Speaker
Description
Electron cyclotron (EC) waves offer several advantages as a heating system in a tokamak fusion reactor, both from the technological and the physical point of view. Among the required functions of EC waves in a reactor are the sustainment of part of the plasma current and the stabilization of MHD instabilities like the neoclassical tearing mode (NTM). These issues are explored through beam tracing calculations with TORBEAM [1], which assumes a linear regime for power absorption and employs an adjoint method for the determination of the driven current. It is known both theoretically [2] and experimentally [3] that comparatively high ECCD efficiency in the plasma centre can be achieved by injecting the wave from an elevated position. On the other hand, the efficiency deteriorates in the colder, outer part of the plasma, so that a prohibitive amount of power would be needed to sustain the plasma current non-inductively in the considered scenarios. An alternative scheme being considered for the outer core or edge is the injection of slow extraordinary mode below the fundamental resonance [4]. The properties of the CD efficiency are discussed. It is shown that a detailed analysis of this scenario should retain a proper description of the Ohkawa effects, which calls for more comprehensive Fokker-Planck simulations as a next step. The role of beam scattering for applications like NTM stabilization [5] is also briefly presented.
[1] E. Poli, et al., Comp. Phys. Comm. 225, 36 (2018)
[2] E. Poli, et al., Nucl. Fusion 53, 013011 (2013)
[3] X. Chen, et al., Nucl. Fusion 62, 054001 (2022)
[4] L. Figini, et al., 21st EC Workshop, ITER Org., #91 (2022)
[5] A. Snicker, et al., Nucl Fusion 58, 016002 (2018)
