Talk:Helium-3

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Contents 1 What is boojum? 2 Why so rare on Earth's surface? 3 template box 4 Cryogenics 5 ppm 6 Common myth part needs to be clarified 7 Contradiction 8 Depth to source

[edit] What is boojum?

Does anyone want to explain what boojum is? 24.91.43.225 17:35, 10 Jun 2005 (UTC)

Cornell University theoretical physicist David Mermin decided that "boojum" was the perfect name for a new phenomenon in low temperature physics. The story began in 1976, when Mermin was thinking about how so-called anisotropy lines would arrange themselves in a spherical droplet of superfluid helium-3, an unusual phase of matter attained by cooling the rare isotope of helium to near absolute zero. It turned out that a symmetrical pattern of lines, although geometrically simple, is not stable and collapses to form a new pattern. Mermin realized this new pattern could be called a boojum, since it can enable the otherwise stable flow of the superfluid to "softly and suddenly vanish away," just as Carroll described it in the final stanza of his poem, "The Hunting of the Snark," DV8 2XL 21:18, 25 November 2005 (UTC)

[edit] Why so rare on Earth's surface?

I was reading that Helium-3 is rare on the surface of the Earth and that its presence in geothermal springs is conclusive proof that the water was in contact with magma. Why is it so rare on the Earth's surface? Does it undergo a nuclear reaction or decay that renders it into something else over the lifetime of the Earth? -- Joseph Lorenzo Hall 20:48, 25 November 2005 (UTC)

Helium-3 gas consists of single very light atoms; if released at the Earth's surface, these helium-3 atoms tend to rapidly escape from the Earth's atmosphere. That's why–despite being the second most-common element in the universe–there's very little helium in our atmosphere. Unlike most other elements, helium-3 doesn't form chemical compounds, so there aren't even any processes available to bind or sequester helium-3 on the surface of the Earth.

Helium-3 is a stable isotope; it doesn't undergo a radioactive decay of any kind, and none is lost by that mechanism.

How the helium-3 gets to the magma in the first place is a question for the geologists. I suspect it may have been trapped when the earth first formed, either as He-3 or as its radioactive precursor, tritium. TenOfAllTrades(talk) 21:02, 25 November 2005 (UTC)

Ha! I distinctly remember doing the gravitational capture calculation in undergrad. astrophysics. Silly (old) me. -- Joseph Lorenzo Hall 04:57, 26 November 2005 (UTC)

If it is stable, what's the meaning of the box with a decay chain link? Jclerman 11:58, 3 February 2006 (UTC)

The decay chain is shown because Helium-3 is the end product of various decay chains. Ardric47 23:53, 6 May 2006 (UTC)

It may be worth pointing out here that He-3 atoms are somewhat faster than He-4 at the same temperature because they are lighter. Hence, they were harder to capture during Earth's formation phase. Deuar 20:08, 19 June 2006 (UTC)

I added more detail about terrestrial sources. Popular theories tend toward some He-3 being in the mantle, but it won't do us much good because we probably can not safely release it. It is often thought that He collected on stellar disk rock surfaces, particularly from the solar wind. There are various estimates of how much He got in the core, how much in the mantle, and in various layers. I only found one source for an interesting idea: In the stellar disk He-3 had a high probability of being converted to H-3 (tritium), and tritium, being Hydrogen, could dissolve in Fe (iron), with tritium decay later producing He-3 inside iron which was later involved in planet formation. (SEWilco 06:13, 27 August 2006 (UTC))

[edit] template box

See previous question. EXPLAIN MEANING OF each element in THIS TABLE OR DELETE IT. It should be clear how to construct such a table, from where to get the information, etc.

Diproton	Isotopes of Helium	Helium-4
Produced from: Hydrogen-3 Lithium-4	Decay chain	Decays to: Stable

Jclerman 19:59, 11 April 2006 (UTC)

[edit] Cryogenics

Helium-3 is used in cryogenics to achieve temperatures as low as a few thousandths of a kelvin; it was discovered by the Australian nuclear physicist Mark Oliphant while based ...

This seems to be a strange statement, and looks pretty dubious the way it is written. Maybe it is dubious?

• Is it really used to achieve these temperatures? Wouldn't you just use some cooling process, without caring what isotope you had.
• Why would it be better than natural abundance Helium, which must be much, much cheaper.
• What was discovered by M. Oliphant? Helium-3, the cooling process, the temperatures?
• Was the discovery of He-3 made during a cryogenics experiment? Is that why it is mentioned in this section? That would be pretty weird - no-one did isotope studies of normal helium previously?

