The bottom and top plates of the large vacuum chamber are almost finished!
Took a lot of machining, I still need to do some polishing.
Also found 60kV cable from an X-ray machine, a 80kV 0.2A diode and an X-ray transformer.
I cannot find any transformer oil (unless I buy 50 litre), anyone out there who can sell me some good transformer oil (no pcb oil from old transformers)?
And I want 5 of these, but they are a bit expensive.
This is the upper plate with the viewport:
The old and big second hand pillar drill works great! Although drilling a 40mm (for the viewport) hole through 20mm aluminum does make the 800W motor a bit warm.
I've also mounted 2 times high voltage (20kV) feedthrough for the octavio core, one 4-pole mid-voltage (4kV) feedthrough for the focus coils. Still have to mount two times low voltage 8-pole feedthrough for the electron guns.
For the current through the core I will use batteries, the batteries can have the same potential (+12kV) as the core, this will simplify building the octavio core.
Just to break the silence.
Have been repairing the bake out heating with heat-conducting high-temperature epoxy.
Started this weekend with the aluminum ground plate, but my pillar drill was not big enough to reach the center of the plate. Tried to hard-solder the stainless hemispheres to fix two holes, but didn't have enough power to reach the desired 600 deg. C.
So, lots of activity, little result....
But, I did buy a second-hand bigger pillar drill, and I bought the "Siever MetalJet" which can reach 2400 deg. C.
A 40mm viewport is also on it's way, and I polished the weblog.
On the left you can see a 3D drawing of the octavio core, just the core, explanation about the core, the 8 focus coils and 8 electron guns will follow.
Back from holyday, have been 800 meters above en 26 meters below sea level :)
Replaced the bearings of the TPH270, with the right tools it isn't very difficult, had some leaks on the outer rings after replacing the bearings, spilling some more ipa on them fixed the leaks.
The DUO 008b pump I have seemed to have a problem with it's thermal protection.
After about an hour it switched off, but sometimes it just switched off randomly.
I replaced the thermal protection switch (a relay with a PTC), and I replaced the off switch. Worked fine for 5 hours continuously after that:
Trying bake out,
Got 4.9e-7 with about 1 hour of bake-out at 70 deg. C. Have to do a lot more bake out to get lower.
Will build a temperature control system to do longer bake out.
Working on the drawings of the "octavio" and will present the ideas here soon.
After cleaning every vacuum component (again) I tried bake out, for a short time, just heating the setup to about 60 deg. C for 10 to 15 minutes, using a paint burner.
Seemed to do the right thing to the H2O pressure, but then my mass spectrometer showed a very low pressure, about 8e-8, which was obviously wrong, the cold cathode gauge was still in the e-6 range.
The researchers at radiantmatterresearch.com had the same problem with the same QMA 064 sensors. They tried cleaning with acetone, without any effect.
After posting it on the fusor board the idea is to start cleaning with H2SO4, NH4OH and H2O2.
We think that over the years various gasses got buried into the collector and were released during bake out, reacting and forming an insulating layer on the collector, so we have to do proper bake out before cleaning it, or the same affect would come up again.
But the bake out did have a positive effect, pressure is now in the e-7 range, to get to e-8 I need longer bake out.
I've ordered 50x Vishay PTC heating elements for 110 deg. C, they can be connected to 230 VAC directly and will heat up until reaching a specified temperature. Very simple and cheap. At 1200 ohms they will start at 44 watt and start giving of less power at about 100 deg. C, and switch off almost completely when the surface temperature is 140 deg. C.
Only a factor 12 to go (indication of the cold cathode is a bit on the high side, so t might be better than indicated):
