Eastside Prep Fusor

Current images of fusor efforts, components, etc. Try to continuously update from your name, a current photo using edit function. Title post with your name once only. Change image and text as needed. See first posting for details.
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Gunnar Mein
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Eastside Prep Fusor

Post by Gunnar Mein »

Thursday 6/3/2021

Today was a banner day. We brought current measurement online, which will let us pursue a plasma club membership, but more importantly, we realized our 2.5 year old goal of measurable X-rays. The 6-7 KV variety, but when the Geiger counter goes wild, it counts.

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Also, our offline log viewer is now here. First, find the log you want to view in https://github.com/EastsidePreparatoryS ... /logs/keep. Now, click on "View raw" at the bottom, and copy the URL of the next page. Then, go to https://eastsidepreparatoryschool.github.io/. Click "Load log" and paste the address you copied before.
For today's X-rays, paste in "https://raw.githubusercontent.com/Easts ... 0test.json".
You can still unselect graph channels by clicking at their names at the bottom of the chart control. To see the X-rays (just after sensors go out after about sec 252), keep GC1, Pirani fine, CW ABS AVG, CW current. You can zoom in by dragging across the time region you want to see. Reset with the reset button on the upper right.

BTW if anyone is getting annoyed by the frequency of our updates - sorry. We are in 7-week period of intense, almost every day work, because we spent a year just talking about the fusor, and doing computational modeling. By next Friday, it will all shut down and get mothballed for summer - not to mention this is my last year with the school, so I will be a volunteer with no keys or credit card when I come back in online in fall - so please excuse our enthusiasm while it lasts.

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Wednesday 6/2/2021

Shielding the new camera, grounded by contact with lead:

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3 sensors and controller boxes now have shielded cases:
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Current measurement!

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Tuesday 6/1/2021

Anyway, today we installed the new camera underneath our vacuum chamber, taking advantage of our acrylic bottom. It needs a bit of shielding, I am thinking aluminum foil, but then we will put things back together again. Much more of an iterative "cut some wood and try here" process than we would have liked, but the acrylic is significantly marred in places.

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New box to hold the TMP controller and its Arduino:

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And, a picture of our lowside measurement box, which will also get shielding and another input for CW current soon:

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Monday 5/31/2021

We took our Fusor out of its shell yesterday, partially because we want to install a new camera that should arrive today. As we recently remembered that we have an acrylic bottom plate, that might make for nice pictures for a while.

First, a picture in the room. By the door, the emergency off switch for the HV system. Left: electronics, low right: rough pump, underneath: HV system (NST plus CW + measurement)

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Then, some close-ups:

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Variac, sensor board, rough pump:

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Then we took the cart out of the lead enclosure:

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Next, some vulnerable items come off:

Camera on arm with mirror

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The gas feed with the needle valve, solenoid, mechanical shutoff, and Arduino:

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The Pirani gauge and Arduino, the latter of which I am hoping to move away from there and into a shielded container today

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The turbo pump controller and its Arduino:

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Now the prep work for the new camera. First the view from the bottom, needs some cleanup:

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The place it sits on:

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And with its new channel and hole for the camera and its USB cable. The cardboard-cutout stands in for the camera.

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Many thanks to Joe who suggested that we look at measuring current at the input return of the CW. We did a couple of LTSpice runs and you have convinced us! And, in the process, a student learned to build stuff in LTSpice, something that will come in handy next year. We are still figuring out how to measure the negative voltage with the Arduino, leaning towards using an opamp. (Update: We see now that the voltage is positive. How convenient!)

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Last edited by Gunnar Mein on Thu Jun 03, 2021 11:47 pm, edited 2 times in total.
Gunnar Mein
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Re: Eastside Prep Fusor

Post by Gunnar Mein »

Updated Wed 6/2/2021
Gunnar Mein
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Re: Eastside Prep Fusor

Post by Gunnar Mein »

Today was a banner day. Details at the top of the post.
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Dennis P Brown
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Re: Eastside Prep Fusor

Post by Dennis P Brown »

The updates are nice and useful for proving work for evaluation for any listing. Nice set of pics - even more captions would be good, too. I really like the remote gas micro-valve gear drive/control system - clever.

I see the lead shielding isn't painted - that is a safety issue that I am surprised you missed. Might want to fix that - all exposed lead surfaces should have a layer of paint. This prevents contact with the lead but more importantly, keeps lead dust under control. Important safety issue for teens and for a school environment.
Gunnar Mein
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Re: Eastside Prep Fusor

Post by Gunnar Mein »

Dennis, your point is well taken. Meanwhile, until we get to do that, procedures are that everybody who touched the lead washes their hands right away - gloves are preferred but we have a shortage now - , and everyone is wearing masks at all times anyway. No students get to generate lead dust. But still, we will cover in tape or paint.
Gunnar Mein
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Re: Eastside Prep Fusor

Post by Gunnar Mein »

Last weekend's recorded run, for the patient. This post is not claiming admission to the plasma club. We are doing better runs where we balance at 25 microns this week, and then break through the curve and run it up to 8k. We also get better visual framerates now. Will see whether we can get one on video.

https://www.youtube.com/watch?v=ltcwAlOb5jU
Gunnar Mein
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Re: Eastside Prep Fusor

Post by Gunnar Mein »

This is our plasma claim. The experiment described here was on 6/10.

