DPS: The Differential Pumping System¶
Differential pumping units (DPS) are pumping schemes developed to maintain different composites elements along the x-ray beam path at different vacuum levels. They consist of a series of a number of pumping stages separated by small size apertures or tubes that will allow keeping different vacuum levels in the two chambers.
Two three-stages differential pumping units are realized in the
overall vacuum scheme, one at each of the two sides of the intensity
and position monitor (XGM). They assure a vacuum level in the pressure
range of 10-9 mbar at the entrance and exit of the XGM, while
the latter is operated in the range of 10-4 mbar. These two
composite elements are named DPS-1 and DPS-2. The vacuum design can be
seen in dps_vacuum.
The design of the DPS vacuum system.
Interlocks¶
If the vacuum goes bad, we want to isolate the DPSs. This is the case if one of the pressures is bad, or if one of the gate valves closes, the latter being an indicator of bad roughing vaccum, which is defined later.
The pressures are all twice the one used for the XGM gas inlet, to give it a chance to close and make the pressure be good again.
The cold cathode gauges¶
We need to protect the cold cathode gauges from too high pressure. We take the neighboring full-range gauges as a proxy for that. This way, we can later take the state of the cold cathode gauge to decide whether the vacuum is fine in the neighboring part.
We put 100 ms timeout on all gauges to prevent electrical noise from triggering the interlocks.
Conditions for the DPS-1, CC3:
| Number | Device Parameter | Operator | Limit | Hyst | Timeout |
|---|---|---|---|---|---|
| c1 | SCS_BLU_DPS-1/GAUGE/PCC4.Value | GT | 1e-4 | 100 |
Conditions for the DPS-2, CC9:
| Number | Device Parameter | Operator | Limit | Hyst | Timeout |
|---|---|---|---|---|---|
| c1 | SCS_BLU_DPS-2/GAUGE/PCC8.Value | GT | 1e-4 | 100 |
And the action for both:
| Number | Logic | Action |
|---|---|---|
| a1 | c1 | COff |
DPS1: GV2_2 and GV3¶
GV3 and GV2_2 are the valves around the DPS-1. The name GV2_2 is weird, our naming systematics unfortunately ended up in two valves being called GV2.
| Number | Device Parameter | Operator | Limit | Hyst | Timeout |
|---|---|---|---|---|---|
| c1 | SCS_BLU_DPS-1/GAUGE/CC3.Value | GT | 1e-6 | 100 | |
| c2 | SCS_BLU_DPS-1/DCTRL/CC3.state.Value | EQ | FALSE | ||
| c3 | SCS_BLU_DPS-1/GAUGE/PCC5.Value | GT | 2e-4 | 100 | |
| c4 | SCS_BLU_DPS-1/VALVE/GV1.state.Value | EQ | FALSE | ||
| c5 | SCS_BLU_DPS-1/VALVE/GV2.state.Value | EQ | FALSE | ||
| c6 | SCS_BLU_DPS-1/VALVE/GV3.state.Value | EQ | FALSE |
GV2_2 needs to be closed if the pressure is bad in the ALAS…
| Number | Device Parameter | Operator | Limit | Hyst | Timeout |
|---|---|---|---|---|---|
| c7 | SCS_BLU_ALAS/GAUGE/PCC2.Value | GT | 1e-6 | 100 |
| Number | Logic | Action |
|---|---|---|
| a1 | c1 or c2 or c3 or c4 or c5 or c6 or c7 | CClose |
…while GV3 needs to be closed if the pressure is bad in the XGM. The same conditions are used for GV4 in DPS2.
| Number | Device Parameter | Operator | Limit | Hyst | Timeout |
|---|---|---|---|---|---|
| c7 | SCS_BLU_XGM/GAUGE/PCC6.Value | GT | 2e-4 | 100 | |
| c8 | SCS_BLU_XGM/VALVE/GV1.state.Value | EQ | FALSE | ||
| c9 | SCS_BLU_XGM/VALVE/GV2.state.Value | EQ | FALSE |
| Number | Logic | Action |
|---|---|---|
| a1 | c1 or c2 or c3 or c4 or c5 or c6 or c7 or c8 or c9 | CClose |
The gate valves should close if the roughing vacuum goes bad, or the turbo pumps fail. One may, however, operate them if the DPS is isolated. This is needed to pump down the DPS initially. We assure that the pressure is really bad in this case, by checking the full range gauge.
| Number | Device Parameter | Operator | Limit |
|---|---|---|---|
| c1 | SCS_BLU_DPS-1/GAUGE/P1.Value | GT | 2e-2 |
| c2 | SCS_BLU_DPS-1/VALVE/SP1_RV.state.IsOpen | EQ | FALSE |
| c4 | SCS_BLU_DPS-1/VALVE/GV2_2.state.IsClosed | EQ | FALSE |
| c5 | SCS_BLU_XGM/VALVE/GV3.state.IsClosed | EQ | FALSE |
to that we add the conditions for each gate valve in front of a turbo pump. The hystersis and timeout are explained later.
