Professor Shigeo Matsuyama has kindly written a detailed article describing the upgrade of the power supply in the Dynamitron particle accelerator: Dynamitron_Power_Supply_Shigeo_Matsuyama.pdf (0.2MB)

Original Equipment Manufacturar documentation for the  "Auto-Regulator " in the Dynamitron power supply: Auto-Regulator_Amp-1.pdf

Quoted from an email by Professor Shigeo Matsuyama, about the K2-XA and USA-3 in the regulated power supply of the Dynamitron. Scroll down for photos and schematics.


Date: Tue, 28 Sep 2010

Dear Joe Sousa,

We have operated 4.5 mega-volt Dynamitron accelerator sonce 1974.

The accelerator has parallel fed cascade voltage generator and obtain 4.5 mega-volt.

The accelerator is controlled via a USA-3 and  a K2XA amplifiers for Philbric.

A 300 volt power supply, R-300 is still running without serious problems.

For the sake of nice amplifier, voltage stability is around 3 x 10-4 (around 1000V for 3MV). The value is not so bad comparing to a recent accelerator.

I attached files of our accelerator.

While the USA-3 and K2XA work without serious problems for more than 35 years, we faced a problem.

The chopper (OAK 660), which had work around 30 years,  were replaced by the chopper CH-2025/60 from STEVENS-ARNOLD INC in 2007, October. It was broken this morning and now replaced the used OAK 660 which worked for more than 30 years.

Now, we finished the last one and  we are operating the accelerator without spare parts.

I would be very glad if you give me how to make the chopper.

In 2007, October, I contact you and you give an advise how to make chopper.

And also you have stocks of the chopper.

I would appreciate if  you give me more precise information on it.

I hope I can hear from you soon.

Sincerely yours,



Date: Fri, 01 Oct 2010


The Dynamitron accelerator was installed in 1974!

At that time, kenotron was used for rectifier, not diode.

While the kenotrons are replaced in 1980s, the other components of the high voltage regulation system are keep original. R-300, USA-3 and K2-XA are still running!

The accelerator was maintained by ourselves.

The accelerator was upgraded in 2007 except for high voltage system,

The Dynamitron accelerator was made by Radiation Dynamics, INC, which was absorbed by IBA company.



The auto-regulator:

The R-300 Philbrick supply:

The original k2-xa was repaired. Now it has no shell:

USA-3 chopper stabilized opamp detail: