2021/07/03 (Saturday)
- Lab in-personnel: Matt
| 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. (DCRCs on overnight - currently source mover board is disconnected) | |
| 1335 | Tower/MC/Coldplate = 374/36.7/194 mK, Still = 1.40 K / 0.080 mbar / 0 mW, G1/G2= 226/208 mbar, 1K Pot = 1.63 K / 20±2 mbar. MB = 27.1% |
| 1340 | Fill LN2 cold trap bath |
| 1340 | Unplug both DCRCs and connect Cable3 to source mover board. |
| Let's try moving the source back to the near endstop, but we'll try lower driver voltage. We'll see whether the equilibrium temperature is lower and whether we get full step efficiency. | |
| 1350 | Do mvNwait -4steps×30times, 45 second wait, with dwell = 40 and power = 6.4 V. (Around 5.28 mm/hour.) First move: V_trimpot = 5.8 V peak-to-peak, Vpower = 6.9 Vpp. First MC peak ~ 57 mK, then each peak was higher for a while. Final peak = 160.8 mK. Final minimum between peaks = 159.7 mK. Over this 22.5-minute sequence Condenser pressure rose from 215 to 235 mbar |
| 1406 | Start LHe transfer @ MB = 26.5% |
| OK let's do another sequence - this time we'll move enough steps to contact the near endstop. | |
| 1427 | Do mvNwait -4steps×20times, 45 second wait, with dwell = 40 and power = 6.4 V. (Around 5.28 mm/hour.) At end of sequence multimeter shows contact with endstop as expected. So looks like 100% step efficiency. |
| 1440 | End LHe transfer @ MB = 89.2% |
| 1454 | Do mv +4 with dwell = 40 and power = 7.2 V. Doesn't quite break contact with endstop |
| 1456 | Do mv +4 with dwell = 40 and power = 8.4 V. Breaks contact with endstop. (So accurate to within around 0.07 mm) |
| OK, so looking at Thursday's analysis, moving here at the same rate but lower voltage, the average power dissipated is about 14% lower (80.8 uW instead of 93.7 uW). That's with the voltage decreased by 11%. |