We have tested the heater to find emissivity, mounted the heater system to the optical table, and have taken irradiance maps of the heater projected onto the screen.

The heater's emissivity was determined by using a thermocouple in conjunction with the FLIR's temperature calibration. To attach the thermocouple to the heater initially, I used Kapton tape and ran both the wires of the heater and the thermocouple through the heater bridge. This allowed for the heater to rest on an optical post and be observed without anyone directly holding it, but there were some measurement issues. The thermocouple had a very wide range of temperatures it was reading, which may have been due to intermittent contact or a short between the two legs of the thermocouple. To solve this and make the temperature measurements more stable, we pried apart the two ends of the thermocouple (to ensure there was no short) and put tape on either side, leaving the end connection bare. This was then taped to the heater, and the thermocouple was much more stable. We also used a K-type thermocouple that has an adhesive tape on it already, which assisted with the intermittent contact as well. With the thermocouple measuring the temperature of the heater, we could point the FLIR directly at the heater and calibrate the emissivity until the FLIR and the thermocouple agreed. Cassidy's emissivity calculator was also used, as I could input a temperature and observe what the emissivity of an area was based on that temperature. We found the emissivity of the heater to be 0.57.

As a note, when observing the heater with the FLIR, it appeared that there was a hot spot in the center, where the Kapton tape sat. Because the Kapton has a different emissivity than the 304 stainless steel of the heater, the FLIR will read it as having a different temperature than it actually does. When using the FLIR in the future, be sure to ascertain whether there is a temperature difference somewhere or if there may be different emissivities.

Additionally, the first heater that I used was taken to a very high temperature and oxidized. The emissivity of this oxidized heater is not known, but could be good information for knowing how oxidation affects these heaters specifically.

To mount the heater system in front of the screen, I used 1/2'' optical posts and the mount I designed using COMSOL's CAD program. The heater was originally 2.5 inches away from the screen, and has since been moved back by an additional two inches so that we could observe the heater side of the screen with the FLIR. We wanted to see what temperature the heater side of the screen was when irradiated by the heater, and how that compared to the camera side of the screen. When the heater ran at 1.12 W of input power, the heater side of the screen had a max temperature of around 29.7 C, and the camera side of the screen read at about 29.5 C. This means that there is very little thermal loss between the two sides of the screen, and any insulation that the screen's adhesive may have is largely negligible. Additionally, the camera was placed at an angle and undetermined distance for these tests, confirming that the temperature measurements compensate well/don’t depend on changes in angle or distance between the camera and the screen. However, there was spots on the back of the screen that the camera was measuring as hot spots where there shouldn’t have been any. I have included an example below. It would be useful to run a test where the camera is directly on the back of the screen without the heater to characterize the screen and see if the hot spots are physically present on the screen or if this is an artifice of the camera because of something like angle of viewing.

Taking irradiance maps of the screen was straightforward. After checking that the emissivity of the screen is 0.99 by viewing it at room temperature, we monitored the max temperature while slowing increasing the wattage the heater was running at. There is not a large change until the heater is at around 95 C, at which point the screen began to rise in temperature from 27 C to 28 C. We took measurements of this while the heater was 2.5 and 4.5 inches away from the screen. The irradiance map has a very symmetrical and circular shape, but does not have the ring pattern that we expected. There may be a few reasons for this: there could be some conduction between the two sides of the screen that is causing the pattern to spread further, the heater setup may not be as ideal as it was modeled to be, or there could be a different, unknown issue.

TO DO:

- It would be useful to run a test of the camera in multiple different positions to ensure our conclusion that the camera’s measurements don’t depend on angle or distance (or that these factors are well accounted for in the current temperature calculations) is correct.

- Measure the back of the screen straight on to identify bright spots and possible reasons as to their appearance.

- Recalibrate camera to ensure it is still correct after testing in multiple positions.

- Take another irradiance map of the screen at a higher input power, as well as moving the heater close/further away to try and replicate the COMSOL irradiance maps. It would be useful to also redo the COMSOL modeling at lower powers and variable distances.

