 Tue Apr 4 09:53:37 2023, Peter, Update, VLC Update, Laser intensity/polarization drift measurements 
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The set up for the next round of beam characterization measurements has begun. The beam is initially passing through a half waveplate, is split at a polarizing
beam splitter, and then stirring mirrors are used to properly aim the beam into photodiodes (not yet installed). This is the current configuration of the
set up. |
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Thu Apr 6 10:20:43 2023, Peter, Update, VLC Update, Laser intensity/polarization drift measurements
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More optical components were added to the optical set up for laser intensity / polarization drift measurements. Both lenses and both PDs were added to the
configuration, as seen in the image below. The beam is already well aligned into the center of both of PDs, and focused nicely by the lens.
Both PD's
take BNC connecting cables, and the Red Pitaya takes SMA connecting cables. Since we are currently without a BNC to SMA cable, and we do not want to cut, |
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Fri Apr 28 11:21:01 2023, Peter, Update, VLC Update, Laser intensity/polarization drift measurements
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The Digi-key cables have arrived, and I have began implementing them in the intensity drift measurements.
There was a slight problem initially in connecting
the SMA to BNC cables from the photodiode to the red pitaya, since the red pitaya was way on the other side of the lab. Cao and I connected the red pitaya
to a new ethernet cable that extended far enough for the red pitaya to sit comfortably on the breadboard with the optics.
Right now the PDAs are not |
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Thu May 18 14:07:08 2023, Peter, Update, VLC Update, 532nm Intensity Measurement
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I figured out a method in which to capture power measurements including the initial seconds in which the beam is first turned on. I first clear and restart
the kernel of the python notebook. Then I run the command to connect the red pitaya oscilloscope package to the input data being taken in both channels.
To my understanding, this allows for data acquisition as the code compiles. I then started looping the 1.074s trigger bunches, and then roughly 2 seconds |
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Tue Jun 6 16:15:09 2023, Peter, Update, VLC Update, Launch Optics for Visible Light Cavity
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I assembled the first few components of the launch optics for the visible light cavity. Below is an image of the current table configuration, and the image
is how the cavity will be oriented on the table. |
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Thu Sep 7 19:24:25 2023, Peter, Update, VLC Update, VLC Launch Chain
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The launch optics up to the Faraday Isolator have been added to the breadboard. In the first image, the optics are (from L to R) the stirring mirror, half-wave
plate, polarizing cube, 100mm f lens, electro-optical modulator, Faraday isolator, 50mm lens (not part of final design), stirring mirror (not part of final
design) |
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Mon Oct 9 11:06:17 2023, Peter, Update, VLC Update, VLC Launch Chain
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Implemented the new stage for the EOM. Took power data at different positions in the launch chain. Beam waist: 0.066mm (beam waist is inside EOM). Power
before EOM: 0.473mW. Power after EOM: 0.452mW. Power after Faraday Isolator: 0.415mW. Might need to adjust better to configure for clipping losses. Images
of setup are attached below. |
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Mon Oct 23 07:28:57 2023, Peter, Update, VLC Update, VLC Mode Matching
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| I have attached a pdf with slides of my latest updates. |
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Mon Nov 6 11:31:25 2023, Peter, Update, VLC Update, VLC Mode Matching
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| See Update Attached |
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Mon Nov 13 06:15:45 2023, Peter, Update, VLC Update, VLC Mode Matching
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| Weekly Updates Attached in pdf |
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Fri Dec 8 11:15:21 2023, Peter, Update, VLC Update, VLC Assembly
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The optics of the visible light cavity have been assembled. The mode matching telescope is folded through the two stirring mirrors at the corners shown
in the image below, with the first lens (f=0.2m) before the first stirring mirror, and the second lens (f=0.5m) between the two stirring mirrors. The distance
from the cavity to the edge of the table is 14cm. There is still some work to be done on the alignment of the cavity, as the beam does not seem to be completely |
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Tue Jan 16 10:01:21 2024, Peter, Update, VLC Update, VLC Faraday Isolator and Mode Matching
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| Attached is a PDF of my weekly updates. |
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Mon Apr 15 11:51:03 2024, Peter, Update, VLC Update, VLC
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| An update on the VLC project is attached below: |
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Mon May 13 14:53:29 2024, Peter, Update, VLC Update, VLC
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| VLC Update WEEK 7 attached below |
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Sat Feb 4 17:01:03 2023, Peter, Update, VLC Electronics, Laser Data
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Peter and Ryan took laser beam data. Configuration: 100mm focal length lens is ~100mm from lens. 150mm focal length lens is ~200mm from first lens. Beam
waist is ~420mm from second lens.
