Accelerator Handbook

Cs Sputter Source Startup Procedure

General Considerations

• Review these illustrations:
  • Cs Sputter Source Labeled Cutaway Diagram
  • Cs Sputter Source Cutaway Diagram
  • Cs Sputter Source High Voltage Supplies
• The proper target must be installed. (See Devon.)
• The base pressure of 2 × 10^-6 torr or less.

General Preparations

1. Ensure that desired beam target is loaded.
2. Set buncher tubes to correct configuration for desired beam species.
3. Check vacuum on LE extension, temperature gauge on cryopump should be at minimum value.
4. Open source gate valve by pressing either button on gate valve control at source gate.
5. Set cesium reservoir controller temperature set point (green numbers): 123C for ones of uAs, 130C for tens of uAs.
6. Remove grounding hook from power supply platform and hang on gate before closing.
7. Close both gates to source area. Orange lights on Glassman supplies should come on at gate closing. (If not, check other gate on the other side of the accelerator; both must be secured.)
8. Press the doorbell button on top the Pelletron AC Power Center. The Extractor and Target Glassman supplies should indicate Voltage Control with red lights.

Startup and Normal Operation (in control room)

1. Turn on and set the Del main extractor supply to the desired voltage for the particular buncher setting.
2. Turn up the ionizer heater. The ionizer operates at 21-22 amps. Keep in mind that the current will fall slightly as the ionizer gets warmer. Keep adjusting the current until the ionizer is stable at 21-22 A. It should take about 1 minute to reach 21 A from the standby value of 10 A.
3. Turn up the Cesium feed tube heater to 0.450 amperes.
4. Set the cesium reservoir heater current to 0.315 Amps. This is an approximate value above the needed power level.
5. Set the Glassman extractor power supply to 12.5 KV. Check to be sure the current is less than about 5 milliamps and the “control milliamperes” light is NOT lit. High current indicates that the source needs to be serviced.
6. Set the Glassman target power supply to 6.5 kV. Check to be sure the current is less than about 5 milliamps and the “control milliamperes” light is NOT lit. High current indicates that the source needs to be serviced. A newly installed pellet may cause instability for the first hour or so, but will become stable.
7. Set the Glassman lens power supply to 1.5 kV.
8. Tune the beam with the inflection magnet, source lens (usually about 1.5 kV), einzel lens A, and 2Y steerer. The 2X steerer should be neutral (5.00 on dial) as X steering is be done by the inflection magnet at this stage.
9. Monitor the target and extractor currents: target current should be around 2.5 milliamps, and no more than 5 mA. If target current gets too high, reduce the cesium reservoir setting.

Out-gassing the source after cleaning

1. The source gate valve should be closed for this operation.
2. Wait for normal vacuum. Normal is when the needle is in the blue mark on the gauge above the TV in the control room.
3. Set ionizer to 10A. This will lead to a rise in the vacuum pressure.
4. Wait for vacuum to fall back to the blue mark on the gauge
5. Raise the ionizer by an additional 2-3 A and wait for the vacuum to fall back into the blue range.
6. Repeat this process until the ionizer is at 21 A and the vacuum is in the blue range, may take 8 hours.
7. Open the source gate valve and carry out the Startup and Normal Operation.

Checklist for Target Pellet Change

• Sputter Source Target Pellet Change

Shut Down Procedure

1. Cesium reservoir: The reservoir has a temperature controller that turns the power on/off as needed for a constant temperature. The controller is located next to the analog temperature meter on the source power platform. The red numbers are the measured temperature, the green numbers are the set point temperature, there is a small red light that indicates when the controller is calling for power. The reservoir current switches between 0.150A and .315A as directed by the controller.
2. Wait until the reservoir controller's red power light is on and you can see about .315A reservoir current on the meter, run the reservoir current down on the digital meter. Make sure that you see controller red light on with minimal amps of current.
3. Wait for the reservoir temperature (red numbers on controller) to drop below 85° C.
4. Turn down the feed tube power supply.
5. Wait for the feed tube temperature to drop below 80° C.
6. Wait for the Target Supply current to fall to less than 1 milliamp.
7. Turn the ionizer current down to 10 amps. (The ionizer current should be left at 10 amps. This helps avoid the “poisoning” of the ionizer.)
8. Turn down target and extractor voltages to zero.
9. Turn off DEL high voltage supply.
10. Close sputter source vacuum gate valve.