 Tue Sep 27 22:29:34 2022, Jennifer Hritz, General, Optical Contacting, Razor test apparatus disassembly pictures 
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| Pictures of the razor test apparatus before and after disassembly, to make future reassembly easier. |
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Wed Sep 28 22:11:31 2022, Jennifer Hritz, General, Optical Contacting, Looked at Thor Lab slides
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While finalizing my work plan for the quarter, I decided to look at the Thor Lab slides. This was instructive because they highlighted the troubles I
will have with working with silicone. They are fragile and their small, thin sizes makes cleaning and manipulating them (without contamination) much
more difficult compared to the glass sides from before. |
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Thu Sep 29 18:36:40 2022, Jennifer Hritz, General, Optical Contacting, Looked at Thor Lab slides (continued)
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Continuining with my casual exploration of the Thor Lab slides, I heated them from off --> low --> med --> high, with 10 minutes on each setting.
The only pressure I applied was 3 larger glass slides, and that was only to flatten out the copper that the smaller, bonded slides sat on top of (so
the contact with the heating plate was even). |
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Fri Sep 30 21:51:31 2022, Jennifer Hritz, General, Optical Contacting, Quick test heat and pressure test
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Given that these glass slides are much thinner than the ones I worked with prior, I suspected they would be more receptive to pressure. I decided to
replicate the tests I performed with the larger slides: I prepared 8 samples, 4 by smushing the slides together with methanol in the middle and
another 4 by cleaning the slides with methanol before pressing them together with my fingers. I put 2 of each type under the cylindrical weight, and |
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Sat Oct 1 23:00:03 2022, Jennifer Hritz, General, Optical Contacting, (RESULTS!) Quick test heat and pressure test
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These are the results from the previous log.
At long last, there was an improvement with pressure and heat! Pressure without heat and pressure with heat both showed a small improvement. Although |
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Sun Oct 2 23:23:07 2022, Jennifer Hritz, General, Optical Contacting, Cause of improved bond: time or pressure
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Before jumping to conclusions based on my previous results, I wanted to check that it was indeed heat and pressure, not time, that led to the bonds improving.
I prepared 4 samples, all with my standard pressing technique (which still leaves room for improvement). 2 samples will simply be left to sit |
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Mon Oct 3 23:32:30 2022, Jennifer Hritz, General, Optical Contacting, Cause of improved bond: time or pressure (Update)
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I was unable to check the samples because I could not get access to Bridge, so they will be checked tomorrow and the results will be added as an edit
to this log.
Given that I was unable to do work in the lab, I instead began a second attempt at writing code for the Arduino to use PWM to control the |
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Tue Oct 4 22:15:23 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM Test #1
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I wrote a program to control the heating rate of the hot plate using Pulse Width Modulation (PWM), and it was a great success!
For roughly 6 minutes, the hot plate was power cycled with a rate of 100 ms on followed by 900 ms off. Based on my calculations, |
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Wed Oct 5 23:24:08 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM Test #2
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I repeated the first test, but let the hot plate run longer. It revealed that the linearity for the lower temperatures completely falls apart at the
higher temperatures. I think it should be fairly straightforward to modify the code to accommodate this. |
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Fri Oct 7 00:21:24 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM Test #3
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The previous test was cycled with 0.3s on follwed by 0.7s off*. This test was 0.7s on followed by 0.3s off. I intended to let it run longer, but I accidetly
knocked the thermocouple over while trying to move the cable father from the hot plate so the plastic would not risk melting.