Beam waist is very small still. Had to input large amounts of error in data collection. Took width data successively
at points near waist and at >= Rayleigh range. Plots are shown below.
Key points:
Took a while to figure out optimum configuration for lenses to |
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Tue Feb 28 19:31:05 2023, Peter, Update, VLC Electronics, 532 M2 Measurements
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Took M2 measurements today. Configuration: Lens 1 (f = 50mm) at 0mm. Lens 2 (f = 150mm) at 200mm, camera at 350mm. The laser beam was being moved in -z
direction on track (so further away from the first lens). Quick data shown in the sheets plot. Not a real fit. I was trying to see where the beam waist
was if there even was one. Seems that it is much further than we have room for on the track. Will need to come back and take more data.
I suggest maybe |
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Thu Mar 9 12:03:59 2023, Peter, Update, VLC Electronics, 532 M2 Measurements
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Took more M2 Data today. Picture of the optical set up is shown below. lens1 f = 100mm, lens2 f = 50mm, lens3 f = 150mm. There was a nice converging/diverging
beam profile, and the beam waist was able to be read by the camera. I took as much data as I could before clipping loss. The M2 value is quite high. |
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Fri Mar 10 12:08:09 2023, Peter, Update, VLC Electronics, 532 M2 Measurements
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Took more M2 laser data today. The configuration is the same as before except now the beam camera is the only component moving. Pictures can be seen below.
The beam shape in x and y is very consistent with low error. However, the M2 value is still a bit high. |
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Tue Apr 4 09:39:58 2023, Peter, Update, VLC Electronics, 532 M2 Measurements
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Final M squared measurements were taken Wednesday, 3/29/23 by Peter and Ryan Hinosawa. 5 separate sets of data were taken, and upon discussion, we declared
the plots shown below in attachment 1 and 2 as the final plots of our M squared measurements.
The optical design of the M squared measurement process
is given in attachment 3. The laser and three lenses shown below are mounted on the optical table. The track is placed behind the third lens, and the camera |
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Tue Apr 4 16:43:53 2023, Jon, Update, VLC Electronics, Additional Thorlabs PDA10A2
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I ordered a second PDA10A2 and mounting post + spacer (which puts the aperture at the VLC's standard 3" beam height). These arrived today and I delivered
them to the lab. They are sitting on the VLC table near the laser. |
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Tue Apr 25 11:56:37 2023, Jon, Update, VLC Electronics, Red Pataya has arrived
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| The Red Pataya 125-14 starter kit that we ordered for locking the 532 nm cavity has arrived. I left it laying on the optical table near the laser. |
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Mon May 1 18:56:57 2023, Peter, Update, VLC Electronics, 532nm Intensity Measurement
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I've configured the two PDA's to the Red Pitaya. I put a 50 ohm resistor connector to each red pitaya input port. This was because the oscilloscope showed
that the voltage reading from the P polarization PDA was almost at 1V, which was the limit of the red pitaya. Once both S and P polarization PDA's were
connected, I opened the red pitaya's oscilloscope. A screenshot of the voltage readings is shared below. Channel 1 (Yellow) is for S polarization. Channel |
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Tue May 2 15:55:33 2023, Peter, Update, VLC Electronics, 532nm Intensity Measurement
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I changed the 1/2 wave plate from the lens mount to the rotational optic mount. This allowed me to rotate the 1/2 wave plate, which changed the respective
polarization power transmitting through S and P polarization. Initially, more power was coupled into the P polarization. Now, with the 1/2 plate rotated,
both channels are experiencing the same voltage reading. Before feeding the PDA signals into the red pitaya, a 50 ohm terminator had to be placed at the |
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Thu May 4 14:01:10 2023, Peter, Update, VLC Electronics, 532nm Intensity Measurement
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I adjusted the rotational mount of the wave plate to see if the power can be 100% coupled into either S or P polarization. The images shown below of the
oscilloscope indicate that this is not possible. The minimum transmitted power we can obtain in either S or P polarization is 75mV. The maximum voltage
we obtain in either S or P polarization is ~ 740mV. This means that at a maximum, we can obtain ~ 90% polarization in either direction, indicating that |
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Tue May 16 11:56:33 2023, Peter, Update, VLC Electronics, 532nm Intensity Measurement
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With the configuration the exact same as before, I used the Jupyter notebook in the red pitaya's development package to collect data from both input channels.
