[gif 38K][png 39K][jpeg 36K] photo - 17-Aug-95
Corona triode Assembly (1 of 3) -- These face the terminal and, by field emission, provide a small amount of
modulated current needed for fine regulation of the accelerator's voltage. A vacuum tube modulates the voltage
between the needles and the plate through which they protrude, varying the E field at each needle's tip and,
consequently, the emitted current. Fully extended, the needles of all three assemblies generate as much as
600 µA of current but, of course, will be operated with as little current as is necessary to provide fine regulation.
[gif 53K][png 47K][jpeg 10K] photo - 4-Jan-96
Marks left on the terminal shell by ions from the corona triode show evidence of self focussing. The marks easilly rub off and are probably
polymerized breakdown products of the SF6 insulating gas.