Utility of extracting alpha particle energy by waves

Fisch, Nathaniel J.; Herrmann, Mark

doi:10.1088/0029-5515/34/12/i01

Cited by 91 publications

(88 citation statements)

References 14 publications

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“…This effect is similar to the alpha channeling effect practiced in tokamaks on the α-particles, which are the charged byproducts of DT fusion [3]. In a tokamak reactor, by channeling the α-particle energy to fuel ions, the tokamak could be run in a hot-ion mode, with the fusion ash removed quickly, and with the effective fusion reactivity more than doubled [4]. The α-particle energy could also be diverted to other useful purposes, like providing the current necessary for steady state operation [5].…”

mentioning

confidence: 64%

Alpha Channeling in Mirror Machines

Fisch

2006

Phys. Rev. Lett.

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confidence: 64%

Alpha Channeling in Mirror Machines

Fisch

2006

Phys. Rev. Lett.

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“…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].…”

mentioning

confidence: 94%

αChanneling in a Rotating Plasma

Fetterman

Fisch

2008

Phys. Rev. Lett.

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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...

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“…By removing alpha particles quickly, the fusion reactivity might be doubled in a system with the same plasma pressure. 17 The alpha channeling concept was recently extended to mirror machines. [18][19][20] In this case, the loss cone produces a convenient phase space boundary through which alpha particles can be removed.…”

Section: Introductionmentioning

confidence: 99%

Alpha channeling in rotating plasma with stationary waves

Fetterman

Fisch

2010

Physics of Plasmas

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An extension of the alpha channeling effect to supersonically rotating mirrors shows that the rotation itself can be driven using alpha particle energy. Alpha channeling uses radiofrequency waves to remove alpha particles collisionlessly at low energy. We show that stationary magnetic fields with high n θ can be used for this purpose, and simulations show that a large fraction of the alpha energy can be converted to rotation energy.

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Utility of extracting alpha particle energy by waves

Cited by 91 publications

References 14 publications

Alpha Channeling in Mirror Machines

Alpha Channeling in Mirror Machines

αChanneling in a Rotating Plasma

Alpha channeling in rotating plasma with stationary waves

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