Connect the 12-V power adapter to high-voltage supply on the back of the plasma disk. Position the disk on the lecture bench so no conducting surfaces are close to ground out the discharge. Use the control on the HV supply to vary the input to the disk and demonstrate the affect on arc brightness and length.
Comments
A fly-back transformer power supply injects 2-kV, 30-kHz input at the center of the disk. Phosphor-coated glass beads and 0.1-atm argon gas between glass plates create a path of lowest resistance for the discharge which extends to the perimeter of the disk. The return path is by capacitive coupling through the glass to the air or objects placed close to the glass. This disk is also useful as a spectral source. View the visible argon spectrum in a darkened room using hologographic gratings handed out to the students.
Apparatus
20-inch Argon Plasma Disk
12-VDC,
12-W Power Adapter