5 research outputs found
Confinement Time and Ambipolar Potential in a Relativistic Mirror-Confined Plasma
Advanced aneutronic fusion fuels such as proton-Boron tend to require
much higher temperatures than conventional fuels like deuterium-tritium. For
electrons, the bulk plasma temperature can approach a substantial fraction of
the rest mass. In a mirror confinement system, where the electrons are confined
by an ambipolar potential of at least five electron temperatures, the tail
electrons which can escape the potential are fully relativistic, which must be
taken into account in calculating their confinement. In this paper, simple
estimates are employed to extend the scaling of the confinement time into the
relativistic regime. By asymptotically matching this scaling to known solutions
in the non-relativistic limit, accurate forms for the confinement time (and
thus the the ambipolar potential) are obtained. These forms are verified using
finite-element-based Fokker-Planck simulations over a wide range of parameters.
Comparing relativistic and nonrelativistic mirror-confined plasmas with the
same ratio of confining potential to electron temperature and
the same mirror ratio , the net result is a decrease in the confinement time
due to relativistic effects by a factor of .Comment: 9 pages, 7 figure
Sensitivity of synchrotron radiation to the superthermal electron population in mildly relativistic plasma
Synchrotron radiation has markedly different behavior in and in plasma. We show that
high-energy electrons which occupy the tail of velocity distribution function
have disproportionate impact on power loss of plasma.
If electrons with energy more than a cutoff energy are redistributed while
keeping the Maxwellian distribution function below cutoff energy intact, both
emission and absorption of synchrotron radiation act to decrease the lost
power. These novel radiation transport effects in non-equilibrium plasma
suggest large utility in the deconfinement of high-energy electrons to reduce
synchrotron radiation in applications where the radiation is deleterious.Comment: 6 pages, 5 figures, submitted to Po