Pictures included of full table setup, the heater mount, the heater with Kapton tape attaching the thermocouple as well as FLIR's measured irradiance map.

Following the problem with contamination particles observed in the the Leybold thermovac TTR 91, we have taken the following step to clean the gauge:

1. Wipe with IPA-wetted Vectra Alpha: Cover the tip of a ziptide with Vectra Alpha wipe corner that has been wetted with IPA, push the wipe around and remove visible particulates
2. Fill the gauge flange with IPA: (following Jon's recommendation to use Lesker's procedure for cleaning their Pirani gauge), flip the gauge up such that the CF flange points upward, fill the flange with IPA all the way up. Use the tip of a SSTL tweezer to agitate the IPA. Let it sits for 20 minutes, agitate every 5 minutes. After 20 minutes, pour the IPA out then spray with dry pure nitrogen
3. Passive drying : Let the gauge sit inside the flowbench for 3 hours (3:30 pm to 6:30 pm)to ensure all IPA has evaporated
4. Baking : Leave the gauge in oven at 50 degree C for 48 hours (maximum allowed temperature is 65 deg C, we use 50 deg C to ensure we are well below this limit). Baking started at 7pm, should finish on Sunday 7pm and ready for assembling to vacuum chamber on Monday morning

Pressure Measured Before Removing Gauge 2.31 E-7 Torr.

Went in and turned on the heating tape in increments of 30 degC until 120 degC was reached. I will let it equilibrate over night and then asses whether or not the chamber can be raised to 150 degC without having the flange to the turbo pump reach over 120 degC as it is not recommended for that flange to be any hotter.

If it can safely be raised to 150 degC, then only 2 days of baking is necessary. If 120 degC is the bake temperature, a week will be needed.

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

[Luke, Luis, Michael]

cleaning cleanroom and particle count

• 8:30 am: started particle count
  • zone 3:
    • 0.3 u: 1195
    • 0.5 u: 177
    • 1.0 u: 132
• zone 4:
  • 0.3 u: 619
  • 0.5 u: 0
  • 1.0 u: 0
• 9:00 am: began surface check and wipedown, including softwalls
• 9:35 am: started vacuuming the floor
• 9:43 am: finished vacuuming the floor
• 9:45 am: started mopping the floor
• 9:55 am: finished mopping the floor
• 9:56 am: started cleaning the buckets
• 10:00 am: started mopping with IPA wipes
• 10:05 am: finished mopping with IPA wipes
• 10:20m: started particle count
  • zone 3:
    • 0.3 u: 2213
    • 0.5 u: 398
    • 1.0 u: 0
• zone 4:
  • 0.3 u: 1150
  • 0.5 u: 177
  • 1.0 u: 44

[Luke, Luis]

Update of current state of vacuum chamber

Current temp: 24°C

Current pressure: Main 1.77e-8, RGA 5.3e-9 [torr] (Gate valve open)

Summary of recent work-->

To try and reduce the leak in the turbo pump by reducing cross-connection, we replaced the copper gasket. This made no improvement to the leaks.

Initially: 1.9e-9 --->

Left side: 1.33e-9, Right side: 3.37e-9 (Gate valve open)

This is still a significant leak. We have tried to tighten the bolts further, but they are as tight as reasonably possible. 

Things of note: While examining the knife edges, we found some very slight imperfections on the reducing cross's flange as seen in 474. This could be the source of our leak. We have replaced this gasket 1-2 times already and consistently have a slight leak. This imperfection is on the right side of the flange, which would be consistent with the measurements above. 

Unless we want to use the liquid sealant or replace the gasket with an annealed gasket, we could try baking the system again, as this allowed us to reach UHV in the main volume before. It also allowed us to pass the RGA scan, which we are currently failing. (see attached)

[Luke, Tyler, Cynthia, Shane, Michael]

Summary of Cleaning Activities:

We began cleaning Room 1119 at 2:00 PM.

