[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

[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

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

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

[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

• pre-cleaning particle counts:
  • zone 3
  • 0.3 mu: 2494
  • 0.5 mu: 748
  • 1.0 mu 124
  • zone 4
  • 0.3 mu: 374
  • 0.5 mu: 41
  • 1.0 mu: 0
• 3:45 pm: Started wiping the surfaces(laser table,chamber, computer) inside the cleaning room.
• 4:05 pm: Finished wiped the surfaces
• 4:08 pm: Began vacuuming cleanroom floor
• 4:28 pm: Finished vacuuming cleanroom floor.
• 4:29 pm: Began mopping the cleanroom floor.
• 5:15 pm: Finished cleanroom clean.
• 6:00 pm: post-cleaning particle counts (full 5 zone measurement) attached below

• Today i wiped, bagged and tagged two cables for the vacuum system. I used IPA wipes for cleaning this two split power cord. I attached a image below.

• 01:50 pm: Starting test position 34 mm distance to black wall.
• Parameters : 0.100 A, 1.5 V and the temperature inside the mirrors 40°C.
• 2:09 pm : Finished the test and figured out this position it is too far the black wall so now we change for more close position.

• 2:17 pm: Starting test in another position: 10 mm distance to the black wall( this measurement is between the black wall and the aluminum lid)
• 2:26 pm : Finished this second tried and take a snap. The image is attached below.
• The name for the picture for this tried is “AcquisitionImage(Apr-21-2023_14 26)”.

Note: The second tried the temperature didn't up more than 40°C for 8 minutes so I change the current for a few seconds. I started with 0.98 A with 1.7 V and up until 0.350 A with 2.5 V, just for a few seconds and in this way the temperature up to 72°C and I get the snap.
The next step should be understand the problem with the shape and work in changes for get the triangle in the FLIR image.

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

The two parts needed to complete the vacuum assembly (ELOG 70) have arrived.

• (10) 5/16"-24 x 1 3/4" threaded rods - for attaching the turbo pump reducing nipple to the CF 4.5" gate valve;
• (1) 45 degree CF 2.75" elbow for attaching the calibrated Ar/He leak to the chamber.

I left them laying on top of the ultrasonic washer. They both need to cleaned and baked following the standard procedure for stainless steel, as the threaded rods are visibly dirty.

FLIR project updates- Initial tests

• 10:00: Starting test in position 2 cm to the black wall.
• Parameters : 0,305 A, 05,5 V and the temperature inside the mirrors 141,8°C.
• 10:23 Finished this first tried and take snap. The image is attached below.
• The name for the picture for this tried is “AcquisitionImage(Apr-19-2023_10 23)”.

• 10:37. Starting test in another position now 3 cm distance to the black wall ( this is more close than the original position.)
• Parameters : 0,348 A, 05,5 V and the temperature inside the mirrors 160,3°C.
• 10:57 Finished this second tried and take a snap. The image is attached below.
• The name for the picture for this tried is “AcquisitionImage(Apr-19-2023_10 57)”.

• 11:03 Starting test another position 1.3 cm distance to black wall.
• Parameters : 0,347 A, 05,5 V and the temperature inside the mirrors 158,7°C.
• 11:18 Finished this second tried and take a snap. The image is attached below.
• The name for the picture for this tried is “AcquisitionImage(Apr-19-2023_11 18)”.

The next step should be fix the problem with the shape (aluminum foil lid).

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

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.

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

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).