16:45 JeffB transition LVEA to laser safe
17:00 Hugh & Corey to HAM6 for CPS work
17:00 PeterK & Ed to PSL enclosure
17:30 TJ to HAM6
17:45 JeffB to LVEA
17:45 Betsy & Travis to EX
19:30 Sheila found sqz and isct6 lasers still on after morning laser safe transition
20:15 Betsy & Travis to EX
20:15 M&M to HAM6
21:30 Peter to PSL
21:30 TJ to HAM6
22:00 Fil to LVEA
22:15 RickS Niko to EX, EY to remove PCAL Camera
22:15 M&M to HAM6
22:45 Sheila transition LVEA to Hazard
Laser Status:
SysStat is good
Front End Power is -0.003262W (should be around 30 W)
HPO Output Power is -0.04724W
Front End Watch is RED
HPO Watch is RED
PMC:
It has been locked 0 days, 0 hr 0 minutes (should be days/weeks)
Reflected power = 0.008512Watts
Transmitted power = -0.02508Watts
PowerSum = -0.01657Watts.
FSS:
It has been locked for 0 days 0 hr and 0 min (should be days/weeks)
TPD[V] = 0.06625V (min 0.9V)
ISS:
The diffracted power is around 3.3% (should be 3-5%)
Last saturation event was 14 days 2 hours and 58 minutes ago (should be days/weeks)
Possible Issues:
Front End Power is Low
FSS TPD is low
LRA out of range, see SYSSTAT.adl
The HEPI trends script was broken this morning when I launched it from the weeklies screen. This was caused by the changes to the EX channel names from the switch over to Beckhoff at that station. I updated the channels to my best guess but it's a little hard to say because the new overview doesn't seem to give a good map compared to the old overview.
Today, Betsy and I prepped the ETMx Quad for removal of the lower structure tomorrow. We swung back ACB, locked down all optics and masses, and disconnected all cables and wire segment necessary for removal of the lower structure. We are in good shape for extraction from chamber tomorrow morning.
Following the installation of the improved TEC controller for the SHG, we started tuning the loop.
Figure 1: A single pole at 0Hz, a zero at 100mHz and with 10mHz selected in the ugf box. There is a fair amount of overshoot and it takes a long time to settle.
Figure 2: The zero has been moved down to 10mHz.
Figure 3: The zero has been moved down to 5mHz.
Figure 4: The zero has been moved down to 7mHz. The overshoot is about 20%. We are sticking with this value for the zero.
Figure 5: Pole at 0Hz, zero at 7mHz, another pole at 1Hz, gain of -1, ugf box set to 30mHz.
Figure 6: Response measurement at 30mHz, indicating that the ugf is around this frequency.
70W install is ongoing
Gerardo noticed this.
Kyle, Dave:
Two changes to the Vacuum cell phone alarms:
| H0:VAC-MY_CP4_253_REGEN_TEMP_ALRM_INTLK | Cell phone texts bypassed for 24 hours, expires Tue Mar 20 10:40:38 PDT 2018 |
| H0:VAC-LY_Y4_PT124B_PRESS_TORR | HIGH alarm raised from 5.0e-08 to 1.0e-07 Torr |
H1CDS_ROC.adl MEDM improved to show alarm levels and current value. Red border follows these alarm levels.
Transitioned the LVEA to laser safe. Locked the ISCT6 and Squeezer cabinets. No other issues noted.
Recall that TC1 has an offset and that it is under-representing the actual temperature it is exposed to by 6C - 10C. Also while at Y-mid, I closed the exhaust valve on the turbo that is pumping CP4, closed the foreline isolation valves and opened the scroll ballast/purge plug. This allowed room air to purge, under viscous conditions, any water that may have condensed between the scroll stages since stopping the UHP N2 purge gas the other day. I restored the configuration after a minute or two of viscous purge. I used the hand-held TC meter to measure the underside of CP4's vacuum vessel (1 ft. radius around vent/purge nozzle represented by TC3) and found the average temperature to be around 65C. It would be interesting to see if we could lessen the temperature striation we are experiencing (HOT air resides at high elevations cooler air found at lower elevations) by heating the inner LN2 reservoir using the regeneration system.
Reminder that when changing setpoint, first turn heater off so that program doesn't flake out.
