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Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Herr Zapp wrote ...
Rather than using the stainless steel worm-gear clamps (which may tend to nick the soft silicone rubber tubing), have you considered the all-plastic ratchet-type clamps?
That's a great idea, Zapp Man and I'll do it. I like the fact that the clips are non-conductive, as I could imagine coronas springing up around the Jubilee Clips, or an invitation to flash over with the metal ones. And they look less likely to seize too. I wonder how the plastic will endure in the presence of intense radiation.
I must say I feel really heartened by the good advice I've received in this thread. Makes the cost and effort of trying to do something a bit different really worthwhile. Wait till we get to the first experiments!
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
Harry wrote ...
... It's a bit late to set up the camera now, but if it is important I'll photograph the flying leads tomorrow. But there is really nothing 'perplexing' about the connections at all. The three flying leads are the two filament leads, and the control grid, so there is essentially nothing to see .
The primary function of the grid is to control Ia so that Vf can remain constant, rather than the tiresome old business of having to supply If across 400mV - 4V with high stability. Iron Man's control grid range is from c. -70V to -250V. ...
Harry, you have a good way with words. no need for photo of wires.
We await your determination of whether the coolant path is electrically isolated from the anode. If not, then is this a three-way fork in your road? * HV-isolated filament winding & adjustable 250-VDC, low-I supply (the normal practice?) * HV-isolated tube mounting, coolant reservoir, and pump or gravity feed * HV-isolated tube mounting, with long hoses and high coolant resistivity.
Some numbers for #3: If you can tolerate 100 megohm leakage path, using effective hose length of 100 cm and area of 0.1 cm^2, could get by with water resistivity of 0.1 megohm-cm. "Ultra-pure" water is 10 to 18 megohm-cm, and one online reference gives a range of 0.02 to 1 megohm-cm for "Purified water". How many megohm-cm can you buy in town? How many minutes or years does it need to stay highly resistive in your system? [edit August 4: The direction of HV leakage current will tend to give your tube a sacrificial anode ]
I don't know the effect of chemicals to retard corrosion & biological activity, but there are industrial applications (even Marx bank capacitors) that depend on DI water as a high voltage dielectric.
Or use a non-aqueous coolant fluid, with heat exchanger if it has to run for a long time. Some kind of oil that's compatible with all the plumbing materials? Fluid pressed from Li-Poly batteries? -- oops, that's non-aqueous but designed for high electrical conductivity.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Thank you for that excellent summary and review!:-)
I do charity work for Rumanian orphanage on Saturday afternoons, so I shan't have time to set up the experiment until Sunday afternoon.
I went to a Polish restaurant for lunch, and after an excellent plate of bacon and cabbage I moved to an outside garden table to drink a final coffee and smoke my pipe in a sunny corner, when the whole problem of Iron Man was revealed to me in the pattern of the woodgrain on the garden table.
Thank goodness Stever McConner spotted my glaring mistake, before I had started cutting metal and plastic stock which I can only really afford to do once for each of my projects. (A cold beer for Dr McConner)
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Cooling Water Silicone Tubing Preferred Values.
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