Veeco MPS-3000 CE, Technical Manual

Page: 44 / 96

40
a. 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.
Actual current values depend on other parameters, such as source size,
cathode filament current request, gas flow, and beam and accelerator volt-
age requests.
b. The ion source should operate and extract an ion beam.
PBN Adjustment
Follow these steps to adjust the system to the chosen operating conditions.
1. Adjust the beam current.
a. Select the chosen beam voltage (refer to Step 11. on page 39 ).
b. Adjust the discharge voltage the recommended voltage is 55V
(refer to Step 4. on page 36 ).
c. Adjust the cathode current to obtain the chosen beam current (refer
to Step 6. on page 36 ).
If the chosen beam current requires an increase in cathode filament cur-
rent, carefully monitor this filament current to ensure it does not exceed the
recommended values of 6.5A for 5cm and smaller sources.
If the chosen beam current is available (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 an 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). Increased
arcing within and around the arc will occur.
Special circumstances may require operating with the discharge voltage
and/or system pressures in excess of the recommended values. While oper-
ating at these conditions is possible, reduced source operating efficiency
and lifetime may occur.
NOTE
CAUTION
NOTE