Flute mode fluctuations in the divertor mirror cell

Abstract

The computer code by reduced magnetohydrodynamic equations were made which can simulate the flute interchange modes ͑similar to the Rayleigh-Taylor instability͒ and the instability associated with the presence of nonuniform plasma flows ͑similar to the Kelvin-Helmholtz instability͒. This code is applied to a model divertor and the GAMMA10 ͓M. Inutake et al., Phys. Rev. Lett. 55, 939 ͑1985͔͒ with divertor in order to investigate the flute modes in these divertor cells. The linear growth rate of the flute instability determined by the nonlocal linear analysis agrees with that in the linear phase of the simulations. There is a stable nonlinear steady state in both divertor cells, but the nonlinear steady state is different between the model divertor and the GAMMA10 with divertor.

Flute instability and the associated radial transport in the tandem mirror with a divertor mirror cell

“…͑11͒-͑13͒ is described in Ref. 8. Time step is ⌬ =5ϫ 10 −5 and ͑x ϫ ͒ = ͑121ϫ 2 6 ͒ meshes are used in the simulation.…”

“…8,30,31 The effects of magnetic field line curvature on the flute interchange modes are included through the specific volume u. The basic equations do not use the long thin approximation, thus these equations can be applied to the divertor fat mirror plasma.…”

“…The flute mode fluctuations can cause a large ion radial diffusion in the steady state. 8 The nonaxisymmetric electrostatic potential in the central cell, which is formed artificially by the electron cyclotron resonance heating, can also enhance the large ion radial transport 9 as well as the neoclassical transport due to the nonaxisymmetric magnetic field. [10][11][12][13] Another operation is the one like a disruption observed in a big torus 14,15 or edge localized mode observed in a divertor tokamak, 16 where the plasma is made lost rapidly from the central cell.…”

The Stability of Flute Modes in the GAMMA10 A-divertor

“…The GAMMA10 A-divertor requires the threedimensional treatment for the flute mode linear analysis. There are the basic equations for the flute mode fluctuations which are applicable to the axisymmetric magnetic field including divertor mirror cell [4,5]. In the paper we carry out the stability analysis by extending the equations to the GAMMA10 A-divertor.…”

Calculation of Ion Orbits in the Divertor/Dipole Regions of the GAMMA10 A-Divertor

“…However, recently the original purpose of installing a magnetic divertor has been changed to be one of performing the simulation experiments of the divertor in the closed system. Thus the investigation of transport on the GAMMA10 A-divertor is in progress [3][4][5]. The study of ion orbits in the divertor and dipole regions is a part of the investigation of the GAMMA10 A-divertor with the aim of plasma wall interaction.…”