Compact Plasma and Focused Ion Beams

246 Compact Plasma and Focused Ion Beams

plasma conditions at 0.15, 0.25, and 0.35 mTorr. Each division along the x axis

is 30 MHz. In vacuum, the spectrum is sharp with typical broadening of

~0.015 GHz, dened at 5% of the peak intensity (P

peak

~ 620 V/cm). Two small

peaks with intensity 100 times lower than the primary peak (2.45 GHz) are

observed at 2.38 and 2.52 GHz, and may be attributed to recirculating elec-

trons in the magnetron, which is often a consequence of aging [17]. In the

presence of plasma, the primary peak is reduced by an order of magnitude

due to utilization of the eld energy for plasma generation and sustenance.

The sma ...