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Fri Oct 7 21:20:08 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM v2 progress
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I had a little set back regarding the non-linear portion of the heating. After about 150°C, if the heating rate is kept constant, the heating graph
transitions from linear to logarithmic. I was able to show graphically that, yes, it is indeed logarithmic, but I could not think of an algorithmic way to
translate this logarithmic curve into the increase in heating rate to maintain a linear heating rate. I do have some ideas which I will test |
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Sat Oct 8 23:22:25 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM v2 test #1
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I had some trouble with the code not working as intended (partially because it has been I while since I coded in C++). However, I was able
to run two tests with the new code, although I ran out of time to type up the data for the 2nd. Graphing the 1st test's data, it appears that my improved
code is an improvement, but the heating is still slowing down as it approaches 200°C. I need to re-run this test, but with v1 of the |
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Sun Oct 9 21:55:53 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM v2 test #1 & 2
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For the following two graphs, I ram four tests: two using the the v1 of the PWM code and two using v2 of the PWM code. The graphs show the
heating rate I was aiming for and the actual results. It turns out, my v2 does not work better than my v1. Before 150°C (which is where I believed
that (assuming the rate is kept constantly) the heating rate shifted from linear to logarithmic), v1 is an overshoot and v2 is slightly less of an overshoot. |
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Mon Oct 10 15:34:13 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM v2.1,2,3 Test #1 and v2.3 Test #2
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Before trying the PWM on actual samples, I wanted to make one final attempt at improving my code (labled as v2.1). This change appears to have 1)
broken the code regulating the basic heat cycling process 2) caused the hot plate to heat up far, far too quick. Since the thermometer strangely turned
off halfway through, I only have two pictures as evidence that this test existed: a screenshot of the Arduino program telling me that the max cycle rate |
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Tue Oct 11 23:59:07 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM v2.3 Test #1 and 2
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Here are the graphed results from yesterday's tests, both by themselves and overlayed with the previous tests. I am satisfied with my code;
it has given me the (roughly) linear heat increase that I desired. The only last thing I would like to test is heating over a signficantly slower
time. |
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Wed Oct 12 23:26:48 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM v2.3 Test #3
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I tried increasing the temperature by 180°C over 20 minutes. As suspected, it did not quite reach the target temperature because the temperature
started to drop off around 100°C instead of 150°C, as the program expected. This should be an easy adjustment, since it is just a matter of
increasing the duration of the cycle at an earlier time. |
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Thu Oct 13 20:56:48 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM v2.4,5 Test #3
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My two corrections ended up being huge overshoots. The drop off time (100°C) is correct, but the default rate increase that worked in the other cases
is not working at all here. |
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Fri Oct 14 21:36:52 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM v2.6 Test #3
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The goal of "v2.X test #3" is to heat the hot plate to 200°C over the course of 20 minutes, and with v2.6, I have effectively succeeded.
There will likely be more issues once I try, for example, to heat the hot plate to 300°C over the course of 60 minutes, but for now, I want to stick
with lower temps and shorter times while I work out the kinks. Now that I understand the difficulties of PWMing a hot plate, adapting the code to combat |
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Sat Oct 15 21:59:13 2022, Jennifer Hritz, General, Optical Contacting, Hot plate PWM v2.6 Test #1, 2, 3
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I realized that, after changing so much from v2.3 to 6, I should check that my first two tests produce correct results with the latest version. This
was good because all three tests turned out to be innaccurate, as they were all short roughly 10°C. However, they were very precise. For
all three, the final temperature was 193.15±1.5°C. |
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Sun Oct 16 14:20:32 2022, Jennifer Hritz, General, Optical Contacting, Samples after 2 weeks under pressure
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Since I was focusing on the hot plate code and therefore did not need my weights, I decided to leave them on top of my samples for roughly 2 weeks.
It appears that an increased amount of time under pressure does not result in any noticable differences. A slight increase in surface area (SA) |
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Mon Oct 17 23:17:25 2022, Jennifer Hritz, General, Optical Contacting, Testing PWM code with actual samples
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Now that I have (relatively) good PWM code, I wanted to do my first real test with actual samples. Since everything went smoothly, I will now work on
building the original set up for the project, which included attaching thermocouples to two plates so we could precisely measure the heat between them.
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Tue Oct 18 19:33:38 2022, Jennifer Hritz, General, Optical Contacting, Setting up thermocouples
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Firstly, last night's heating did not change the contacted surface area greatly, but there is too many factors to speculate as to why that is the
case. I leave that for future testing.
