RE: Popular Mechanics August Issue - H-bombs and Cold Fusion

["Franta, Jaroslav" <frantaj@AECL.CA>]

Bernard Cohen wrote :



The conservation of energy problem can be circumvented by neutralizing the

repulsive charge. This was the principle of the original cold fusion; a

negative meson was attached to one of the nuclei. It almost worked!

<end quote>



The reason it didn't quite work is precisely *because* of the conservation

of energy problem -- those heavy *muons* have a short life (2.2

microseconds) and require a lot of energy to fabricate. If I remember

correctly, the energy break-even point for that cold fusion scheme (called

"muon-catalyzed hydrogen fusion") was about 370 fusion reactions per meson

(before it disintegrates).

There is some detail about the program at TRIUMF at

http://www.triumf.ca/welcome/h-fusion.html but nothing definitive.



Quote :



The Muonic Hydrogen Collaboration http://www.triumf.ca/muh/muh.html is a

group of research physicists from Asia, Europe, the USA and Canada, who

study muon interactions in hydrogen at TRIUMF. The goal of the research is

to understand the atomic, molecular, and nuclear reactions involving muons

and different isotopes of hydrogen, particularly those which are important

for muon-catalyzed fusion.  The muon is an elementary particle which can

have a negative or positive charge and has approximately 207 times the mass

of an electron. The negatively charged variety carries the same charge as an

electron; like the electron, it can be part of an atomic system or bind

atoms together in a molecule. 

Intense beams of muons are produced at TRIUMF from the decay of pions, which

are in turn produced when hydrogen ions (protons) moving at 3/4 the speed of

light strike a stationary target. The muon decays with an average lifetime

of only 2.2 microseconds (millionths of a second), but it participates in a

rich variety of processes in that short period.  

There are three isotopes (varieties) of hydrogen atoms. First there is

protium (H), by far the most common of the three, which has one proton (a

massive positively charged particle) as its nucleus. The single positive

charge of the nucleus is balanced by one electron to form the neutral

protium atom. Then there is deuterium (D), whose nucleus is made up of one

proton and one neutron (slightly more massive than a proton, and with no

electric charge) bound together as a deuteron (d). About 0.015% of all

hydrogen atoms in nature are deuterium. Finally there is tritium (T), with a

proton and two neutrons forming a triton (t) to make up the nucleus. Tritium

is radioactive and its safe handling and containment require special

experimental procedures. 

Two atoms from any combination of these isotopes can be bound together by

orbiting electrons to form a hydrogen molecule (the most common of which is

2 protium atoms making normal hydrogen gas).  



A negative muon can, like an electron, also bind any two hydrogen atoms into

a molecular ion. A molecular ion is just a molecule in which the charges of

the nuclei are not exactly neutralized by the surrounding electrons, or,in

this case, the negative muons. Because the muon is so much heavier than the

electron, its normal orbit is much closer to the two nuclei, so the muonic

molecular system is much smaller and more tightly bound than its electronic

version. 



When at least one of the isotopes is deuterium or tritium, the hydrogen

nuclei can fuse together, forming a heavier nucleus, and releasing energy.

The muon effectively shields the repulsive electrical force between the two

positive hydrogen nuclei, allowing them to come together closely enough to

bind via the "strong" nuclear force. 



The muon in most cases survives so that it can cause further muon molecular

ion formation and fusion. Because the muon acts as a catalyst to enable the

process without being consumed, this is known as muon-catalyzed fusion. 



If the same muon could go on to catalyze enough reactions, we could use the

energy created as a source of clean and inexpensive power. However,

sometimes the muon sticks to a charged fusion product such as an alpha

particle, and is lost to the cycle. To date, over 100 fusions per muon have

been recorded in experiments at other laboratories, but it is estimated that

it would take somewhat more than this in order to "break even" energy-wise.





Unlike other fusion processes, muon-catalyzed fusion can occur at or below

room temperature. In fact, the TRIUMF group uses a target of solid hydrogen

at about 3 degrees Kelvin (-270 degrees Celsius). To create muon-catalyzed

fusion, a beam of negative muons is stopped in a frozen layer formed from a

mixture of hydrogen isotopes. The unique method allows us to study the

formation of muonic molecular systems, to determine the parameters which

control the fusion processes, and to learn more about the sticking of the

muon to a fusion product. 

The solid target experiments can show features of the reactions which are

not accessible via other methods. Even though the production of clean,

inexpensive energy from muon-catalyzed fusion is beyond our present

capability, we are able to learn more about the fascinating behaviour of

negative muons in hydrogen. 

	

For more information, see the Muonic Hydrogen Collaboration Home Page.

<http://www.triumf.ca/muh/muh.html> 

Welcome Page <http://www.triumf.ca/welcome/index.html

Research Areas <http://www.triumf.ca/welcome/research.html>	

This page maintained by the Scientific Services

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Last changes: Jan 02, 1997.