SPARK SOURCE OF SOME METALS AND CARBON

Experimental results of comparative tests of a spark ion source (close d geometry) with a MEVVA ion source (open geometry) are presented in t his paper. Carbon (graphite) and some pure metals (such as Al, Cu, Ta) have been used as the working substances. It was discovered that the vapor ionization degree in the spark depended on the discharge gap sha pe that changed in time and became self-sustaining during the tests. I t is supposed that this dependence had been determined both by the con siderably increased value of power density released in the discharge, accompanied by the intense working substance transfer, and by a voltag e drop growth in the spark ion source which led to deeper ionization o f the vapors by fast electrons. Prolonged tests of the closed shape io n source (22 000 pulses, f = 0. 3 Hz) have been carried out. Spectra h ave been obtained for different times from the beginning of the test. Results are discussed.