Target cooling water system isolation?

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steve_rb
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Target cooling water system isolation?

Post by steve_rb » Mon Feb 01, 2010 5:09 am

Target for ICP needs cooling. I am thinking about using tap water to cut the costs but with three phase and about 130Kv connected to target only possible way of using tap water I can think of is using a closed recirculating water loop using a battery powered DC circulating motor and pump with the whole system floating in good isolation (about 50 cm above the ground). Any idea or advice with this?

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Re: Target cooling water system isolation?

Post by Tyler Christensen » Mon Feb 01, 2010 5:38 am

You might want to look into Fluorinert. It's not cheap, but it's a nonconductive fluid that has good thermal cooling properties. Running a charged cooling loop is very difficult and might be asking for disaster unless done extremely well.

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Doug Coulter
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Re: Target cooling water system isolation?

Post by Doug Coulter » Mon Feb 01, 2010 6:46 pm

Use anything other than water. Mineral oil is a lot cheaper than fluoinert, and doesn't have the heat capacity of water (few things do), so just pump it faster. Which is now easy as the pump and so on don't have to float off ground. Hydraulic fluid (cheap and pretty thin) would probably work too. Most refrigerants would be good if you can stand the hassle of keeping them contained at some pressure.

Water is actually a good insulator but only if it is *very* pure, and it will only stay that way if you purify it more or less continuously, as it leaches impurities out of just about everything it comes into contact with -- they call it the universal solvent for good reasons. Not worth it on our smaller scales IMO.
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Re: Target cooling water system isolation?

Post by Carl Willis » Mon Feb 01, 2010 9:42 pm

Hi Steve,

From experience I can attest to the use of deionized water conveyed in rolls of PE tubing to cool kilowatt loads at ~50 kV. Extension to 100 kV would not be difficult in principle, but much thought about the layout is necessary.

Obviously, having mobile, pressurized water at high potential creates a special brand of electrical hazard, one that needs to be contained.

Fluorinert is a good idea also. It evaporates easily, so should be kept in a sealed system. The circulation pump and other components must be chemically compatible. PE tubing is adequate.

Moving insulating liquids can transport charge a la Van de Graaff generators, and water can conduct if your DI cartridge dies or the water has not had time to clean up. Attention should be taken to ground all metallic components in the flow loops that are not at the high potential by design.

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Doug Coulter
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Re: Target cooling water system isolation?

Post by Doug Coulter » Mon Feb 01, 2010 9:50 pm

Fluoinert comes in many flavors, some of which do *not* evaporate easily at all, but it's still way too expensive. I use a type here for vapor phase reflow soldering that doesn't boil until a couple hundred C plus -- solder melting point or a little above. It stays in the coffee can for years, no loss, no problem, so it matter to say which part number/boiling point you are talking about within this family of chemical products.

I bet you could push some refrigerant in gas form through most things fast enough to get decen cooling, but haven't tried that. Or just use a refrigerator compressor and some other parts stolen from a junk fridge, like the condenser and so on. You'd just have to find some high pressure tubing that was also a good insulator -- maybe hard to do?

I hadn't considered the VanDeGraff effect, but no kidding, the laws of physics don't change just becasue you forget one or two of them....Ow! But assuming you're going to have a grounded reservoir and pump, it should only cause some parasitic current draw, not other troubles, I think.
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Re: Target cooling water system isolation?

Post by John Futter » Mon Feb 01, 2010 10:00 pm

We use
Low odour Base solvent to cool the cathode on our Negative ion source.
This stuff is like keroscene with out the smell
small gear pump drives it around to the ion source 85kV away from earth with water cooled heat exchanger at earth end.
tubes are 3/8 bore polythene

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Re: Target cooling water system isolation?

Post by derekm » Mon Feb 01, 2010 10:46 pm

John Futter wrote:
> We use
> Low odour Base solvent to cool the cathode on our Negative ion source.
> This stuff is like keroscene with out the smell
> small gear pump drives it around to the ion source 85kV away from earth with water cooled heat exchanger at earth end.
> tubes are 3/8 bore polythene

sounds like automotive parts for diesel and diesel would work with a domestic boiler heat exchanger

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Re: Target cooling water system isolation?

Post by DaveC » Mon Feb 01, 2010 11:45 pm

I once used Activated Alumina to de-odorize Kerosene. Also removed all color, too. But I never measured it resistivity. I did it because we were trying A.Alumina on everything, and this stuff really smelled. Afterwards, it was great.

Ordinary mineral oil or silicone oil, works quite well with a gear pump and low pressures. AS Carl notes, you should have a piece of grounded metal tubing somewhere in the loop, down near the pump, obviously to handle leakage and injected charge.

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Re: Target cooling water system isolation?

Post by steve_rb » Tue Feb 02, 2010 5:22 am

What about HV transformer oil? I have seen they are used in 110 KV power transformers?

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Re: Target cooling water system isolation?

Post by JohnCuthbert » Tue Feb 02, 2010 6:52 am

Just for the record pure water isn't an insulator. It's a lousy conductor. Low odour mineral spirit seems as good an answer as any, but remember its still combustible.

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