At 2:30 PM, we moved to Room 1129 and continued cleaning.

Cleaning tasks included wiping down dust-collecting surfaces and vacuuming the floors.

Once the labs were clean, we proceeded to the cleanroom. 

• Wiping down surfaces and soft walls
• Vacuuming, mopping the floor, and finishing with IPA wipes

Particle Count Measurements:

• Pre-cleaning (2:30 PM):
  • Zone 3:
    • 0.3 µm: 973
    • 0.5 µm: 354
    • 1.0 µm: 132
  • Zone 4:
    • 0.3 µm: 486
    • 0.5 µm: 177
    • 1.0 µm: 0
• Post-cleaning (4:10 PM):
  • Zone 3:
    • 0.3 µm: 619
    • 0.5 µm: 132
    • 1.0 µm: 0
  • Zone 4:
    • 0.3 µm: 397
    • 0.5 µm: 0
    • 1.0 µm: 0

[Luke, Liu]

Over the winter break I have been working on this desmos toy model of the Frosti. There are still a few rough spots but I belive that it is a good visual representation of a 2D slice of the frosti. 

[Luke, Cece, Luis]

Particle Count Measurements:

• Pre-cleaning (12:15 PM):
  • Zone 3:
    • 0.3 µm: 1325
    • 0.5 µm: 265
    • 1.0 µm: 0
  • Zone 4:
    • 0.3 µm: 618
    • 0.5 µm: 132
    • 1.0 µm: 44

• Started Cleaning (3:20 pm)
• Finished Cleaning (4:20 pm)

• Post-cleaning (4:35 PM):
  • Zone 3:
    • 0.3 µm: 1106
    • 0.5 µm: 221
    • 1.0 µm: 0
  • Zone 4:
    • 0.3 µm: 530
    • 0.5 µm: 44
    • 1.0 µm: 0

[Luke, Luis]

The vacuum chamber is currently baking. 

We stepped up to 120°C by increments of 30°C starting at 60°C. We took about an hour break at 90°C to let the temperatures equilibrate.  

Current state as of 12:20:

The gate valve is open, the calibrated Argon leak is open, and the filament of the RGA is on.

The temperatures are as follows:

PID right barrel upper: 113°C,  RGA volume: 120°C

PID left barrel lower: 121°C, Lid: 114°C

The lower temperatures should climb as the whole system heats up. 

[Luke, Mary, Luis]

Particle Count Measurements:

• Pre-cleaning (8:40 am):
  • Zone 3:
    • 0.3 µm: 441
    • 0.5 µm: 44
    • 1.0 µm: 0
  • Zone 4:
    • 0.3 µm: 353
    • 0.5 µm: 176
    • 1.0 µm: 44

• Started Cleaning (3:16 pm)
• Finished Cleaning (4:10 pm)

• Post-cleaning (4:15 pm):
  • Zone 3:
    • 0.3 µm: 574
    • 0.5 µm: 265
    • 1.0 µm: 132
  • Zone 4:
    • 0.3 µm: 177
    • 0.5 µm: 44
    • 1.0 µm: 0

Today we started vacuum chamber assembly work

• 10:16 am: Particle count measurement of clean room
• 10:34 am: Particle counting finished: meets ISO 5 standard
  1. Zone 3 :
     • 0.3 u: 3159
     • 0.5 u: 789
     • 1.0 u: 83
  2. Zone 4 :
     • 0.3 u: 498
     • 0.5 u: 41
     • 1.0 u: 0
• 10:45 am: Assemble vacuum feedthrough
• 11:08 am: Finish assembling feedthrough
• 11:14 am: Assemble inverted magnetron pirani gauge
• 11:29 am: Finish assembling magnetron gauge
• 11:31 am: Assemble calibrated Ar Leak
• 11:47 am: Finish assembling Ar leak
• 11:49 am: Assemble up to up-to-air valve
• 11:59 am: Finish assembling up-to-air valve
• 12:00 pm: Break for Lunch
• 1:00 pm: Came back from lunch
• 1:20 pm: Assemble 45 degree elbow [RGA Line]
• 1:35 pm: Finish assembling 45 degree elbow
• 1:35 pm: Assemble Reducing nipple [Pump Line]
• 1:49 pm: Finish assembling Reducing nipple

