S3-Vault Vacuum Procedure Scattering Chamber

S3-Vault Vacuum Procedure Scattering Chamber

(Revised 5/5/2011, Sebastian George)

The pumping and venting procedure of the scattering chamber is computer-controlled. Use the computer on the second floor balcony in S3 vault or any Data-U Windows machine.

·  Open under Windows the program “PanelMate” (-> All Programs -> NCS -> PanelMate).

·  Load the template “S800vac.ui” (-> File -> Open -> “\\exp\files\control\ncsdata\General\Qt\Templates\S800vac.ui”)

·  Page 05 (Figure 1) is runs Venting and Pumpdown Procedures (see below)

·  Page 06 (Figure 2) includes S800 (downstream and upstream) vacuum related controls and remote pressure readings

·  Controls do not work if the “PanelMate” is open somewhere else.

Venting Procedure

1) CLOSE GATE VALVES:

·  Close upstream gate valve I246GV (Page 05): select I246GV control button (Fig 1:yellow arrow) and click close (pops up on the right)

·  Close downstream gate valve I255GV (Page 06): select I246GV control button (Fig 2:yellow arrow) and click close (pops up on the right)

·  Both gate valves have to be connected to the control box, so that the program is able to read their status (open/closed). Without connection the automated venting procedure will stop.

2) TURN OFF ION GAUGE:

Turn of ion gauge “Main Scattering Chamber” (I252IG on Page 5, see magenta box Fig 1 and blue box Fig 4) with the “EMIS” button on the control unit, which is the fourth unit from top in the third rack on the second floor balcony in S3 (see Fig 3). The “EMIS” button is marked with an arrow and displays “OFF” when it is off.

3) START VENTING:

·  Select “Vent Status” (see magenta box Fig 1)

·  Click “Begin Venting Procedure” (pops up on the right)

·  The rest of the procedure is fully automated. Because the chamber vents to air, there is no risk of over-pressurizing the chamber. The Pirani Gauge I252PG (see orange box Fig 1 and green box Fig 4) reads ~1000 Torr when fully vented.

o  I252GV (Turbo pump gate valve) will close (Fig 1: yellow ellipse)

o  “Cryopump Gate Valve” will close (Fig 1: white ellipse)

o  “Vent Delay Timer” (Fig 1: red circle) is supposed to count down from 10s in order to give the user the option to stop the venting procedure by clicking the “Stop Venting Procedure” button on the right. If the timer is not counting down one can manually vent by selecting the “Vent Valve I252VV” button (see white box Fig 1) and choose “Vent with air” on the right. Be careful: The gate valve will immediately be fully open!

·  The venting occurs through the venting valve I252VV

·  The control unit of I252VV (green arrow in Fig 5) can be connected to two valves at the chamber (red arrows in Fig 5). The left one opens the chamber immediately. A needle valve is attached to the right one to vent steady in order to protect fragile parts (e.g. targets) in the chamber.

4) STOP VENTING:

·  Click “Stop Venting Procedure” when done.

·  Stop nitrogen flow if vented with dry nitrogen.

Pumpdown Procedure

1) STOP VENTING:

·  Click “Stop Venting Procedure” when done.

·  Stop nitrogen flow if vented with dry nitrogen.

·  Check that upstream/downstream gate valves are closed.

·  Check that ion gauge I252IG is off.

·  Close doors. The doors should be clamped shut in a rotating pattern. Large extra C-clamps at spots marked on the door with a red or black marker are generally necessary to get below 1 or 2 E-5 Torr.

2) START PUMPING:

·  Select “Pump Status” (see red box Fig 1)

·  Click start to start the automated pumpdown start button.

·  The gate valves for the turbo and cryo pumps open automatically at the correct pressure. (Plotting pressure with QtChart may be desirable to track progress.)

3) TURN ON I252IG:

·  once the pressure is in the milliTorr range.

·  Ion Gauge should never be open when the pressure is above the 0.1 Torr range.

· 

4) TRICK FOR EXTRA PUMPING POWER:

·  If the vacuum is good (tens of E-6 Torr range), check if the spectrograph or upstream beam lines have better (E-6 Torr) vacuum. If so, open a gate valve to those sections for increased pumping power. Contact Ed Bernard for leak testing.

FOR FASTER ROUGH PUMPING: In the special case where there are no sensitive foils or equipment in the chamber that may tear with strong winds, use the “Quick Rough Down System” button in the

bottom row of Page 05 in s800vac.MT2 on PanelMate in place of Step 2 in the standard pumpdown

procedure. This opens the cryo and turbo gate valves at 2Torr instead of 0.1 Torr.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5