The mark 3 fusor has electrically isolated hemispheres (both hemispheres are insulated from each other and the vacuum system) allowing the collected ion/electron current in each hemisphere flowing to ground to be measured independently for examining if the asymmetry generated by the presence of the grid stalk insulator and ion injectors effects shell current distributions in the fusor.
The insulating break is made by using a viton o-ring shielded by a ceramic fabric limiter, the conflat bolts are insulated and the bolt rings are separated by thin fiberglass shims preventing direct electric contact between the flanges. As I will might be changing to a copper o-ring for the hemispheres in order to achieve better vacuum levels, I conducted some tests to see the effects.
Measurements were taken by connecting each hemisphere to ground through a multimeter and measuring the grid current with the power supply. The injectors are driven by DC-DC converters that separate them from ground leaving the only return path through the multimeters.
It was determined that for an insulated grid stalk, when the fusor is operating in glow discharge mode(18 mTorr) with no ion injectors on there is equal current collected on both hemispheres. At lower pressures(2.5mTorr) with all ion injectors on, there is definite difference in collected current on each hemisphere. With both hemispheres left floating, a single injector can drive them to about 180v difference, when shorted together through a multimeter, an injector can drive about 2mA from one hemisphere to another. Adding voltage to the grid will drive current to both hemispheres, superimposing it on top of the current flowing between hemispheres driven by the injectors.
Measurement setup
Electrical connections
Top injectors on showing ion current being collected in bottom hemisphere
Using injectors to null out current being collected in bottom hemisphere with grid current present
Floating hemispheres with grid current off showing injectors driving the hemispheres to 187v diffrence
Asymetry in collected current on each hemisphere
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- Steven Sesselmann
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Re: Asymetry in collected current on each hemisphere
Andrew,
Interesting experiment, where how did you hook up ground on the PSU?
Are you operating with a double grid?
Steven
Interesting experiment, where how did you hook up ground on the PSU?
Are you operating with a double grid?
Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG
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Re: Asymetry in collected current on each hemisphere
The grid power supply ground is connected to the negative leads of the multi meters connected to the hemispheres. The positive leads are connected to the hemispheres which are isolated from the aluminum frame, vacuum system, and each other.
This is with a single grid.
This is with a single grid.
Andrew Seltzman
www.rtftechnologies.org
www.rtftechnologies.org
- Richard Hull
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Re: Asymetry in collected current on each hemisphere
Nice effort, Andrew. Now to figure out what this means in a real scenario where fusion is done. Very interesting, indeed.
Richard Hull
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment