Preliminary Study of Uncertainty-Driven Plasma Diffusion II
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We have constructed a semiclassical collisional diffusion model. In this model, a field particle is treated as either a point charge or a spatially distributed charge. The test particle is treated as a distributed point charge with Gaussian distribution. It was shown that the collisional changes in velocity in our model is of the same order as the classical theory for a typical proton in a fusion plasma of T = 10 keV and n = 10<sup>20</sup> m<sup>−3</sup>. It was also shown that the spatial extent of the distribution, or the quantum-mechanical uncertainty in position, for the test particle obtained in our model grows in time, and becomes of the order of the average interparticle separation Δl ≡ n<sup>−1/3</sup> during a time interval τ<sub>r</sub> ∼ × 10<sup>7</sup> Δl/g<sub>th</sub>, where g<sub>th</sub> = √ 2T/m is the thermal speed, with m being the mass of the particle under consideration. The time interval is 3-4 order of magnitudes smaller than the collision time. This suggests that particle transport cannot be understood in the framework of classical mechanics, and that the quantum-mechanical distribution of individual particles in plasmas may cause the anomalous diffusion.
- Plasma and Fusion Research
Plasma and Fusion Research (5), S2025-S2025, 2010
Japan Society of Plasma Science and Nuclear Fusion Research