RESIDENCE TIME AND CHARGE-STATE OF SILVER AND ZINC IONS GENERATED FROM MICROSECOND VACUUM AREA

One mm vacuum gaps with silver or zinc needle-cathode were fired by a 13 mu s duration sinusoidal are or a 9 mu s duration exponentially dec aying are. Time-of-flight (TOF) ion measurements were made at variable ion extraction times after the are ignition to measure the charge sta te and residence time of the ions. Ag+, Ag++ and Ag+++ ions were gener ated from silver cathode and Zn+ and Zn++ were generated from zinc cat hode. Residual gas atom ions were generated together with the metal io ns. Residence times of silver and zinc ions at the acceleration space, which was 15-25 mm apart from the needle cathode, were 5 mu s and 17 mu s, respectively, regardless the waveform of the are current. Charge state fractions of silver and zinc ions were determined from the TOF ion currents and were compared with the results by other researchers.