Relationship between Filament and high Volatge on a grounded Cathode Oxford Tube

[MikeD99]

I bought an Oxford Instruments Jupiter 5000 tube on eBay. I have some experience with radiation. I am 70 years old and extremely careful.

I have a Spellman 30KV power supply. I have a variable bench supply: https://www.ebay.com/itm/373813103232

I think I understand that the filament and the high voltage are connected together in the tube at the cathode side. The positive high voltage side of the Spellman goes to the HV wire in the tube.

My question is:
Can I just hook up the filament wires across the two filament wires (being careful to account for polarity)? I would account for the correct polarity and ground the earth grounds all together and to earth.

I may not sound like I know what I am talking about but I am simplifying things slightly.

The tube I bought is shielded and I have some lead shielding and I have some geiger counters and a bunch of Vicoreen Ion chamber x ray detectors to use to see if I am irradiating myself and not knowing it. I have been in gamma spectroscopy and neutron detecting for years. I am trying to be careful. I have a scope. I made a three tube Cosmic ray Muon detector: https://fusor.net/board/viewtopic.php?p=101259&hilit=miked99+cosmic+ray+muon#p101259

Thanks and I am open to any questions about what I am doing and especially want advice.

Thanks,
Mike Driscoll
Leesburg, Va

[klugesmith]

Welcome, Mike.   We share some interest in radiation detection and x-ray generation, and most of our time on Earth.

What's your initial objective with the Jupiter 5000 tube?  [edit] An Internet search answered most of my questions about the tube.

Don't burn out your filament!  Then how about setting up to measure current in the HV circuit; monitor that while ramping up filament voltage.

It doesn't take much x-ray intensity to absolutely saturate a GM tube, so ion chambers are the way to go.
I found that ordinary dental exposures are on the order of 10 milliroentgens, maybe less in this era of electronic image detectors.
Running a dental tube at 65 kVp and 7 mA is like taking the lid off a 1000 curie radioisotope source.

I have some lead bibs to give away.  Lead bibs are still used in dental practice, as I can attest from an experience yesterday.

[edit] to your question: yes, one end of filament (or center tap of a filament transformer secondary) connects to negative side of HV power supply and, in this case, to ground.  Optionally with a milliammeter or current sense resistor in connection to PS negative.

[MikeD99]

Thanks for answering the gist of my question.

I have a current limited bench power supply that I was going to use to limit the filament current. I have all the spec sheets and the app notes for the tube. I got it used from ebay is why I bought this particular one and it's shielded alredy. I have a 50 KV ps on it's way. I think it's a .4 something tube aperture.

Are you really giving away aprons? I will pay the postage.

Thnx

[Luca c.]

Hi Mike, I was reading the datasheet and noticed that the tube has a 127um Be window, that is used to transmit even very low-energy X-rays, which would be useful for some applications but not for taking xrays of living things, what is your application that require those low energy rays?
Also, ave you already tried to measure the produced X-rays with the ion chamber? I would be curious how many roentgen are produced by 50W x-ray source.

[MikeD99]

Hi,
I have done nothing except research so far. And lots of it. I have not powered it up. I am extremely careful. I have since gotten this power supply:
https://www.ebay.com/itm/186363475179?_nkw=spellman+mnx&itmmeta=01J6BJVCCR0WNGKVP1MCJ3J4VM&hash=item2b6420f4eb:g:oM0AAOSwWORmAwHr&itmprp=enc%3AAQAJAAAA0HoV3kP08IDx%2BKZ9MfhVJKkQp57poHHhj559stDLuUc0uXH14%2Fyq1yyrzMzhwEY%2BRXCyoFXFwv9qEN0y2mM%2FO68anc%2BaUDiLAIlKn85YJNhssGhw35caUOdZWs9PVJ5lwXvlgoNauiFnyhAvv6ULGGXFy%2FCowJwudNLK3LtCTQWpsVVpGiCQtHwq%2F154woXfdiwbea6S3Y9Uvazkk4xCaPK6JKn5MpnNgmx7mz73eHwfrmhxpu6fwG3w2zLyGSmzYN4qb9g0ajLOUq%2BwBI%2F0LWs%3D%7Ctkp%3ABk9SR77G7fKyZA

Download the power supply's manual:
https://www.spellmanhv.com/-/media/en/Technical-Resources/Manuals/MNXMAN.pdf

and am figuring how to make a panel to display the available info on DVMs. I have a very helpful EE genius friend who lives in Tx (I live in N. Va - so it's all over the phone and I am trying to not wear out my welcome) who is giving me advice. I am afraid of 50KV and/or XRays so I am being very careful.

The power supply is made for my tube. It has remove monitoring and control and manuals and the proper cable(!).

I am not going to XRay any living things. I have some of these kind of things, but not this exact one, to cast an XRay shadow upon, with the dirt of my yard as the ultimate X Ray destination:
https://www.ebay.com/itm/276065415924?_nkw=x+ray+image+cassette&epid=1167750015&itmmeta=01J6BMT76NCC0CGTBMXPNQK6RT&hash=item4046c7f2f4:g:Y0sAAOSwTFVlEYr6&itmprp=enc%3AAQAJAAAA8HoV3kP08IDx%2BKZ9MfhVJKko9O%2FYlFy9pd%2BdT2hM3DDntRSnVsZ6Oa%2FUmJhr05fhg6D7VjCzaljoaw3K0hdP3KgY0gtJA%2FfvYsocfx9xM8TcmSjKDXJ82Ow%2FfsQbfHAphErleeBUvNiVxhkTA2joyb0Sr7qbawLCphppuOjOhqMEN%2B0z35tO7q%2FYKVEEgAwkybrHVko%2B8mHBB903TN1JuH3hFJ8rCczxCvs82NckWoKxBtKBefSurBmh%2BTIN7i%2B55l3X9sUD8%2FXPTTDCruEHqdVdfI%2F0X%2FjlffFy6OZTDvTn3zP62YCDBq3QywP5qRz8CQ%3D%3D%7Ctkp%3ABk9SR7Tz6PSyZA

I am going to X Ray things in my shop like a pack of firecrackers and an automotive feeler gauge. Hey, I'm a wild man...

That is my plan.

Thanks,
Mike D.

[PhotonLab]

Hi Mike,
you may need an intensifying screen, they are available on eBay. Agfa 300 speed are very good for taking pictures using a good camera with manual control.
You should set up a remote control to energize the tube and activate the camera shutter, in the following picture here's the setup I used for my home built x-ray machine.



Good luck and take care
Mario