• 1:53 pm: Attempt to install gate valve [Pump line] but bolts could not fit to the gap between 2.5" reducing nipple (0.95" length, shortest 5/16 bolt is 1.5" in total length).
  Thickness of of CF flange on reducing nipple is 0.75" inch. Ideally, we want to have 0.2" engagement to the gate valve, thus0.95" + 0.25" head thickness = 1.2" > 0.95" gap.
  We thus most likely will need a replacement for the reducing nipple. We decided we would hold up on installing the rest of the pump line until we have got components to fix this problem

• 2:05 pm: Assemble gate valve [RGA line]
• 2:15 pm: Finish assembling gate valve [RGA line]
• 2:18 pm: Assemble 4-way cross [RGA line]
• 2:30 pm: Finish assembling 4- way cross [RGA line]
• 2:37 pm: Assemble manual bellow sealed angle valve [RGA line]
• 2:43 pm: Finish assembling sealed angle valve [RGA line]
• 2:45 pm: Assemble inverted magnetron pirani gauge [RGA line]
• 2:55 pm: Finish assembling magnetron pirani gauge [RGA line]
• 2:56 pm: Assemble vacuum hose, thin wall [RGA line]
• 3:04 pm: Finish assembling vacuum hose, thin wall [RGA line]
• 3:45 pm: Packing up for the the day
• 4:00 pm: End-of-date particle count measurement
  1. Zone 3
     • 0.3 u: 1080
     • 0.5 u: 124
     • 1.0 u: 83
  2. Zone 4
     • 0.3 u: 540
     • 0.5 u: 83
     • 1.0 u: 83

[Pamella, Cao and Julian, Shane]

• Particles account
• 10:37 am: Starting the particles account
1. Zone 3:
   • 0.3u: 1662
   • 0.5u: 872
   • 1.0u: 415
2. Zone 4:
   • 0.3u: 831
   • 0.5u: 124
   • 1.0u: 0
• 11:14 am: Start removal of calibrated leak to install 45 deg elbow
• 11:21 am: Elbow installed, re-install calibrated leak back on
• 11:29 am: Finished re-install calibrated leak, start installing gate valve on pump line
• 11:47 am: Finished installing gate valve, start installing reducing cross onto gate valve
• 12:02 pm: Finished installing reducing cross, start installing 90 deg elbow to reducing cross
• 12:17 pm: Finished installing reducing cross, lunch break
• 01:24 pm: Come back to the lunch break.
• 01:26 pm: Start installing vacuum hose to elbow.
• 01:40 pm: Finished installing vacuum hose.
• 01:43 pm: Start installing turbo pump.
• 02:00 pm: finished installing turbo pump .
• 02:10 pm: Start installing standard wall hose from turbo pump to scroll pump
• 02:21 pm: finished installing hose onto scroll pump, start installing lid. Remove lid from chamber, insert viton O-ring. Place lid back
• 02:30 pm: Secure lids with screw. Start installing turbo pump controller cable: Pass cable from outside (controller) up the top of clean tent and connect to 8 pin connector on turbo pump
• 03:00 pm: Installing air cooling unit for turbo pump, found 8 M3 screws for air cooling unit in the C&B cabinet to install the fan bracket onto the back of turbo pump. Fan control cable is routed up to the top of the cleanroom to the controller
• 03:15 pm: Installing full-range gauge cable to the controller outside cleanroom. Ethernet cables 1 and 2 are used. Cable 1 is used on the RGA line gauge. Cable 2 is connected to the main body gauge. Cable1 and 2 are connected controller's channel 1 and 2 respectively.
• 04:00 pm: Finish installing gauges cables. Cables are routed up along the frame to the controller sitting outside the cleanroom
• 04:15 pm: Finished. End-of-date particle count
  1. Zone 3:
     • 0.3u: 3699
     • 0.5u: 1454
     • 1.0u: 872
  2. Zone 4:
     • 0.3u: 1662
     • 0.5u: 706
     • 1.0u: 290

This afternoon I made up a green 10 AWG grounding cable and connected it to the vacuum system.

