Today I brought in a fresh supply of zip ties (we now have 1500 in the tool chest) and used them to permanentize the cable routing for the gauges, pumps, and RGA.

I also brought and installed a 3-foot 15A extension cable for powering the scroll pump. Installing the cable required shutting down the pumps, which I did and then reverted via the following procedure:

1. Close the 4.5" gate valve, 2.75" gate valve, and the bypass line angle valve.
2. Shut down the turbo pump.
3. Shut down the scroll pump.
4. Unplug the scroll pump and install the extension cable.
5. Power on the scroll pump.
6. Power on the turbo pump.
7. Open all three valves.

Incidentally, before I started, I noticed that the pressure in the main volume had reached 7E-7 torr, which is lower than the pressures seen last week. The system quickly returned to this pressure after I restarted the pumps.

For future reference, the calibrated Argon source has a leak rate of 7.55E-8 atm cc/s, or equivalently 5.74E-8 torr L/s. This can be used to calibrate RGA scans to units of physical leakage (outgassing) rate.

The electrical overload problem encountered in ELOG 130 has been resolved. The two heater controllers, which draw up to 14.1 A each, overloaded the UPS and tripped one of its circuit breakers, shutting off power to both power strips mounted above the optical table.

I reset the circuit breaker and rerouted the two heater power cables instead to two separate 20 A outlets in the overhead cable tray outside the cleanroom (both on the LP3B 6 circuit). The two high-limit temperature controllers are now permanently positioned, as shown in the photos. For now, the PID controllers have been left sitting at the table level. I am ordering extension cords that will enable us to move those up to the overhead shelf, as well. I ran the heaters in their new configuration for several minutes without issue. Thus we should be able to now proceed with baking the chamber.

For future clarity, I added labels to power strips around the lab indicating which ones are powered by the UPS. To avoid overloading the UPS, only sensitive electronics or devices that could be damaged by a sudden loss of power should be connected to these.

In response to reports that ants have been observed in the lab, I placed five ant bait traps around the room today. Each is sitting on the floor on top of a piece of aluminum foil, in areas unlikely to be inadvertently stepped on. They contain liquid which will spill out if picked up, so please take care not to disturb them.

Update: After seeing the strong response to the first set, I redistributed them to the hottest spots and added one more trap.

I delivered new NEMA 5-15 (120V / 15 A) power cables to the lab for the following items:

• WS2 (cleanroom) cart - 10ft cable
• Electronics workbench overhead LED - 10ft cable
• Both PI heater controller sets - (2) 6ft cables

I installed the new cables on the WS2 cart and the workbench myself, and left the two 6ft cables (as pictured below) for Aiden to install on the PID controllers after the current bake is finished.

[Jon, Tyler, Aiden, Peter]

Upgrade of the UHV system to a larger turbo pump began today. After obtaining a final RGA scan in the old configuration (Aiden to post), we vented all three volumes and proceeded to disassemble the 4.5"-diameter pump line. We completed installation of the new 6"-diameter pump line to the point where the new turbo pump will attach. This includes a 6" manual gate valve, 6"/2.75" reducing cross, and 6"/8" conical reducing nipple, as pictured below. Strain relief was also installed due to the longer length and greater weight of the new fittings.

Tomorrow we will continue with attaching the Varian TV 551 pump and perform a pump-down test. If this pump is confirmed to be operable, then we will relocate the entire system ~18" closer to the middle of the table and permanentize the setup.

By 5:30 pm Friday, the pressure had reached 8.6e-8 torr and was continuing to fall. So it seems we are OK to proceed with permanentizing this configuration (cable routing, heater tape reinstallation).

[Jon, Tyler, Shane, Peter, Luis]

Today we completed the first phase of lab clean-up. Activities included:

• CF/KF parts stored under the cleanroom table were removed and transferred to Physics 1129
• Cleanroom workbench cleared, with all FROSTI hardware collected into one of the large SS bins
• High surfaces outside the cleanroom (lights, table enclosure frames, rack, cabinets) wiped down with IPA wipes
• Floor HEPA-vacuumed outside the cleanroom
• Sticky mats changed throughout the lab

Tomorrow, we will complete turn-over of the cleanroom (HEPA vacuuming of floors, mopping of floors, IPA wiping of softwalls and work surfaces). Shane will post a forthcoming measurement of the cleanroom particulate levels, post-turnover.

1. Run a second RGA degas cycle, but next time with the main volume valved off with only the RGA volume being pumped (through the bypass line). This will prevent "boiled off" particulate from entering the main chamber and will also increase the pumping rate for the RGA volume, reducing the amount of particulate that resettles on the RGA filament.
   
