Showing 72 results for Author: C. Christopher Klepper
Mar, 2018
Journal
ICRH was extensively used in the 2015-16 JET-ILW (ITER like wall) experimental campaign; bulk heating together with high-Z impurity chase-out from plasma centre importantly contributed to the good DD fusion performance obtained recently in JET. Power up to 6 MW was launched in H-mode deuterium plasmas and 8 MW during the hydrogen campaign. The ILA was re-installed and cont…
Oct, 2017
Journal
For simulation of plasma-facing components' erosion in fusion experiments, an analytical expression for the ion velocity just before the surface impact including the local electric field and an optional surface biasing effect is presented. Energy and angular impact distributions and the resulting effective sputtering yields were produced for several experimental scenarios…
Feb, 2017
Journal
Radio-frequency (RF)-enhanced surface erosion of beryllium (Be) plasma-facing components is explored, for the first time, using the ERO code. The code is applied to measured, RF-enhanced edge Be line emission at JET Be outboard limiters, in the presence of high-power, ion cyclotronresonance heating (ICRH) in L-mode discharges. In this first modelling study, the RF sheath e…
Oct, 2016
Conference Paper
The detection limit for helium (He) partial pressure monitoring via the Penning discharge optical emission diagnostic, mainly used for tokamak divertor effluent gas analysis, is shown here to be possible for He concentrations down to 0.1% in predominantly deuterium effluents. This result from a dedicated laboratory study means that the technique can now be extended to intr…
Jun, 2015
Conference Paper
One of the ITER diagnostics having reached an advanced design stage is a diagnostic RGA for the divertor, i.e. residual gas analysis system for the ITER divertor, which is intended to sample the divertor pumping duct region during the plasma pulse and to have a response time compatible with plasma particle and impurity lifetimes in the divertor region. Main emphasis is pla…
May, 2015
Journal
Interaction of radio-frequency (RF) waves with the plasma in the near-field of a high-power wave launcher is now seen to be important, both in understanding the channeling of these waves through the plasma boundary and in avoiding power losses in the edge. In a recent Letter a direct non-intrusive measurement of a near antenna RF electric field in the range of lower hybrid…
Aug, 2014
Journal
An exploratory study was carried out in the long-pulse tokamak Tore Supra, to determine if electric fields in the plasma around high-power, RF wave launchers could be measured with non-intrusive, passive, optical emission spectroscopy. The focus was in particular on the use of the external electric field Stark effect. The feasibility was found to be strongly dependent on t…
Apr, 2014
Conference Paper