One end is tightly connected to the bottom flange of the vacuum chamber (photo 1). It is run along and up the table framing to the top of the cleanroom, where it exits into the overhead cable tray in the same location as the other power cables. It drops down from the top of the server rack all the way to the bottom, where the other end is connected to the lab's electrical ground in the rear of the 240 V UPS (photo 2).

The connections were confirmed to be secure, but continuity testing with an ohmmeter remains to be done to confirm that the chamber and tabletop are indeed grounded.

[Cao]

Continuity Test

• Chamber wall to optical table: continuity confirmed, resistance: 0 Ohm
• Chamber wall to ground point connection on chamber: continuity confirmed, resistance: 0 Ohm
• Turbo pump to ground point connection on chamber: continuity confirmed, resistance: 0 Ohm
• Turbo pump to optical table: continuity confirmed, resistance: 0 Ohm
• Optical table to chassis frame outside cleanroom: continuity confirmed, resistance: 0 Ohm
• Front of chassis frame to earth point: continuity confirmed, resistance: 0 Ohm

After Jon's comment yesterday that some of the connection did not seem to have good metal-metal contact, in particular the gate valve connection, I went through the ConFlat connections today and retighten them. I found a lot of the CF connections are not particularly tightened and there were a lot of range left that can be tightened with the wrench. After re-tightening, the copper gaskets are not visible anymore. For example, see the attached images for the difference before and after tightening.

Note for future installation of CF

• After tightening the bolts/ screws in jumping order (to provide uniform torque) and there is resistance appearing in further tightening, start going through each screw/ bolts in a direction, each time applying a small torque until it resists to further tightened
• After each time going all the bolts/ screw and returning to the starting point, one will find they can further tighten the screws/ bolts. Repeat the process until no further tightening can be achieved
• The copper gasket should not be clearly visible at the connection

[Julian, Cao]

• 03:00 pm: Particle count
  1. : Zone 3
     • 0.3 um: 498
     • 0.5 um: 124
     • 1 um: 124
  2. : Zone 4
     • 0.3 um: 748
     • 0.5 um: 457
     • 1 um: 374
• 03:32 pm: Installing Pirani gauge onto pump line
• 03:51 pm: Finish installing Pirani gauge, start installing RGA probe
• 04:03 pm: Finish installing PRGA probe, start routing cable from gauge controller to Pirani gauge
• 04:30 pm: All ethernet cables are routed and connected to gauge controllers
• 04:48 pm: Power gauge controller up, all gauges are recognised and readout shows atmospheric pressure as expected (1000 mbar)
• 04:51 pm: End-of-work particle count
  1. : Zone 3
     • 0.3 um: 1413
     • 0.5 um: 872
     • 1 um: 623
  2. : Zone 4
     • 0.3 um: 374
     • 0.5 um: 166
     • 1 um: 166

[Jon, Cao]

1. Re-routing of cables

We re-routed the connections between the turbo pump and its fan to the controller. Instead of going through the side of the server rack, they are now routed along the the cable tray and came down from the top of the server rack.

