2021/06/23 (Wednesday)
- Lab in-personnel: Matt, Gabe, Scott
| Status | Run 74 in progress. First cooldown after IVC rebuild. |
|---|---|
| Tower thermometer is reading high, probably this is a thermometer problem and the actual temperature is much lower. High noise in some of the charge channels. | |
| Setup: DIB1/2+acc → SL 41/43 → 3.2 MHz filters → cables 2/3 → nothing/Source_mover_board+HV_diverter_board → DCRC50(3)/55(1). Kepco 40V supplye → HV BNC. No lead/poly shield. | |
| 1255 | Tower/MC/Coldplate = 90.5/30.8/173 mK, Still = 1.10 K / 0.080 mbar / 0 mW, G1/G2= 198/191 mbar, 1K Pot = 1.64 K / 24±2 mbar. MB= 37.1% |
| Tower reading has dropped considerably. Maybe all the heating from the source mover yesterday did…something? Coldplate and Still thermometers seem to be in their “low” modes. | |
| 1300 | Fill LN2 cold trap bath. |
| We moved the source yesterday, far enough to hit the near endstop, assuming 1) it's moving in the +y direction (we don't know, it's 50-50) and 2) it's actually moving and not missing steps. Currently the source should be 15.20 mm past the center, and contact with the near endstop should occur at 13.12 mm. Contact with the far endstop should occur at -41.35 mm. So let's keep moving it and see if we ever hit the far endstop. Note - I also keep watching the waveforms on the scope, and monitoring the temperature changes. If we hit an endstop and don't know it, if for example the wiring is broken, the mover will probably get jammed if we keep trying to move in the same direction, and we may see a difference in the current or temperature patterns. |
|
| 1308 | Do mv +64. MC rises quickly to 111 mK, then falls Waveforms look ok, same as before. |
| 1308 | MC peaks at 111 mK. Tower = 1.93 K and falling. |
| Endstop-to-chassis still open. Theoretically 3.13 mm past near endstop distance. But still 25.10 mm away from far endstop distance. | |
| 1320 | MC = 54 mK and cooling. Tower = 0.49 K and cooling. |
| 1322 | Do mv +128. MC rises quickly to 150 mK, then continues rising more slowly. Waveforms look ok, same as before. |
| 1324 | MC peaks at 173 mK. Tower = 2.05 K and falling. |
| 1352 | MC = 40 mK and cooling. Tower = 0.33 K and cooling. |
| Note - I just noticed that the Dwell is at the default 15 ms, rather than 40 which is what we usually set it to. Since the Arduino connection isn't persistent, it keeps going back to 15. So probably for almost all the moves we've done it's been at 15 rather than 40. | |
| 1400 | Reset Dwell to 40 |
| 1400 | Do mv +32 with dwell = 40. MC rises quickly to 135 mK, then falls. Waveforms look ok, same as before. But - period is ~320 ms, whereas before it was ~120 ms.  |
| this difference makes some sense: the full square wave period appears to be exactly 8x the dwell setting. And a full period represents 4 steps - so it seems that 1 step takes 2x dwell periods. | |
| 1400 | MC peaks at 135 mK. Tower = 1.47 K and falling. |
| 1448 | Begin LHe transfer @ MB = 33.3% |
| 1456 | MC = 32 mK and cooling. Tower = 0.18 K and cooling. |
| 1459 | Do mv +128 with dwell = 40. MC rises quickly above 200 mK, then keeps rising. Waveforms look ok. |
| 1500 | MC peaks at 390 mK. Tower = 2.25 K and falling. |
| MC peaking higher than before, is that because of the longer dwell? Tower though did not go as high. | |
| 1519 | MC = 63 mK and cooling. Tower = 0.45 K and cooling. |
| 1524 | End LHe transfer @ MB = 91.1% |
| 1528 | MC = 45 mK and cooling. |
| 1529 | Do mv +128 with dwell = 40. MC rises quickly above 200 mK, then keeps rising. Didn't get the waveforms, must have had the scope set wrong. |
| 1531 | MC peaks at 400 mK. Tower = 2.31 K and falling. |
| 1550 | MC = 61 mK and cooling. Tower = 0.45 K and cooling. |
| 1551 | Do mv +128 with dwell = 40. MC rises quickly above 200 mK, then keeps rising. Waveforms look OK |
| 1553 | MC peaks at 400 mK. Tower = 2.31 K and falling. |
| 1622 | MC = 44 mK and cooling. Tower = 0.33 K and cooling. |
| 1624 | Do mv +128 with dwell = 40. MC rises quickly above 200 mK, then keeps rising. Waveforms look OK |
| 1625 | MC peaks at 378 mK. Tower = 2.25 K and falling. |
| 1734 | MC = 31 mK and flat. Tower = 0.17 K and cooling. |
| 1737 | Do mv +128 with dwell = 40. MC rises quickly above 200 mK, then keeps rising. Waveforms look OK |
| 1738 | MC peaks at 367 mK. Tower = 2.26 K and falling. |
| Endstops-to-chassis still read open. Position now should be 29.44 mm, contact with far endstop should occur at 41.35 mm, so 11.91 mm left to go. |