Soft x-ray spectroscopy of magnetically confined fusion plasmas using flat multilayer mirrors as dispersive elements

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1993

OSTI ID:7041642

Post Zwicker, A P

Flat multilayer mirrors (MLMs) are used as dispersive elements to study soft x-ray impurity radiation from tokamak plasmas. MLMs provide the means to create simple, high throughput, near-normal incidence soft x-ray monochromators. Two MLM-based monochromators were built and data from both was analyzed to determine the useful amount of diagnostic information available from the resulting low resolution spectra. The first, mounted on TEXT, used a Mo/B[sub 4]C MLM to measure the spectrum between 120-170 [angstrom]. The spectrum was compared to a spectrum calculated by an impurity transport code coupled to a collisional-radiative model to demonstrate the ability of the MLM spectrum to distinguish changes in the transport of TEXT's dominant impurity, titanium. The second monochromator was mounted on DIII-D. It had a spectral range between 10-170 [angstrom]. Along with a grazing incidence spectrometer, the monochromator was used to measure the ratio of Ly[sub [alpha]]/H[sub [alpha]] of hydrogen-like carbon (33.7[angstrom]/182 [angstrom]) during radio frequency heated discharges and ohmic H-mode discharges. The ratio was compared with calculated values which showed that the transport of carbon was changing during these two discharge phases. Spectra throughout the entire range of the instrument were also analyzed. The characteristics of different MLMs were measured between 10-330 [angstrom]. A calibration facility built at JHU to measure MLMs for [lambda] < 114 [angstrom] is described. Above 114 [angstrom], MLMs were measured using the SURF II storage ring at the National Institute of Standards and Technology. The JHU calibration facility was also used to measure the spectrum between 130-175 [angstrom] from a small laboratory plasma source. The MLM spectrum was compared to a high resolution spectrum from a grazing incidence spectrometer. The MLM spectrum was sufficient to distinguish changes in the plasma parameters from changes in the plasma discharge conditions.

• Research Organization: Johns Hopkins Univ., Baltimore, MD (United States)
• OSTI ID: 7041642
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700320* -- Plasma Diagnostic Techniques &amp; Instrumentation-- (1992-)
CLOSED PLASMA DEVICES
CONFINEMENT
CONSTRUCTION
ELECTROMAGNETIC RADIATION
FLAT MIRRORS
IMPURITIES
IONIZING RADIATIONS
MAGNETIC CONFINEMENT
MIRRORS
MONOCHROMATORS
PLASMA CONFINEMENT
PLASMA DIAGNOSTICS
PLASMA IMPURITIES
RADIATIONS
SOFT X RADIATION
SPECTROSCOPY
TEXT DEVICES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
X RADIATION
X-RAY SPECTROSCOPY