2. Planning for vacuum assembly re-configuration

• Move the entire RGA arm to the mirrored CF port, where the Up-to-Air valve is at
• Move the Up-to-Air valve to the calibrated leak port
• Move the calibrated Ar leak the main chamber full-range gauge port
• Move the full-range gauge to the RGA line port

3. First test pump-down

1. With all valves closed, we started scroll pump, pump line quickly got down to 6.08 mbar from atmospheric 1000 mbar (measured by Pirani gauge, channel 3 on controller )
2. We open Lesker angled valve and let the RGA arm pumped down, Pirani gauge read 6.3 mbar while the full-range guage on RGA line reads 4.9 mbar ( channel 1 on controller )
3. We open the pump line gate to expose the pump to the main volume, all gaugues readout immediate rise back up 1000 mbar. After 3 minutes, we started to see channel 3 slowly dropped down. A minute later channel 1 and 2 (main body) also dropped down. The slow pressure dropping speed and 6.3 mbar measured earlier got us suspected that there is some large leaks
4. We proceed to tighten all the ports as the vacuum is pumped down. In particular, we found that large feedthrough port still required a lot of tightening up
5. As we tighten up all the ports, after 40 minutes, the gauges are now
   • Channel 1 : RGA line full-range gauge: 2.55E-1 mbar
   • Channel 2 : Main chamber full-range gauge: 2.60E-1 mbar
   • Channel 3 : Pump line Pirani gauge: 2.94E-1 mbar
   Compare this to the scroll pump manual , Table 1, page 3, the ultimate pressure of the scroll pump is 2.5E-1 Torr (3.3E-1 mbar), we thus managed to achieve scroll pump ultimate pressure
6. Turn on turbo pump : Change turbo pump controller from REMOTE to FRONT PANEL mode by pressing both "COUNTERS" and "MEASURE" buttons at the same time, select "MODE=FRONT"
7. Shorting interlock pin: since we do not have an interlock signal for the controller, use the provided DB-9 connector that has pin 3 and 8 shorted and connect this to the P1 IN connection at the rear of the controller (see attachment 1 )
8. Press "START" on the controller to start the turbo pump
9. The pressure readout from the gauges quickly dropped down. After 3 minutes, the Pirani range is maxed out at 0.5E-3 mbar. After 20 minutes, we recorded the following values:
   • Channel 1 : RGA line full-range gauge: 1.50E-5 mbar
   • Channel 2 : Main chamber full-range gauge: 1.89E-5 mbar
   • Channel 3 : Pump line Pirani gauge: 5.0E-4 mbar
   This is Medium vacuum , we want to further reduce this by 2 orders of magnitude. However, we can run RGA test + helium leak test at this pressure
10. Turn off turbo pump, wait for 10 minutes, turn off scroll pump, open Up-to-Air valve, all pressure gauges indicated pressure returned back to atmospheric pressure

3. To-do actions

• Run RGA test to get information about contamination status of vacuum
• Implement suggested changes in section 2
• Check and modify suspected poor connection: Pirani gauge on pump line. A gap can be seen between connection. There's no good way to tighten it with the screw. Maybe use threaded pin + hex bolt?
• Controller communications

Today we started re-configuring the vacuum chamber components.

