Page 8 - Transport studies in high-performance field reversed configuration plasmas

yield), as other explanations have been eliminated (D in the beams, fast-thermal ion head-on collisions, and miscalculation of Ti). We propose that the hydrogen beam generates an energetic ion population that then drives collective modes in the plasma, giving rise to an instability and increased fusion rate. An electromagnetic (EM) particle-in-cell (PIC) code [44, 45] is used to simulate beam-plasma interaction and a two-body correlation function is employed to determine computational D-D reactivity enhancements. Modifying the experimentally injected beam’s distribution function supports this theory. There are now two hypotheses which support the observed physical behaviors of the beam-driven FRC system: (i) Norman’s Conjecture, (ii) the hypothesis of robustness of waves with a high phase velocity thus introduced.
The C-2U experiment, in the case of the deuteron plasma driven by the hydrogen beam, shows that the neutron (and proton) yield is enhanced over the value that may be attributed to the estimated thermonuclear value, so long as the beam is turned on and a short time has elapsed (some 0.1ms after the beam turn-on, we also observe enhanced magnetic fluctuations in the frequency region of 550 kHz that covers the typical ion cyclotron frequency in the core plasma (See Fig. 5.)
FIGURE 5. Magnetic fluctuation spectrum in the C-2U FRC plasma. In the absence of beams, the broadband magnetic fluctuation is high. Broadband magnetic fluctuations are suppressed for higher beam power. Resonant peak increases with beam power.
It is our working hypothesis that the observed enhancement of the fusion reactivity beyond the thermonuclear value and the increased magnetic fluctuations are incurred by a beam-driven kinetic instability whose frequency range is in the ion-cyclotron frequency domain. Nonlinear saturation of the exited waves reaches a large amplitude to drive the kinetic beam-plasma instability. Note that when the beam is composed of deuterons, the predominant fusion reaction occurs not between plasma deuteron particles, but rather between the beam deuterons and plasma deuterons, i.e. the beam-target fusion rate is larger than the target-target interaction.
We have constructed a theoretical analysis and computational simulation of the beam-plasma interaction process.
ω2 ∞ 2n2
pi ∑exp[−λi]In(λi) 2 2 2 +
λi n=1 ω2 ∞
ω−nΩi
cb Jn(ν)[Jn−1(ν)−Jn+1(ν)]= (1)
2n2ω
k v b n = 1 ω 2 − n 2 Ω 2b
pi ∑
⎛ω ⎞2⎛ ω2 ⎞
where
1+⎜pe⎟⎜1+ pe⎟ Ω ⎜ c2k2⎟
⎝e⎠⎝⎠
ν = kvb Ωb ,
λi =0.5(kρi)2
.
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