Magnetic field lines (top plot) and on-axis distribution of the magnetic field strength (bottom plot) in the GDT device (z = 0 corresponds to the middle plane of the trap, z = 350 cm is the coordinate of the mirror throat, z = 305.5 cm is the coordinate of the electron cyclotron resonance (on-axis) at 54.5 GHz). The evanescent region at 54.5 GHz (shown hatched) is formed by the R-wave cut-off (outer border) and the upper-hybrid resonance layer (inner border). The latter corresponds to the quasi-transverse propagation with respect to the ambient magnetic field, i.e., while is constant. The outermost thick solid magnetic field lines stand for the boundary of a plasma column as introduced in Sec. III.
Top: Geometric-optical rays for a set of launching angles 15°–70° with respect to the vertical. The bulk plasma density is 1.5 · 1019 m−3. Bottom: Rays launched with the same angle 55° for a set of plasma densities in the range of N 0 = 0.5–2.5 · 1019 m−3.
Operating windows in angle–density plot for three positions for the ECRH launcher. Launch 1 has been finally selected for manufacturing.
Top, middle: Power deposition profiles over the radial (top) and longitudinal (middle) coordinates for a set of 10 geometric-optical rays with launching angles 50°–55°. The bulk plasma density is 1.5 · 1019 m−3. Bottom: Power deposition over the electron velocities measured in thermal velocities, .
Schematic of the different miter bends used in the transmission line.
Output polarisation after the universal polarizer depending on the tilting angles ψ1 and ψ2. Isolines of elongation of the polarization ellipse (red curves online) and its inclination with respect to the incidence plane (measured in degrees, blue curves online) are shown. The inрut wave beam is linearly polarized. A–C: Linear polarization like the incident one; D: clockwise circular polarization; E: counter-clockwise circular polarization; F, G: linear polarization perpendicular to the incident one.
Schematic of the ECRH launcher consisting of a plane mirror (1) and two parabolic focusing mirrors (2,3).
Overview of the GDT facility and positions of the ECRH ports.
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