Questions about Antimatter

I have seen some threads that discuss antimatter as a fuel source and
it has been said that you need equal parts of each to achieve power (or
energy)

But what if you didnt use equal parts? Would it "dillute" the mix? Or
would the mix only use equal parts and expell the rest in the release
of the energy?

I have heard also that it is a proton with a negitive charge, and that
this occurs naturaly near the surface of the sun during solar storms.

Is it possible to "force" an electron to collide with a proton? and if
so, what happens? Or does it automatically create a hydrogen atom?

Just Curious....


Star

Jeff Root wrote:
Hello, Star!

(My friends are into astronomy and Space exploration as
much as I am. Their daughter's real first name is Star.
She just graduated from high school.)

I have seen some threads that discuss antimatter as a
fuel source and it has been said that you need equal
parts of each to achieve power (or energy)

But what if you didnt use equal parts? Would it "dilute"
the mix? Or would the mix only use equal parts and expell
the rest in the release of the energy?

Most likely, the matter would be hydrogen atoms, and the
antimatter would be anti-hydrogen atoms. Each hydrogen
combines with one anti-hydrogen, destroying both and
converting them into gamma rays. The gamma rays have very
high energy, and could either be used as the propellant
(if you can find some way to efficiently direct them out
the back of the rocket engine like any other propellant),
or they could be used to heat a much larger number of
hydrogen atoms, and those hot hydrogen atoms would be the
propellant.

The first method would be more efficient, but there is no
way known to direct gamma rays in a particular direction.

The second method is less efficient, but is within the
realm of things that could actually be built. It has a
huge problem of transferring as much of the energy from
the gamma rays as possible to the hydrogen atoms. Gamma
rays like to zip right through everything. Probably most
of the gamma rays would have to be absorbed by some kind
of metal shielding on the inner surface of the combustion
chamber, and the heat energy then transferred to the
hydrogen propellant. The crew or other payload of the
vehicle needs to be protected from the gamma rays, too.
It is generally thought that making the vehicle extremely
long, to put a lot of distance between the crew and the
combustion chamber, is more efficient than using the large
amount of shielding that would be required. That hints
at how inefficient the material of the combustion chamber
would be at absorbing gamma rays.

It is great in principle, but turning the energy into a
directed flow is an unsolved problem which may not have
any really good solution.

I have heard also that it is a proton with a negative
charge, and that this occurs naturally near the surface
of the sun during solar storms.

An ordinary hydrogen atom consists of a positively-charged
proton and a negatively-charged electron. In a sense, the
lightweight electron orbits the much heavier proton. (It
doesn't literally "orbit", but that simplified description
of what it does is easy to visualize.)

An anti-hydrogen atom consists of a negatively-charged
antiproton and a positively-charged antielectron. (Also
called a "positron".) The lightweight antielectron
"orbits" the much heavier antiproton.

When the hydrogen atom and anti-hydrogen atom come into
contact with each other, the electron and anti-electron
annihilate each other, giving off energetic gamma rays,
and the proton and anti-proton annihilate each other,
giving off *very* energetic gamma rays.

None of this happens on or in the Sun.

The Sun is mostly hydrogen, with some helium and a bit of
just about every other element. But mostly hydrogen.

The Sun's heat is enough to rip the electrons from the
hydrogen atoms. This leaves a mixture of free protons
and free electrons called a "fully-ionized plasma".

At the Sun's surface, radiation in the form of visible
light, infrared, and ultraviolet light carries away the
heat. So the surface is cooled. Which means the surface
we can see is mostly not hot enough to be fully-ionized
plasma. But sometimes, as in a solar storm, such plasma
does erupt from the Sun, energized by the Sun's powerful
magnetic fields, and escapes into Space. The lightweight
electrons reach the highest speeds, and escape most easily,
so the Sun gets a slight positive charge. It never gets
to be a very strong charge because opposite electric
charges attract each other, so the positive charge on the
Sun pulls back on electrons that would otherwise be moving
fast enough to escape, and recaptures them.

Is it possible to "force" an electron to collide with a
proton? and if so, what happens? Or does it automatically
create a hydrogen atom?

Creating a hydrogen atom from a free proton and a free
electron is as easy as falling off a log. They attract
each other naturally, so pulling them apart and keeping
them apart are what takes a bit of energy. A few thousand
degrees will do-- nothing particularly exotic is needed.

On the other hand, it is also possible to force a proton
to combine more closely with an electron to form a neutron.
A neutron is only stable when inside the nucleus of an
atom that also has protons in it. The simplest such
nucleus is that of deuterium, which is just a fancy name
for hydrogen that has one proton and one neutron in the
nucleus. Another name for it is "heavy hydrogen".
Duterium has one electron, just like ordinary hydrogen,
and is electrically neutral overall, just like ordinary
hydrogen.

The energy required to force a proton and electron together
and form a neutron is so great that it is usually enough to
make them instantly fly apart again. It is easier to force
an electron into a nucleus and make it stay there if the
nucleus has many protons. One of the protons absorbs the
electron and becomes a neutron, and the atom changes into
the next element lower down the list in the periodic table.
The nucleus has one less positive charge, so the atom has
one less "orbiting" electron.

Depending on the number of protons and neutrons, the new,
slightly heavier nucleus may be stable or unstable. If it
is unstable, it may give off the electron it just gained,
returning to the element it previously was, or it could
give off a whole neutron, becoming a lighter-weight atom
of the new element it had just become, or it could give off
an even-larger alpha particle, which is the nucleus of a
helium atom, or, in the case of a very large nucleus, it
could break into two nuclei each about half the size of
the original. Stable nuclei of elements after hydrogen
tend to have roughly twice as many neutrons as protons.

-- Jeff, in Minneapolis


Thanks man

Dear Rising-Star8471:

"Rising-Star8471" wrote in message
ups.com...
....
But what if you didnt use equal parts? Would it "dillute"
the mix?

Yes. Just as too much air cools down the exhaust of an engine.

Or would the mix only use equal parts and
expell the rest in the release of the energy?

Depends on the engine design.

I have heard also that it is a proton with a
negitive charge,

antiproton.

and that this occurs naturaly near the surface
of the sun during solar storms.

Usually takes *very* high energy photons to generate these.

Is it possible to "force" an electron to collide
with a proton? and if so, what happens? Or
does it automatically create a hydrogen atom?

Just Curious....

The most likely result is hydrogen. If you combine an electron,
a proton, and an anti electron-neutrino you can get a neutron.
If you combine an electron, and a proton you can get a neutron
and an electron-neutrino. The whole "charge thing" ceases to be
very important when you get to the size of the nucleus... the
strong and weak interaction forces are much more powerful.

"Beta capture" is a mirror image process to "positron emission".
In beta capture, an orbital electron (essentially) is consumed by
the nucleus, and one of the protons is converted into a neutron
(and a neutrino goes sailing away...). This can happen with
isotopes of many of the elements.

David A. Smith