Simulation of α-channeling in mirror machines

2009

Physics of Plasmas

Self Cite

Alpha-channeling can, in principle, be implemented in mirror machines via exciting weaklydamped modes in the ion cyclotron frequency range with perpendicular wavelengths smaller than the alpha particle gyroradius. Assuming quasi-longitudinal or quasi-transverse wave propagation, we search systematically for suitable modes in mirror plasmas. Considering two device designs, a proof-of-principle facility and a fusion rector prototype, we in fact identify candidate modes suitable for alpha-channeling.

Section: Introductionmentioning

confidence: 92%

“…The energy conversion rate in such processes was estimated [29] to be approximately 25%. This suggests that α-channeling can potentially be a more effective energy transfer mechanism, also capable of fusion ash removal and fuel ion injection [24,33].…”

Section: Introductionmentioning

confidence: 99%

Waves for alpha channeling in mirror machines

Zhmoginov

2009

Physics of Plasmas

Self Cite

“…Similar advantageous uses of α-channeling can be expected in mirror machines [12]. With several waves, a significant amount of the α-particle energy can be advantageously channeled in both tokamaks [13] and mirrors [14]. However, in previous considerations of α-channeling, the plasma was not rotating strongly.…”

mentioning

confidence: 98%

“…The waves necessary for a channeling effect have been calculated in the static mirror case [12,14]. Two conditions were considered to be important.…”

Section: Figmentioning

confidence: 99%

See 1 more Smart Citation

αChanneling in a Rotating Plasma

Fetterman

2008

Phys. Rev. Lett.

The wave-particle α-channeling effect is generalized to include rotating plasma. Specifically, radio frequency waves can resonate with α particles in a mirror machine with E × B rotation to diffuse the α particles along constrained paths in phase space. Of major interest is that the α-particle energy, in addition to amplifying the RF waves, can directly enhance the rotation energy which in turn provides additional plasma confinement in centrifugal fusion reactors. An ancillary benefit is the rapid removal of alpha particles, which increases the fusion reactivity.In magnetic mirror fusion devices, centrifugal forces can significantly enhance the magnetic confinement [1,2,3]. A radial electric field induces rapid E × B plasma rotation, leading to the centrifugal force that directly confines ions axially. Electrons are then confined axially through the ambipolar potential. The radial field thus not only enhances the plasma confinement, but also produces the necessary heating for the plasma, as injected cold neutral fuel atoms are seen as moving at the rotation velocity in the rotating frame. Lately there has been a renewed interest in this effect [4,5,6,7], strengthened by recent findings of reduced turbulence due to sheared rotation [8,9].What we show here is that in a DT (deuterium-tritium) centrifugal fusion reactor, the energy of α-particles, the byproducts of the fusion reaction, might be advantageously induced to directly produce this rotation. The predicted effect relies on exploiting the population inversion of the birth distribution of α particles. This is a generalization of the alpha channeling effect, where injected wave energy can be amplified at the expense of the α-particle energy, with the alpha particles concomitantly removed as cold particles [10]. In tokamaks, if the wave energy is damped on ions, the fusion reactivity might be doubled [11]. Similar advantageous uses of α-channeling can be expected in mirror machines [12]. With several waves, a significant amount of the α-particle energy can be advantageously channeled in both tokamaks [13] and mirrors [14]. However, in previous considerations of α-channeling, the plasma was not rotating strongly.In strongly rotating plasma, significant new effects can occur because there are two further reservoirs of particle energy, namely rotational and potential energy. For example, through a suitable choice of wave parameters, particles can now absorb wave energy yet cool in kinetic energy, with the excess energy being stored in potential energy. Alternatively, particle potential energy might be lost to wave energy with kinetic energy constant. These possibilities could not be achieved through particle manipulation in stationary systems, where the only coupling is between the kinetic energy with the wave energy. What is important for centrifugal mirror fusion is that radiofrequency waves can drive a radial α-particle current, with the dissipated power extracted from the α-particle birth energy, thereby maintaining the radial potential which produces the nece...

Flux control in networks of diffusion paths

Zhmoginov

2008

Physics Letters A

A class of optimization problems in networks of intersecting diffusion domains of a special form of thin paths has been considered. The system of equations describing stationary solutions is equivalent to an electrical circuit built of intersecting conductors. The solution of an optimization problem has been obtained and extended to the analogous electrical circuit. The interest in this network arises from, among other applications, an application to wave-particle diffusion through resonant interactions in plasma.