Overdense microwave plasma heating in the CNT stellarator

Hammond, K. C.; Diaz-Pacheco, R.; Köhn, A.; Volpe, F.; Wei, Y. L.

doi:10.1088/1361-6587/aa9a7c

Cited by 8 publications

(4 citation statements)

References 45 publications

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“…Regarding the parameter L_n, it can have much influence on the conversion of the O mode to the SX mode. The smaller L_n is, the more efficient will be the mode conversion, a dependence which should be assessed specifically [12].…”

Section: Power Transmission Windowmentioning

confidence: 99%

Study Electron Cyclotron Double Mode Conversion in Overdense Plasma

et al. 2019

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Double mode conversion from ordinary mode O to extraordinary mode X is used to achieve electron Bernstein wave (EBWs) for the electron cyclotron resonance heating (ECRH). The efficiency of the mode conversion depends on many parameters including the density gradient L n , magnetic field source B 0 and optimum launching angle N z. An analytical formalism together with a numerical computation have been employed, considering W7X stellarator main parameters, such as 140 GH z , k 0 = 29 cm −1 , 2.5 T and 2.4 ×10 20 m −3 , in order to investigate the efficiency of the mode conversion. The values of the density gradient Ln, obtained by numerical simulation, are from 1 to 10 cm. These values of L n correspond to the power transmission window T OSX from 88 to 29%. Moreover, the dispersion relation of the EBW mode propagation up to 10 harmonics, ω = 10ω ce , has been plotted to help a better visualization of the EBW mode heating. Finally, the power deposition profiles around the resonance layers were calculated and presented.

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Section: Power Transmission Windowmentioning

confidence: 99%

Study Electron Cyclotron Double Mode Conversion in Overdense Plasma

et al. 2019

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“…CNT was the first device to toroidally confine non-neutral plasmas [32][33][34] and plasmas with various degrees of quasi-neutrality [35]. Its focus has recently shifted to 3D diagnostic image inversion [36], error fields [37], high beta [38] and overdense microwave heating [39] in neutral stellarator plasmas.…”

Section: Tilted Interlinked Planar Coil Torsatronsmentioning

confidence: 99%

Large vacuum flux surfaces generated by tilted planar coils

Austin

Hammond

et al. 2019

Plasma Phys. Control. Fusion

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Helical equilibria can be generated by arrangements of planar coils similar to tokamaks, but without a central solenoid and with the toroidal field (TF) coils tilted with respect to the vertical. This is known from earlier numerical works, e.g. P.E. Moroz, Phys. Plasmas 2, 4269 (1995). However, such concept tends to need large coils (of low aspect ratio) but form small plasmas (of large aspect ratio). Here it is numerically shown that larger, more attractive vacuum flux surfaces -relative to the size of the device-can be generated by carefully optimizing the inclination of the TF coils and currents in the various coil-sets. Vacuum configurations of aspect ratios as low as 4 are found for 6 tilted TF circular coils. Higher numbers of TF coils have advantages (smaller effective ripple) and disadvantages (lower rotational transform, smaller plasma). Finally, the aspect-ratio A of the vacuum flux surfaces is quantified as a function of the ratio A c of the coil-radius to the radial location of the coil-center. It is found that, in order to minimize A, it is beneficial to interlink or marginally interlink the TF coils (A c 1).

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“…Microwaves are also being employed for many studies, such as the generation of plasma sources and diagnostics [5][6][7][8][9][10]. Its absorption leads to plasma heating [11], which is important in several contexts, such as tokamak [12,13], stellarator [14,15], particle * Authors to whom any correspondence should be addressed. acceleration [16,17], microwave heated chemical reactions [18] and mirror machines [19,20].…”

Section: Introductionmentioning

confidence: 99%

Harmonic generation in magnetized plasma for electromagnetic wave propagating parallel to external magnetic field

Trishul

Juneja

Goswami

et al. 2023

J. Phys. D: Appl. Phys.

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The harmonic generation has always been of fundamental interest in studying the nonlinear nature of any physical system. In the present study, Particle - In - Cell (PIC) simulations have been carried out to explore the harmonic generation of Electromagnetic waves in a magnetized plasma. The EM wave propagation is chosen to be parallel to the applied external magnetic field. The simulations show the excitation of odd higher harmonics of RCP (Right circularly polarized) and LCP (Left circularly polarized) when the incident wave is linearly polarised. The harmonic generation is maximum when the incident EM wave frequency matches the electron cyclotron frequency. When the incident EM wave has a circular polarization, no harmonics get excited. A theoretical understanding of these observations has also been provided. The studies thus show that by appropriately tailoring of plasma parameters EM waves of higher frequencies and desired nature of circular polarization can be generated.

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Overdense microwave plasma heating in the CNT stellarator

Cited by 8 publications

References 45 publications

Study Electron Cyclotron Double Mode Conversion in Overdense Plasma

Study Electron Cyclotron Double Mode Conversion in Overdense Plasma

Large vacuum flux surfaces generated by tilted planar coils

Harmonic generation in magnetized plasma for electromagnetic wave propagating parallel to external magnetic field

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