Friday, March 23, 2007

Polywell - As I Currently Understand It

I have been trying to understand the Polywell Fusion Reactor invented by Robert Bussard. Here is my understanding to date.

You have six magnets. They are on the face of a cube. The north poles of the magnets all face into the cube. There is no magnetic field in the center of the cube, because identical poles repel each other's fields.

Behind the cusps formed in the magnetic field is a grid. The grid conforms to the cusps of the field.

Surrounding all this is a vacuum chamber.

The vacuum chamber is at ground potential. The grid at some high + voltage (H).

There are gas atoms in the chamber. Deuterium (D).

Electrons are injected into the chamber from the chamber walls.

The electrons are accelerated by the high voltage to H ev (electron volts - a measure of energy).

Some electrons moving into the center of the vacuum chamber ionize some of the D to D+ due to collisions.

Through some mechanism I'm not yet clear on the electrons clump in the center of the chamber forming a virtual cathode (negative electrode) and in conjunction with the + grid forms a field internal to the grid.

This field attracts D+ to the center of the chamber.
Stuff happens.

Electrons repelled by their clump in the center of the machine and attracted by the field made by the clump and the + grid, head for the + grid. The magnetic field deflects them so they do not contact the grid. As they get outside the grid the field between the + grid and the chamber walls attracts the electrons back towards the grid wich they sail through because it is mostly empty space and decelerate towards the center where the electrons are clumped.

You can follow my evolving understanding of the Bussard Reactor at:

Polywwell - Adding Details
and
Polywell - Making The Well

2 comments:

tom said...

>Through some mechanism I'm not yet clear on the electrons clump in the center of the chamber forming a virtual cathode (negative electrode) and in conjunction with the + grid forms a field internal to the grid.

is this because the magnetic field pushes the electrons to the middle causing them to head to the center, overshoot and then get pushed back to the center ? seeing the electrons spend more time in the center than anywhere else there is a virtual negative well at the center ? no sure if this is right, but that is how i thought it works

Harry Kier said...

I think I can help a bit with your understanding. (1) The electrostatic field of the grid pushes the electrons toward the center, not magnetic force. They don't 'clump' at the center, but their 'center of charge' is at the center. (2) The magnetic field is just to keep the charged particles from bumping into the grid wires and getting absorbed. (3) The magnetic field is generated by running current through the grid wires. The magnets and grid are not separate entities.