Video of my console during the experiment: https://www.youtube.com/watch?v=MjG2LAlxjRU. The camera is at the bottom of the chamber (see previous entries in this post).
Offline version of the console is at https://eastsidepreparatoryschool.github.io/, load the log "fusor-2021-06-10T13-25-06_plasma claim.json"
Video by student with camera https://youtu.be/MfnVroZrUDs and https://youtu.be/NprYQc7Tk0o (ok so I asked them to show the room and the people, apparently that didn't happen)
Picture of part of team on year-end-day a couple of days later:

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List of students who made meaningful contributions to this project over the last 6 years, alphabetical by first name:

Alex K, Andrei E, Andrew Z, Audrey W, Brandon R, Cadence C, Che L, Christopher N, Connor V, Dameli U, Egan T, Ellie H, Gavin U, Grant F, Henry H, Henry M, Henry S, Jackson F, Jake B, Jamin Z, Jan E, Karin S, Lara L, Logan P, Maggie Y, Mason K, Natalie A, Paul M, Piper H, Praveer J, Quinn B, Rory G, Ryan C, Ryan S, Sam B, Sam F-K, Sophie G, Subi L, Sydney V, Taras P, Thomas H, Thomas S, Trajan E, Trevor N, Tristan H, William B, Zach H

Mentors:

Dr. Charles Whitmer, Particle Physics, TerraPower
Dr. Ioan Leuca, Nuclear Physics, Rutgers University (retired)
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Joe Gayo
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Re: Eastside Prep Fusor

Post by Joe Gayo »

The plasma seems erratic and may be due to impurities/surface irregularities on the cathode grid. I think you need to increase the voltage (in order to increase the current) to obtain a more stable discharge regime. It may also help to run for an extended period to help condition the cathode surface. Bottom line: you need more power in the discharge.
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Richard Hull
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Re: Eastside Prep Fusor

Post by Richard Hull »

Joe is absolutely correct! the bright pulses go away with operation as the rough spots flash off the grid and other energized metal components. I am surprised you did not kick in the ass a bit more, but that is your business. In the end, you did, indeed, satisfy the criteria for the plasma club, albeit a less than spectacular visual display. I have logged you into the plasma club, having satisfied the conditions set forth.

For grins here was my old plasma display in my old demo system in the glass bell jar in 1998 11.3kv @ 6ma at a pressure of 11 microns of air. (taken from a color photo) No fabulous data logger via computer like you folks rigged up. I just used a voltmeter, ammeter, and TC gauge running for about 4-5 minutes straight at this level. There was no plasma club then and no amateur had done fusion yet. This was the first amateur fusor demo and the first demo system to show star mode. 10 months latter, I would do the first recorded fusion in an amateur fusor in 1999. My first real fusion star is my avatar to the left done in Fusor III in early 1999. (taken from a video screen at first fusion event)

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Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Gunnar Mein
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Re: Eastside Prep Fusor

Post by Gunnar Mein »

Thank you Joe and Richard. Fwiw, we did run the system up to 15 KV (what it would have been in vacuum), but we get quite a bunch of soft X-Ray activity and pressure swings out of control between 13 and14 microns, and inevitably lose control of sensors and dials a few minutes later. I’ll post one of those, too. But no clean plasma for us yet. We are thinking of replacing our USB connections with RS 485, and making some other improvements. But first, we go dormant until at least August.
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Joe Gayo
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Re: Eastside Prep Fusor

Post by Joe Gayo »

That sounds like a ground/electronic shielding problem and probably isn't related to the x-rays.

If the discharge is unstable, then there will be high pulse current from the capacitors in the multiplier. The energy in the capacitors increases with the square of the voltage so the discharge current will be very high if there is an arc. Large current pulses produce magnetic and electronic interference that thin walled shielding will not effectively attenuate.

Is there any series resistance in the multiplier or between the multiplier and cathode? There should be! Even though the variac helps limit power, once the voltage is raised the multiplier can deliver significant energy.
Gunnar Mein
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Re: Eastside Prep Fusor

Post by Gunnar Mein »

This is currently running with our 12 MOhm ballast. Yes, X-rays and trouble might very well be coincidental. I really do need to find you a recording what goes down in that scenario, though.
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Richard Hull
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Re: Eastside Prep Fusor

Post by Richard Hull »

Like Joe, I am positive x-rays play zero role in your issues. I run my fusor on a 60 hz supply as well and just run full wave rectification at 40-45kv with zero filtering. I find any effort to filter even straight out of the high voltage transformer at 60hz in the fusor environment creates unwanted issues, as Joe notes. Just too much joule energy stored in any attempt to filter or smooth things out. Naturally, with a multiplier you must have the capacitance to multiply the voltage and therein lay the rub. The folks with HF switching supplies are more immune to this issue. A stable supply in the fusor arena in a must. Few, if any other devices, work in the region of gas plasmas and narrow, workable pressure ranges found in a working fusor. Thus, the power supply is critical.

RFI abounds in the fusor environment as a norm! However, it is manageable with good practices in place. With modern electronic monitoring and data collection systems using RF sensitive, low level signals entering sophisticated computers and microcontrollers, the noise riding on these signals will reset microprocessors or send them off to process nothingness, or lock up at critical data collecting times. In high joule pulses, the noise peaks can often destroy microcontrollers.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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