Large radius transport channel studies for applications on Saturn

High-current relativistic electron beams (e-beams) produced on the Saturn pulsed power accelerator at Sandia National Laboratory (SNL) can be used to generate high dose bremsstrahlung radiation. Typically, multiple concentric ring diodes on Saturn produce currents of approximately 10 MA at voltages of about 1.8 MV. For some applications, radial convergence of the outer rings to smaller radius is required; one convergence technique studied here is Z-discharge transport (ZDT). To study the beam characteristics and transport efficiencies in ZDT channels at various pressures, 2D fluid/PIC hybrid simulations and bench-top experiments are performed in which R/sub channel//spl sim/L/sub channel/. Self-fields and collisional effects were modeled self-consistently using a tenuous medium model. Although simulations of an idealized ZDT channel demonstrated the efficacy of this scheme, bench-top experiments to generate the required discharge currents and plasma density profiles were discouraging. As an alternative, injection and transport of the e-beams through an un-ionized gas and focused by a current carrying cylindrical wire-array were simulated and found to be promising.