Pulse Induction History and Theory

[Ferric Toes]

I have quite a lot of historical material and background theory so the idea of a separate thread is to keep much of it in one place, particularly complete papers. They will not necessarily be in date order, but to start things off here is a landmark paper by F. B. Johnson of the Signals Research and Development Establishment. The paper was written in 1956 when the Army was interested in investigating new technology for locating unexploded bombs. The research covered the basic theory of PI in some depth and is still relevant today. At the time though, the military lost interest because they felt that there was a likelyhood that a magnetically activated fuze would respond to the pulsed field and explode the bomb.

Eric.

Johnson FB005.pdf

[Tinkerer]

Eric, thank you very much for starting this thread and posting these documents which are of great importance and help to us.

Tinkerer

[joop]

Very nice... almost all of the design criteria for both the coil and the electronics are discussed in this paper, even though it is from 1956. Thanks!

[Davor]

The comments on the margin are also very informative. Thanks.

[Ferric Toes]

The comments on the margin are also very informative. Thanks.

Here are some further comments, corrections, and observations by John Alldred, who worked for me in the 1970's.

Eric.

John A's Comments001.pdf

[Aziz]

Damn it!, where can I get a thyratron? *LOL*
(No, I'm not going to build a thermo nuclear bomb igniter with it.)

Thanks Eric. Very interesting.
Aziz

[Ferric Toes]

Damn it!, where can I get a thyratron? *LOL*
(No, I'm not going to build a thermo nuclear bomb igniter with it.)

Thanks Eric. Very interesting.
Aziz

You don't need anything as high tech as a thyratron, just use an ordinary iron clad mains switch. It was good enough for Johnson.

[Ferric Toes]

Here is the next installment, although going backwards in time to 1955. This is the paper by Westcott that Johnson cites in his work.

Eric.

Westcott002.pdf

[Ferric Toes]

Eddy Current Method for Measuring the Resistivity of Metals. 1959.

A paper from 1959 which is relevant to PI.

Eric.

Bean et al001.pdf

[Ferric Toes]

Utilisation of Magnetic Viscosity Effects in Soils for Archaeological Prospection

1966 paper on the application of PI to location of buried pits, ditches, etc.

Eric.

Colani 1966 001.pdf

[Thomas]

I really enjoy reading your pdf articles, keep'em coming. Thanks!

[Prospector_Al]

Here are some further comments, corrections, and observations by John Alldred, who worked for me in the 1970's.

Eric.

[ATTACH]22392[/ATTACH]

Thyratrons can be found on Ebay--I bought one for experimentation. Advantages: very low on resistance, can handle very high currents and can tolerate high voltage without breakdown, in contrast to semiconductor devices.

Prospector_Al

[Ferric Toes]

Thyratrons can be found on Ebay--I bought one for experimentation. Advantages: very low on resistance, can handle very high currents and can tolerate high voltage without breakdown, in contrast to semiconductor devices.

Prospector_Al

In 1975 John Alldred and I tried a 2N5574 TRIAC device for a 1/2 sine transmitter. Worked fine and a pity we did not pursue it further.

When I worked at Mullards there was a thyratron device that pulsed current through a 1/2in square copper bar to magnetize magnetron magnets. Hate to think what the peak current was but the bar was hot after just two or three pulses. The pulser was in a room of its own and you could audibly hear the thump of the current when the discharge button was pushed.

Eric.

[proscan]

Thanks Eric for sharing.

Since you skipped to the 1975, I am adding Colani's article from 1968. It is in German. I believe it is still interesting for all.

Actually, I would love to see more materials in German, Russian or other 'not-english' languages.

proscan

[Prospector_Al]

Thyratrons

Thyratrons can be found on Ebay--I bought one for experimentation. Advantages: very low on resistance, can handle very high currents and can tolerate high voltage without breakdown, in contrast to semiconductor devices.

Prospector_Al

Hi Eric,

I have two EEV CX1622 thyratrons. 35 kV/5000 A. This is for the "Giant Nugget" detector, for Australian use.

You can have one ($600.00) if you wish--bought on Ebay--condition unknown at this time, but they look great.

Allan