photo of corona triode[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.
photo of emitters

Corona triode assembly shown installed inside accelerator tank
photo - 4-Jan-96 [jpeg 20K][png 86K][gif 98K]

photo of JRA[gif 57K] [png 50K][jpeg 19K] photo - 4-Jan-96
Jim R. Allen making adjustments to the corona triode electronics.

photo of JRA looking at marks

Jim R. Allen inspecting ion discharge
marks on the terminal shell.
photo - 4-Jan-96 [jpeg 23K][png 75K][gif 85K]

photo of marks[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.