Pulse x-ray generators from ebay

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Rich Feldman
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Pulse x-ray generators from ebay

Post by Rich Feldman » Mon Jun 01, 2020 10:56 pm

This is to repost some bits from a discussion on Trading Post board in May, 2020, after a tip by Andrew Seltzman on April 26.
Andrew Seltzman wrote:
Sun Apr 26, 2020 7:33 pm
150kVp, 50ns pulses. 2.5mR/pulse at 12"
These are cold cathode tubes, unfortunately they use a positive pulse so they can't be used to drive a pulsed fusor.

Seller will take $120 best offers, possibly lower.
The one I got works fine, it can run off of 24-29Vdc by connecting to the battery terminals.

https://www.ebay.com/itm/Golden-Enginee ... 2749.l2649

Partial Manual:
inspector200.pdf
The product is by Golden Engineering, called Inspector 200.

A week later, Alan Sailer replied that he bought one to mess with.

There was some back and forth about detection, concluding that GM tubes (and pretty much any other detector-counter system) will report any 50 ns pulse of x-rays as one count.
Dosimeters and other detectors based on an ionization chamber, with no charge multiplication in the medium, work.
As would a fluorescent screen or scintillator followed by measurement of total light output (e.g. eyes or camera).

May 5:
Rich Feldman wrote:
Wed May 06, 2020 5:06 am
Thank you for the tip, Andrew. I just ordered a unit myself, perhaps the penultimate specimen in that lot.
Got anxious about competition and offered $160, which was accepted.

In previous post I mentioned a billion photons per cm^2, as a SWAG value.
Ran the numbers properly today and got values between 10 to 100 million, depending on the x-ray spectrum.
radh.jpg
radh.jpg (36.19 KiB) Viewed 1254 times
.
The least potent photons, for exposure (roentgens) or air kerma (grays), are at about 60 keV.
Those with more energy naturally pack more of a punch.
Those with less energy lose it in a much smaller mass of air.

Online literature generally agrees that at 0.060 MeV, it takes about 30 billion photons/cm^2 to get 1 roentgen, and 14% more to get 1 rad = 1 centigray.
For chart above, mass energy-absorption coefficients, μen/ρ, come from
https://physics.nist.gov/PhysRefData/Xr ... b/air.html
Conversion to kerma K and exposure X follows references like
https://www.utoledo.edu/med/depts/radth ... andout.pdf
May 14:
Rich Feldman wrote:
Thu May 14, 2020 7:09 pm
My "The Inspector" arrived on May 13. Time to figure out how to connect power, turn it on, make it go, etc.
rad21.jpg
rad21.jpg (34.84 KiB) Viewed 1254 times
It was surprising that the field-emission x-ray tube has a "film" window, visibly concave on the air side.
Why not something more substantial, like the beryllium in this stock picture of a tube by L-3, used in Fexitrons and Febetrons?
rad22.jpg
[edit] found and downloaded a manual more complete (?) than the one in Andrew's OP.
11610450.pdf
(433.12 KiB) Downloaded 69 times
...
Break time.
For later: shortened story of my unit having been mis-assembled by some previous custodian, but working (with x-ray detection 3 ways) after fixing the obvious thing.
And the follow-up on June 1 about commercial Marx banks, which Alan Sailer suggested privately as possible implementation of step-up to 150 kVp in the portable devices we are talking about.

If voltage multiplication is by Marx, it might be not too hard to get -150 kV out of same module, e.g. for a pulsed fusor.
Hey AS #1, are you set up to get a radiograph of the multiplier section?
All models are wrong; some models are useful. -- George Box

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Re: Pulse x-ray generators from ebay

Post by Rich Feldman » Wed Jun 03, 2020 3:28 pm

Moving along, before Richard deletes the thread in Trading Post, here is a picture of device with the lid and control board off.
At far end are HV transformer module (around the FE tube) and HV multiplier module (behind and maybe around the tube).
20200517_124533.jpg
.
Found that my "Inspector" had been abused by some previous custodian. Felt like when you open up a vacuum pump (or, say, oil pump in a car) and find a part missing or installed backwards.

