A self-consistent picture for hyper-velocity metal dust in FTU

Abstract

Numerical simulations of the propagation of plasma blobs in the scrape-off layer (SOL) of the Frascati Tokamak Upgrade (FTU) are presented. The maximum distances that a plasma blob may travel in the radial direction are calculated under FTU physical conditions and geometry, taking into account the dissipation due to the presence of dust. It is found that a relatively small amount of nanometre iron dust particles can dissipate blobs before they reach the wall. The amount of dust required is of the same order as, or smaller than, that needed to produce hyper-velocity dust particles, so that a consistent interpretation is reached for experiments in FTU where evidence of the dust impact ionization was reported.

Collection strategy, inner morphology, and size distribution of dust particles in ASDEX Upgrade

“…Since the late 1990s particles have been collected in various fusion plasma devices during vents for post-mortem analysis [2,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35], and several attempts have been made to model the behaviour of dust particles in a fusion plasma [3,11,12,[36][37][38][39][40][41][42]. In ASDEX Upgrade (AUG), starting after campaign 1999, the complete transition from a carbon to a full tungsten first wall [43,44] was monitored.…”

Molecular Dynamics Simulations of Deposition and Damage on Tungsten Plasma-Facing Materials by Tungsten Dust

“…Aerogels have been used to collect dust particles bombarding on PFMs in HT-7 [26] and TEXTOR [27,28] in order to analyze their amount and velocity distribution. In addition, high-velocity metal dust grains of the order of 10 km/s have been detected in FTU [29,30] . High-velocity dust grains can seriously damage a PFMs surface, which may produce more dust grains or impurity atoms.…”