Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: Re: Magnetic protection and scattering
Date: Jul 02, 4:09 am
Poster: Dave Cooper

On Jul 02, 4:09 am, Dave Cooper wrote:

>They use the current to create a magnetic field that protects against particle bombardment, but like I stated, I'm not sure that you can do this without scattering the ions, unless you make a larger grid and then you loose density.


You will scatter both the ions and electrons but with different radii. For the same energy, gas ions wil have larger radii by the ratio of sqr root of mass - about 60 to 90 times the electron radius.

You can get a rough idea of the radius of curvature by calculating B as a function of radial distance out from the wire, for reasonable currents in a single grid wire. Then either doing the complete scattering calculation for different trajectories, or simply estimating the radius of curvature based on the strongest field intensity just off the grid surface for a trajectory approaching normal to the surface...you can see what current it takes to keep paritcles from colliding with the surface for different energies.

As you think this through, it becomes clear that for all the trajectories that are not normal to the grid surfaces, the electron/ion is scattered in a spiral path. There is some angle off normal beyond which, all particles are scattered away. the angle would seem to be mass dependent. The right grid spacing and circulating current, would be such that particle scattering was always at less than the critical angle. Haven't run the numbers, so I don't know if it would be a physically realizable structure.

Dave Cooper