
33
Step 3)
Turn on the water cooling
.
If the source has water cooling, turn it on at this time. The water cooling must have a flow switch
connected to the interlock string. If the source cooling stops flowing, the power supply output will
shut off.
Step 4)
Turn the source on and allow it to warm-up
.
CAUTION
Make sure all electrical connections have been properly made and that
the power supply interlock has been satisfied.
Turn the power supply on.
Set the cathode current and discharge voltage to the recommending starting conditions in Table 4.3.
Similarly, adjust the neutralizer starting current.
Table 4.3: Recommending starting cathode current, discharge voltage and neutralizer current
Source
Cathode filament I (A)
Discharge V (V)
Neutralizer filament I (A)
3 cm Source
3
40
3
8 cm Source
4
55
4
Turn on the source by pressing the SOURCE button. When the SOURCE button is pressed, the
power supply will begin to apply power to the cathode, discharge and neutralizer. The cathode and
neutralizer heaters will ramp to their respective set point (or last setting). The discharge voltage will
ramp to an ignition voltage that is typically higher than 150V. As soon as a discharge starts, the
discharge voltage will ramp to its starting set point.
An established plasma discharge is indicated when the discharge current is detected. A reasonable
discharge current range for source warm up is 0.5 to 0.7 A. If the discharge current is not within
this range, increase or decrease the cathode heater current appropriately.
The recommended warm up period is 10 minutes. If the neutralizer current is sufficient, an
emission current will be present. As the source heats it may release trapped water vapor gases which
may result in a temporary increase in chamber pressure.