DC Linac Project, Potential Drop Accelerator

[lutzhoffman]

Hello:

Here is a great picture of a recent design DC accelerator, this one is a 750KV unit, it was developed by RRCAT in India for use with electrons for industrial applications. I would highly recommend the RRCAT web site to all, they have a user freindly easy to search site, covering many areas which relate to this site, it is in my opinion worth a look.

These folks have done a lot of recent work in the DC accelerator area, they also developed the IGBT ZVS high voltage power supplies to feed their CW high voltage multipliers. My feeling is that there is no need to "re-invent the wheel" in building one of these. Instead the time is much better spent in the direction of improving the basic design for lower power, and ion acceleration use. My design layout is very close to the unit pictured below, except on my version it will taper from about 40cm D in the lower 6 stages, to 35cm D in the upper 8 stages, with a 14" or 35cm terminal on the top.

I wanted to post this image because it is one of the few which shows the complete layout of the components in a modern accelerator design. This unit is the basic blueprint which I am planing to base mine on. Due to the massive beam current output of this electron unit, you can see the huge HV diodes stacked for higher KV rating (The black hemisphere shaped units), this unit was designed for about 10KW+.

The capacitors which I already have, look almost the same as the blue ones in the picture, except mine are brown. Some parts that I still need to find, are: 14" and 16" D x 1-1.5" stainless steel equipotential rings, I will need six of the 16" ones, and eight of the 14" ones. I want to use SS because it is much better than Aluminum for anti-corona application. I recently built a small VDG electrostatic generator for corona control experiments, and sure enough it will reach a 15-25% higher voltage with a SS terminal. The reason seems to be the insulating oxide coating which forms on Al. Copper works fine also, I suspect this is because CuO is a conductor at HV, but it is very soft and expensive. If I cannot find SS hoops to use, then I will have to use sand filled Cu pipe, and bend it myself. The crazy thing is that I see such SS hoops on finished products like bar stools, and wheelchairs etc. But I cannot seem to find them on the net? I suppose the problem is that I am not searching under the correct name. I recently for example found SS Toroids on the net, listed as: "Welding Donuts", and hollow SS spheres as "gazing balls" in the garden supply stores. The SS hoops however, still remain to be found.


Thank you everyone for the great ideas and input, here is the picture:

PS: Thanks John for reducing the photo while my PC was down so that it could be posted, it is much appreciated