Response Time of Ion Beams in a PIG Ion Source

Abstract

The response time (τ) of hydrogen ion beam is investigated with a modified PIG ion source by appling the radio frequency. The control electrode is biased at 70 volts negative with respect to the source plasma and modulated by the radio frequency in the interval of 0.05–15 MHz. The response time is proportional to the square root of the gas pressure (P) and to the reciprocal ion density (n). Moreover the time depends on the amplitude of the radio frequency. These effects on the response time can be explained from the recovery time of the perturbed ion density written as τ=250(PE)^1⁄2⁄n where E is the mean field strength.