Making a Magnetic Sail: Challenges & Benefits

[sanman]

What are the challenges to making a magnetic sail, or a magnetic plasma bubble to surround a spacecraft as a radiation shield?

I was reading this:

http://www.ess.washington.edu/Space/PlasmaMag/


If we have a suitable nuclear reactor as our power source, then what are the chief technical challenges in achieving the rest of this idea?

 

[Astronuc]

In brief, the challenges are:

The power plant required to produced the current which produces the magnetic field.

The configuration of the conductors that carry the current that induces the magnetic field.

The magnetic intensity and the potential for leakage into the living areas (where astronauts reside).

The radiation (nuclei, electrons, and ions) that would travel along the field lines and increase brehmsstrahlung (EM) radiation and other secondary radiation in the vicinity of astronauts and sensitive electronics.

 

[sanman]

Just to better understand the last you made - do you mean incoming charged particles would travel along the field lines by mere coincidence, or are you saying that the magnetic field itself would deflect such incoming particles to travel along the field lines, or else are you referring to the plasma itself being the source of charged particles traveling along the field lines?

 

[Astronuc]

Charged particles in space (e.g. solar wind) travel along magnetic field lines. That's how auroras form - when charge particles travel along the lines, enter the atmosphere and ionize the gas atoms/molecules.

That's also the principle behind the magnetic mirrors in the tandem mirror (fusion) reactor.

 

[sanman]

But whereas incoming charged particles can be stopped by solid walls of a spacecraft , that's not necessarily the case for electromagnetic radiation.

My understanding of the plasma magnet described in the link above, is that the field lines are rapidly rotating, to keep a bubble of locally released ionized gas confined and enveloping the spacecraft . To me, this precludes allowing incoming particles to hit your spacecraft . The enveloping plasma is supposed to be able to absorb the incoming electromagnetic radiation, while acting as a cushion/sail against the incoming charged particle radiation, absorbing their momentum.