Today I did a successful test of the Langmuir probe:
Here is a voltage reading of the floating potential:
Langmuir Probe Test
29 07 2011Comments : 5 Comments »
Categories : Langmuir Probe, Sydney Experiment
Galling!
21 07 2011The nuts and bolts for the large flange are galling:
This set is shot.
These sets are pretty expensive, so I asked MDC for a free replacement… which they gave me!
Galling is pretty common with stainless on stainless. One solution is to use anti-sieze:
But this introduces goopy hydrocarbons to my clean chamber.
MDC’s recommended solution is silver plated stainless steel bolts. At $77 for a large conflat it’s very expensive… but the way to go.
Comments : 1 Comment »
Categories : Uncategorized
If At First You Fail: Cheat
21 07 2011The delicate assembly I made yesterday fell apart when I tried to assemble it today.
So I’m taking the easy way out… I will use one strand from this stranded silver-plated teflon-insulated wire:
Much sturdier!
Now I have a fully assembled Langmuir probe:
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Categories : Langmuir Probe, Sydney Experiment
Building the Langmuir Probe
20 07 2011Today I began fabricating the Langmuir probe.
I am using a tungsten light bulb filament as the probe tip:
The rest is just ceramic tubing to hold it in place. The filament is so thin and so fragile.
I use insulating varnish to hold it all together. I have to let this cure over night:
This will attach to the feedthrough:
The Langmuir probe will show the floating potential of the plasma… The dependent variable in the Sydney Experiment.
Comments : 3 Comments »
Categories : Langmuir Probe, Sydney Experiment
Electron Gun: Spark the Plasma
19 07 2011Just completed a test of the new electron gun with air plasma. Looks good:
To get here I had to reconnect all the ground leads:
And wire up the high voltage:
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Categories : Electron Gun, Sydney Experiment
Mass Flow Controller Upgrade
18 07 2011Today I upgraded the Mass Flow Controller (MFC):
Previously I used a 9V battery + a potentiometer as a quick hack to control the MFC.
For the sake of fewer parts I wanted to remove the battery from the circuit. The power supply for the MFC provides +15V, which is way over the 0 to +5V I need to control the MFC.
To prevent over voltage I used a TVS diode which shorts to ground above +6V.
It seems to all work! Don’t have to worry about a dead battery now.
Schematic:
The hard part is the craftsmanship needed so it won’t short out. Work in progress:
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Categories : Mass Flow Controller, Power Supply
Glazed Ceramic 3D Printing
7 07 2011This BoingBoing post illustrates the latest in glazed ceramic 3D printing.
I purchased this coffee cup:
I bought it because it’s cool, and to test the electrical and outgassing properties of the printed ceramic.
It may be possible to build custom ceramics for the magrid/standoffs with this process.
If I can braze this ceramic to metal… we can build almost anything.
Here are the design rules for this printing process.
Comments : 2 Comments »
Categories : Fabrication
Back in the Lab
6 07 2011My work contract is complete, so I’m back in the lab.
First I need to clean off my desk:
As a life experiment I’m switching to a standing desk. My shop neighbor Kennen graciously made me some risers:
Clean desk:
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Categories : Uncategorized
Prometheus Fusion Perfection 