Last week, I was able to take data, yet only for a very short period of time, and I did not know how to change it. I went online to the red pitaya's user
manual to figure out how to change the sampling period for longer. The link to the page is here: https://redpitaya.readthedocs.io/en/latest/appsFeatures/examples/acqRF-samp-and-dec.html#s-rate-and-dec |
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Mon May 22 16:43:28 2023, Peter, Update, VLC Electronics, Laser intensity/polarization drift measurements
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In order to fully analyze the polarization data taken last Thursday, I needed to convert the signal output (which is in volts) to power (units of watts).
I used the power meter to accomplish this. Keeping the exact same configuration of PD's and beam splitting, opened the red pitaya's oscilloscope package.
I then took the power meter, and held it in front of the PD to measure the amount of Watts at each PD. I then wrote down the corresponding voltage being |
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Wed May 24 14:28:26 2023, Peter, Update, VLC Electronics, Laser intensity/polarization drift measurements
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I went in and took polarization drift data for 16 hours. The run started at 6:08pm and finished at 9:15am the next day. The four plots below are the same
plots shown for the 2 hour collection and previous trials, except they extend to 16 hours. The only one that is different is the Power vs. Time graph.
This is a graph of the actual incoming power of the laser (as opposed to the signal voltage that the PDA's output into the red pitaya). This was done using |
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Wed Apr 12 16:13:19 2023, Cao, Physics, VAC, Vacuum prep and installation
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Aiden, Pamella, Peter, Shane, Cao
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
Zone 3 :
0.3 u: 3159
0.5 u: 789
1.0 u: 83
Zone 4 :
0.3 u: 498
0.5 u: 41
1.0 u: 0
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 Fri Apr 21 00:06:43 2023, Jon, Update, VAC, Vacuum prep and installation - parts have arrived
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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 |
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Thu Apr 27 16:23:44 2023, Cao, Pamella and Julian, Physics, VAC, Installing vacuum system (cont.)
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[Pamella, Cao and Julian, Shane]
Particles account
10:37 am: Starting the particles account
Zone 3:
0.3u: 1662
0.5u: 872
1.0u: 415
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: |
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Thu Apr 27 21:43:07 2023, Jon, Physics, VAC, Grounding vacuum system
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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 |
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Fri Apr 28 18:16:57 2023, Cao, Physics, VAC, Grounding vacuum system
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Quote:
This afternoon I made up a green 10
AWG grounding cable and connected it to the vacuum system. |
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Fri Apr 28 19:00:13 2023, Cao, Physics, VAC, Tighten CF ports on vacuum chamber
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[Cao]
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 |
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Mon May 1 17:10:25 2023, Julian, Cao, Physics, VAC, Installing Pirani gauge and RGA probe onto to vacuum chamber
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[Julian, Cao]
03:00 pm: Particle count
: Zone 3
0.3 um: 498
0.5 um: 124
1 um: 124
:
Zone 4
0.3 um: 748
0.5 um: 457
1 um: 374
03:32 pm: Installing Pirani |
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Tue May 2 17:03:14 2023, Jon, Cao, Physics, VAC, First pump-down test of vacuum chamber
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[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 |
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Wed May 3 19:03:47 2023, Julian,Pamella and Cao, Physics, VAC, Modify vacuum asssembly and install RGA
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[Pamella, Julian, Cao]
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 |
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Tue May 9 15:49:20 2023, Jon, Infrastructure, VAC, Permanent cable routing
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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, |
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Tue May 9 20:55:12 2023, Jon, Infrastructure, VAC, Calibrated Ar leak rate
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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. |
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Fri May 12 20:28:34 2023, Aiden, Cao, Physics, VAC, Vacuum chamber Helium leak test
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[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 |
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Tue Jun 13 21:08:46 2023, Pamella, Infrastructure, VAC, Heater system - Installation
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[Pamella, Cao and Jon]
Heating system installation
Today we started installing the equipments for the heating system.
