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: Inner Grid Supports
Date: May 31, 2:35 pm
Poster: Richard Hester

On May 31, 2:35 pm, Richard Hester wrote:

In order to operate at lower pressure and higher input voltages it will be necessary to use some sort of dispenser cathode and intermediate grid to ionize the gas close to the outer grid. I am currently working on small cylindrical fusor where I plan to us a grid consisting of a zig-zag web of tungsten wire supported by mica or machinable ceramic disks, held against the inside of the fusor by spring pressure. The grid wire would be heated by an isolated transformer and biased negative with respect to the outer shell. This approach is easy to demount and change, and requires no permanant changes to the fusor other than the installation of a double HV feethrough of modest size.
With a spherical fusor, it will be more difficult to do a symmetrical outer grid. One of the approaches I am considering would be to use a stud welder to apply pieces of threaded rod to the inside of the spherical shell. These would be used to attach ceramic standoffs, which would in turn support the dispensor grid.Another approach would be to pressure fit the insulator supports in small blind holes drilled in the inside of the outer shell. To allow the fusor to be taken apart, I envision a spiral grid in each hemisphere, heated and energized by a common power supply.

People with alternate approaches, please sing out. We can all benefit by the exchange of ideas and maybe avoid false starts.

Richard Hester