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Wed Oct 19 21:51:10 2022, Jennifer Hritz, General, Optical Contacting, The trials and tribulations of the thermocouples
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I intended to test the new thermocouple set up today, but when I plugged them in, both did not read a temperature. It took me a long time to figure out
what went wrong: when installing the K Type thermocouple connector, the wires of the thermocouple need to be pushed in as far in as possible, otherwise
the circuit would not be completed. It took a lot of trial and error to figure this out. I first created a test "circuit" with wire and a resistor |
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Thu Oct 20 22:43:05 2022, Jennifer Hritz, General, Optical Contacting, Wired the thermocouples backwards
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Since the two devices are giving different temperature readings, I would like to find out if this imprecision is linear (e.g. they are always 3°C
off, so I just need to add/subtract 3°C after taking the measurements). If not, some sort of calibration is probably required. I decided to figure
this out by running the heating tests I did before, but this time with the plates. This also serves as a test to see how the plates heat up. |
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Fri Oct 21 22:22:37 2022, Jennifer Hritz, General, Optical Contacting, PWM v2.6 on new thermocouple set up
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I performed the same tests I have been doing prior (+180°C in 10 minutes) but now with the (correctly wired) thermocouples attached to the metal
plates. The top plate is thermocouple #1 attached to the Fluke and the bottom plate is thermocouple #2 attached to the TPI (the lime green one).
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Sat Oct 22 21:18:56 2022, Jennifer Hritz, General, Optical Contacting, PWM v3.0
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With v3.0, I took a couple steps backwards by getting rid of the feature that increases the heating rate so I can isolate the base heating rate
for the two plates. In my experience, the best way to figure out how to modify the program is to try a bunch of different target temperatures and heating
times and look for correlations. I started with (attempting) to increase the plates by 280°C in 10 minutes. |
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Sun Oct 23 21:01:40 2022, Jennifer Hritz, General, Optical Contacting, PWM 3.0 (+280°C in 5)
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I decided test how fast the plates would heat up if the heat was just on constantly on for 5 minutes. In general, these tests are raising a
lot of questions in regards to controlling the temperature given the hysteresis in the system. It is also apparent that the bottom plate heats
up signficantly faster than the top one, which means I need to heat the samples much longer than, say 10 minutes, if I want to avoid unevenly heating both |
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Mon Oct 24 21:23:22 2022, Jennifer Hritz, General, Optical Contacting, PWM 3.1 longer off times in cycle
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To combat the bottom plate heating up much faster than the top plate, I decided to try increasing the cycle period from 1000ms (1s) to 10000ms (10s).
In other words, taking the test I today ran as an example, the hot plate will now be on for 1000ms then off for 9000ms then repeat. Hopefully this should
give more time for the heat to transfer to the top plate, but even in this short test, it still appears to be a problem. |
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Tue Oct 25 18:55:38 2022, Jennifer Hritz, General, Optical Contacting, PWM 3.1 very slow heating
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| [I'm behind on data processing, but I'm creating an entry on the day I actually run the tests] |
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Wed Oct 26 21:27:23 2022, Jennifer, General, Optical Contacting, PWM 3.1 (more) very slow heating
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| [I'm (once again) behind on data processing, but I'm creating an entry on the day I actually run the tests] |
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Thu Oct 27 19:54:20 2022, Jennifer Hritz, , ,
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Somehow I never thought of this before, but instead of increasing the "on" time of the hot plate to account for the heating drop-off, I should
keep that constant and instead decrease the "off" time. That feels more logical given that I am trying to keep the temperature of the two plates
as close as possible. |
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Thu Oct 27 22:12:21 2022, rana, General, Optical Contacting, plotting and PID
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The Arduino / AC PWM interface looks good. I recommend that you maintain the code in GitHub and post a link to the repo whenever you update the code.
Use detailed commit messages so that it makes sense.
For the plotting, it would be good if you can use grid lines and markers for the data points. Then we can see the difference between the data |
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Sat Jan 7 16:07:13 2023, , General, General,
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The bond quality measurements can be split into two categories: destructive and nondestructive. For destructive, we have measuring tensile
and shear strength, and for nondestructive, we have gap distrance and mechanical quality. I am also
currently searching for more ways to measure the strenght, but I am having a hard time finding any others. |
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Sat Jan 7 17:08:47 2023, Sophia Adams, General, Optical Contacting,
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I am getting started on building the arduino circuit as well as setting up my computer so I can communicate between jupyter notebook and the arduino.
