Structure of the radial electric field and toroidal/poloidal flow in high temperature toroidal plasma

The structure of the radial electric field and toroidal/poloidal flow is discussed for the high temperature plasma in torodidal systems, tokamak and Heliotron type magnetic configurations. The spontaneous toroidal and poloidal flows are observed in the plasma with improved confinement. The radial electric field is mainly determined by the poloidal flow, because the contribution of toroidal flow to the radial electric field is small. The jump of radial electric field and poloidal flow are commonly observed near the plasma edge in the so-called high confinement mode (H-mode) plasmas in tokamaks and electron root plasma in stellarators including Heliotrons. In general the toroidal flow is driven by the momentum input from neutral beam injected toroidally. There is toroidal flow not driven by neutral beam in the plasma and it will be more significant in the plasma with large electric field. The direction of these spontaneous toroidal flows depends on the symmetry of magnetic field. The spontaneous toroidal flow driven by the ion temperature gradient is in the direction to increase the negative radial electric field in tokamak. The direction of spontaneous toroidal flow in Heliotron plasmas is opposite to that in tokamak plasmas because of the helicity of symmetry of the magnetic field configuration

Thickness of the layer of high shear radial electric field in JFT-2M H-mode plasmas

The poloidal rotation velocity profiles both in low-confinement (L) and high-confinement (H) mode measured in JAERI Fusion Torus 2 Modified (JFT-2M) [Phys. Rev. Lett. 65, 1364 (1990)] are compared with H-mode models based on ion orbit loss. The profiles of poloidal rotation velocity measured in L and H modes are consistent with the calculation which consists of ion orbit loss model. The observed dependence of the thickness of the layer of high shear E_r on poloidal gyroradius is explained by the radial transport of poloidal rotation velocity

Edge poloidal rotation profiles of H-mode plasmas in the JFT-2M tokamak

Parameter dependence of the radial structure of edge poloidal rotation is studied with spectroscopic measurements for L- and H-mode plasmas in the JFT-2M tokamak [Y. Miura et al., in Plasma Physics and Controlled Nuclear Fusion Research, Proceedings of the 13th International Conference, Washington 1990 (IAEA, Vienna, 1991), Vol. 1, p. 325]. The poloidal flow is in the electron diamagnetic direction and appears suddenly near the plasma edge at the H-mode transition. The poloidal rotation velocity profile in the H mode has a peak at the separatrix. No critical normalized ion collisionality, nu_*i, for the transition of the L to the H mode is observed. The size of the poloidal flow in the H mode has no dependence on the poloidal gyroradius. Physics of Fluids B: Plasma Physics is copyrighted by The American Institute of Physics

Density peaking in the JFT-2M tokamak plasma with counter neutral-beam injection

A significant particle pinch and reduction of the effective thermal diffusivity are observed after switching the neutral beam direction from coinjection to counterinjection in the JFT-2M tokamak. The particle pinch measured in the counterinjection phase shows good agreement with the prediction of the inward pinch model related to the electric fields

Observation of non Diffusive Term of Toroidal Momentum Transport in the JFT-2M Tokamak

Toroidal rotation velocity profiles are measured with multi-chord charge-exchange spectroscopy for the discharge that the neutral beams are interchanged from parallel (co) to anti-parallel (counter) to the direction of the plasma current. Transport analysis of toroidal momentum in the transient phase suggests the existence of non-diffusive term in the toroidal momentum transport. This non-diffusive term appears as spontaneous source of the toroidal momentum in the direction of anti-parallel to the plasma current