Ionization and toroidal dispersal of laser blow-off injected aluminium beam in the MT-1 M tokamak

Abstract

Abslract-Aluminium impurities were injected into the plasma of the MT-IM Tokamak. Line radiation of diRcrent aluminium ions (from AI I t o AI VIII) were identified. Two velocities were found for the toroidal dispersal: one is of the order ofU.1 cm fisc' for a few cmlimetres in the vicinity of the injection. the other is highcr than I cm for the whole Tokamak.fo!!owing. The ifijc&d ions gain !heir toroidal yp!ficity throcgh Co~!omb co![isiofis

High resolution charge-exchange spectroscopic measurements of aluminum impurity ions in a high temperature plasma

“…Medium-Z metallic impurities including aluminum, injected into the plasma via laser blowoff, are often used for impurity transport studies in tokamaks [6]. These measurements, however, are usually limited to lower charge states, and they are often chordaveraged.…”

“…Densities of other aluminum charge states are calculated with the help of a collisional radiative model, ADAS405. This program calculates the fractional abundances of the ions of an element in equilibrium in a thermal 6 plasma as a function of density and electron temperature [9]. The plasma parameters used for this calculation are T e ∼ 1.5 keV, T i ∼ 1.2 keV, n e ∼ 1.2 × 10 19 m −3 and n n ∼ 7 × 10 14 m −3 .…”

Toroidal transport studies in TEXTOR using lithium laser blow-off injection

“…Impurity injection is often used for edge investigations in tokamak plasmas. Beside edge-plasma parameter measurements (Pospieszczyk and Ross 1988 ; Kocsis et al 1989) and radial-transport investigations (Marmar et al 1982 ;Pasini et al 1990), which have been performed intensively in the past, the toroidal transport (Kocsis et al 1992(Kocsis et al , 1993 of the injected particles has been a relatively neglected topic both experimentally and theoretically. However, it seems that the study of toroidal impurity transport can give valuable information in several respects.…”

Transport of impurity ions along the field lines in magnetized plasma

“…In the last decade the radial transport of the impurity ions [1][2][3][4][5] was mainly investigated and little attention has been paid on their transport parallel to the magnetic field lines, [6][7][8] although several interesting phenomena associated with parallel transport have emerged. For instance, the toroidal spread of the injected impurities, the expansion of the pellet cloud, and the dispersal of the impurities eroded from the limiter are such processes.…”

“…9 Several experiments have been performed to investigate the toroidal dispersal of injected impurities by the use of a gas-puff 6,7 and the laser blow-off method. 8 In order to understand the results of the gas-puff experiments, both analytical and numerical models have been developed. [9][10][11] It was also concluded that the nature of the parallel transport of the injected ions depends on the ratio of the mean-free path of the ions along the field lines to the width of the parallel distribution of the ions.…”