Disentangling the emissions of highly ionized tungsten in the range 4-14 nm RID A-6962-2012 RID B-4438-2010

Author:

Putterich, T  Neu, R  Biedermann, C  Radtke, R  

Journal:

JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS

Issue Date:

2005

Abstract(summary):

In this work EBIT measurements in the spectral range of 4-7 nm with electron energies from 0.7 keV to 4 keV are compared in detail with, tokamak spectra from ASDEX Upgrade. The energy and temperature dependence of spectral lines and features are investigated and an identification of the charge states W39+-W-451 for spectral lines between 4.5 nm and 6.5 nm is possible by taking cross sections from atomic data produced by plane-wave Born calculations via the Cowan code. In the range 12-14 nm the identification of spectral lines emitted by tungsten is improved even though no EBIT measurements are available, as special tokamak discharges have provided ideal possibilities for analysis. These discharges show spectra which are dominated by the emissions from a small region with a narrow electron temperature range. Therefore, only very few ion states contribute to the emission in contrast to the usual case where in the tokamak spectra the emissions of a larger number of ion states are superimposed. Tokamak spectra for varying electron temperature are also used to investigate the correlation to EBIT spectra for the quasicontinuum feature at 5 nm which is emitted by ion states W27+-W35+. We conclude that the narrower features in the EBIT spectra at a certain electron beam energy result from the smaller number of coexisting ion states.

Page:

3071---3082