FAQ - Fusor gas delivery and pressure control system

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Richard Hull
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FAQ - Fusor gas delivery and pressure control system

Post by Richard Hull » Sun Dec 31, 2017 5:32 am

This is in answer to how do I get the deuterium into the fusor and control its pressure. This entire FAQ is for a high pressure, tanked, deuterium gas cylinder system only!

This is a two fold issue
1. Hooking the deuterium cylinder to a tightly controlled gas flow line taking the tank pressure (1000 PSI) down to only 2 PSI in the main gas line and then pinching this 2 PSI down to a whisper of gas slowly leaking into the fusor.
2. Maintaining a near constant internal operating pressure of a flowing deuterium gas from the gas line against a mighty vacuum pumping system trying to get the vacuum in the fusor to a near outer space vacuum level, incapable of producing the needed conductive fusion plasma.

In short, taking a 1000 psi gas cylinder internal pressure of deuterium down to a few millionths of an atmosphere inside the fusor, allowing it to fuse without wasting the valuable flowing gas. Remember, in a flowing gas fusor, you are constantly vacuuming out the expensive gas that you are letting into the fusor and throwing it away to the atmosphere via the mechanical pump's exhaust port.

I attach a diagram that shows an idealized system for accomplishing this. I will cover each component and explain each function.

NOTE*** I have placed asterisks by each component's name. Four asterisks mean this component is not optional and is a must have. Three asterisks mean this is a more of less vital component...Without it you will have major issues. A single asterisk means it is a very nice thing to have but can definitely be considered optional.

All tanks of deuterium gas purchased from a supplier are of the "lecture bottle type". They are all the same size from 10 to 50 or slightly more liters in the cylinder. The more deuterium in the cylinder, the higher the gas pressure is within. Typically, this pressure is between 500 and 2000 PSI.
Thus, you absolutely must have a suitable gas pressure regulator going between the cylinder and the lower pressure main gas line to the fusor.
A two stage regulator is ideal. The left most gauge reads the tank pressure and indicates how much gas you have remaining in the tank. The right most gauge is a much lower pressure gauge.

You will verify that the regulator control valve is in the zero flow mode. Typically, this is all the way out (counter clockwise). Then you can open the tank valve and the left gauge will leap up to read the pressure the pressure in the cylinder. Once the system is in place and all valves in the line are closed so that no gas can flow or leak into the fusor, you can adjust the regulator valve clockwise very slowly. the rightmost pressure dial will start to climb off the zero peg. Smart money and the adroit hand can just barely get the needle off the peg. Running 5 PSI on the fusor line prior to the needle valve is rather ridiculous. Try and keep it at 1 or 2 PSIG. Most low pressure regulators don't have this fine an indicating gauge, but just off the zero needle is ideal.

After the main regulator, I prefer to use 1/8-inch copper line from this point on. (pro's use 1/4-inch lines with VCR fittings). Swagelock fittings cost much less and are quite suitable.

The low pressure line runs from the tank regulator to a micrometer needle metering valve. Ideally, this should be a bellows valve, but with good packing, a non bellows needle valve will suffice. This is your main micro gas flow adjustment. If you do not use this, you better find an equivalent... Then, you are on your own.

Next in the line is a conductance flow restriction device. This can be a 20 foot long rolled up coil of tiny capillary tubing or a precision laser drilled disk in the line. This is a nice thing to have, but with good components elsewhere in the system, it is normally not needed. Such a constrictor will allow much finer control over the fusor reactor's pressure.

From here you just connect the line to the fusor.

Critical******

The ultra important item is the gate or conflat bellows valve separating the fusor from the inlet of the diff pump or turbo pump. This is the last must have component! It is used to throttle the mighty vacuum down to the point that the pressure in the chamber against the vacuum is maintained. It is imperative that this valve be capable of a complete seal-off of the diff pump's ability to vacuum out the fusion chamber. In real world use, with flowing deuterium gas into the fusor, this valve is barely cracked open.

If this throttle valve is opened too much during operation, you will have to open your needle valve in the gas supply line more to maintain fusor operational pressure and, thereby, waste huge amounts of gas. I have given critical operation instructions of this system in another FAQ on fusor system startup and operation procedures.

Richard Hull
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Re: FAQ - Fusor gas delivery and pressure control system

Post by ian_krase » Sun Dec 31, 2017 7:23 am

Is it viable to use a series of needle valves (maybe one full-on micrometer needle valve and several more standard ones) as conductance limiters?

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Re: FAQ - Fusor gas delivery and pressure control system

Post by Richard Hull » Sun Dec 31, 2017 10:34 pm

Any suitable impediment or series of them to 2 PSI line pressure is fine, provided you get enough flow to make the fusor chamber pressure in the fusion range.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: FAQ - Fusor gas delivery and pressure control system

Post by Noah_Finlinson » Tue May 08, 2018 12:35 pm

How exactly is the line connected to the fusor?

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Re: FAQ - Fusor gas delivery and pressure control system

Post by Richard Hull » Tue May 08, 2018 5:32 pm

This is just more spoon feeding. All of this is discussed in past posts and FAQs.

Swagelock gas fittings or VCR gas line fittings are used. This information is already noted in this very FAQ! Apparently you did not critically read the entire FAQ or you would have seen this regarding all gas line fittings after the high pressure tank regulator. This includes the last gas line fitting to the fusor body.

Speed reading will not convey any detailed science or engineering in a technical document. Speed reading is effectively "skimming". This only gets the gist of things. It is great for plowing through novels and who-done-its. Critical technical reading is a tediously slow process where details are given and must be grasped and not merely scanned.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: FAQ - Fusor gas delivery and pressure control system

Post by John Futter » Wed May 09, 2018 7:54 pm

Noah
You do not ask questions in FAQ's
your question should have been asked in the "New User Chat Area"

Richard please remove this and Noahs ? in a few days to keep the FAQ clean

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Re: FAQ - Fusor gas delivery and pressure control system

Post by Richard Hull » Thu May 10, 2018 6:47 am

John is correct, of course.

Questions in a FAQ posting are not a good thing to do. However if you have something to add to a FAQ's value, (additional details), or you have spotted an error and would like to report it, post by all means.

I will purge all of this following the FAQ is a couple of days.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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