Particle count
• 10:45 am : Starting the particle count in the clean room.
• 11:13 am : Finished the particle count in the clean room.
• Zone 3 :
  • 0.3 u: 2535
  • 0.5 u: 1413
  • 1.0 u: 789
• Zone 4 :
  • 0.3 u: 457
  • 0.5 u: 290
  • 1.0 u: 207
  Starting the reconfiguration.
  • 11:21 am: Started removing up-to-air valve
  • 11:30 am: Finished removing up-to-air valve.
  • 11:33 am: Started removing calibrated Ar Leak and the elbow.
  • 11:35 am: Finished removing calibrated Ar Leak and started assembling the up-to-air valve.
  • 11:47 am: Finished assembling up-to-air valve.
  • 11:48 am: Started removing magnetron gauge.
  • 11:55 am: Finished removing magnetron gauge.
  • 11:57 am: Started installing the elbow and calibrated Ar Leak and started removing the RGA probe
  • 12:13 pm: Finished installing the elbow and calibrated Ar Leak.
  • 12:20 pm: Break for lunch.
  • 01:25 pm: Come back from lunch break.
  • 01:30 pm: Started removing RGA line.
  • 01:39 pm: Finished removing RGA line.
  • 01:39 pm: Started removing gate valve [RGA line] and finished removing gate valve.
  • 02:00 pm: Started installing gate valve in the new position.
  • 02:08 pm: Fished installing gate valve [RGA line].
  • 02:09 pm: Checked the screws in the elbow to gate valve. [RGA line].
  • 02:28 pm: Finished checking the screws in the elbow to gate valve [RGA line].
  • 02:29 pm: Started installing RGA line.
  • 02:39 pm: Finished installing RGA line.
  • 02:50 pm: Started installing magnetron gauge.(In this part we assembled gauge with the used gasket)
  • 03:02 pm: Finished installing magnetron gauge.
  • 03:04 pm: Started installing RGA probe [RGA line].
  • 03:13 pm: Finished installing RGA probe [RGA line].
  • 03:15 pm: Connected the cables to the magnetron gauge.
  • 03:20 pm: Started the testing in the vacuum chamber.
  • 04:30 pm: Started installing the RGA 200 and connected the cables (power cable and DB9 cable).
  • 04:52 pm: Finished installing the RGA 200 and connected the cables (power cable and DB9 cable).
  • 04:53 pm: Started testing the RGA connections. Logrus is able to recognize and connect to RGA unit. We are leaving the turbo pump on for a few hours before checking back for pressure readouts.
  • 05:00 pm : Starting the particle count in the clean room.
    1. Zone 3 :
       • 0.3 u: 2244
       • 0.5 u: 997
       • 1.0 u: 207
    2. Zone 4 :
       • 0.3 u: 2993
       • 0.5 u: 1579
       • 1.0 u: 498
  • 05:30 pm : Finished the particle count in the clean room.
  • 05:34 pm: Test pressure readout from the gauges.
    1. Channel 1 : 1.06E-5 mbar
    2. Channel 2 :8.89E-6 mbar
    3. Channel 3 :5.0E-4 mbar
  • 05:59 pm: Test pressure readout from the gauges.
    1. Channel 1: 9.09E-6 mbar
    2. Channel 2: 7.75E-6 mbar
    3. Channel 3: 5.0E-4 mbar

[Aiden, Cao]

1. Helium leak test

• 2:00 pm: Uninstall regulator from nitrogen gas tank and move to helium gas tank. Place helium onto cart and move to the rear door of the clean tent. With the tank remaining outside, feed hose through the flexible wall to use in clean tent - See attached image
• 2:25 pm: Start Helium leak test: At each CF connection, He gas is sprayed while its level is monitored with the RGA in leak detection mode. A constant flow of helium is maintained until the level of helium detected by the RGA plateaus out.
  • All connections show low helium leak detected (< 3e-11 Amp)
  • The connections with highest leak detected are from reducing cross to flex hose and cross to RGA. They are on 2 - 3e-11 Amps. All other connections are less than 8e-12 Amps. We verified tightness of these two connection but they cannot be tighten any further

2. Argon calibrated leak test

• We opened the Ar calibrated leak. Upon opening the valve to allow Ar to flow through, we can see a surge in pressure measured by the gauges from 6.7e-7 mbar to 1.2e-6 mbar. This is then drop down and stabilised around 8.9e-7 after 5 minutes.
• Upon the the equilibrium is reached, we ran RGA scan twice in Analog mode with the following settings:
  • Points Per AMU: 10
  • Start Mass : 1
  • End Mass : 100
  • Focus Voltage: 90 V
  • Channel Electron Multiplier (CEM) : On
  • CEM Voltage: 1060 V
  • Unit: Amps (ion current)
  The settings is saved as rga100amu_scan.rga RGA application file in C:/Users/controls/Documents/Vacuum/VacuumChamber/RGA. The data file is saved in Data folder as ArLeak_230512.txt. This file contains the current values for corresponding AMUs. Using this dataset, we can obtain our chamber outgassing rate.
• Using RGA_scan_process.py , which is adapted from Mike Zucker's Matlab code E2000071, and the Ar calibrated leak posted in elog 95 we can compute the outgassing rate to be 150.5E-10 Torr l/s . Our outgassing rate is 37.5 times higher than the required (4.00E-10 Torr L/s per E080177)
• See image attached for the spectrum and the hydrocarbon (HC) tracer masses used to evaluate outgassing
• All codes and data are stored in Vacuum git repo . I'll qrite up an instruction to use the code and post it on our wiki page.

