2021/03/24 (Wednesday)
- Lab in-person: Matt
- Virtual partner: Zach
| Status | Run 74 in progress. Recooled the fridge after a partial warmup intended to pump out He, hoping to fix the short in q4. Now we can't cool to base, stuck around 0.4 K. |
|---|---|
| Setup: DIB1/2+acc → SL 41/43 → 3.2 MHz filters → cables 2/3 → nothing/HV_diverter_board → DCRC50(3)/55(1). |
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| 0913 | MB = 24.6% |
| 0855 | Tower = 0.38 K, cooling very slowly. |
| 1020 | Noise in DCRC3qI/qO/DCRC1qI/qO = 26/3.2/96/6.8 e-6 @ 10 kHz. A bit worse than yesterday. |
| 1022 | Start 31min series of +11V data (bias applied after 1 min), with 1000 beginning randoms, trigger threshold off/off/350/off on DCRC3qI/qO/DCRC1qI/qO, no in-run randoms, with 1.6384 ms pulses (8192 length) and 400 us prepulse (500 length). Use sequence r74_takeandflash_dcrcbias.msl |
| 1025 | Bump the DCRC1qI threshold up to 400 |
| This data looks a little better than yesterday, but it's pretty terrible. Compared to earlier data the resolution of the 60keV line is a lot worse. Noise is of course worse, probably mostly due to the elevated temperature. | |
| 1355 | Matt enters lab |
| 1400 | Tower/MC/Coldplate = 0.38/0.41/0.53 K, Still = 1.46 K / 0.24 mbar / 5 mW, G1/G2 = 637/599 mbar, 1K Pot = 1.65 K / 28±2 mbar. |
| Still doesn't look bad but MC and Coldplate are elevated. So probably a touch from one of those stages to a warmer stage… | |
| Let's try the source mover. Refer to run diary from July 25. Also refer to arduino instruction page. | |
| 1430 | Power down DCRCs, unplug cables. Plug Cable 3 into source mover diverter board. |
| 1445 | Disconnect source mover from Arduino and plug in the spare motor, to test it. Plug power in from GWiNSTEK supply and set to 7.1 V, light on red board comes on. Plug usb from fridge computer into arduino. Doubleclick Arduino_Create_Bridge_shortcut on desktop and open arduino web editor page. Used “sign in with google” and I guess it used my account, we're in. On Monitor tab type Help to remind myself of the commands. Try some moves on the spare motor - it works. |
| 1450 | With GWiNSTEK power off, plug source mover wires back into arduino (red board), then connect USB. |
| Now referring to Aug 13 run diary | |
| I think everything is plugged in correctly - we left things as is, hopefully nothing is unplugged. From the diverter board 4 wires go to the breadboard with the RC filters. 4 wires from that breadboard go to the arduino. | |
| 1505 | OK let's try a move. Do mv +4. No change in Tower temperature, stays at 0.376 K. (It has been cooling since disconnecting the DCRCs, and it's still cooling.) OOPS - I did not have the GWiNSTEK power on… |
| 1505 | Turn on GWiNSTEK power, set to 8 V |
| 1510 | Do mv +4. Tower temperature rises to 0.81 K, then falls. After 7 minutes it cools to 0.45 K, getting close to the current crappy base. This does not seem to be an improvement compared to the last run. |
| 1520 | Fill LN2 cold trap bath |
| 1520 | Do rd dwell, it's 15 ms; 40 ms is standard. Before changing it, let's undo the last move, theoretically getting us back to the start point. |
| hmm - had a temperature spike to 0.72 K. Didn't actually do anything; but the connection on the web editor seemed to be lost, so I just reloaded the page and it came back, and I did the read dwell command. Something there caused the temperature spike. | |
