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Author(s):
V.L. Vdovin and I.V. Kamenskij
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Title:
3D Electromagnetic Theory of ICRF Multi Port Multi Loop Antenna
Date of publication:
Jan. 1997
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Key words:
Antenna, ICRF, port, multi-loop, current drive, plasma heating, ITER, tokamak, code, plasma, impedance matrix
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Abstract:
In this report the theory of three dimensional antenna in lon Cyclotron Resonance Frequency (ICRF) is developed for a plasma with circular magnetic surfaces. The multi loop antenna is located in ITER several ports. Circular plasma and antenna geometry provides new important tools to account for: l) right loading antenna impedance matrix calculation urgently needed for a matching of RF generator with an antenna; 2) right calculation of an antenna toroidal and poloidal excited spectra because the DIFFRACTION, refraction and REFLECTION effects for the Fast Waves (FW) are in FIRST time are included self consistently in 3D ICRF antenna - plasma treatment; 3) right calculation of RF power deposition profiles because self consistently found 3D antenna - plasma FW excited spectra in non slab plasma model are important ones in a weakly dissipated plasma for Fast Waves (even for ITER parameters). In the developed theory multi loop antennae are located in several ITER ports with arbitrary relative toroidal and poloidal positions. It gives great flexibility of investigation possibility for production of an optimal ICRF antenna directivity in conditions of limited toroidal space in a reactor port and a possibility to control widness of excited FW k - spectra to control RF power deposition profiles into a plasma. The above theory allows to calculate RF losses on a Faraday screen bars. In the model developed each loop is located in a special individual recess in a tokamak port to control in some extent mutual coupling between loops through a vacuum port region and simulteneously to support the Faraday screen bars. The theory developed accounts for two options for poloidal loops: to be located INSIDE of each sub recess (with a smaller mutual loops coupling) and to be located OUTSIDE of each sub recess (more closely to plasma) with an increased antenna loading resistance. Radial antenna loops feeders are taken into account as well. The MULTI PORT structure of the theory gives another important tool to control mutual coupling of loops: it is possible to locate one port just near another one with, for example, only two loops in each sub PORT just simulating contineous conducting boundary between several loops (besides of sub recess walls). Another possibility is to simulate extended toroidal port size to improve an antenna directivity. The information about plasma properties comes into antenna theory through plasma surface impedance matrix Y_mm and is calculated separately by fast MlNTOR2 code described in Part A. According to theory developed the ANPORT code has been written. The first runs indicated strong mutual loops coupling of ITER now designed antenna. The work is under progress.
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