In collaboration with researchers at Kodak Research Labs, we have been developing a probe intended to measure how the energy distribution of electrons in a RF plamsa varries during a single peroid of the driving potential. In particular, this work was targetted towards 40 kHz plasma which Kodak used for a time in producing their Advantix film.
In capacitively coupled 40 kHz plasmas, one significant mechanism which supports the plasma is ion bombardment of the driving electrodes. When an ion hits an electrode, secondary electrons are produced and accelerated back into the plasma. The majority of the electrons in a plasma have energies on the order of 10 eV. Since a typical driving waveform has an amplitude of 1000V, the secondary electrons are much more energetic. Using flux probes which efectively average over time, there has been some evidence collected that these electrons remain "hot" for a significant period of time. Additionally, the "hot" electron population would presumably be modulated at the frequency of the driving potential. The goal of the probe is to measure this time-varrying electron energy distribution.
Here is a electronic version of the poster presented at NYNanotech, a regional symposium organized by the Upstate New York chapter of the AVS in August 2002. The poster explains the methodology and shows the state of understanding at that point.
In November 2002, additional data taking revealed and corrected a instrumentation problem. This problem had been responsible for some of the odd features of all data taken previously, including data shown on the poster above. Analysis of that data is still in progress.