2021/07/06 (Tuesday)
- Lab in-personnel: Pramod, 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. (Currently DCRCs off, only source mover board plugged into Cable 3) | |
| 1200 | Tower/MC/Coldplate = 77.9/30.7/187 mK, Still = 1.32 K / 0.080 mbar / 0 mW, G1/G2= 241/223 mbar, 1K Pot = 1.64 K / 22±2 mbar. MB = 62.0% |
| 1205 | Fill LN2 cold trap bath. |
| 1207 | Do mv -4 with dwell = 15 and power = 7.2 V. (Forgot to reset dwell to 40.) This is not quite far enough to contact the endstop. V_trimpot = 6 Vpp, Vpower = 8.0 Vpp. Tower peaks at 0.88 K |
| 1212 | Do mv -4 with dwell = 40 and power = 7.2 V. Multimeter shows contact with endstop. V_trimpot = 6.6 Vpp, Vpower = 8.0 Vpp. Tower peaks at 1.05 K |
| OK on Saturday I tried reducing the driver voltage to 6.4 V and we got lower temperature and 100% step efficiency. We'll try and even lower voltage now. First let's move away from the endstop at 7.2 V, then we'll try moving back at a lower voltage. | |
| 1221 | Do mvNwait +4steps×30times, 45 second wait, with dwell = 40 and power = 7.2 V. (Around 5.28 mm/hour.) First move: V_trimpot = 6.6 V peak-to-peak, Vpower = 8.0 Vpp. First MC peak ~ 67 mK, then each peak was higher for a while. Final peak = 173.4 mK. Final minimum between peaks = 171.4 mK. Over this 22.5-minute sequence Condenser pressure rose from 235 to 255 mbar |
| 1347 | Do mvNwait -4steps×30times, 45 second wait, with dwell = 40 and power = 5.6 V. (Around 5.28 mm/hour.) First move: V_trimpot = 4.8 V peak-to-peak, Vpower = 5.9 Vpp. First MC peak ~ 47 mK, Then it climbed for the first 15 moves, peaking at 133 mK, min between peaks 132 mK. But then the peaks started getting lower each time. Final peak = 122 mK. Final minimum between peaks = 121 mK. Over this 22.5-minute sequence Condenser pressure rose from 240 to 248 mbar |
| Not yet seeing contact with endstop. Let's move a little more. | |
| 1438 | Do mv -4 with dwell = 40 and power = 7.2 V. Multimeter still does not show contact with endstop. |
| 1439 | Do mv -4 with dwell = 40 and power = 7.2 V. Multimeter still does not show contact with endstop. |
| 1440 | Do mv -4 with dwell = 40 and power = 7.2 V. Multimeter still does not show contact with endstop. |
| 1442 | Do mvNwait -4steps×10times, 45 second wait, with dwell = 40 and power = 7.2 V. (Around 5.28 mm/hour.) |
| Multimeter still does not show contact with endstop. | |
| 1450 | Do mvNwait -4steps×10times, 45 second wait, with dwell = 40 and power = 7.2 V. (Around 5.28 mm/hour.) |
| After 4th move, multimeter shows contact with endstop. So - after the 30 moves at 5.6 V, we needed 17 moves to get back to where we started. That means that the 30-move sequence at 5.6 V only moved the source an equivalent of 13 moves. 13/30 = 43% step efficiency. So: 5.6 V is definitely too low to drive the stepper motor, though 6.4 V seems to work. |
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| 1530 | At 10kHz noise in DCRC3qI/qO/DCRC1qI/qO = 4.0/1.1/21/6.3 e-6. This is q3/q1/q4/q2 At 3kHz (peak) noise in DCRC3qI/qO/DCRC1qI/qO = 54/9.8/27/222 e-6 |
| 1540 | Turn off DCRC3 and disconnect Cable 2. At 10kHz noise in DCRC1qI/qO = 46/6.5 e-6. At 3kHz (peak) noise in DCRC1qI/qO = 43/90 e-6. So not really any improvement. |
| 1545 | Turn off DCRC1 and disconnect Cable 3. At 10kHz noise in DCRC3qI/qO = 2.2/1.0 e-6. At 3kHz (peak) noise in DCRC3qI/qO/ = 50/24 e-6 A little better @ 10kHz. |
| 1555 | Reconnect both DCRCs and cables |
| 1605 | Move DSub connectors around on DCRC55(1), significantly improve the noise… |
| 1605 | At 10kHz noise in DCRC3qI/qO/DCRC1qI/qO = 3.4/0.84/1.2/4.6 e-6. This is q3/q1/q4/q2 At 3kHz (peak) noise in DCRC3qI/qO/DCRC1qI/qO = 45/5.3/6.3/99 e-6 All significantly better than before. |
| 1615 | Try setting q4(DCRC1qI) threshold - can set as low as 25 without any noise triggers. |
| 1618 | Start 45 min series of Start sequence with Start button. |
| Noticed later that cables from power supply to bnc for detector bias were connected the wrong way. This was supposed to be 0V/-15V but actually was 0V/+15V |