High-repetition-rate pulsed operation of a wire ion plasma source

Summary form only given. The wire ion plasma source (WIPS) has the potential as a high-density-plasma source and a large-cross sectional ion source that can be used for the secondary emission electron gun. The secondary emission electron gun of this type usually operates under the pulse mode and is suitable for high repetition rate operations. The WIPS is a cold-cathode gaseous discharge device based on the low-pressure wire discharge. The anode is a thin tungsten wire (/spl phi/0.2 mm). The cathode consists of a stainless steel cylinder (40 mm i.d., 100 mm long) which is set coaxially to the wire anode and the plates having central apertures (/spl phi/20 mm) at both ends. This configuration produces not only a radial logarithmic trapping potential but also an axial one for electrons, and permits low-pressure (/spl sim/10/sup -2/ Torr in helium) gaseous discharge to occur with very low applied voltage (/spl sim/1 kV). Pulsed discharges were accomplished by firing a capacitor bank of 24 nF. The charging voltages of the capacitor bank. were 3/spl sim/10 kV. The voltages were usually fed to the anode wire through a thyratron switch which has a short life time. So we developed a new method of initiating the pulsed discharge, which is accomplished by controlling the axial trapping of electrons.