Cyclotron Resonance ion source designed to operate at 28 GHz, is nearing completion. Tests with the superconducting magnet assembly produced axial magnetic field strengths of 4 T at injection and 3 T at extraction and a sextupole field of 2 T at the plasma wall. These fields are sufficient for optimum operation at 28 GHz. We expect a shift to higher charge states and an increase in the beam intensities (about 4 times) compared to those obtained with the AECR-U, which operates at 14 GHz. Initial operation will be at 18 GHz, but best performance is expected when operation with a 10 kW, 28 GHz gyrotron becomes possible. The high beam intensities and the large axial magnetic field at extraction make it challenging to extract, analyze and transport the beam into the 88-Inch Cyclotron. The analyzing system which consists of a solenoid lens and a large gap 18 cm spectrometer-magnet with higher order field corrections has been optimized utilizing 3D magnet and ray-tracing codes including space charge effects. The status of the construction and design aspects of the source and beam transport system are described below