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Instructions for reaching a static fill of gas in the IP while the DPS is running.

This guide assume the fill is being performed in a state where both the upstream and downstream Be windows have holes, and that a fixed Be window exists on the upstream side of the IP and a movable Be window on the downsstream side.

Step-by-step guide

Setup procedure:

  1. Verify vacuum conditions in the IP of approximately 1e-6 Torr.
  2. Verify both US-DPS and DS-DPS pumps are running and operating as normal.  Also check VPIO:LI20:3164 to ensure the ion pump is on.
    1. This is how the DPS looks under nominal operation:
    2. image2022-7-29_16-16-2.png
  3. Start a strip tool and load the file: DPS_Gasjet_Pressures.stp
    1. Find the VGCM:LI20:M3203:PMONRAW pressure - this is the 10 Torr capacitance manometer gauge that will provide the IP pressure.
  4. Verify the oven fill line is connected to the gas bottle of the desired gas type and the flow regulator is closed.
    1. Gas bottles and flow regulator location:
  5. Open the fill valve #1 to evacuate the line and leave open for several minutes then close. 
  6. Open the gas bottle and set the regulator to 10 psig.
  7. Read the gas bottle pressure and ensure that there is enough gas to last for the intended fill.
    1. Previous measured rate of He usage at 5 Torr IP pressure = 165 psi/day (one full 2500 psi bottle drained in ~15 days)
  8. Verify gas bottle on fill line #2 is closed and that the fill valve for this line is closed.
  9. Open the fill valve #1 and set flow rate on the flow regulator to 0.1 SCFH to purge He through the fill line for several minutes.
  10. Close the fill valve to stop the flow and evacuate the IP again.
  11. If operating the Li oven, follow the E300 procedure to prepare the Li oven for a static fill.


Start the fill:

  1. Close angle valve VV3202 isolating the plasma beamline from the plasma turbo
  2. Close valve FV-PB on the foreline of the Picnic Basket. Turn off Picnic Basket turbo
  3. Close Beryllium window valve VV3208
  4. Adjust the flow regulator to reach the desired fill pressure. There is a slow so make changes slowly.
    1. In previous tests a setting of ~0.8 SCFH results ~5 Torr for He
  5. It will likely take 5-10 minutes for the pressure to approach the pressure setpoint. Make small changes and wait for 5-10 minutes for the pressure to stabilize before proceeding with more adjustments.
  6. Continue to monitor the IP pressure and make minor adjustments to the flow rate if necessary.


Drain the IP:

  1. If using the Li oven, follow appropriate procedures to shut down and secure the oven
  2. When ready to drain the He gas - close the fill valve. The IP pressure will drop at an initial rate of ~1 Torr/min.
  3. Open valve FV-PB on the foreline of the Picnic Basket to aid in the pump down
  4. Start the PB turbo when the IP pressure is below 1 Torr.
  5. Close the valve on the gas bottle.
  6. Open the DS Beryllium window valve VV3208 after the IP pressure is <<1 Torr.

Recovering from faults:

If a single stage in the DPS trips off, the IP pressure should not be effected significantly so the fill valve, oven valves, and oven heaters should remain open or on.  The decision to halt operation of the oven should be made depending on the nature of the fault. The problem should be fixed as soon as possible to regain redundancy in the DPS system.

Depending on the fault, the beamline pressure may trip the beamline valves and stop beam delivery. The problem will need to be fixed before resuming beam delivery.

Use this guide to trouble shoot faults with the DPS: DPS Pump Troubleshooting


Test results: DPS Stability and Failure Modes

Summary of 3 day test of stability with the manual flow control, and reaction of the IP pressure levels to various DPS failure modes.

dstorey - 2022-12-14 - DPS Stability and Failure Mode Tests.pdf



  • The DPS watcher should behave normally under a static fill of the IP.
  • If filling with hydrogen gas then the purge gas should be used on stages 1 and 2. If you don't, the foreline pressure will build up slowly and eventually impact beamline pressures.
    1. Open the valve on the 6 pack and ensure regulator reads about 10 psig
    2. Open the purge gas valves on US1 and DS1 - Channels 1 and 2 on Beckhoff controller "N".
    3. Be sure to stop the purge gas and close the valves when finished.

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