   
2. I also noticed that the SRS manual states that the filament is designed to be long-lived and it is recommended to leave it on any time the RGA is on. By leaving the filament on all the time (i.e., hot), we could reduce the amount of particulate that is evidently settling on it between scans. I am checking whether LIGO Lab does this in their own chambers.

As a follow up ELOG 261, I have received advice from one of the vacuum experts at LIGO Hanford on best practices for our RGA:

1. For future RGA degassing, definitely keep the main volume isolated, since it could contaminate the main volume with everything that just got cooked off of the filament. So the procedure should be to (i) close both gate valves, (ii) ensure the angle valve on the bypass line is open, (iii) initiate the degas cycle on the RGA, (iv) pump the RGA volume through the bypass line, until its pressure returns to its pre-degas level.

2. Repeated degassing of the filament will definitely wear it down much faster, so do this operation sparingly.

3. As long as the pressure of the RGA volume is in the UHV range (~1e-9 torr), best practice is to leave the filament on. This keeps it hot which helps prevent particulate from settling on it. However the electron multiplier should stay off when not actively taking scans, as it will wear down if left on all the time.

Update: I was able to put the FROSTI power controller on the lab network. It is connected to the switch in the top of the rack and is assigned a static IP address of 192.168.1.12 and an NDS hostname of relay1.

The controller can be remotely accessed through an SSH command line interface as well as an HTML webpage, which can be opened from any web browser on the lab network by navigating to the above IP address (the login credentials are the same as for the workstation computers).

There is also an unofficial Python package for interfacing with the controller: dlipower. We will investigate using this package to interface the controller with soft EPICS channels hosted on the CyMAC. This will allow us to create a custom MEDM screen for controlling the FROSTI heater elements.

Edit: The login credentials were set up to be the same as for the CDS workstations.

[Jon, Tyler, Shane, Luis]

On Wednesday we completed the migration of the electronics workshop from 1119 to the large new workbenches in 1129. The two workstations pictured closest to the front of the room are for electronics assembly and testing, while the two in the rear will house LIGO CDS workstations. We moved all of the tools, cabling, and soldering and test equipment from 1119 to this new location. We also moved the large tool chest to 1129, as pictured, and moved the smaller tool chest to 1119 in its place.

The electronics workbench is ready for use. 

Below is the procedure we will follow to assemble the FROSTI prototype.

1. Install SS guide rods and bottom Macor spacers in bottom reflector
2. Install AlN elements on top of bottom Macor spacers
3. Install upper Macor spacers on top of AlN elements
4. Feed unterminated power and RTD leads through slots in upper reflector
5. Install upper reflector, using guide rods to slowly lower into position
6. Install vented SS bolts for reflectors; Macor bolts for heater elements
7. Remove SS guide rods
8. Bundle power and sensing cable with PEEK cable ties and SS cable mounts
9. Terminate power and sensing cable bundles with PEEK DB25M connectors

[Jon, Tyler, Aiden, Luke]

On Friday we completed assembly of the new stainless steel-topped benches in 1129. We then moved the clean and bake equipment from 1119 to its new larger space in 1129. This included the HEPA flow bench, ultrasonic washer, deionized water drum, nitrogen tanks, and forced-convection oven. The oven was re-anchored to the wall with earthquake restraints in its new location.

The power cords still need to be permanently routed, but the new clean and bake lab is otherwise ready for use.

Update: I have completed permanent routing of the electrical cables. I also ran the ultrasonic washer's drain line to the sink drain (the current hose does reach). The new clean and bake lab is now fully operational.

The custom front and rear panels for the RTD readout chassis arrived last Friday. I installed them in the chassis frame to check their fit. They fit very well, so all that now remains is to complete the internal wiring and test the connections.

The chassis panel designs are archived to LIGO-D2300452 and LIGO-D2300453.

[Jon, Tyler, Aiden, Shane, Pooyan, Michael, Cynthia, Luke]

On Wednesday, we completed long list of work towards making the new lab (1129) fully operational and enabling the next phase of FROSTI testing. 

Cabinet Installation

Three new VWR cabinets with sliding glass doors were installed in 1129. Each unit measures 48" (W) x 22" (D) x 84" (H) and sits along the back wall (see attachment 1). The 350-lb. cabinets were laid in place by Facilities on Monday and permanentized on Wednesday. Work included:

• Earthquake anchoring to the masonry wall
• Sliding glass doors leveled
• Shelving installed
• Wiping down of interior and exterior surfaces with IPA wipes

Server Rack Installation

A new Tripp Lite 42U open-frame rack was laid in place in 1129 and anchored to the floor (see attachment 1). This rack will house all of our general-purpose and simulation computers, which will be relocated from the 1119 rack at a later time.

