Argon density measurements from charge–exchange spectroscopy

Abstract

Charge–exchange spectroscopy is widely used to determine the profiles of fully stripped low-Z ions (carbon, oxygen, neon) in fusion plasmas. Continuing interest in the use of heavier impurities for radiative cooling in boundaries and divertors of fusion plasmas has encouraged the expansion of this technique for elements such as argon which are not completely burned out in present machines. As a first step, it has been necessary to predict the wavelengths of transitions from Ar XVI to Ar XVIII from theoretical calculations. Several of these have been detected in the DIII-D tokamak [Plasma Physics Controlled Nuclear Fusion Research, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159] subsequent to argon puffing into neutral-beam injected plasmas, and the experimentally determined wavelengths are in good agreement with the predicted values. Argon ion densities have been determined using recent Classical Trajectory Monte Carlo (CTMC) computations of the charge–exchange cross sections, and some radial profiles for specific ionization stages have been measured.

X-rays from solar system objects

“…Those that have been observed in the laboratory typically fall into the extreme ultraviolet or visible range. For example, a variety of such lines have been employed as diagnostics in tokomaks (Stratton et al 1990;von Hellermann et al 1995;Whyte et al 1998), and the crossed-beam technique has been used to study the emission from lithium-like or beryllium-like ions in the extreme ultraviolet regime (Bliek et al 1998;Lubinski et al 2000;Ehrenreich et al 2005). These systems are close analogs to the hydrogen-like and helium-like ions.…”

Dynamic instabilities in the interaction of transverse modes in a class-B laser

“…That is, with a greater number of trajectories that could be computed, the statistical errors of the results for the small cross sections and for large quantum numbers could be made small enough to produce more and more complete data sets. For example, CXRS CTMC data sets for C 6+ and O 8+ [13], He 2+ [14], Ne q+ (q = 7-10) [15] and Be q+ (q = 2-4) [16] colliding with H(1s) have been produced in addition to our previous Ar q+ (q = 15-18) [5] results.…”

“…The use of the extrinsic impurity argon in CXRS with hydrogen neutral beam injection in a number of fusion experiments, for example, DIII-D, JET and ASDEX-U, has motivated the calculation here of a wide range of relevant data for future experiments, significantly expanding our work of a decade ago [5]. The new calculations address the need identified for consideration of additional collision energies relevant to neutral beam energies, namely 40, 70, and 250 keV/u, and, since the beams contain half and one-third energies, 20, 13.333, 35, 23.3333, 125 and 83.3333 keV/u as well.…”

“…The present work has yielded 72 tables of the state-selective charge transfer cross section (for the nine collisions energies, four projectile ions and two target states), each containing results for capture states up to a principal quantum number of 30. Since these tabulations of data needed for CXRS analysis are too large to reproduce here, they have been posted on the web site of the Oak Ridge National Laboratory's Controlled Fusion Atomic Data Center in a location and manner similar to those posted accompanying our previous work [5].…”

Plasma code for astrophysical charge exchange emission at X-ray wavelengths

“…To obtain the cross section as a function of collision velocity v, we compiled the results reported in previous theoretical calculations (Ryufuku 1982;Shipsey et al 1983;Fritsch & Lin et al 1984;Phaneuf et al 1987;Janev et al 1988Olson & Schultz 1989;Belkić 1991;Harel et al 1998;Whyte et al 1998;Perez et al 2001;Errea et al 2004;Schultz et al 2010;Wu et al 2011;Nolte et al 2012) and experimental measurements (Fite et al 1962;Olson et al 1977;Meyer et al 1979Meyer et al , 1985Crandall et al 1979). A complete list of the data sources is shown in Table 1.…”