E-gun
Filament
Mounted on bellows drive on 4-5/8 shell penetration above ? , next to pump duct. Uses repurposed electron beam source from LTX e-beam evaporators. Dual unpolarized electrical feedthrough for filament current and bias. Single feedthrough is leftover from use as e-beam, was used to ground anode through a resistor to measure anode current. Tungsten filament can handle ~20A.
Originally constructed as an electron beam, the filament is designed to be negatively biased against a grounded accel grid. Operated as an e-gun, however, the bare filament projects into the vessel, and emits a broad cloud of electrons toward all grounded surfaces, rather than a directed beam.
Power supplies
Heating
Filament heating current is provided by a variac mounted in the Yellow/Green coil capacitor bank rack on the north side of the test cell. The variac panel is labeled "CDX-U Thermionic Emission Filament" (Fig. 1). The variac provides low voltage, high current AC to the filament, typically run at about 35%.
Bias
To increase the electron emission, the variac is biased with a GenTek supply in the yellow cap rack using Twinax connector (Fig. 2).
The filament bias power supply only needs to be switched on for operation (VERIFY THIS), since the bias voltage setting is computer-controlled.
Bias automation
GenLAN GUI, launched from the blue icon pinned to the taskbar on LTX-Zoidberg, controls the GenTek supply over ethernet. The e-gun power supply must be powered on before running the GUI.
On running, click the first green box that pops up. Enter IP address 192.168.1.18 when instructed by the second green box, then click the green box. Set current and voltage limits (PC MAX and PV MAX respectively); typical maximum settings are 630V and 1A. To enable output click OUT (right-most button on second control row from bottom). Click OUT again to disable output before entering test cell.
