HAM-ISI Unit #6 was balanced, and CPS readouts were within acceptable range, on 07/03 when we left it for long TF measurments. When checked this morning, CPS readouts featured an offset of approximately +/-3000 counts:
|
|
07/03 |
07/09 |
Difference |
|
H1 |
-387.82 |
2014.8 |
2402.62 |
|
H2 |
-15.363 |
2259.8 |
2275.163 |
|
H3 |
291.12 |
2534.3 |
2243.18 |
|
V1 |
-80.917 |
-3112.1 |
-3031.183 |
|
V2 |
-38.773 |
-3118.5 |
-3079.727 |
|
V3 |
119.34 |
-3054.5 |
-3173.84 |
There is no drive/offset on MEDM channels.
Coil drivers were turned off. The CPS readouts remained unchanged.
CPS interface chassis were turned off, and then turned back on. The CPS readouts remained unchanged.
Dataviewer plots are attached. They show the drifting of the CPS readouts.
We experienced high temperatures over the last few days.
| 3-Jul | 9-Jul | Difference | |
| H1 | -387.82 | 2014.8 | 2402.62 |
| H2 | -15.363 | 2259.8 | 2275.163 |
| H3 | 291.12 | 2534.3 | 2243.18 |
| V1 | -80.917 | -3112.1 | -3031.183 |
| V2 | -38.773 | -3118.5 | -3079.727 |
| V3 | 119.34 | -3054.5 | -3173.84 |
| 3-Jul | 9-Jul | Difference | |
| H1 | -387.82 | 2014.8 | 2402.62 |
| H2 | -15.363 | 2259.8 | 2275.163 |
| H3 | 291.12 | 2534.3 | 2243.18 |
| V1 | -80.917 | -3112.1 | -3031.183 |
| V2 | -38.773 | -3118.5 | -3079.727 |
| V3 | 119.34 | -3054.5 | -3173.84 |
The ISI was re-blanced this morning. Reasonable values were obtained along Z.
However, re-balancing the ISI did not correct the out-of-specification offset observed on horizontal CPSs.
CPS readouts, after re-balancing this morning, are presented below:
| H1 | 1901.6 |
| H2 | 2268.7 |
| H3 | 2417 |
| V1 | -34.45 |
| V2 | 47.896 |
| V3 | -201.18 |
In order to get a better understanding of what was happening, we collected data from GS13/L4C pressure sensors. Data shows:
- Pressure increased for the past 4 days (+3 kPa, fig, 1). Pressure data is well correlated between sensors.
- CPS readout drifting is highly correlated to pressure variations. (Fig. 2)
- Pressure is still high: 103-4kPa (Fig. 3, just measured)
- Figure 4 shows the pressure/CPS-readout evolution over 2 days. From 7am to 7am.
Notes:
- Dataviewer time = PT+7h
- Mean values displayed. Fluctuations due to runnning excitations.
The ISI was locked. CPS readouts are within expected range.
| H1 | -348.96 |
| H2 | 297.36 |
| H3 | -156.01 |
| V1 | 252.29 |
| V2 | 155.3 |
| V3 | 323.62 |
The drifting we observed was not caused by a malfunctioning of the CPSs.
We later found that one circuit of our air conditioning had failed and therefore we could not maintain normal conditions in the staging building. There is no record of the indoor temperatures during this event but I estimate that the temperature excursions were on the order of 5-10 degrees F. Normal excursions (night-day) are probably 2-3F and perhaps closer to 1F during the day only (if you exclude the cooling overnight.