Since the pressure only reached 1.0E-6 after 2 full days of pumping, I decided to leak check again. There was no leak 180° from the past leak on the plate I rotated, indicating the plate was fine (a visual inspection showed it to be fine as well). There was a leak in the same place as last time (bottom right (south) of the west 6" x 12" plate that goes to the 2D MOT), but maybe smaller, around 2.5E-10 Torr L/s. Interestingly, closing the valve at the end of the leak check spiked the measured leak rate to 4.8E-10 Torr L/s.

I vented the chamber and removed the plate to inspect it and the frame. There was very slight discoloration on the plate in a few places, but I couldn't feel anything. The chamber looked fine. I replaced the plate. Putting in the screws was harder with the 2D MOT in the way, but I don't see an easy way to redesign. We shouldn't have to take this plate to add or adjust components in the vacuum chamber. Due to the awkward angle, I very lightly stripped the top of the head of a screw. This is cosmetic as I could easily get a hex key in, but the screw should be thrown out if we take off the plate again.

I started the scroll at 10:55 PM. Since I suspect the 2D MOT is tugging on the plate through the bellows, I pushed the plates that hold the 2D MOT foward after the pressure was ~1 Torr. I turned off safe start and turned on the turbo at 11:01 PM, the turbo quickly ramped up to speed, maxing out at 99 W drawn. As of writing this at 11:39 PM, the pressure is 3.9E-6 Torr and slowly dropping. If the pressure doesn't get close to 1E-7, I want to take off the 2D MOT, rotate the plate, and add a 2.75" blank flange. We should also use the RGA to confirm the presssure is from a leak and not outgassing. If the leak stays in the same place, the next step would be taking apart the frames, which would be a total disassembly. Being able to valve off the turbo would also make leak checking a lot better, so hopefully the gate valve arrives soon.

Based on this leak checking, there seems to be a singular problematic area. The easiest idea is to rotate the square plate next to the area to see if that fixes anything or the leak moves. There could also be an installation error this would fix.

I turned off the turbo pump, waited for it to stop spinning, then turned off the scroll pump. I turned on the N₂ line and slowly opened the needle valve. I waited for the pressure gauge to read over pressure, removed the screws (a bit of air rushed in), rotated the plate 180°, put it back on, tightened at 10, 20, 30, 40, and 70 in-lb (twice). I then turned off needle valve and N₂ line. I turned on the scroll at 4:37 PM and the pressure was 6.7E-2 just 5 minutes after turning on scroll, faster than before. I turned on turbo at this point, keeping soft start on for a pure comparison, but we should turn it off soon.

After 16 total minutes, the pressure was 5.5E-6 Torr (slightly better than LFC, ~20x better than Dewer at this time), 5W drawn (LFC 10W, Dewer 16W at this time), 1167 Hz pump speed. I am hopeful this was the fix as we've reached a better pressure much sooner. There is a chance the pumps run better the second time, but it took 2 hours of pumping to reach this presssure last time on the RbQ vacuum chamber.

I made slots on both ends of three 1/4-20 to 3/8-18 thread adapters for use with a flat-head screw driver. I used the band saw meant for steel and held the adapters with a collet (a 15/64" collet and 11/32" collet I think) and a square collet holder. Ian checked that a flat-head screwdriver fits into the slot.

I leak tested the RbQ Vacuum Chamber with LIGO's leak checker. Since the 4.5" gate valve hasn't arrived yet, we had to keep the turbo on which makes leak checking more difficult. However, I did fine at least one leak: the bottom of the rectangular prism to cube interface on the south side (roughly 5 Torr*L/s, but this is pretty arbitrary since the turbo is on (and helium spray level ambiguous)). I also discovered all three screws that secure the windows were loose. I gently tightened them. I turned off the leak checker and the helium line. 

I plan on letting the turbo pump a bit longer and seeing if the pressure gets lower. I want to take off, inspect, and reattach these plates since it should be easy. i could rotate the 6" square plate to try to see if that changes the leak spot. The leak could also be caused from the rectangular prism to cube interface itself. We would have to take off 8 plates to fix that, so I want to try that last. If we do that, I think I want to take off the cube entirely and evaluate the pressure with just the rectangular prism. We can make a MOT without the cube, but not a conveyer belt. We could attach the tee and include the ion pump as well as the electronics flange.

[Jeff, Torrey]

After the setup of new monitors in the control room, the USB connection to the Teraxion laser was disrupted. To restore the connection required rebooting the laser while it was USB connected to the computer.

The laser was able to connect via USB to the lab laptop without a reboot, so it seems to be a quirk of our extender that it may require a reboot of the device to properly forward it to the host computer.

[Ian, Torrey]

We tested how much the lab goggles are blocking light at 775 and 1550 nm. We did this by setting the power meter on the table in an existing path, recording the value, and then putting the goggles just before the power meter and recording the values. We also cleaned the goggles before testing. We did this with 5 different goggles randomly chosen from the box of goggles. For the "dark count" of the, we turned off the light and blocked the beam up stream. I think there was a large amount of scatter because the dark count was always higher than the goggled blocked measurement. The values were as follows:
 

The goggles claim to be OD 7+ @ 696-1550nm. 

