High-voltage coincidence

I’m in need of a high-voltage, low current DC power supply temporarily for an experiment in the lab, prices for these from the usual suppliers run into the hundreds of pounds. Given that all (all but the very best ones anyway) they consist of is a string of diodes and capacitors in a Cockcroft-Walton configuration, I decided to build one.

C-W generators are reasonably safe devices unlike their very similar cousins, the Marx generator. The voltage developed by the generator might be very high in both cases, but the C-W generator supplies very little current, whereas the Marx gen will deliver something more fatally akin to a lightning bolt. That’s not to say you can’t hurt or kill yourself with a C-W gen, just that you’ll have a bit of a harder time managing it. If you have an ioniser in your house, it will be very little more than a few stages of a CW gen and some resistors for further current limiting.

So, that’s the high-voltage, where does the coincidence come in? It happened that yesterday while flicking though my copy of the December CERN Courier, I spotted a feature on Cockcroft and Walton splitting the atom using equipment based around the generator bearing their name. I may going into the details of their achievement in another post, but for now a photo of them in their finery (and not just because I can then count this as an EDW post. Oh no…)


Ernest Walton, Ernest Rutherford and John Cockcroft.

Elegantly dressed Wednesday – Me

Lately, I spend much of my working day the cleanroom, well , either of two cleanrooms.

Room-A is a pretty basic cap and gown type affair – the room isn’t really clean (class 100,000 to 10,000 depending on how often used; more usually high than low), the kit is really there to control access (limited kit = limited number of users) to the room and provide nominal clean standards. Room-B, on the other hand, is a bit more serious; usually class 1000, sometimes approaching class 100 after a few weeks of no use, you need to get properly kitted up to enter this room.

Yesterday I found myself in the changing room for room B with a camera, so here is a self portrait showing me about to start work.


Elegance this Wednesday is yards of blue nylon and nitrile. Or something.