Active Sheilding

>
> You still have the problem of the X-Ray bath caused by all the
> electrons hitting the metal grid.
>
> Tom - But if the grid is a KM away, the reduction per inverse
square law will be substantial. Modest shielding will still be
necessary, and I am not arguing against passive shielding, but only
that active shielding should be kept on the table and studied.
>

Actually the X-Rays would increase in radiation. The inverse square
law works for a point source radiating energy away. This is a sphere
radiating energy towards the a point.

In reality the sphere would end up being a grey box with a radiation
level in it porportional to T^4. The real question is what would T end
up at.

> To do it properly you need a magnetic field to divert the
electrons
> from the grid. Once you have that the billions of volts you will
have
> to be dissappiate all that energy that gets converted to heat. So
we
> are again at the heat dissapiation problem.
>
> Tom - This would require further analysis.
>
I don't discount active shielding, but I don't think it would be
feasible for anything other than the smallest vessels.

> Anyway, there is a whole class of neutral particles that will be
> totally unaffected by electromagnetic shields that could easily
kill
> everyone.
>
> Tom - The only neutral particles I know of are neutrons, and they
will have decayed long before arriving on site. Naturally, X and
gamma rays must be shielded passively.
>
Actaully any charged particle leaving the sun could pick up all the
electrons it needs to neutralize, and still be travelling at 3/4 of
the speed of light.

> I'm still into the passive shields camp. It is a low maintanence
> solution.
>
> Bill
>
> --- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
> wrote:
> > Bill,
> >
> > So, I take it you now agree that active shielding can be used to
at
> least deal with cosmic rays and positively charged ions from the
sun?
> By the way, we are talking about billions of volts, not millions
since
> I believe that cosmic rays have an energy equivalent to 30 billion
EV.
> >
> > Now, lets proceed with dealing with those pesky electrons.
Since
> they have a relatively low mass and can be compelled to turn at
very
> sharp corners, we can use either an electric or magnetic field to
> divert them.
> >
> > From a distance, a 1km diameter shell appears to be a point
> charge. Instead of charging the exterior of the colony with the
high
> charge, lets charge instead a spherical wire grid surrounding the
> colony. Electrons are attracted to the positively charged grid
and
> are neutralized or diverted, and positively charged nuclei are
> repelled. Only problem remains to maintain the charge and
> construction.
> >
> > Cheers,
> >
> > Tom
> >
> >
> > From: bill t
> > To: spacesettlers@egroups.com
> > Sent: Saturday, December 23, 2000 2:18 PM
> > Subject: [spacesettlers] Re: Active Sheilding
> >
> >
> >
> >
> > If you are a million volt positive charge, every electron in
the
> > solarsystem will be attracted to you. When they hit the outer
> shell
> > they will have a million eV energy each. when a electron hits
a
> metal
> > (the outer shell) it produces X-Rays. These X-Rays will be
> directed
> > towards the interior of the habitat. Thus you will have a
constant
> > X-Ray source inside the habitat.
> >
> > Finally, for every positive charged nuclei that gets thrown
out of
> the
> > sun, there is at least one electron that has been dissaciated
from
> it.
> >
> > Bill
> >
> > --- In spacesettlers@egroups.com, "Tom Tucker (Olympia)"
> > wrote:
> > >
> > > From: Ian Woollard
> > > To: spacesettlers@egroups.com
> > > Sent: Thursday, December 21, 2000 8:57 PM
> > > Subject: Re: [spacesettlers] Active Sheilding
> > >
> > >
> > > bill t wrote:
> > >
> > > > The main problem with Active Shielding...
> > >
> > > The main problem with active shielding is that it doesn't
> > > work. Period.
> > >
> > > > You can arrange a magnetic field to deflect the
electrons,
> but
> > I'm
> > > > wondering what the weight of the material, and the power
> > utilization
> > > > is. All the power is heat that has to be radiated away.
This
> > means
> > > > more radiators.
> > >
> > > Radiators aren't a problem. The problem is that people die
> > > from radiation poisoning (10% chance of cancer per 5-10
years
> > > if I remember correctly), caused by cosmic rays. Active
> shielding
> > > doesn't touch cosmic rays- they're waaaay too high energy.
We
> > > can't even produce rays that powerful in our particle
> > > accelerators that are miles across and use whole power
> > > stations to keep them running; active shielding
> > > has absolutely no chance of even deflecting it,
> > > and quite a lot of the particles aren't even charged
> > > anyway.
> > > Tom Tucker - Bill, cosmic rays are nuculi that have been
> stripped
> > of their electrons which makes them positively charged. Solar
> flares
> > are a storm of charged particles with the bulk also consisting
of
> > ionized nuculi. Both of these types of deadly radiation can
be
> > repelled by a positive high voltage charge. Since in space,
there
> is
> > no place for a charge to arc or to drain from via ionization
as
> there
> > is when in an atmosphere, one could perhaps build-up a charge
of
> > billions of volts which is comparable to that of cosmic rays
and
> in
> > excess of that found in solar flares. The positive charge
would
> be
> > maintained/generated by the use of an electron gun/accelerator
> located
> > a few KM from the space craft on the end of a conductive
tether.
> In
> > space, we can generate much higher voltages than we can on
earth.
> > > Particle accelerators produce very heavy nuculi at hear
the
> > velocitiy of light, but this is not relevant to the
electrostatic
> > shielding under discussion here.
> > > Proof of concept has yet to be attempted, but
hypothetically,
> it
> > can be done.
> > >
> > > X-Rays from the sun and stars are a much smaller worry and
> some
> > light shielding would still be needed for these EMF for which
> active
> > shielding will be ineffective. How much would be needed? Need
more
> > data. Perhaps the few CM of steel that a "cruise ship type
> habitat"
> > would use would be sufficient?
> > >
> > > 6 foot of just about anything non radioactive works
wonders.
> > >
> > > If a lunar mass driver is used that's not ridiculous.
> > >
> > > I worked out about $100/ft^2 ballpark. Getting some
> > > near earth asteroids should be cheaper still (some
> > > of them have delta-vs of tens of meters - yes that's
> > > right meters not kilometers, per second.)
> > >
> > > Living in asteroids will be much cheaper. Shoring up the
> > > inside of an asteriod you've mined out is pretty simple
and
> cheap
> > > in microgravity.
> > >
> > > You get the outside for free pretty much. You don't have
to
> > > move anything anywhere, just tie the rubble down, smelt
your
> > > aluminium and sling up some big mirrors and put a sign
outside