[Jon, Pooyan]

Moved Chimay from the server rack in Physics 1119 to a new rack in Physics 1129. It is connected to the switch in that rack and has the same ip address as before.

All services are up and running.

It appears that JupyterHub creates some processes whenever a user connects to an instance of it, but in some cases does not stop those processes after the user is not using that instance. This results in having lots of running idle processes, each using a small bit of the resources. Those processes are killed now as a result of rebooting. It might be a good idea to manually restart JupyterHub (or the whole machine) every few months to avoid this.

One ongoing work is to make all lab machines automatically backed-up on Scribe on a daily basis. The updates should be boatable and stored for some time (potentially a few weeks) on Scribe. Making whole disk images has already been tried for some of the machines with no problems. (e.g., Cymac and WorkStations)

The same thing can not be done with Chimay though, as it currently has one huge RAID-controlled volume that stores all the information (OS, home directories, and NDS-downloaded data). Creating daily full disk images of such a system is not practical. 

Here is the plan we came up with to overcome this issue:

1. Create one full disk image of Chimay and store it on Scribe (it was already done)
2. Move the nds-downloaded raw data temporarily to Scribe and remove it from Chimay
3. Make another full disk image of Chimay
4. Burn this image to a single disk and boot chimay with it

5. Restore the rest of Chimay disks and move the NDS data back

    

On the weekend (Sat and Sun 9/7-8) I tried to execute these steps. There wasn't enough free space left on Scribe to move all the NDS data to it, so I stored part of this data temporarily on WS4. Then I also checked storage-consuming directories and, in one case, removed some non-important stored files. As there was no free space left on Scribe to execute step no. 3, I initiated storing the image on WS3. Unfortunately, a couple of different trials of the image-creation process failed as there was not enough free space on WS3 to accommodate Chiamy image as well. I was not able to reduce the image size such that it can be stored on WS3. 

These are the options left for us to get this work done. 

1. Distribute the NDS files between different machines to make enough free space on Scribe for the image and then follow the previous plan
2. Shrink the Chimay drive size, create the image and then follow the previous plan
3. Temporarily transfer some services to Megatrone (Network gateway, Wiki, elog) and recreate chimay and its services from scratch

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.

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, 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.

I have been looking at the feasibility of an alternative heater element design for FROSTI that replaces the original ring-like heater elements with n rectangular elements with straight edges. They form an n-sided regular polygon that could well approximate the original annular ring if n is large enough. This eliminates curved surfaces requirement for the heater elements, which was the source of the many month production delay for the prototype parts.

This design was implemented in COMSOL, shown in the attached. From the face on view, each element has a trapezoid shape with straight edges. The edges between neighboring elements are parallel, with a space of 2 mm in between them.

The ray tracing and thermal analysis obtained from COMSOL are shown in the attached pdf.

In particular, the 2D irradiance profiles were obtained from the ray tracing (so far from the front heating surfaces only). The 1D radial profiles were integrated and shown in the attached. The power delivery efficiency for the original ring-like heater element design is integrated to be roughly 65%, for comparison. The plot also shows the radial irradiance profiles for three different straight-edge designs, which correspond to 16 edges, 18 edges, and 24 edges. We see that with the straight-edge designs, the irradiance profiles stay in a good Gaussian shape. In addition, with a larger number of edges, the power efficiency increases, but is always less than the case for the optimized ring-like design.

The thermal distortions for the TM were also obtained from COMSOL, using the irradiance profiles at the TM HR. As shown in the attached, with the straight-edge design, the effects on the thermal lens OPD and the HR surface deformation are similar to the ring design, but with less severe edge roll-off for instance.

In the previous post, we saw that for the heater element design with straight edges in replacement of the current eight-element ring-like design, it provides the similar Gaussian-like irradiance profiles, but with smaller power delivery efficiencies, as shown in the plot. This turned out to result in similar but less prominent thermal effects.

