We have identified a general final compression section for HIF drivers, the section between accelerator and the target. The beam are given a head to tail velocity tilt at the beginning of the section for longitudinal compression, while going through bends which direct it to the target at specific angle. The aim is to get the beams compressed while maintaining a small centroid offset after the bends. We used a specific example 1MJ driver with 500MeV Rb+1 ion beams. We studied the effect of minimizing dispersion using different bend strategies, and came up with a beamline point design with adiabatic bends. We also identified some factors that lead to emittance growth as well as the minimum pulse length and spot size on the target.

No abstract

No abstract

will be shown of the vacuum diode performance. The intense beam emitted by the diode presents unique design complications in connection with extractior of rf power. Various considerations are discussed such as the trade-offs between beam potential and kinetic energies, optimum shunt, impedance values, and advantages of discrete vs. distributed circuits. The various circuits that have been considered include conventional singlt gap designs, a distributed interaction structure, and a single gap triaxial circuit. Designs have been analyzed using analytical methods, rf codes, and particle in cell simulations. A description of the experimental hardware is given along with results of cold tests and power extraction results ~ §GPO6

Emittance posts limits on the key requirements of final pulse length and spot size on target in heavy ion fusion drivers. In this paper, we show studies on the effect of nonlinear space charge on longitudinal emittance growth in the drift compression section. We perform simulations, using the 3D PIC code WARP, for a high current beam under conditions of bends and longitudinal compression. The linear growth rate for longitudinal emittance turns out to depend only on the peak line charge density, and is independent of pulse length, velocity tilt, and/or the pipe and beam size. This surprisingly simple result is confirmed by simulations and analytic calculations.