UKAEA Journals

Showing 1 - 10 of 10 Journals Results
2018
UKAEA-CCFE-PR(18)68

Helium is widely used as a fuel or minority gas in laboratory fusion experiments, and will be present as ash in DT thermonuclear plasmas.  It is therefore essential to have a good understanding of its atomic physics.  To this end He II population modelling has been undertaken for the spectroscopic levels arising from shells with principal quantum…

Preprint Published
2018
UKAEA-CCFE-PR(18)31

Spectra line power by medium and heavy weight elements is a main source of radiative loss in tokamak plasma and sets operational limits on the design of ITER and DEMO. The preferred comprehensive basis of impurity line power coefficients provided by ADAS is theoretical, using the Autostructure code with distorted wave electron impact cross-sections…

Preprint
2015
CCFE-PR(15)48

Carbon and nitrogen impurity transport coefficients are determined from gas puff experiments carried out during repeat L-mode discharges on the Mega-Amp Spherical Tokamak (MAST) and compared against a previous analysis of helium impurity transport on MAST. The impurity density profiles are measured on the lowfield side of the plasma, therefore this…

Preprint Published
2014

Time-dependent helium gas puff experiments have been performed on the Mega Ampere Spherical Tokamak (MAST) during a two point plasma current scan in L-mode and a confinement scan at 900 kA. An evaluation of the He II spectrum line induced by charge exchange suggests anomalous rates of diffusion and inward convection in the outer regions of both L-m…

Published
2005

This paper focuses on the diagnostic analysis in magnetically confined fusion plasmas with attention drawn both to the methodology in common with that in astrophysics and to points of departure – such as species, transport, high density and the role of neutral hydrogen. Comment is also made on the state of high quality theoretical collision data …

Published
2004

The impurity line and continuum emission for International Thermonuclear Experimental Reactor ( ITER ) reference H-mode and Internal Transport Barrier ( ITB ) plasmas were modeled using the SANCO impurity transport code. Using the instrument sensitivity for a spatially resolving crystal spectrometer array with doubly-curved crystals and two-dimensi…

Published
2001

The equilibrium state in tokamak core plasmas has been studied using the relative intensities of resonance x-ray lines. A full spatial analysis involves comparison of the line intensities with ion diffusion calculations, including relevant atomic rates. A zero-dimensional model using a global ion loss rate approximation has also been demonstrated b…

Published
1996

Crystal and synthetic multilayer diffractors, deployed either as flat Bragg reflectors, or curved, as in the Johann configuration, are used to study the spectrum of COMPASS-D and other tokamaks in the wavelength region of 1–100 A. In this article, we concentrate on the measurement of absolute photon fluxes and the derivation of volume emissivitie…

Published
1994

Quantitative measurements of the line and continua emissivities and the analyses of spectral line profiles are essential steps in the interpretation of the x-ray emission from high-temperature fusion plasmas. One method of placing the emissivities on an absolute basis is to use an absolutely calibrated spectrometer to record the data. The overall s…

Published