When a non-grounded metal object, or a long thin metal object grounded on one side, is placed in a microwave oven a charge builds up on the metal surface. This charge is released by arcing to a ground such as the wall of the microwave. In the Plasma-Preen system a highly conductive plasma engulphs the work. The plasma allows any charge to leak off and limits the amount of charge that can accumulate.
The water cooled flat surfaces allows for the following:
1. Cools the "O"-Ring eliminating outgassing.
2. Keeps the work surface at a uniform temperature.
3. Accomadates flat work peices.
4. Temperature control is achieved by placing a glass plate under the work thereby increasing the thermal resistance to the base plate.
5. Thermal uniformity reduces exponential temperature dependent reaction rate differentials.
The Plasma-Preen system can be calibrated by using it as a calorimeter. When a fixed amount of water is heated for a specified time the temperature increase can be related the the applied microwave power.
Procedure to determine the calibration of the power knob of the Plasma-Preen System:
1. Place a flat glass container like an upturned bell jar with exactly 1000 grams of water inside the Plasma-Preen reactor.
2. Using a thermometer that can read to 0.1 deg Farenheight (A meat thermometer works just fine) measure the temperature of the water .Do this while using the thermometer to stir the water. Record the temperature (T1).
3. Set the power knob to zero and run the reactor for exactly one minute. (Press the 1 button)
4. Measure the temperature again and record (T2).
5. Set the power knob to 10 and run the microwave again for 1 minute.
6. The second reading of the first run will serve as the first reading for the second run.
7. Continue doing this until the water gets too hot, allow it to cool and take another set of measurements starting from the power setting where the water was allowed to cool off.
8. Calculate the watts for each run as follows:
9. Power ( Watts) = (T2-T1) * 4.18 * 1000 / (60 * 1.8)
10. Graph watts vs. Power setting.
NOTE: The 4.18 converts calories to watts
the 60 is seconds/minute
the 1.8 converts change of degrees Farenheight to change
in degrees Centagrade