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Dr James Cook

Position: Research Fellow

Line Manager: Dr Erwin Verwichte

Project Title: Compressional Alfvén eigenmodes in toroidal plasmas

Contact: j. w.s.cook{@}warwick.ac.uk, +44 (0) 24 7657 3874


The understanding of the fundamental physical processes acting in magnetised plasmas responsible for sta-bility and the transport of particles, momentum and energy is essential for the successful development of viable fusion energy via the route of magnetically confined fusion envisaged in the international ITER and DEMO tokamak programs. Magnetohydrodynamic (MHD) waves play an important role in the redistribution of fast fusion-born ions (α-particles) whose energy is required to heat and sustain fusion. MHD waves are driven unstable by fast ions leading to anomalously high diffusion away from the plasma core and could lead to losses that damage the tokamak walls.

Compressional Alfvén eigenmodes (CAEs) are high-frequency fast magnetoacoustic waves near the ion cyclotron frequency, which are localised within a wave guide inside the tokamak governed by the radial Alfvén speed profile. They are driven unstable by super-Alfvénic ions and contribute to the redistribution and losses of fast ions. CAEs may also contribute strongly to the channeling of energy from α-particles to the bulk plasma. Furthermore, high-frequency CAEs parasitically absorb ion cyclotron resonance heating, which affects heating and current drive efficiency.

Dr Verwichte and I have developed a linear eigenmode code for solving the Hall-MHD in axisymmetric plasmas. At the moment the we able to model plasma in the zero-beta limit with one ion species only. We will remove these restrictions in the next version of the code.



Publications:

J. W. S. Cook, R. O. Dendy, and S. C. Chapman. Gyrobunching and wave- particle resonance in the lower hybrid drift instability. Plasma Physics and Controlled Fusion, 53(7):074019, 2011.

J W S Cook, S C Chapman, R O Dendy, and C S Brady. Self-consistent kinetic simulations of lower hybrid drift instability resulting in electron current driven by fusion products in tokamak plasmas. Plasma Physics and Controlled Fusion, 53(6):065006, 2011.

J. W. S. Cook, S. C. Chapman, and R. O. Dendy. Electron current drive by fusion-product-excited lower hybrid drift instability. Phys. Rev. Lett., 105(25):255003, Dec 2010.