Deuar 20:17, 19 June 2006 (UTC)

[edit] ppm

Don't link to confusing Parts per notation which can be understood as Parts "per notation" or "Parts per" notation. Jclerman 15:39, 24 June 2006 (UTC)

I don't understand. The point of the link is that you can click on it, and the article Parts per notation is not ambiguous. —Keenan Pepper 16:55, 24 June 2006 (UTC)

The article is fine. No problem. What I find confusing, ambiguous, is its title. (Yes, I'm not so smart, it took me a long time to understand that perhaps its meaning was not

• Parts per notation (as in ppn),

but perhaps the alternate

• Parts per notation (as in pp notation).

Then, I couldn't verify its meaning at the NIST either, where I looked for verification of ppn after I didn't find a parts per notation in their website. Jclerman 17:27, 24 June 2006 (UTC)

In that case, we should move the article to a different title, not remove links to it. Would Parts-per notation, with a dash, be better? —Keenan Pepper 17:33, 24 June 2006 (UTC)

Sure. I reverted the link because when mousing over the link I got a label I couldn't understand. The article could be renamed as you suggest, or as in the only mention I found at [1] as:

Table 3 shows the sequence in “parts per” notations to describe lower and lower concentrations

Also, note that notations (i.e. in plural) is more comprehensive of all the notations it applies to rather than notation (i.e. in sigular). Like used in the quoted title to the table. Jclerman 17:56, 24 June 2006 (UTC)

[edit] Common myth part needs to be clarified

"A common myth is that due to the rarity of helium-3 on Earth, any reliable sources of the fuel have to come from other bodies in space. This is untrue. Helium-3 is a byproduct of tritium decay, and tritium can be produced through neutron bombardment of lithium, boron, or nitrogen targets."

While that may be true, there certainly is a good reason why USA and China want to go to the moon and extract the Helium 3 from there, instead of bombarding lithum, boron, or nitrogen with neutrons. This needs to be explained. Malamockq 13:54, 11 August 2006 (UTC)

Explained. (SEWilco 05:59, 27 August 2006 (UTC))

[edit] Contradiction

From the 'Manufacturing' section:

"Commercial use of fusion reactors would require tens of tons of helium-3 each year to produce a fraction of the world's power."

From the 'Lunar supplies' section:

"Accordingly, helium-3 seems less likely than other reactants for use in fusion power generation"

I've amended the sentence from the manufacturing section to make it clear that helium-3 is only one of several possible fusion fuels by changing it to:

"If commercial fusion reactors were to use helium-3 as a fuel, they would require tens of tons of it each year to produce a fraction of the world's power."

I'm pretty sure this is the correct resolution of this contradiction.

[edit] Depth to source

SEWilco, please do not revert things just because I made the edit.

If you want to know why I edited it, it is because the statement "Geologists use how much this ratio is altered as a measure of depth of the source of the helium, with ratios above 200ppm expected to be in mantle material." is false. By reverting this edit you are merely showing that you do not understand the science of helium isotope geochemistry, nor about geology. Allow me to explain;

The ³He/³He ratio within the mantle is 8 Ra, 8 times the ratio of th atmosphere. ie; if you have 200-300ppm ³He in 1,000,000 parts of a sample o helium in the mantle, you have 25 ppm ³He in helium in the atmosphere. Correct?

So, how do we determine the depth, which is an absolute measurement, of a reservoir of helium which we sample, via seeing how the ratio alters? By the wording of what I edited, the indference is that as the ratio of the helium changes, a geologist can determine the depth from which this helium originated.

This is patently false. There is no rule to say that 1km from the surface all helium is found with a ratio of, say 35ppm ³He. That at 10km from the surface, helium reservoirs have a ratio of, say, 70 ppm ³He. This is absolutely and incontrovertibly false, and thus the sentence was removed.

In fact, within the crust, oceanic or otherwise, the ratio of ³He changes not with depth but with time, as alluded to correctly elsewhere within the article, via radioactive decay via alpha emitters.

In reality, the best science can do is determine the contribution of 'mantle helium' to a reservoir by observing concentrations of ³He in excess of atmospheric (ie, an Ra >1,) or by observing concentrations of ³He in deficiency of atmospheric. Most crustal reservoirs have a ³He/⁴He ratio of 0.01 or less.

So, please do not revert this again or I will have to seek arbitration, and I know how popular you are for your grudges.Rolinator 01:35, 30 September 2006 (UTC)

I edit the text, not the editor. I reverted your deletion of information, not you. Your latest expansion provides more detail which will be helpful. My earlier summary was awkward and at least needed rephrasing, including your clarification of the main article on the subject (which I had stub-created). (SEWilco 04:02, 30 September 2006 (UTC))