Micro-Channel Plates: Difference between revisions

Latest revision as of 14:02, 20 May 2026

Open EPICS "ED2 to SSD" or "ED2 to IC" Page - depending on which detector is installed.
Turn the needle (manual) valve DRAMV74 (see Fig.1) located under the final slit box (West side) fully clockwise.

Manual valve DRAMV74 under final slit box.
Ensure VV52 is closed.
Ensure, the MCP foils have been moved out of the beamline.
Turn on DRA:RP21.
Wait until pressure at DRA:CG21B is below 50 mTorr
Open DRA:RV54.
Watch Vacuum Gauges DRA:CG52 and DRA:CG52C to see that pressure drops by less than 1 Torr/second. Ideally watch the rate on a laptop, while adjusting the needle valve if necessary. To be extra careful, one can open RV54 with the needle valve closed, and slowly start opening it while watching the rate. This avoids fast pressure drops that could potentially destroy the fragile foils. You may have to further adjust the valve during the pump down.
When Pressure drops to about 2 Torr on DRA:CG52, close DRA:RV54 and open DRA:RV52.
Turn on DRA:BP31.
Open DRA:PV31.
Close DRA:RV52.
Open DRA:BV52.
Turn on turbo pump DRA:TP52.
When pump starts up turn on DRA:IG52.

Go to EPICS "ED2 to SSD" or "ED2 to IC" Page - depending on which detecor is installed.
VV52A under final slit box.
Close DRA:BV52.
Turn off DRA:IG52 ion guage.
Turn off DRA:TP52 turbo pump and allow the pump to spin down. Otherwise, the pump could be damaged severely. To tell that DRA:TP52 has spun down, check that you can no longer feel the pump vibrating and on the controller that it is no longer spinning. This takes approx. 1 hr, but it is important to do so to avoid severely damaging the turbo.
Ensure all the DRAGON vent valves are closed. DRA:VNT1 located on the "Differential Pumping" EPICS page should be checked. Other vent vales are labelled VV## where ## is the number.
Ensure the manually adjustable vent valve (labelled "VV52A", see Fig.2) physically located near VV52 is fully closed before proceeding.

Open the nitrogen gas cylinder located next to MD2, and activate the "dead man" 30 min time out switch. Remember to reset the switch as the venting procedure will take at least an hour.
Open DRA:VV52.
Slowly open VV52a until the pressure in the final slit box (DRA:CG52 and DRA:CG52C) starts to rise. The target rate of rise should be a few hundred mTorr/s. Ideally monitor the rate on a laptop while adjusting the manual valve VV52a
Close DRA:VV52 when DRA:CG52C and DRA:CG52 read atmosphere (760 Torr) or have saturated. The latter can happen at values below 760 Torr, when the gauge is slightly out of calibration
Close the Nitrogen gas cylinder.

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 * [[File:VV52A.jpg|thumb|VV52A under final slit box.]]Close DRA:BV52.
 * Turn off DRA:IG52 ion guage.
-* Turn off DRA:TP52 turbo pump and allow the pump to spin down. Otherwise, the pump could be damaged severely. To tell that DRA:TP52 has spun down, DRA:CG52 and DRA:CG52C will equilibrate (+/- some offset) and you will be able to physically feel that the turbo is not spinning. This takes approx. 1 hr, but it is important to do so to avoid severely damaging the turbo.
+* Turn off DRA:TP52 turbo pump and allow the pump to spin down. Otherwise, the pump could be damaged severely. To tell that DRA:TP52 has spun down, check that you can no longer feel the pump vibrating and on the controller that it is no longer spinning. This takes approx. 1 hr, but it is important to do so to avoid severely damaging the turbo.
 * Ensure all the DRAGON vent valves are closed. DRA:VNT1 located on the "Differential Pumping" EPICS page should be checked. Other vent vales are labelled VV## where ## is the number.
 * Ensure the manually adjustable vent valve (labelled "VV52A", see Fig.2) physically located near VV52 is fully closed before proceeding.