Initial operation of the national spherical torus experiment fast tangential soft x-ray camera

Abstract

Fast, two-dimensional, soft x-ray imaging is a powerful technique for the study of magnetohydrodynamic instabilities in tokamak plasmas. We have constructed an ultra-fast frame rate soft x-ray camera for the national spherical torus experiment (NSTX). It is based on a recently developed 64ϫ 64 pixel charge-coupled device (CCD) camera capable of capturing 300 frames at up to 500 000 frames per second. A pinhole aperture images the plasma soft x-ray emission ͑0.2-10 keV͒ onto a P47 scintillator deposited on a fiber-optic faceplate; the scintillator visible light output is detected and amplified by a demagnifying image intensifier and lens-coupled to the CCD chip. A selection of beryllium foils provides discrimination of low-energy emission. The system is installed on NSTX with a wide-angle tangential view of the plasma. Initial plasma data and an assessment of the system performance are presented.

Extreme ultra-violet movie camera for imaging microsecond time scale magnetic reconnection

“…7 Since visible light technology does not work at EUV wavelengths, conventional optical schemes based on mirrors and lenses cannot be used to collect radiation and form images. Various EUV imaging methods have been used previously, most particularly pinhole cameras 3,4,6,7 and diode arrays. 1,2,5 Pinhole cameras consist of a small pinhole to form an image, a micro-channel plate intensifier shutter that converts EUV into fast electrons, a scintillator/phosphor to convert the fast electrons into a visible light image, and a visible light camera to record the phosphor image.…”

“…Time-resolved fast imaging of extreme ultra-violet (EUV) and soft x-ray radiation is useful to understand magnetic reconnection, magnetohydrodynamic (MHD) activity, particle and energy transport, plasma stability, and turbulence in laboratory plasmas such as tokamaks [1][2][3][4] spheromaks, 5 reversed field pinches, 6 and stellarators. 7 Since visible light technology does not work at EUV wavelengths, conventional optical schemes based on mirrors and lenses cannot be used to collect radiation and form images.…”

Tangential SX Imaging for Visualization of Fluctuations in Toroidal Plasmas

“…This kind of camera system has been developed since early 80 s [9][10][11]. However, it became possible to measure the fluctuations of the plasma after we adopt the large diameter scintillator and the fast framing visible camera, which was available late 90 s. It is noted that similar type of SX camera system developed by different groups also began to work simultaneously [12,13].…”

Passive Spectroscopic Diagnostics for Magnetically-confined Fusion Plasmas

“…Both fast CCD detectors 164 and fast gaseous electron multiplier (GEM) detectors with a two-dimensional anode array 165 have been used. Small, onedimensional detector arrays on a single substrate have enabled construction of compact XIS arrays, allowing several cameras to be used at a single toroidal location for improved radial…”