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Deuterium Amount

Posted: Thu Feb 06, 2014 9:37 pm
by Aidan Kehoe
As I'm sure everyone on this site knows, deuterium is expensive. I've considered electrolysis, I've asked my school if they could order the gas at a discount, but it seems to me as if there is no way around the price. I'm curious as to the amount of deuterium necessary in a reactor. Is there a ratio of total volume to deuterium volume? It would be very helpful if someone could tell me the approximate volume of their fusor and the amount of deuterium they used.
Thank you very much,
Aidan Kehoe

Re: Deuterium Amount

Posted: Thu Feb 06, 2014 10:09 pm
by Richard Hull
The amount of running deuterium in a fusor is tiny, but varies wildly, fusor to fusor, based on operational experience, the volume of the fusor and settings made by the operator. So there will be no answer of of great precision.

A general, broad brush estimate might be as follows: Using a 6" sphere. the total volume used over a 30 minute run might require a few cubic centimeters at STP provided a skilled operator is at hand. Thus, a 50 liter STP lecture bottle might run a fusor for 100-200 hours or more producing 2 million fusions/second over that period. Of course, no fusor is normally operated for more than 10-30 minutes in a run with 3 or 4 runs on a very active day. Few real fusors ever see more than about 1 run per month. Thus, the lecture bottle might be expected to power a fusor for about 2-3 years of normal, single amateur operation by a skilled operator.

My current 50 liter cylinder is going on its fourth year.

Richard Hull

Re: Deuterium Amount

Posted: Thu Feb 06, 2014 10:56 pm
by Aidan Kehoe
Great, thank you! How much did your cylinder cost, if you don't mind me asking?

Re: Deuterium Amount

Posted: Thu Feb 06, 2014 11:12 pm
by Scott Moroch
I will spare Richard the time of responding to your question. While I do not know where specifically Richard bought his deuterium, most people buy their deuterium from Sigma-Aldrich. They have relatively good prices for a large amount of deuterium. Here is a link with assorted prices: http://www.sigmaaldrich.com/catalog/sea ... partialmax

Re: Deuterium Amount

Posted: Fri Feb 07, 2014 3:31 pm
by Richard Hull
My last cylinder was a 50 liter lecture bottle and was about $375 delivered. (Cambridge Isotopes) That included the hazmat delivery fee. That was in line with the info. that Scott supplied......

A hydrogen regulator is needed and an adapter for the regulator to the lecture bottle and that is usually adds about $150.00 extra. Figure on $500.00 for the deuterium gas system with a 50 liter cylinder. You'll note that smaller quantities are not that much cheaper. It all depends on your long term needs.

Hydrolysis of heavy water will drop the cost to under $100.00 for everything, but it is a crap shoot so far as purity of what you let in the chamber.

Bottom line, bottled gas is easier and a snap to use and setup. Hydrolysis is much cheaper, but is difficult to mechanize and correctly administer to the fusor system.

Richard Hull

Re: Deuterium Amount

Posted: Fri Feb 07, 2014 5:05 pm
by Aidan Kehoe
Great, thank you! I will keep that in mind. Does the purity effect the amount of deuterium you have to add, or just the probability that the atoms will fuse? Furthermore, you mentioned that the cost decreases when doing electrolysis, but don't you have to buy a litre of heavy water to obtain a little less than a litre of deuterium?
Thanks,
Aidan

Re: Deuterium Amount

Posted: Fri Feb 07, 2014 9:31 pm
by Rich Feldman
Re. needing a liter of heavy water.

Perhaps not in the FAQ's, but we don't expect to be teaching elementary chemistry & physics.

What is the mass of 1 liter of air at STP?
What is the mass of 1 liter of H2?
What is the mass of 1 liter of D2 gas (hint: double the previous answer).

Compare that to the mass of 1 liter of heavy water.
What fraction of the latter is deuterium?
For extra credit: what volume of heavy water is consumed by evolving 1 liter of D2?

Aidan, I hope you will favor us with actual numerical answers, within 10% or so. Most of them can simply be looked up on the Internet, or found with help from a science teacher.
Thanks!
-Rich

Re: Deuterium Amount

Posted: Fri Feb 07, 2014 10:53 pm
by Aidan Kehoe
1. 1.29 g
2. 0.09 g
3. 0.18 g
4. 2/3
5. 1.324

Re: Deuterium Amount

Posted: Fri Feb 07, 2014 11:18 pm
by Rich Feldman
Thank you, Aidan. Results are:
1. Right
2. Right
3. Right
4a. no answer
4b. Unexpected right answer (question was ambiguous)
5. Probably very wrong (but you didn't state a unit of measurement).

Would you mind another try, starting in the middle?

4a. What's the mass in grams of 1 liter of liquid D2O?
4b. Yes, 2/3 of the atoms are deuterium. What fraction of the MASS is deuterium, if each O atom weighs as much as 8 D atoms?
4c. What's the mass of deuterium in 1 liter of liquid D2O?
5. How many liters would that be in the form of D2 gas? (Refer to answer #3).

Re: Deuterium Amount

Posted: Sun Feb 09, 2014 10:44 pm
by Aidan Kehoe
4a. 1.1056 kg
4c. 1/5
4b. 0.22112 kg
5. 6.1422 litres