After finishing with Ar cal leak test, we close Ar valve, disconnect and turn off RGA. The He tank is moved back to the wall mount. The chamber is ready for baking installation

I set up the new Windows 10 laptop (pictured below), which arrived yesterday. This laptop is intended to be used for running lightweight Windows-only programs, such as the Thorlabs beam profiler software or the SRS RGA client. However, none of that software is installed yet.

Configuration details

As usual, the computer is configured with one shared account (username: controls) and the standard password. Note that it is connected to the campus wifi (UCR-SECURE).

If a connection to the lab's local network is required, then the laptop must be connected by an Ethernet cable to the switch in the top of the server rack.

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

Jon, Cao

Today we raised the height of the shelf overhanging the cleanroom laser table by 8 inches. This was done to create more vertical clearance between the top-loading vacuum chamber and the bottom of the shelf. The added clearance should make both removing the chamber lid and inserting large parts easier.

The procedure required unmounting the shelf and removing all eight vertical support posts (1" x 1" x 18.5" pieces of 80/20 unistrut). The support posts were taken to the machine shop and cut, retapped, and cleaned (coarsely, with IPA wipes) prior to reinstallation. We took care to minimize the contamination introduced into the cleanroom, but some amount of particulate from disturbing the shelf was unavoidable.

This work is completed, and the cleanroom is now ready for final cleaning (HEPA vac, mopping, and wiping down of all surfaces including the softwalls).

The Linux workstation (ws2) that used to sit on the blue workbench (now inside the cleanroom) has been mounted on a mobile cart, as pictured below. This is intended to be a clean cart that will be housed inside the cleanroom.

The cart is currently dirty and will need to be throughly wiped down (along with the computer monitor and peripherals) prior to being moved into the cleanroom. Once the cleaned cart has been moved inside, it should never be brought back outside the cleanroom and should never be touched with ungloved hands.

I also upgraded the OS to Debian 11.6 and upgraded the CDS workstation tools.

Jon, Cao, Peter

This morning Facilities delivered and installed two new cabinets with sliding glass doors.

The smaller of the two (36" W x 13" D x 84" H) has been installed in the Clean & Bake area adjacent the flow bench. The larger one (48" x 16" D x 84" H) has been installed in the back of the room next to the electronics bench. Both cabinets have been securely anchored to the wall in two places each for earthquake safety.

We also installed the sliding glass doors and leveled them. However, we have not installed any of the shelves yet because the cabinets are quite dirty from the installation. Everything needs to be wiped down with IPA wipes, and it will be easier to do that before the shelves are in place.

Jon, Cao

In effort to try to reduce the noise level inside the cleanroom, we have dialed all four HEPA fan-filter units (FFUs) down from HIGH to MEDIUM speed. These dials can only be accessed from inside the cleanroom, by bringing in the large ladder and opening adjacent ceiling tiles.

We tested three configurations, in each case with all the FFUs on either HIGH (initial state), MEDIUM, or LOW. We measured the ambient noise in each configuration.

Going from HIGH to MEDIUM yields the largest improvement, reducing the ambient sound intensity by 6 dB (i.e., by a factor of 4, corresponding to a ~35% reduction in perceived volume).

An additional 3 dB of noise reduction can be achieved by further reducing the fan speeds to LOW. However, even after allowing some extended settling time (few hours), we found the particle counts to be fluctuating right at the threshold zone for ISO Class 5. Thus we dialed the fan speeds back up to MEDIUM with the expectation that this will be sufficient for Class 5 performance.

The cleanroom now needs to be recertified with a fresh round of five-zone particle count measurements.

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.