On Nov 29th, 2019 (Applied Science) uploaded a video called
DIY mass spectrometer measures potassium in dietary salt substitute^a880 where he built a mass spectrometer based on the
American Association of Physics Teachers article
Poor Man's Mass Spectrometer (1967)^34d2 by: John W. Dewdney.
This topic–like many of the projects on
Applied Science–is something I have had in the back of my mind for a long time, and even something I had put some of my time in to researching. However I didn't get very far. So I had to get ahold of the paper and figure things out.
The original article
Follow up pieces
A piece in
The Amateur Scientist
How to Construct a Molecular-Beam Apparatus and a Mass Spectrometer [LOCKED] (July, 1970) by: C. L. Stong^4acc
- Here we get many hints, as well as a decade later update
- Like LMC6001 for the amplifier!
- Was the magnet hint here?
??Where is the paper about this thing, I think we saw stuff about the magnet there?
The instrumentation amplifier
In the second article (How to Construct a Molecular-Beam Apparatus and a Mass Spectrometer) There is mention of the LMC6001 amplifier, so lets start with that.
- Here we see the usage of 1Mohm resistance, and a shunt capacitor of 2nF
An electronic electroscope^5e58 Pay-dirt! Pretty much a guide to building the amplifier circuit using the aforementioned LMC6001!
The magnet setup
Original (Alnico) Magnet
In the original they are using a modified radar (Cavity Magnetron Tube) C-magnet (see below)
Electomagnet (based on "Undergraduate Mass Spectrometer")
The vacuum system
I know that time and time again it is advised against, but I want to try a household service compressor as a vacuum. Possibly with modifications for cooling and lubrication. Weee!
CircuitJS of original circuit
I made it!^61a6[^a880]: "DIY mass spectrometer measures potassium in dietary salt substitute", Applied Science, Nov 29th, 2019, https://www.youtube.com/watch?v=nIKhUizkXxA
[^34d2]: "Poor Man's Mass Spectrometer", American Journal of Physics 31, 932 (1963); https://doi.org/10.1119/1.1969211 / American Association of Physics Teachers, John W. Dewdney, 1967
[^7c93]: Dewdney, John W. "Undergraduate Mass Spectrometer." The American Journal of Physics 28.5 (1960): 452-456.
[^4acc]: "How to Construct a Molecular-Beam Apparatus and a Mass Spectrometer", The Amateur Scientist, C. L. Stong, July, 1970
[^6847]: "Can I get help with measuring particle charge using oscilloscope", Physics stackexchange (web), Anjan Tripathi, Jun 2nd, 2015, 18:40
[^6c7f]: "LOW CURRENT MEASUREMENT", Tektronix and Keithley Web Forum, vitsrt, July 19th, 2015, 11:15 am
[^61a6]: "CircuitJS of original circuit", Circuit Simulator version 2.2.12js, Jane Hacker, Feb 25th, 2020
[^5e58]: "An electronic electroscope", Article in Physics Education Volume 49, Number 1, Frank Thompson, January 2014, DOI: 10.1088/0031-9120/49/1/18