If you saw a previous version of this where we were claiming different numbers, we didn't account for the ambient room light being at uW levels. Turning out the room lights accounts for this.

I grabbed the LIGO Lab leak checker from Maty Lesovsky and put it in B111A to leak check the RbQ Vacuum System. We can also use it to leak check the SNSPD Dewer. Maty said she shouldn't need it for a few weeks.

I added a 2.75" CF to KF25 adapter to the RbQ vacuum chamber composite angle valve in preparation for using the leak checker (which uses a KF25 hose). I tightened the bolts until there was flange to flange contact all around. The pressure didn't change from 2.6E-6 Torr during any of this work.

I plugged in RbQ Vacuum Chamber turbo controller into the wall outlet. After warming up, the pressure was "over pressure". I enabled soft start, hit show decrease speed, changed the gas load to air (I don't think this does anything), and changed the pressure units to Torr. I plugged in scroll into the wall outlet and turned it on at 11:57 AM. It starting pumping after 35 seconds, and the pressure gauge showed numerical readings a few seconds after that. I put the interlock bypass D-Sub into the turbo controller and started turbo at 8E-2 Torr, 6.5 minutes after turning on scroll. While in the soft start, the turbo pump drew up to 95W, around 4E-5 Torr 11.5 total minutes in and 2E-5 13.5 total minutes in. After 18 total minutes, the pressure was 1.6E-5 Torr (2x worse than LFC, 10x better than Dewer, all 12 minutes after starting the turbo), 16 W drawn (LFC 10W, Dewer 16W, all 12 minutes after starting the turbo), 1167 Hz pump speed (this is manually set). The pressure was 7.2E-6 at 1:11 PM. I think we can get below 1E-6 Torr, but this is still too high for an Rb MOT, which should be near 1E-8 Torr (the Berkeley class lab operates aaround 4E-8 Torr). The cube baseline pressure is 1E-7 Torr. We probably need to leak check.

I used some 70:30 DI:Isopropanol wipes to clean the surface above the B111A optics tables. These top surfaces were quite dirty, with grime, wood shavings, screws, and wire scraps. It's not perfect now but it's much cleaner.

[Ian, Daniel]

We installed the 6" to 2.75" CF Zero Length Reducer Flange on the 6" Gate Valve on the IFO Cube for the ion pump. I tightened the bolts to 34 Nm. There was a very small gap at the bottom of the flange, but otherwise there was flange to flange contact all around.

I then attached a 2.75" CF 4 way cross which had a composite angle valve (for venting the ion pump section) already attached from the Holometer to this reducer flange. I added a pressure gauge (down to 1 mTorr) that was on an elbow and a small ion pump. I plugged in the gauge and it read ~810 Torr after a few minutes.

I attached an all metal 2.75" CF angle valve to a 2.75" CF Tee. This is meant for the residual gas analyzer.

I tightened all the bolts unitl there was flange to flange contact.

[Jeff, Ian, Daniel]

We put the Agilent TwisTorr 74 on the 4.5" to 2.75" 4 way reducer cross and tightened the bolts to 20 Nm as per the manual. We had to put the bolts up and use nuts as the TwisTorr 74 does not allow for 2" long bolts to be placed through it. We used these clipped 5/16" ID washers and they worked very well. I connected the fan to the turbo pump and the turbo pump to the IDP 7 scroll pump. I connected the turbo controller to the turbo pump, to the pressure gauge, and to the fan. I did not connect it through the computer, plug it into the wall outlet, or put in the interlock bypass D-Sub. We put the IDP 7 scroll on the platform and flipped a switch so that it expects 115 V from the wall, but we did not plug this in either.

We connected the 1/4" ID tubing from the N₂ source to the up-to-air valve. I couldn't get the hose clamp to work for the barbed adapter, but it shouldn't matter. We briefly purged the tube before installing it on the up-to-air valve.

I cleaned with puffs of air the 4.5" CF window, AR coated for 780 nm light and installed it on the vacuum chamber opposite the 2D MOT. I used the molded viton gaskets which worked very well here by staying next to the knife edge (I tried a few weeks ago to no success). I tightened the 1" long 5/16-24 screws to 2.2 Nm. The chamber is now completely sealed.

While it works, the KF25 tubing is too long. We should get 30" long tubing instead of 48" long tubing and use the 48" long tubing for the GQuEST IFO vacuum chamber that it was originally bought for.

Tomorrow, I hope to turn on the pumps.

[Ian, Torrey]

We added the two-monitor setup to the control room. This should allow us to have more real estate to see more screens in the Moku software. We also switched the computers' positions, so now Gouy is on the left. This is because Gouy is the only one that has two HDMI ports. I also tidied up some of the cables that were in the cable tray. 

I took apart the 4.5" CF Gate Valve from Alan Rice in hopes of cleaning it effectively since it was sitting out and exposed on a shelf and is over 40 years old. It was visually dusty. I took apart the top screws (probably 1/4-20) and pulled out the sealing flange and the machinery to make the gate valve open and close. The parts are horribly discolored. As a sanity check, I was able to put everything back together and I then put it away in a bag. There is no one-time-use gasket sealing the system, but instead a silver colored square ring that is 3.5" x 1.5" on the outside, a horizontal thickness of ~0.095", and a vertical thickness of 0.033" (1/32"?). There didn't appear to be a knife edge. There is a separate set of screws by the handle of the gate valve that come off but there wasn't any gasket there.

