Inductively coupled plasma (ICP) is a common method of ionizing the residual gas in a vacuum chamber. A RF source (commonly 13.56mhz) is connected to a coil (usually outside of the chamber) which induces currents in the nearby gas volume because of the time-varying magnetic fields.
I used a 10 meter (28mhz) 100 watt ham radio transmitter at 60mTorr with multiple coil designs to create an inductively coupled plasma. Even while minimizing the reflected power with a matching network (antenna tuner) the plasma was difficult to ignite. By briefly powering an anode layer ion source in proximity to the ICP coil I was able to ignite and sustain the ICP at lower power levels.
Once the ICP is sustained, the ALIS is powered off and the RF ICP remains on.
Paper written by Samuel Zeloof and Joshua Newstadt: A Brief Analysis of the Interactions Observed in Ion Clouds Created by Electric and Magnetic Fields From Multiple RF and DC Ion Sources
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