Development of a low inductance metal vapor vacuum arc (LIZ-MEVVA) ion source*

We are continuing development of a Low Impedance Z-Discharge Metal Vapor Vacuum Arc (LIZ-MEVVA) to produce high charge state metallic ions. The plasma arc occurs in a diode connected to a 1.4$\mu $F capacitor by a low impedance transmission line. The capacitor is charged to between 6 and 12kV and stores up to 100J of energy. Currently the electrode material is aluminum and the system has been run in two regimes: an LC dominated ``ringing'' arc of period 4.1$\mu $s and a 1-3$\mu $s wide ``pulsed'' arc, where a small series resistance has been added to critically damp ringing. The current in the plasma arc can be up to 30 kA. A 1$\mu $s pulsed extraction voltage of up to 10kV, which has a variable delay with respect to the start of the arc current, is used to accelerate the ions. Ions are analyzed using time-of-flight and, more recently, a Thomson parabola. To date we have detected Al$^{+}$, Al$^{++ }$and Al$^{+++}$.