The objective: My main objective was to observe the infrared spectrum through electrically charged gas resulting in a plasma. I will be studying the transmission of infrared light through the plasma. I hypothesized that the plasma would not affect infrared viewing.
To test my hypothesis I designed a 4" x 24" plasma chamber constructed from Pyrex. On each end of the chamber is a tungsten electrode. Directly in the center on each side of the chamber is a 2" opening. One opening has a 16 gauge steel plate which is coated with flat black high heat paint. On the other opening is a 2" germanium window. The steel plate was heated by a hand warmer reaching 130 degrees attached directly to the outside. Another heat source I used was a rectangular one gallon metal can that was filled with water and heated by a fish tank heater. I used a Spectroradiometer, which operates in the spectral range from 2.5 to 14.5 um, and an 8-12 micron infrared camera with digital imagery. Testing was performed on Argon, Helium, and Neon plasmas. Before each test, the chamber was evacuated and held at 0 Torr for 6 minutes. Each gas was then inserted through the same vacuum hose to exactly 7 Torr. The power supply was a 5.5kV with 2.0 Amps current, and a frequency of 20 kHz. Clips were attached to the tungsten leads and power was turned on by a pull switch. The plasmas were tested in a controlled environment and photographed before and during the testing.
Using the SR5000 Spectroradiometer wide range capabilities, I was able to look at one micron at a time with each plasma tested. After the SR5000 testing, I was the able to proceed using the information that I had gathered and test with the infrared imaging system on the same plasma to visually look for change in transmission.
The data from both types of test supports my hypothesis that Argon, Helium and Neon plasma had no affect on the transmissivity in the infrared spectrum.
This project was an experimental investigation of high voltage, low current and high frequency observation of plasma in the infrared spectrum.
Science Fair Project done By Shay C. Edwards