I have noted the following voltages on the Laser Filter Cavity (LFC) Ion Pump Controller and the pressure according to the Agilent FRG702 pressure gauge. The voltage corresponds to the current draw by the ion pump. These are only from "steady" times, not when there is a sudden change in the system, for example turning the ion pump on or closing the gate valve to the turbo pump. I graphed this data. The fit appears linear, but the lowest voltage (not steady state) I've seen is 2.1 V when first turning on the controller, so the fit seems good up to ~1.4E-6 Torr. Maybe this is when the current maxes out, assuming a constant current to voltage conversion.

This is a continuation of LeeLog 12105. TLDR - Teraxion laser is fully installed and functioning correctly except for the modulation port required to lock a cavity.

We put the swap on hold as a result of there being no internal Faraday Isolator in the teraxion seeder. Lee mentioned this should be fine for the short term. We plan on buying an isolator soon. In the mean time we should be fine to run this test.

Notes for the swap:

-Powered down amplifier. Turned off Thorlabs seeder.

-Secured laser module to the breadboard.

-Connected the module via USB extension to the BREWSTER computer. Connected fiber output to the power meter via fiber adapter. Turned power on.

-Installed the teraxion LXM laser control GUI on the BREWSTER computer.

-We successfully turned on the laser via the LXM laser control software. Note the software has an interlock system with a password, this password is 1234 and can be found in the manual. The initial output of the laser is 45mW as seen in the photo. I have concerns with controlling the laser via this little GUI. I don't know how closing the program or disconnecting the USB effects the continuous operation of the laser. This is important to ensure that no damage is done to the amplifier. We may test how easy it is to disrupt operation of the laser module before connecting to the amplifier. Testing in the software, there is no "are you sure button" when disabling the output. One click disables it.

-The laser has ADCs and a popout in the software to track parameters of the laser like TEC current, laser temp, etc. See adc.png.

-I decided to test the continuous operation of the laser. Click the "Exit" button in the bottom right of the software does not disrupt lasing. I will assume that the laser will not shut down unless commands in the software are giving. This alleviates my worry outlined above.

-I plan on replacing the fiber PBS with a 75:25 fiber BS. This means one laser will have significantly reduced output. I need to double check the nominal output of the thorlabs laser to see if output*.25 is high enough to properly seed the amplifier.

-Replaced the fiber PBS with the 75:25. The output for the thorlabs seeder after the :25 path in the fiber beam splitter is ~10 mW (using the power meter, this value will change for the amplifier threshold power detector), which is most likely below the required input for the amplifier. Reminder: "Turn the Key ON: if the input power is lower than the pre-determined lower threshold power (typically 10-20 mW), there is an Alarm LIP (low Input Power), otherwise the preamplifier turns ON." Alternatively, we can swap the outputs of the fiber BS to avoid any alarms. The white output fiber should be used for the teraxion, the red output fiber for the thorlabs. Otherwise just getting one of these but a 50:50 would avoid having to ever swap any fiber connections. This is recommended.

-The teraxion is now seeding the amplifier. The power meter read 30.3 mW, the amplifier seeder is reading 27 mW. Both of the values are above the threshold. Continuing with turning on Amplifier.

-Turned key and hit enable on amplifier. The amplifier is now in pre-amplification mode. ~300 mW at the output, seeded by the teraxion.

-There is no 775 light. No light seems to be exiting the SHG. I suspect the wavelengths of the 2 lasers are different enough that the temperature controller needs to be tuned to the proper temperature for the SHG. I don't need 775 light for this test however so I will just note it and move on. Alternatively the wavelength of the laser can be tuned via a temperature controller. You most likely can tune to the same wavelength as the thorlabs controller so the SHG temperature controller doesn't have to be touched.

-The last step is we need to be able to modulate on the new laser. The manual says "please refer to the device test sheet to determine if your laser module accept ±2.5 V input or 0-4 V". Our test sheet on the wiki says +/- 2.5V. If using the moku this will never be a problem as we can't operate above +/- 2V in MIM anyways.

-Connected a moku output to the modulation port of the teraxion laser via patch panel and SMA adapter.

-Everything is connected. Scanning 2 V pp on the modulation port doesn't flash the cavity. I don't think anything is actually scanning. The scan amplitude is .2 GHz. The FSR is 125 MHz. Even at half the scan range we should see something. I tuned the temperature controller to have the cavity naturally flashing, and then turn on the modulation scan and still don't see anything. Manual shows a diagram connected to a waveform generator with a "10-100kHz" signal. Changed the scan frequency to this range, no change. I confirmed the moku is outputting a voltage via T-ing off the output and checking on a different scope. There is a triangle wave. 

-Not sure what else to try so I checked the Ultra Narrow Linewidth Mode that is unique to the LXM-U that we have. It works.