## Trampoline analogy for Wiffleball border in the Polywell.

Discuss how polywell fusion works; share theoretical questions and answers.

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D Tibbets
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Joined: Thu Jun 26, 2008 6:52 am

### Trampoline analogy for Wiffleball border in the Polywell.

Trampoline analogy for Grad's high Beta conditions, or the Wiffleball border in the Polywell.

I have promoted a pool table and Funnel analogy for the Wiffleball border. With thoughts about the use of multiple variable softness layers to demonstrate the B field exclusion/ inflation of the Wiffleball radius as proposed by Tom Ligon

viewtopic.php?f=10&t=6072&p=123995#p123995

I have come up with another analogy for the Wiffleball/ High Beta border as described by Grad. This analogy does not address the cusp confinement changes directly, but the hardness or stiffness of the reflecting border under high Beta conditions versus low Beta conditions (as measured at the deep cusp radius). Like the B field at low Beta, a trampoline can have a loose, highly mobile surface. If you jump on it, you sink in to a relatively deep extent, then raise up a modest extent, and continue to oscillate with the surface of the trampoline mat. You are sort of captured on the surface of the trampoline. Now, tighten up the trampoline springs, the mat surface becomes stiffer. When you jump on it now, you sink in a shorter distance and spring back off the trampoline surface entirely, almost to the extent of your original approach. Your interaction is only 1/2 of an oscillation and you spring back towards the center or height from which you came. Actually you spring back on a vector ~ 180 degrees from you approach vector. The interaction becomes more brief. This limits effects with a B field , bouncing back and forth along field lines becomes less pronounced, or even stopped entirely. As such, mirroring becomes less important for describing the particle motions associated with cusp confinement and direct rebounding effects (term used to differentiate from bouncing, as this is a common term for mirroring/ reversing spiraling motions along a B field lines) and differentiates the mechanisms associated with low Beta cusp confinement (mirroring) to those of high Beta Cusp confinement (rebounding) as described by Grad. It may even have significant effects on the rate of ExB diffusion, at least McGuire at Lockheed claimed this.

Dan Tibbets
To error is human... and I'm very human.