Search

A high‐current ion source is described in which a metal vapor vacuum arc is used to create the plasma from which the ion beam is extracted. An ion beam current of up to about 1 A has been measured at an extraction voltage of 25 kV for a range of metallic species spanning the periodic table from lithium to uranium. Multiply ionized charge states are seen up to as high as Q=6+ in the case of uranium. In the metal vapor vacuum arc, regions of intense current concentration are formed at the cathode, and it is at these regions, the cathode spots, that the cathode material is vaporized and ionized to form a dense, quasi‐neutral plasma which plumes away from the cathode surface. The plasma plume is caused to impinge upon a set of extractor grids, and the ion beam is extracted from the streaming metal plasma. A preliminary survey of the performance of the source has been made. We describe here the principle of operation of the source, the source design, and the results of those measurements that we have made to date.

An ion source in which ions of normally solid materials are easily produced. A plasma is generated in a gas adjacent the solid material from which ions are to be produced. The solid is negatively charged and the gas plasma ions bombard the solid, sputtering off ions of the solid. This is accomplished through the use of a Penning discharge with a cold cathode-type source and a centrally positioned and negatively charged dynode upon which the solid material is mounted, the dynode being electrically connected to the cathode and provided with an exit slit through which the metallic ions are extracted from plasma potential.

Microwave power resonant to the local electron cyclotron frequency has been coupled into the plasma discharge chamber of a hot‐cathode PIG (Philips or Penning Ionization Gauge) ion source. The extracted ion beam was monitored for changes in characteristics of the beam with and without application of the microwave power. No change was seen in the ion charge state distribution. A small but significant reduction in the beam noise level was seen, and this technique may thus find application in situations where beam quiescence is important.

We have investigated the effect of applying microwave power at the electron cyclotron frequency on the characteristics of the ion beam extracted from a hotcathode PIG ion source. No change was seen in the ion charge state distribution. A small but significant reduction in the beam noise level was seen, and it is possible that the technique may find application in situations where beam quiescence is important.

A new sputter-ion PIG source and magnet system, optimized for intermediate charge states, q/A of 0.02-0.03, is described. This source will be used with the new Wideroe-based injector for the SuperHILAC. Pulsed electrical currents of several emA of heavy metal ions have been produced in a normalized emittance area of .05? cm-mr. The source system is comprised of two electrically separate anode chambers, one in operation and one spare, which can be selected by remote control. The entire source head is small and quickly removable.