Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: McKay on 20/09/2014 21:13:26
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Can two protons be made "invisible" (or weakly "visible" ) to each other by putting electrons/ electron beam between them?
Well, they can, but what I am specifically interested in is comes from the experiments of muon-induced nuclear fusion - heavier muon replaces an electron in hydrogen atom, making the atom much smaller, to a point where the weak nuclear force can reach further than the charge neutralizing muon shell, making nuclear fusion possible at relatively low pressures and temperatures.
I understand that electrons cant get as close as muons to the nuclear core/ proton in an atomic-like structure, but: in a chamber with a very narrow, single electron beam forming from anode to cathode and two free protons, each in the opposite sides of the beam - the two protons would be attracted to the electron beam (and its anode), not "seeing" very much of each other, not enough to resist the attraction of the beam ... and what happens? Can the electrons block the protons same charge enough for fusion to occur or the protons will inevitably capture one of the electrons each and nothing interesting will happen? Perhaps if the beam is fast/ hot enough, the protons wont be able to capture and retain the electrons (being ionized immediately) getting close enough for weak nuclear force to take action?
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What happens when an electron gets close to a proton? Hydrogen. To keep them apart you need to create a really hot plasma, and then squish the protons together, which is exactly what fusion engineering is all about.
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Can two protons be made "invisible" (or weakly "visible" ) to each other by putting electrons/ electron beam between them?
Classically that would require placing the electron at a position between the two protons such that the force on both protons is zero. However there is no such position. In quantum mechanics this kind of arguing doesn't work since you can't speak of electrons and protons being at a particular place in space before it's observed.
Well, they can, ...
What makes you say that?
...but what I am specifically interested in is comes from the experiments of muon-induced nuclear fusion -
The proper term is Muon-catalyzed nuclear fusion.
...heavier muon replaces an electron in hydrogen atom, making the atom much smaller, to a point where the weak nuclear force can reach further than the charge neutralizing muon shell, making nuclear fusion possible at relatively low pressures and temperatures.
Yep. It seems to be similar to cold fusion.
I understand that electrons cant get as close as muons to the nuclear core/ proton in an atomic-like structure, but: in a chamber ..
I don't know what you mean by a chamber. Can you please explain?
I don't understand the rest either. Please clarify.
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If the electrons have more than about 13eV of energy, the proton won't retain the electron - it will fly past, or be knocked free by one of the following electrons. Unfortunately, the most common way to get a beam of electrons in a vacuum is to have a potential difference of hundreds to thousands of volts (ie 100-1000eV).
Lets assume that a proton does capture an electron (eg by firing the protons into a neutral gas). The electron will take up an orbit defined by the Schrodinger equation, which has a fairly large radius (when measured as a multiple of the proton size). The rate of fusion at this radius is negligible.
However, a Muon captured by a proton will take up an orbit defined by the Schrodinger equation for Muons, which has a much smaller radius. In the microsecond or so before the Muon decays, there is a finite probability that two hydrogen nuclei will fuse.
Unfortunately for energy suppliers, the energy to produce a Muon is far higher than you get from the number of fusion reactions it can catalyse before it decays.
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Muon-catalyzed fusion, yes, sorry about that.
Well, I gues I am asking - why cant the electrons get closer to the nuclear core/ protons, even when they are very fast/ energetic and just passing by.
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Electrons (in fact all matter) has properties of both a particle and a wave, but usually the wave nature of matter is invisibly small.
You have to look very closely (such as in an electron microscope) to see the wave nature of an electron.
An electron microscope can't take images of individual atoms because the wavelength of an electron is much larger than the size of a hydrogen atom. You can see a bit closer by using higher energy electrons, but this high energy quickly tears apart the object you are trying to examine with the electron microscope.
An electron is said to be "delocalised", ie when it is traveling it does not exist at a single point in space, but you can describe the probability that it may be detected at a particular point in space.
So I guess the answer is that electrons have too big a wavelength to bring two hydrogen nuclei close enough for fusion. They can only bring the two nuclei close enough to make a hydrogen molecule.
From a human viewpoint, this is a good thing - if electrons could bring hydrogen atoms close enough for fusion to occur, then nearly all of the Hydrogen in the universe would already have fused to Helium, leaving no Hydrogen left over for carbon/hydrogen lifeforms like you and me.