Effect of the E × B drift on the redistribution of the divertor particle flux in the HL-2A ECRH plasmas

Abstract

Double-peaked distribution (DPD) of particle flux has only been observed on the outer divertor target in electron cyclotron resonance heating deuterium plasmas with [Formula: see text] toward the X-point in the HL-2A tokamak using high spatiotemporal Langmuir probe arrays. The experimental results demonstrate that the formation of the DPD is mainly due to the enhanced poloidal [Formula: see text] drift flow stimulated in the divertor region, which is dependent on the plasma density, heating power, and divertor structure. The experimental results are qualitatively consistent with the SOLPS simulation. The experiment also shows that the formation of the DPD might be related to the enhanced cross field transport in the far scrape-off layer. This experimental findings presented here reveal the crucial role played by the synergistic effect of poloidal E × B drift flow and the closed divertor structure in the redistribution of the particle flux, which provides a potential way for the control of high heat flux in future fusion devices.

Plasma rotation and axial flow velocities in Magnum-PSI from cross-correlation measurements

“…Moreover, sheared plasma rotation in poloidal/azimuthal direction, which is mainly driven by E × B and diamagnetic drifts, is related to the achievement of the magnetic confinement in fusion reactors [21] and the transport of particles and heat in the divertor region [22]. The latter aspect includes the inner-outer divertor asymmetry [23], the redeposition and transport of the divertor sputtered material [24], the distribution of particle flux [25] etc. The sheared plasma flow has been intensively studied and more information can be obtained from the reference lists of the cited papers.…”

Facilitated core-edge integration through divertor nitrogen seeding in the HL-2A tokamak

“…The width of the divertor entrance is approximately 2 cm. The purple dotted circles represent Langmuir probes installed at two toroidal locations about 170 • apart at both the inner and outer divertor targets, with a spatial resolution of 6 mm and a data acquisition frequency of 1 MHz [47,48]. The divertor impurity injection system is shown by the red line of sight [40].…”