I'll be at Y-mid checking in on the CP4 bake. I'll also "pop" in and look at the X-end and LVEA purge-air supplies. Gerardo M. has been notified. I expect to be hear less than 90 minutes and will make a comment to this entry when I leave.
Turbo pumping CP4 very close to overheating -> Valved-out turbo's UHP N2 purge and foreline pressure dropped from 2.5 x 10-2 Torr to 7.4 x 10-3 Torr. Also, stopped PLC PID bake, lowered the SETPOINT to 110C down from 130C. We easily have enough heat now with the extra 10kW but are suffering from a significant Top to Bottom temperature gradient. This is a fundamental consequence of this initial setup and can't be easily addressed without stopping the current bake-out and then making significant modifications. Eliminating leaks between the insulating blankets would help some and can be done while bake is in progress. Also, use of the Regeneration System could also lessen the gradient but comes with its own added risks. 1555 hrs. local -> Kyle leaving site now.
Kyle has requested the high alarm level for PT243 (Y1 beam tube, adjacent to MY) be increased as it is now reading above 5.0e-08 Torr. He requests it be increased to 1.0e-07. I have done this and restarted the alarm system.
H0:VAC-MY_Y1_PT243B_PRESS_TORR (VE gauge, MY Y1-beamtube, CC )
current value = 5.419e-08 Torr
low alarm level = 1.000e-10 Torr
high alarm level = 1.000e-07 Torr
(Regarding camera view of CP4's bake-out control PLC display) I noticed that TC1 has acquired an offset as of this morning. This TC is the closest to the heat source and, until this morning, has consistently been the "hottest" of the four displayed TCs on the PLC display. Now, it is consistently below TC2 which is the next TC downstream in the heated air flow. I am sure that this is the result of its extension wire connector being disturbed during the installation of the second duct heater this morning. This extension wire connector is located very near where the work was being done and would have been in the way. As the TC is what the PLC is using to determine the heater output, it is important that it represent the actual temperature of the air exiting the heater. If this TC's value differs too much from TC2 or becomes "bogus" we could have a problem of the PLC overheating or underheating. I'll keep a close eye on it over the weekend.
Verbal alarms just reported high vacuum alarms at BSC2, BSC7, HAM6 and PT245. I can understand the ones at HAM6 and PT245 (CP4), but I'm not certain about the ones at BSC2 and BSC7. Is this due to the change in verbal alarms code [alog 41046]?
Minute trends for last 30 days.
I don't see any reason why we should be getting any alarms from the Corner Station. PT110, PT120 and PT170 shouldn't be alarming at current pressures. I don't know what the alarm levels are currently set at for the Y-mid station (PT210, PT245 and PT246) but we are monitoring regularly from home due to the fact that we are currently baking out CP4. I think that Chandra's intention was for Dave B. to have recently increased PT210's alarm threshold from 5 x 10-8 Torr to 1 x 10-7 Torr. This was so as to reduce potential nuisance alarms resulting from the Y-mid pressure rising as CP4's temperature slowly increased to its eventual maximum of 130C (Sunday? Monday?).
The threshold in Verbal for all vacuum chambers, except for HAM1 & HAM6, is set at 7e-8Torr. We are definitely above that for all of the alarmed chambers so the alarms make sense. I currently have the vacuum alarms to repeat every two hours if they are still in their alarm condition. This seems to be a bit much, but I erred on the cautious side with data taking operations in mind.
Since this is creating alarm noise while we are venting, and the vac crew has their own alarm systems in place, I will drop the threshold until we are back under normal operations.
Nutsinee Terry Daniel
OPO locking:
Fibers:
Translation stage:
Next:
Taking the 62% dip in reflection at face value, we can calculate the crystal loss assuming we know the input coupler (nominally 98% reflectivity) and neglecting any effects from mode mismatch:
| R input coupler | Crystal Loss | Finesse | Power buildup | Crystal Loss | Finesse | Power buildup |
| 0.975 | 0.60% | 200 | 103 | 10% | 48 | 6.1 |
| 0.980 | 0.48% | 250 | 129 | 8.2% | 59 | 7.5 |
| 0.985 | 0.36% | 335 | 173 | 6.2% | 79 | 10 |
There are two possible solutions. However, the high loss solution is not very likely.