TPU240 TCP600 and maxigauge

A few words... the "octavio" is not going to work, sorry.
Got a new plan, have a new setup, all CF rings, I'm using my old setup for plasma cleaning.

Way too busy to spend time on this blog, this weekend second try in plasma cleaning (first try too many things broke down)

Here is TCP600, TPU240, DUO008B, maxigauge, mechanical feedthrough stuff etc, gets into the E-7 range in about 30 minutes without bake-out.

lamps and controllers just arrived for bake-out inside chamber, also got my CoSm magnets for the ion guns.

Pressure control

I tried to control the pressure by placing an electric valve between the DUO008b and the turbo pump, and switching the valve on and off with the TPG251 single gauge controller.

It worked, but it wasn't really stable, for example; setting HI en LO on the TPG251 to 6E-5 and 5E-5 resulted in a situation where the pressure dropped from 6E-5 to 1E-5 when the valve opened.

So then I connected the relais of the TPG251 to the external on/off function of the TCP121 turbo pump controller.

And that worked perfect!

Just switching the turbo pump on and off was enough to control the turbo speed, pressure was controlled within 10% for all desired values in the 1E-3 to 1E-6 mbar range.

The TPG251 has an external input for setting HI and LOW, should be easy to control it from the computer.

Xray transformer under oil

Have been busy with the Xray transformer.
It's under oil now, the outgassing with vacuum took some time, lot's of bubbles :)

I tested the transoformer with 10V input, output was about 700V, I expected more, but maybe it's not that linear at low input voltages.

Negative HV supply for PMT's

The idea of making a high voltage with a DC-DC converter and a voltage multiplier can also be used to generate a negative supply for PMT's:

There is no need to use a P-channel mosfet, just reversing the diodes in the voltage multiplier reverses the polarity of the output.
The feedback circuit needs to be adapted to a negative output, when the PCB's for the positive supply are in, I will extend the design and make one ciruit board which can generate -3kV...+3kV with jumpers to switch polarity (changing in and out of the voltage multiplier and changing the feedback circuit).

10mm polycarbonate for the 85000V supply

Have been working on the (very small..) saw table today, sawing some polycarbonate sheet for the high voltage supply:

It's big enough for the Xray transformer which is going to be immersed in transformer oil (the real thing, 60kV/mm), to get the air out I will use vacuum, which will create a force of about 2900N on the biggest sides. The sides will be glued together with epoxy, the edges are 45 degrees.

I also got a preview of the circuit board for the neutron counter power supply (eurocircuits.nl):

Circuit board voor HV supply

The SNM-10 and another detector tube need about 1600V.
This is the circuit board:

Designed with Eagle.
The circuit is VERY DANGEROUS, it can deliver a few milliamps at 3kV, the capacitors are charged at 3kV. If you build this thing, make sure that you know what you are doing!
Eagle BRD file
Eagle SCH file

40nF 100kV

For the 85000V supply, a capacitor bank:

The capacitors are 10nF, 20kV, so the 110 capacitors should be 44nF (5x series of 22x parallel).
The cap meter shows 40nF total, only 10% off. The bank will be in oil, and I still need to find the right resistors (5x 200Mohm, 2W, or enough other values make 200Mohm)