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):
The eduards pump started to make vary scary sounds.
Got a really cool (ehh, getting quite hot actually) second hand Pfeiffer & Balzers DUO 008 B.
Still don't have 5E-8 mbar, which is what I need, mass spectro meter shows about 60% H2O, and some junk at higher masses (35...45, probably hydrocarbon), N2 was at 1E-8, so no leaks.
Conclusion: I should do better cleaning, and bake out.
In the rack you can see the second hand water pump (from a central heating system) and the car radiator (Toyota), seems a bit of an overkill for cooling the turbo pump, but the cooling system is going to pump water though a heat exchanger for the oil cooling of the electromagnets.
It can handle about 2kW if the fan is turned on.
The QMG 064 mass spectrometer can be completely controlled with a computer by using the rs232 interface.
If anyone would ever like to connect a QMG 064 to a computer, this should be the cable:
on the DB9 connector connect pin 4 and 6 with each other.
DB9 pin 2 -> DB25 pin 2
DB9 pin 3 -> DB25 pin 3
DB9 pin 5 -> DB25 pin 7
on the DB25 connector connect pin 4 and 5 with each other, and connect pin 6, 8 and 20 with each other.
Set the "code 10" at value 9 (9600 baud) on the QMG 064 and put it in terminal mode by setting "code 5" to 3.
On the unix system (assuming /dev/ttyS0 is your serial port):