First: Started installing the heating cable on the top lid and covered it with aluminum tape.
Second: Started installing the insulation
cover on top of the chamber lid.
Third:Started installing the heating cable from under the vacuum chamber and covered with aluminum tape.
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Wed Jun 14 15:35:36 2023, Pamella, Update, VAC, Heating system installation
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[Pamella and Cao]
Heating system installation - Second day.
Today we kept installing the equipment for the heating system.
First: Started installing the two heating cable around the chamber vacuum, the arms and covered it with aluminum tape.
Second: Started
installing the insulation stuff around the vacuum chamber and around the connections points (the arms) in the vacuum chamber.
Third:Started |
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Tue Jun 20 22:14:24 2023, Pamella, Cao, Infrastructure, VAC, Short term testing of vacuum heater controller units
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[Pamella, Cao]
Fuse replacement
Replace blown 10A fuse in ucontroller outside cleanroom
Replace 10 A fuse in
main power connection slot of the controller unit inside cleanroom
Pamella wiped down unit outside cleanroom.
Controller units
turned on and temperature setpoint set to be 80 deg C
Temperature settle in approx. 15 minutes(as recorded by the RTD). No problems with |
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Wed Jun 21 20:25:05 2023, Cao, Infrastructure, VAC, Vacuum chamber bake attempt 1 6x
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TL;DR:
We are not yet able to bake the chamber at 150 deg C due to some current limit, most likely caused power supply switching off. Also,
smoke was observed at some insulation points, mainly in the small arm sections, This is likely because the insulation does not fit well and the velcro
came into direct contact with heat tape. Some Velcro (made from Nylon/ Polyester) has lower melting temperature point (in 90-120 deg C range)
Full |
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Tue Jun 27 21:47:56 2023, Jon, Infrastructure, VAC, Vacuum chamber bake attempt 1
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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. |
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Wed Jun 28 15:58:56 2023, Shane, Cao, Infrastructure, VAC, Power trip problem remains, source of smoke is insulation
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[Shane, Cao]
With the new change in wiring configuration described in elog 136, we tried
to power up the heaters for baking the vacuum chamber again.
Given that we were worried about the turbo pump overheats, we set the setpoints of of bother high temperature controller and PID controller to |
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Thu Jun 29 18:27:26 2023, Jon, Cao, Infrastructure, VAC, Vacuum bake attempt 3: success!
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[Jon, Cao]
Summary : We resolved problems with heaters tripping power and were able to proceed with chamber baking
1. Circuit connection adjustment
After yesterday elog 137, today we resolved
most of these issues. After Jon contacted Facilities, the LP3B 6 circuit was reset and the cleanroom filter & light panels resumed to work as normal.
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Mon Jul 3 14:32:24 2023, Cao, Infrastructure, VAC, Cooling down vacuum chamber
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[Cao]
After leaving the the chamber to bake at 120 deg C from Thursday 3:41 pm. Today I started to cool the chamber down to room temperature at
11:30 am (total bake duration: 91 hours 49 minutes). Ideally, this process should be ramped down slowly, approx. 6 degree per hour. However we had no ramping
function with out controller. The only method to tune this cool/ heat rate is to tune the PID parameters, which are:
Pb : Proportional |
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Wed Jul 5 15:46:47 2023, Aiden, Cao, Infrastructure, VAC, Vacuum Chamber Baking Update
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Cao and Aiden put the RGA back on to the chamber and measured the outgassing rate after the chamber has cooled down from its first bake. The figure
attached shows the RGA measurements with the Argon leak open.
Also put the Full Range Gauge #2 [RGA line] back onto the system to measure the pressure and got a reading of 2.78 E-7 Torr. We believe it |
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Thu Jul 6 16:16:03 2023, Aiden, Summary, VAC, Vacuum Chamber Baking Update
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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 |
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Fri Jul 7 15:11:39 2023, Aiden, Update, VAC, VAC System Heating Update
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The temperature of the flange connecting to the turbo pump after reaching equilibrium is 74 degC. This means that it is safe to proceed with raising
the temperature from 120 degC to 150 degC.
Raised the set temperature of the chamber from 120 degC to 150 degC in 15 deg steps.
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