The missing cover-attachment screw turned out to be stuck in its normal place, with just the head missing.
But wait, there's more. Removing blue anodized cover reveals the connection between control board (under handle) and the vertical main power board. Bottom side is a standard DE-9P, mated blindly unless you pay attention by looking through battery compartment. Somebody didn't mind the registration, and I found two pins bent over. Bet they'd been shorted to the D shell. Oh, and a spacer is missing next to the right side battery connector.
rad24.jpg
.
After straightening the bent pins and tracing some circuits, I decided to go ahead with test on DC power, which had worked for AS#1 but not for AS#2.

Hooked up battery terminals with 12 AWG wire, probably much heavier than necessary. Set power supply current limit to 12 A, same ballpark as the 15 amp fuse between battery and HV inverter.
Initial run had rotary switch set to 5 pulses, and dosimeter set 4 or 5 inches from nozzle. Got 5 cycles of a sound better recorded than described, and then the dosimeter indicated about 100 mR. Yay! (Dormant 3-inch electromagnet can be seen next to power supply.)
rad30.jpg
Not quite caught up, Richard!
All models are wrong; some models are useful. -- George Box

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Re: Pulse x-ray generators from ebay

Post by Richard Hull » Thu Jun 04, 2020 3:19 am

Let me know when you are done and I will kill the sale thread.

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Re: Pulse x-ray generators from ebay

Post by John Futter » Thu Jun 04, 2020 8:30 am

Thumbs up Rich

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Re: Pulse x-ray generators from ebay

Post by Richard Hull » Thu Jun 04, 2020 10:11 pm

Anyone willing to go through the hassle of moving and saving data and doing the work needed, deserves every consideration. I am the garbage man, the destroyer of wrongful things placed here and, sadly, even valuable data put in the wrong location where long held and often repeated warnings are clearly given. I may be bad and play the "heavy", but I am not evil.

I now await confirmation as to when to take out the garbage in the for sale forum.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Rich Feldman
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Re: Pulse x-ray generators from ebay

Post by Rich Feldman » Fri Jun 05, 2020 2:29 am

"A _very_ casual run 2, with alpha viewing film and room lights off (but bright indicator lights and panel meters on), showed no visible glow after 3 pulses. Dosimeter moved some more."

Third and final run (so far) yielded a DC current measurement and X-ray detection two more ways.
Cued a burst of 5 pulses while video camera was rolling, facing the x-ray generator. Geo's Fluorescent Film covered the nozzle, and mirror offered view of panel meter on power supply.

Here is a still from early in video, with setup lighted by flashlight.
rad31.jpg
.
Here's a frame from, I think, the middle pulse. Power supply panel meter says 7.9 amps. Note sparkles from unfocused irradiation of camera sensor, and blue fluorescent glow.
rad28.jpg
That report concluded with a snip from video when the 5-pulse burst happened. Now reposted without the silly slow-motion effect, but retaining the silly aspect ratio of a vertical smart-phone-cam. There are artifacts from sweep of "shutter" across each frame.
20200518_224008 - Copy_Trim (2).mp4
(890.33 KiB) Downloaded 60 times
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All models are wrong; some models are useful. -- George Box

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Re: Pulse x-ray generators from ebay

Post by Rich Feldman » Fri Jun 05, 2020 2:50 am

Here's an update on the last significant content ( a matter of opinion ) from Items for Sale thread.

As of June 4, ebay seller Bravosource has one left (down to $285 OBO) and different seller Panhandlesurplus has one about the same ($999 OBO). 113416380923 and 133008279419; you can paste an item number into ebay search window.

On my unit, after that successful test on DC fed into battery terminals, I have not yet tried AC power (which is supposed to work with or without battery pack).

Regarding the oil-potted "HV multiplier" module which surrounds the tube axis and stands behind the HV transformer module, Alan Sailer mentioned possible Marx bank. That seems to fit the observed and advertised behavior and performance.

Field Emission tubes are also used in the much more powerful Fexitrons and Febetrons by L-3 Pulse Sciences. Here's a picture of one of their spare parts: a T module for megavolt Marx bank, which goes on top of a stack of alternating L and R modules. I think the spark gaps all have line of sight to those in neighbor stages, which matters.
https://hofstragroup.com/product/l-3-pu ... n-pulsers/
rad29.jpg
.
Maybe someone can come up with a radiograph of the multiplier module in one of the Inspector units.
If it's a Marx bank, then maybe not hard to adapt for negative HV, e.g. for pulsed fusor.
All models are wrong; some models are useful. -- George Box

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