I will need a USB adapter for my computer before I can make much more progress. |
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Mon Jan 9 16:18:50 2023, Sophia Adams, General, Optical Contacting,
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Mon Jan 9 21:03:53 2023, Koji, General, General, Heavy item transport - preparation
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1) Paco cleared the path in the DOPO lab. We'll need a flat dolly or wooden bars (covered with a mylar sheet) to place the lid on it while we will
remove the suspension. The suspension will be placed next to the wall and wrapped with mylar sheets.
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 Tue Jan 10 23:30:25 2023, Koji, General, General, Heavy item transport - preparation
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[JC, Stephen, Paco, Gabriele, Aidan, Radhika, Koji]
We have successfully extracted the crackle suspension from the chamber at the DOPO lab. We ended up using the engine hoist brought from the cryo
lab instead of the yellow Skyhook as Skyhook's arm was too short. |
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Thu Jan 12 11:38:26 2023, Koji, General, General, How to move the large engine hoist through the narrow door
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| See the attachments. |
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Thu Jan 12 11:54:08 2023, Koji, General, General, Heavy item transport 7x
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[JC, Koji]
Caltech transport came in this morning. They first went to the OMC lab and moved the 3ft x 4ft table out. They lifted the heavy objects only
with human power. |
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Thu Jan 12 15:36:22 2023, Koji, General, General, Crane configuration for the suspension test chamber
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I made a quick investigation of the crane configuration for the suspension test chamber.
Conclusions:
The table and the suspension test chamber need to be placed in the northwest corner of CAML where the ceiling height is 105"
The |
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Thu Feb 2 17:28:37 2023, Sophia Adams, General, Optical Contacting, Test of Temperature Reading of One Plate
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The arduino was able to read temperature data and send it to a python program that graphed the data. |
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Mon Feb 6 15:36:39 2023, Jennifer Hritz, General, Optical Contacting, Papers on making Q measurements of bonds
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Upper limits on the mechanical loss of silicate bonds in a silicon tuning fork oscillator​ and
Temperature Dependence of Losses in Mechanical Resonator Fabricated via the Direct Bonding of Silicon Strips
https://www.sciencedirect.com/science/article/pii/S0375960117302359 |
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Fri Mar 24 20:27:46 2023, Jennifer Hritz, General, Optical Contacting, Controlling hot plate and recording temperature with one Arduino
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Previously, we had one Arduino taking the two thermocouple readings and another, separate one controlling the PWM of the hot plate. I have since
combined them together, which is better because now only one computer and one set of Arduino code is needed to do all of the work. This also gives us the
potential to, in the future, use re-time temperature feedback to control the heating rate. |
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Mon Jun 26 13:53:40 2023, Sophia Adams, General, Optical Contacting, cantilever geometry to find the quality factor of a silicon bond
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I am trying to design a cantilever setup to find the quality factor of optically bonded silicon. The cantilever will be given an impulse, and the ring
down will be measured. In order to determine the Q of the bond, the relative energy contributions from each part of the cantilever must be analyzed. The
primary energy contribution should come from the bond. |
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Fri Aug 26 14:24:57 2022, Radhika, General, Heat Load, Mariner TM Cooldown model 6x
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Here I describe the current radiative cooldown model for a Mariner test mass, using parameters from the most recent CAD model. A diagram of all conductive
and radiative links can be seen in Attachment 1. Below are some distilled key points:
1. The source of cooling power is an infinite reservoir at 60K - realistically |
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Mon Aug 29 15:44:46 2022, Radhika, General, Heat Load, Mariner TM Cooldown model
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Here is a more detailed analysis of varying the length and radius of the snout.
Attachment 1 plots the heat load (W) from the snout opening as a function of temperature, for different combinations of snout length and radius.
The model using the CAD snout parameters (length=0.67m end-to-end; radius=5.08cm) results in ~0.3W of heat load at steady state. The plot shows that the |
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Wed Sep 7 10:42:12 2022, Radhika, General, Heat Load, Mariner TM Cooldown model
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The attached plot (upper) compares the heat load delivered to the test mass from various snout lengths (end to end), as a function of test mass temperature.