Lab Clean-Up

Following installation of the new cabinets and rack, we proceeded to organize and clean both labs. Work included:

• Moved parts and equipment into permanent storage in 1129 cabinets
• Wiped down surfaces in 1119 and 1129 with polypropylene IPA wipes
• HEPA-vacuumed floors of 1119 and 1129
• Mopped floor in 1119 with Liquinox solution
• Installed new sticky mats in 1119 and 1129
• Regular cleanroom cleaning and particle counts (see 302)
• Positioned new stainless steel gowning bench outside the cleanroom (see attachment 2)

At this point, the only piece of lab equipment still to be delivered is a HEPA garment cabinet for reusing our (semi-disposable) bunny suits. It is schedule to arrive in mid-February and will sit outside the cleanroom in 1119, in the former location of the HEPA flow bench.

Summary

Today I finished implementing an RTS model to read out the integrated FROSTI RTDs (temperature sensors) via the CyMAC. The model is named "MSC" and is located at cymac:/opt/rtcds/usercode/models/c1msc.mdl. We successfully tested it with the heater elements operating in vacuum at low power (12 VDC), finding them to reach an average steady-state temperature of 160 C.

From the cymac host, the MEDM control screen can be accessed with the terminal command "sitemap" (from any directory).

Measurement Technique

Each FROSTI heater element [299] contains an internal two-wire RTD placed near the front emitting surface, which enables the temperature of the blackbody emitter to be directly monitored. From the measured temperature and the emissivity of the uncoated aluminum nitride surface (known to be ~1 in the IR), the radiated source-plane power can also be estimated.

The resistance of each RTD is measured via a ratiometric technique. The RTDs are powered in series with a 1 kΩ reference resistor located inside the readout chassis [305], whose temperature is not changing. The signal is obtained by taking the ratio of the voltage difference across each individual RTD to the voltage difference across the reference resisitor. The advantage of this technique is that the ratio of  the voltage differences is insensitive to changes in the current through the resistors (since they are all in series; see [271] for wiring diagram).

Implementation Detail

The signal flow is shown in Attachment 1. The eight RTD signals enter through ADC channels 0-7, along with the reference resistor signal on channel 8. The first set of filter modules apply a calibration gain to convert the signals from raw ADU counts to units of input-referred voltage. The ratio of each RTD signal to the reference resistor signal is then taken. The second set of filter modules multiply the voltage-difference ratios by the resistance of the reference resistor, 1 kΩ ± 0.01%, to obtain the RTD resistances in physical units of ohms.

Finally, a freeform math module is used to invert the quadratic relation between each RTD's resistance and temperature. The final signals passed to the third set of filter modules are the RTD temperatures in physical units of degrees C. The temperatures of the tungsten RTDs are estimated assuming TCR coefficients of A=0.0030 C^-1 (±10%) and B=1.003E-6 C^-2, which were provided by the manufacturer.

One DAC channel is used to provide the excitation voltage for the RTD measurement, which is visible on the far right of the control screen. At its maximum output voltage of +10 V, the DAC can drive a maximum current of 10 mA.

I ended the bake of the UHV system (that began on Monday) at 6:23 pm today by switching OFF both PID controllers. The heaters elements were run at max power (24 V DC / 200 mA per element) during this bake, and I left them powered at the same level.

At the time, the instrument readings were as follows:

• Left high-limit controller: 138 C
• Right high-limit controller: 128 C
• Left PID controller: 100 C
• Right PID controller: 100 C
• Main volume pressure: 8.17e-7 Torr
• RGA volume pressure: 4.63e-7 Torr

On Thursday we installed the power conditioning/distribution equipment and networking equipment in the new 1129 rack. The hardware is identical to the setup in the 1119 rack and includes:

• Tripp Lite SU5KRT3UTF - 208V, 5kVA on-line UPS with 120V transformer
• CyberPower PDU20M2F12R - metered power distribution unit, (14) NEMA 5-20R
• Ubiquiti USW-Pro-48 - 48 port 10Gbps network switch

The UPS is connected to a 208V NEMA 6-30R outlet in the overhead cable tray, which is on the building's "standby" (backup power) circuit. An 8-ft L6-30 extension cord has been ordered to permanently run the power cable through the cable tray.

