PPPL, Princeton, New Jersey, USA
A recently developed novel perturbative Hamiltonian transformation method which allows the determination of approximate matched kinetic quasi-equilibrium solutions for an intense charged particle beam propagating through a periodic focusing quadrupole lattice is presented.* Using this method we have identified numerically the class of self-consistent periodic kinetic 'equilibria' for intense beam propagation in alternating-gradient focusing systems, and extended the nonlinear perturbative particle simulation method to intense beam propagation in such systems. The new method has been implemented in the nonlinear perturbative particle-in-cell code BEST which is used to study properties of the newly constructed beam 'equilibria'. The results of these studies are presented and analyzed in detail.
* E.A. Startsev, R.C. Davidson and M. Dorf, Phys. Rev. ST Accel. Beams 13, 064402 (2010).
PPPL, Princeton, New Jersey, USA
LLNL, Livermore, California, USA
A variety of masks were installed on the Paul Trap Simulator Experiment (PTSX) cesium ion source in order to perform experiments with modified transverse distribution functions. Masks were used to block injection of ions into the PTSX chamber, thereby creating injected transverse beam distributions that were either hollow, apertured and centered, apertured and off-center, or comprising five beamlets. Experiments were performed using either trapped plasmas or the single-pass, streaming, mode of PTSX. The transverse streaming current profiles clearly demonstrated centroid oscillations. Further analysis of these profiles also shows the presence of certain collective beam modes, such as azimuthally symmetric radial modes. When these plasmas are trapped for thousands of lattice periods, the plasma quickly relaxes to a state with an elevated effective transverse temperature and is subsequently stable. Both sinusoidal and periodic step function waveforms were used and the resulting difference in the measured transverse profiles will be discussed.
PPPL, Princeton, New Jersey, USA
LLNL, Livermore, California, USA
Columbia University, New York, USA
Neutralized drift compression offers an effective means for particle beam focusing and current amplification. In neutralized drift compression, a linear longitudinal velocity tilt is applied to the beam pulse, so that the beam pulse compresses as it drifts in the focusing section. The beam intensity can increase more than a factor of 100 in the longitudinal direction. We have performed an analytical study of how errors in the velocity tilt acquired by the beam in the induction bunching module limits the maximum longitudinal compression. It is found in general that the compression ratio is determined by the relative errors in the velocity tilt. That is, one-percent errors may limit the compression to a factor of one hundred. However, part of pulse where the errors are small may compress to much higher values determined by the initial thermal spread of the beam pulse. Examples of slowly varying and rapidly varying errors compared to the beam pulse duration are studied.
LLNL, Livermore, California, USA
LBNL, Berkeley, California, USA
PPPL, Princeton, New Jersey, USA
UMD, College Park, Maryland, USA
Intense heavy-ion beams have long been considered a promising driver option for inertial-fusion energy production. This paper briefly compares inertial confinement fusion (ICF) to the more-familiar magnetic- confinement approach and presents some advantages of using beams of heavy ions to drive ICF instead of lasers. Key design choices in heavy-ion fusion (HIF) facilities are discussed, particularly the type of accelerator. We then review experiments carried out at Lawrence Berkeley National Laboratory (LBNL) over the past thirty years to understand various aspects of HIF driver physics. A brief review follows of present HIF research in the US and abroad, focusing on a new facility, NDCX-II, being built at LBNL to study the physics of warm dense matter heated by ions, as well as aspects of HIF target physics. Future research directions are briefly summarized.