(At steady state, our point of interest is 123K.) Note that these curves use the original CAD snout radius of 5.08cm (2").
The greatest marginal reduction in heat load comes from increasing the end-to-end snout length to 1m, |
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Wed Apr 12 12:03:34 2023, Radhika, General, Heat Load, Mariner TM Cooldown model
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Here we lay out the Mariner cryocooler requirements and discuss the most recent cooldown model, which includes a cryocooler that cools
down the inner shield and a separate LN2 dewar that cools the outer shield.
The chosen cryocooler must supply at least 2x the cooling power to the TM than the heat loads on the TM, |
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Fri Jun 2 11:31:29 2023, Radhika, General, Heat Load, Mariner TM Cooldown model
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Summarizing the current Mariner ITM cooldown model assumptions:
- Inner shield and outer shield have snouts of equal length (1 m end-to-end)
- Laser off during cooldown |
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Fri Jun 23 15:37:39 2023, Radhika, General, Heat Load, Mariner TM Cooldown model
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I simulated the Mariner cooldown with an additional LN2 tank connected to the main cold strap shared by the cryocooler.
LN2 can aid in the initial cooldown from room temperature, and once the inner shield is sufficienly cold the cryocooler can take full control. (The LN2
should not be on the whole time - once the inner shield crosses 77K the LN2 would be contributing heat.) In the model I |
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Fri Aug 4 17:07:41 2023, Radhika, General, Heat Load, Mariner TM Cooldown model
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Here is the model including an additional LN2 tank aiding in inner shield cooldown, applied
to Voyager [Attachment 1]. The same assumptions have been made as in the previous ELOG.
The LN2 is switched off once the inner shield reaches 90K. |
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Tue Aug 22 10:16:54 2023, Sophia Adams, General, Optical Contacting, Matlab fminsearch Cantilever Geometry Optimization
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I am trying to use fminsearch to find the best cantilever dimensions to maximize the bond/cantilever energy ratio. Fminsearch takes in a function and
a set of intial parameters. The function that is passed in should be a function of the parameters, but my getEnergy function does not work unless the COMSOL
model is passed in as an argument. I tried to make a helper function, but I run into the same problem. |
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Tue Aug 22 12:12:05 2023, Sophia Adams, General, Optical Contacting, Matlab fminsearch Cantilever Geometry Optimization
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The code works now. If the function is specified by a file, there should be an @ symbol front of it when it is passed into fminsearch.
Quote:
I am trying to use fminsearch |
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Tue Aug 22 13:14:22 2023, Sophia Adams, General, Optical Contacting, Matlab fminsearch Cantilever Geometry Optimization
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Restricting the search to nothing less than the initial parameters (L = 2 cm, h = 0.3 mm, d = 0.55 mm), fminsearch outputs L = 2.0088 cm, h
= 0.3000 mm, d = 0.5776 mm.
With the search restricted to L >= 1 cm, h >= 0.1 mm, and d >= 0.5 mm, fminsearch outpus L = 1.0313 cm, h = 0.1000 mm, and d = 0.5033 |
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Wed Aug 23 11:13:58 2023, Sophia Adams, General, Optical Contacting, Matlab fminsearch Cantilever Geometry Optimization
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I am trying to get a plot of the fminsearch data, but I was not sure how to extract the data. But fminsearch has built in plots that I think capture
the data pretty well. |
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Wed Aug 23 16:34:47 2023, Sophia Adams, General, Optical Contacting, Matlab Cantilever Geometry Optimization
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| Here is the code to generate a random list of parameters and evaluate the energy ratio of each. |
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Fri Aug 25 13:25:05 2023, Radhika, General, General, Summary of JPL/Ball cryocooler discussion
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Here is a summary of the cryocooler discussion hosted at JPL.
Dave Glaister of Ball Aerospace presented on their low-vibration cryocooler assemblies (CCAs). A summary of their work can be found in
this paper. Ball has their own cryocooler vibration testing setup that they use to assess/characterize their platforms. They did not show frequency-dependent |