The network switch will be connected to a Cat6 cable that was recently run by ITS from the 1119 rack, allowing the lab's LAN to be extended into 1129. This Ethernet link remains to be tested.

Summary

Following Wednesday's cleanroom cleaning [333], we proceeded to vent the vacuum chamber, remove the heater elements and their mount structure, and install the FROSTI reflectors. The reflectors are the final components to undergo RGA testing before the FROSTI prototype can be assembled. After installing the reflectors, we pumped the chamber back down and initiated a 48-hour 125 C bake.

Vacuum Vent

At ~1:00 pm, we shut off power to all eight of the FROSTI heater elements. Prior to shutoff, all were operating in vacuum at roughly 300 C. We then waited approximately 30 minutes for the elements' temperatures to fall below 50 C.

At this point, we isolated the RGA volume from the main volume by closing both gate valves, leaving the RGA volume to continue to be pumped through the bypass line. We then backfilled the main volume via the needle valve connected to one of the 2.75" ports. Once the pressures had equalized, we removed the chamber lid via our usual procedure (requiring only a small amount of flathead-screwdriver prying) and extracted the heater element assembly.

Reflector Assembly

We then removed the FROSTI reflectors from their protective packaging (for the very first time) on the cleanroom tabletop. We tested the fit of the Macor and stainless steel hardware in the reflectors' tapped holes. The Macor standoffs and bolts appear to fit perfectly. However, the 1/4-20 tapped holes for joining the two reflector halves are too shallow by ~1/4". As a temporary fix, we used some on-hand stainless steel washers (which had already been cleaned and baked) to securely fasten the two halves together. In the final assembly we will replace these with slightly shorter 1/4-20 vented bolts.

Pumpdown and Bake

The two fastened reflector halves were placed inside the chamber, sitting on top of the two mounting legs (see attached photos). We then reinstalled the lid. In order to rough the main volume, we isolated the RGA volume from the pumpline (by closing the bypass line valve), shut down the pumps, and then backfilled the pumpline via the manual vent valve on the turbo pump.

Once the pressures had equalized, we opened the 6" gate valve separating the pumpline from the main volume and powered on the roughing pump. Once the main volume pressure fell below 0.5 Torr, we powered on the turbo pump as well. The main volume pressure reached 5e-6 Torr within ~30 minutes, consistent with previous experience, and was continuing to slowly fall.

Lastly, we initiated a 125 C bake-out of the entire system following our usual procedure. We plan to run this bake for 48 hours (i.e., through the end of the day Friday).

FROSTI assembly began today. After a final set of RGA scans were taken, the vacuum chamber was vented and the reflectors were removed. The chamber was then resealed and pumped down again. 

Today we completed the installation of the Macor hardware and heater elements between the two reflector halves. Tomorrow we will route, bundle, and terminate the power and sensor cables. 

Set-up of the first CDS workstation for 1129, ws3, is complete and the machine is ready for use. The login credentials are the same as the other lab machines.

All that now remains is to install a permanent cable tray for running the new Ethernet cables between the electronics rack and bench (they are currently dangling from the suspended lights).

Today I installed the second desktop workstation in 1129. The new machine is an Intel NUC13ANHi5, with a 12-Core Intel i5-1340P CPU, 32GB DDR4 RAM, and a 1TB SSD.

I loaded it with a fresh installation of Debian 12 and installed the LIGO CDS workstation (control room) tools. It is assigned the hostname ws4 and and the static IP address 192.168.1.19 on the local lab network. Like the other CDS workstations, there is just one user account accessible with the usual credentials.

The machine is fully set up and ready for use.

Today I fixed the final bit related to the nitrogen gas tank, which is to apply sealing tape to M-NPT connector of the hose to prevent leakage (file: AirGunSealed.jpg)
After application of the tape, no audible leak can be heard from connection between the hose and the air gun.

The general operating procedure for the gas tank is as following:

1. Turn the regulator (blue handle) anti-clockwise still it's loose
2. Turn the valve on nitrogen as tank anti-clockwise, immediately the RHS meter of the regulator would jump to approx 2000 psi. This is the standard pressure for high pressure gas tank
3. Turn the regulator clock-wise slowly until the pressure one the LHS meter face reads approx 60 psi. This is sufficient for drying parts with. At this point, the flow pressure still should register zero
4. Press the trigger on the air gun, a high pressure air flow should come out and the flow meter should increase
5. When finished, close the gas tank valve, turn the regulator anti-clockwise, then press the air gun trigger to release gas left in the hose/gun