| No | Device Parameter | Op | Limit | Hyst | Timeout |
|---|---|---|---|---|---|
| c3 | SCS_BLU_DPS-1/GAUGE/PCC4.Value | LT | 1e-4 | 1 | 100000 |
| c6 | SCS_BLU_DPS-1/TPUMP/TP1.state.RPM80 | EQ | FALSE | ||
| c7 | SCS_BLU_DPS-1/VALVE/RV1.state.IsOpen | EQ | FALSE |
| Nu | Device Parameter | Op | Limit | Hyst | Timeout |
|---|---|---|---|---|---|
| c3 | SCS_BLU_DPS-1/GAUGE/PCC4.Value | LT | 1e-4 | 1 | 100000 |
| c6 | SCS_BLU_DPS-1/TPUMP/TP2.state.RPM80 | EQ | FALSE | ||
| c7 | SCS_BLU_DPS-1/VALVE/RV2.state.IsOpen | EQ | FALSE |
| No | Device Parameter | Op | Limit | Hyst | Timeout |
|---|---|---|---|---|---|
| c3 | SCS_BLU_DPS-1/GAUGE/PCC5.Value | LT | 1e-4 | 1 | 100000 |
| c6 | SCS_BLU_DPS-1/TPUMP/TP3.state.RPM80 | EQ | FALSE | ||
| c7 | SCS_BLU_DPS-1/VALVE/RV3.state.IsOpen | EQ | FALSE |
The actions for the gate valves are a bit complicated. There are two parts, covering three scenarios:
- We are in operation, all the roughing vacuum is fine an the turbo pump is running. That is the left side of the actions. If anything fails, we close the gate valve.
- We want to pump down a vented chamber. The pressure is bad, but gets better while we are pumping. This is why we have a timeout on the pressure in the conditions. Once a good pressure is reached for some time, we consider the DPS in operation, the right side of the condition becomes true.
- The turbo is running, the valve is closed but the chamber is vented. The it is just illegal to open the valve.
| Number | Logic | Action |
|---|---|---|
| a1 | (c1 or c2 or c6 or c7) and (c3 or c4 or c5 or not c6) | CClose |
DPS2: GV4 and GV5¶
| Number | Device Parameter | Operator | Limit | Hyst | Timeout |
|---|---|---|---|---|---|
| c1 | SCS_BLU_DPS-2/GAUGE/PCC7.Value | GT | 2e-4 | 100 | |
| c2 | SCS_BLU_DPS-2/DCTRL/CC9.state.Value | EQ | FALSE | ||
| c3 | SCS_BLU_DPS-2/GAUGE/CC9.Value | GT | 1e-6 | 100 | |
| c4 | SCS_BLU_DPS-2/VALVE/GV1.state.Value | EQ | FALSE | ||
| c5 | SCS_BLU_DPS-2/VALVE/GV2.state.Value | EQ | FALSE | ||
| c6 | SCS_BLU_DPS-2/VALVE/GV3.state.Value | EQ | FALSE |
GV5 needs to be closed if the pressure is bad in XOX.
| Number | Device Parameter | Operator | Limit | Hyst | Timeout |
|---|---|---|---|---|---|
| c7 | SCS_BLU_XOX/GAUGE/PCC10.Value | GT | 1e-7 | 100 |
| Number | Logic | Action |
|---|---|---|
| a1 | c1 or c2 or c3 or c4 or c5 or c6 or c7 | CClose |
GV4 also re-uses the XGM conditions loop1 from above.
| Number | Logic | Action |
|---|---|---|
| a1 | c1 or c2 or c3 or c4 or c5 or c6 or c7 or c8 or c9 | CClose |
As for DPS1, the gate valves should close if the roughing vacuum goes bad.
| Number | Device Parameter | Operator | Limit |
|---|---|---|---|
| c1 | SCS_BLU_DPS-2/GAUGE/P3.Value | GT | 1e-2 |
| c2 | SCS_BLU_DPS-2/VALVE/SP3_RV.state.IsOpen | EQ | FALSE |
| c4 | SCS_BLU_DPS-2/VALVE/GV4.state.IsClosed | EQ | FALSE |
| c5 | SCS_BLU_XOX/VALVE/GV5.state.IsClosed | EQ | FALSE |
to that we add the conditions loop1 for each turbo pump:
| Number | Device Parameter | Operator | Limit |
|---|---|---|---|
| c3 | SCS_BLU_DPS-2/GAUGE/PCC7.Value | LT | 1 |
| c6 | SCS_BLU_DPS-2/TPUMP/TP1.state.RPM80 | EQ | FALSE |
| c7 | SCS_BLU_DPS-2/VALVE/RV1.state.IsOpen | EQ | FALSE |
| Number | Device Parameter | Operator | Limit |
|---|---|---|---|
| c3 | SCS_BLU_DPS-2/GAUGE/PCC8.Value | LT | 1 |
| c6 | SCS_BLU_DPS-2/TPUMP/TP2.state.RPM80 | EQ | FALSE |
| c7 | SCS_BLU_DPS-2/VALVE/RV2.state.IsOpen | EQ | FALSE |
| Number | Device Parameter | Operator | Limit |
|---|---|---|---|
| c3 | SCS_BLU_DPS-2/GAUGE/PCC8.Value | LT | 1 |
| c6 | SCS_BLU_DPS-2/TPUMP/TP3.state.RPM80 | EQ | FALSE |
| c7 | SCS_BLU_DPS-2/VALVE/RV3.state.IsOpen | EQ | FALSE |
We recycle the actions definition from DPS1.