They only differ from the original baseline design by a source power rescaling, however, as shown in the plot, where we see the power-rescaled irradiance profiles for the straight edge designs are close to that for the ring design. The resulting temperature profiles and thermal distortions are shown in plot and plot. The thermal effects for the 16 straight-edge design with renormalized source power for instance are strikingly similar to that for the original ring design.

An alternative straightened heater element design has also been investigated with COMSOL FEA simulation. As shown in the attached, in this new design each heater element component is cut with multiple straight edges but remains connected, shown in the same colors (green and red). In the example, four straight edges are cut from each of the four heater components (4x4=16 edges in total). There is no spacing between the neighboring edges from the same element component, but the edges from different components are separated by 2mm, as can be seen in the attached. This new N-in-one straight edge design offers similar irradiance compared to that for the evenly-spaced N-sided regular polygon straight edge design with the same number of edges, as shown in the plot. It however has fewer heater components, four in this case, which makes it easier to implement in assembly and wiring, and less vulnerable to electrical and thermal shorts with their fewer heater element pins.

Upon further inspection, one adjustment was made to the FROSTI profile analysis: changing the transmission value of the ZnSe viewport. It was initially assumed that the viewport possessed an AR coating, which would bring the transmission into the 90% range. Without the coating, it drops to roughly 70%. Assuming no coating, the estimated delivered power was calculated to be 11.7 W. This is consistent with the estimated power given from the Hartmann sensor analysis, thus it is believed that the viewport indeed had no coating.

For a quick projection for the resonant frequencies going from aLIGO to CE, the height and width of the BS are increased assuming the mass is increased from 14 kg to 70 kg, while keeping the aspect ratio fixed. The resonant frequencies for the two mechanical modes as a result becomes smaller, to 1.43 kHz and 2.11 kHz respectively, risking getting in the detection band.

Next step is to implement a mechanical ring with high stiffness outside the BS barrel to combat the decrement of the resonant frequencies of the relevant mechanical modes.

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

I reproduced Cao's CE beamsplitter code (see below for example plots). I received the current info on the beamsplitter parameters for A+ and A# from GariLynn also. The next steps are to perform a similar power loss analysis on the anticipated A# beamsplitter.

After taking data for each of the individual heater elements, I imported them into python and overlayed them to produce an average temperature profile. I rotated the 7 of the elements to align with element 1's profile and averaged them out. By setting the range to 28C - 33C (this gave the best visibility of the heating pattern) it gave the profile attached.

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.

To access and control the Red Pitaya using Python locally on a machine within the local network, one should follow these steps:

1. Start the SCPI server. This is achieved by first log onto the Red Piatay page

   rp-xxxxxx.local/ 

2. Go to Development >> SCPI server and turn the server on. (Note : The server is currently running)
3. Communication with Red Piataya is done through PyVista, install PyVista with:

    sudo pip3 install pyvisa pyvisa-py 

   This has been installed on Chimay. Ensure that you have pip3 install, if not, you can install it using:

    sudo apt-install python3 pip 

4. To start talking to the RedPitaya, ensure you have the scipt

    redpitaya_scpi.py 

   in your local folder. This is the standard class that you will import to your code to establish connection with the Red Pitaya. This code can be found in directory

    ~/RedPiatya 
    or this link
   

Finished ADC-DAC loopback testing today (see attached xlsx file or access directly here). All looks well with the first 8 channels, with the gain hovering just under 2. Also edited c1msc model in simulink to add channels 7-15 (the last 8 channels), and changed the rate back to 64K. See image 1 for the updated c1msc model. The last 8 channels are also looking good and show no problems, with slightly more scattering for the gain, but all values very close to 2.

We also installed the new eight-channel Perle IOLAN SDS8 terminal server today. Image attached.

NOTE: When we were installing it, we noticed an energized wire dangling from the 24V power supply. Has since been fixed and put back into place.