| 1510 | With Tower = 0.49 K and cooling, do mv -4. Tower temperature spikes to 1.00 K, then falls. |
| Basically I think this means the source mover is working. The only way to be sure would be to move it to an endstop, and that would take too long (presumable we still need to move it slowly). | |
| Can refer to Oct 28 run diary for tests of the source mover by viewing waveforms. Don't want to do that now though, getting lateish. | |
| Let's start warmup. | |
| 1535 | Stop circulation by closing V6. |
| 1540 | Condenser falling, Still pressure rising, Tower temperature rising |
| 1540 | Turn off 3He pump. Close 1K Pot needle valve. |
| Notice that cryostat-side transfer line was never removed after transfer 2 days ago! Remove it now. | |
| 1545 | 1K Pot → 1.44 K / 3.4 mbar. Condenser = 360 mbar and falling. Still pressure off scale. Tower = 1.29 K and rising. |
| 1550 | Turn off GWINSTEK power supply to source mover driver board, then unplug Arduino. |
| 1550 | Tower/MC/Coldplate/Still = 1.43/1.72/2.90/2.21 K |
| 1555 | Close 1K Pot speedivalve. Let's see if 1K Pot temperature rises, then maybe pump more gas out of it. Get it pretty empty. (This isn't really necessary - we know the overpressure relief valve works.) |
| 1600 | 1K Pot → 1.9 K. Close V4a, open 1K Pot speedivalve, then open V4a in spurts to pump out pot without letting the pressure rise above ~ 10 mbar. 1K Pot → 1.42 K / 3.0 mbar. |
| 1605 | Turn on camera to monitor recovery meter every 2 minutes |
| 1610 | Do one more cycle of closing 1K Pot speedivalve to let it warm a bit (to 2.25 K) then pump out again. |
| 1615 | Close 1K Pot Speedivalve, close V4a and valve at 4He pump, switch 4He pump outlet to Exhaust, close Recovery valve from 1KPot exhaust, turn off 4He pump. |
| 1615 | Tower = 1.74 K and rising, Condenser(G1) = 167 mbar and falling, 1K Pot = 2.0 K and rising. |
| 1620 | Turn on MC heater → 20 mW. Increase Still heater → 20 mW. Tower temperature starts rising more quickly. |
| 1620 | MB = 11.7% |
| 1625 | Open V3, letting gas from condenser side to still side. Condenser pressure falls a bit, 152→123 mbar. |
| 1615 | Tower/1K Pot = 2.77/3.00 K and rising, Condenser(G1) = 260 mbar and rising. |
| 1635 | Open V9 to let mixture into dump (through LN2 Trap 2). |
| 1640 | Recovery = 13.8 cuft/hr |
| 1640 | Matt exits lab |
| 1725 | Tower/1K Pot = 3.30/4.35 K, G1(fridge+dump) = 465 mbar and rising. (Is this kind of high?) |
| 1925 | Tower/1K Pot/Sorb = 8.3/>7/10.3 K, G1(fridge+dump) = 569 mbar. |
| 1930 | Start pumping fridge and trap to dump, through V6 = 13%. Open V6 → 13.5% after a few minutes. P1 falls to 5 mbar. |
| 1940 | Isolate fridge and pump only on LN2 Trap 2 to dump, using V5. |
| 1950 | Isolate LN2 Trap 2 (using V12b, although V12b speedivalve needs to be closed too). Start pumping fridge to dump again, both sides, V6→25%. |
| 1955 | Tower/Sorb = 9.7/14.4 K, P1(fridge) = 0.18 mbar, G2(dump) = 749.3 mbar |
| 2005 | Tower/Sorb = 10.3/15.3 K, P1(fridge) = 0.08 mbar, G2(dump) = 749.7 mbar |
| 2005 | Close V6 to stop pumping on fridge. Leave V1 and V3 open, we can watch if any contaminants boil off on P1 and G1. |
| 2020 | MB = 6.5% |
| 2030 | G2(dump) has fallen to 748.5 mbar, kind of strange. Maybe the barometric pressure is changing? Close V9 to isolate dump and turn off 3He pump |
| 2030 | Tower/Sorb = 10.6/17.1 K, P1(fridge) = 0.20 mbar |
| 2030 | Recovery = 15.2 cuft/hr |