托卡马克位形优化.pptVIP

* 托卡马克位形优化 (2) 高庆弟 SWIP 核工业西南物理研究院 成都 Nonlinearity of LH wave absorption The plasma temperature in HL-2A is much lower than that in future reactor. To establish RS configuration, the LH driven current should be located off-axis where the plasma temperature is even lower, and the plasma absorption of high phase velocity LH waves is too weak to ensure the waves are damped during their first pass. In the weak electron Landau damping condition LH wave rays make many passes through the wave propagation domain in plasma and undergo numerous reflections at the propagation boundaries. Considering the propagation of lower-hybrid waves in a tokamak. The phase space energy density of the rf field is denoted by U( x, k, t), where x is the position vector, k is the wave vector. U obeys the WKE, After determining U( x, k), we can calculate physical quantities such as the (time-averaged) absorbed power density, THE CYLINDRICAL APPROXIMATION Appropriate canonical coordinates in tokamak geometry are (x, k)?(r, ?, ?, kr, m, n). We consider the source S = Pin(2?)-2 ?(r - ro) ?(kr – kr0), the solution of ( 1) is The (time-averaged) energy density in the rf parallel electric field, Here follows from the cold plasma dispersion relation. The damping rate ?e for electron Landau damping can be written as follows: where The absorbed power density, , with The above solution of the WKE can be classified into two distinct para-meter regimes: (i) the multipass regime (for ? ? 1), when U tends to be uniform along the entire ray orbit in the (r, k) plane, and (ii) the single-pass regime (for ? 5) when nearly all the power is absorbed before the ray reaches the caustic. In the multi-pass regime, the absorption due to electron Landau damping is strongly peaked at the caustic. Fig. 10 Radial profiles of P and |E//|2 for multipass absorption of a single field harmonic (m = 100, n = 450) in the cylindrical approximation. In the tokamak toroidal geometry intri