Wire vs Ring Grid Comparison

[Emma Black]

Switched out my grid from a tungsten wedding ring to a 3 loop wire grid made from 1mm tungsten welding rod. In this short cross arrangement, the plasma still seems to be mostly concentrated into just two beams.

Both of these are the first runs with D2 after the chamber was opened after a high current high pressure bakeout. The first data set (i.e. the ring) was also before major leak issues took hold.

The voltages and current are the same at 35-40kv and 4ma. With the tungsten ring grid, every once in a while I would need to up the D2 flow to maintain the current. The pressure in the chamber would increase but be able to support a higher voltage. With the wire grid, the same thing happened but over a much shorter time, peaking at a higher value.

[Richard Hull]

Nice comparison report. In all cross configurations of small size, two beams would be expected. smooth spheres tend to even out the electrostatic field from a true spherical wire grid.

When I did a true geodesic back in 2000 the real beauty comes out in a spherical fusor. (attached images)

After melting a few of these tough to make grids in my early years, I switched over to the simple three loop grid (attributed to Jon Rosenstiel)

Richard Hull