Progress toward a microsecond duration, repetitive, intense-ion beam accelerator

Summary form only given. A number of intense ion beam applications are emerging requiring repetitive high-average-power beams. These applications include ablative deposition of thin films, rapid melt and resolidification for surface property enhancement; advanced diagnostic neutral beams for the next generation of Tokamaks, and intense pulsed-neutron sources. In the Physics Division at Los Alamos National Laboratory, we are developing a 250 keV, 15 kA, 1 /spl mu/s duration, 1-30 Hz intense-ion beam accelerator called CHAMP (Continuous High Average-Power Microsecond Pulser). The accelerator will use a magnetically insulated extraction diode in ballistically focused geometry (45/sup 0/ full focusing angle with 30 cm focal length). The 450 cm/sup 2/ active plasma anode can utilize any gaseous species allowing selection of the ion penetration depth to optimize various materials applications, and allowing the use of hydrogen isotopes for D-T fusion neutron production. Gas is supplied from a puff valve located on the system axis and is ducted through a radial flow channel. The valve will be actuated by a metallic diaphragm driven either by eddy currents or a voice-coil mechanism. The anode plasma is formed by currents induced in the gas by a fast-rising (1.25 /spl mu/s quarter cycle risetime) current (15 kA peak) in a two-turn, flat, spiral wound coil with four parallel sets of windings. Higher frequency oscillations at 8 MHz will be induced in the windings to promote rapid and complete ionization of the gas. The insulating transverse magnetic field (B/spl sim/2B/sub crit/) will be generated by two magnetic field coils on the grounded cathode focusing cones. The final magnetic coil power system will use solid-state switching and energy recovery.