Veeco MPS-3000 CE, Technical Manual

Page: 32 / 96

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15. Press the BEAM ON/OFF switch. The word BEAM appears above the
switch.
• A beam current value should appear on the Beam Current dis-
play.
• An accelerator current value should appear on the Accelerator
Current display.
The actual current values depend on other parameters, such as source size,
cathode filament current request, gas flow, and beam and accelerator volt-
age requests.
16. The ion source should operate and extract an ion beam.
FC Adjustment
Follow these steps to adjust the system to the chosen operating conditions.
1. Adjust the beam current.
a. Select the beam voltage (refer to Step 11. on page 27 ).
b. Adjust the discharge voltage to the chosen level (refer to Step 4. on
page 24 ). When operating with argon, the recommended voltage
is 55V.
c. Adjust the cathode current to obtain the chosen beam current (refer
to Step 6. on page 24 ).
If the chosen beam current requires an increase in cathode filament cur-
rent, carefully monitor this filament current to ensure that it does not exceed
the recommended values of 6.5A for 5cm or smaller sources.
If the chosen beam current is obtainable, (i.e., within specified perfor-
mance limits) but not reachable without exceeding the recommended
maximum filament current, increase the discharge voltage and/or gas
flow.
• If the discharge voltage is less than 55V, increase the value to
acquire the beam current.
• If the beam current is not acquired with a 55V discharge
request and a maximum recommended filament current,
increase the gas flow.
Avoid system pressures in excess of 6.7 x 10
-2
Pa (5 x 10
-4
Torr). This
increases arcing within and around the ion source.
Special circumstances may require operation with the discharge volt-
age and/or system pressures in excess of the recommended values.
While operating at these conditions is possible, reduced source operat-
ing efficiency and lifetime may be experienced.
NOTE
CAUTION
NOTE