SPECTROSCOPIC DIAGNOSTIC COMPLEX

FOR STUDYING PULSED TOKAMAK PLASMAYu. Golubovskii, Yu. Ionikh, A. Mestchanov,

V. Milenin, I. Porokhova, N. Timofeev

Saint-Petersburg State University, Physical Faculty, Optics Department,

Saint-Petersburg, Russia

4 October 2005, Saint-Petersburg

- extremely fast image recording 1GB/s,

- high resolution (1280x1024 pixel),

- exposure time range 1 μs-5 s,

- image memory in camera (camRAM up to 4 GB),- interframing time 75 ns,- standard interface.

Digital high speed CMOS camera pco.1200 hs (PCO.IMAGING)

-     pixel size – 12μm x 12μm,-         full well capacity – 63 000 e-,-         peak quantum efficiency (520 nm) – 27%,-         dynamic range – 59.6 db,-         readout noise – 85 e-rms,-         pixel scan rate – 66/86 MHz,-         spectral range – (290-1100) nm,-         dark current – 5900 e-/pixel-s.

The resolution 1280x1024 pixel enables to make about 500-600 frames per second (fps) that is not suitable for the study of the plasma in question. Coupling the camera with a spectrograph enables us to use the camera with the lowest number of pixels in vertical direction produced by PCO.IMAGING: 1280x16 pixel. This makes it possible to increase the number of frames per second till about 40 000. The number of points during a Tokamak current pulse with the duration ~ 1 ms could reach ~ 40.

corrected spherical and chromatic aberration

- focal length: 12-24 mm,

- maximum aperture: f/4,

- lens construction: 11 elements in 7 groups (3 aspherical lens and 2 ED (extra-low dispersion) lens elements),

- picture angle: (99-61)o,

- closest focus distance: 0.3 m

Objective NIKON AF-S DX Zoom-Nikkor ED

internal image correction with original polished aspheric optics,

triple grating turret,

stepping motor scanning system with 32-bit microprocessor control,

RS 232 and USB computer interfaces,

scan control software for Windows.

Three gratings are chosen so that all needed spectral regions can be investigated

Monochromator / Spectrograph SP-2358

Monochromator / Spectrograph SP-2358 Gratings

Spectrograph SP-2358one usual exit slit temporal scan of any wavelength gap

300mm focal length, f/4 imaging monochromator/spectrograph with one micrometer controlled entrance slit, fixed entrance diverter mirror, one micrometer controlled side exit slit, motorized exit diverter mirror and multichannel detector flange in end position

Grating density, 1/mm 300 1200 2400

Spectral region, nm300 – 1100

300 – 950

290 – 800

Dispersion, nm/mm 9.6 2.3 0.94

Focal plane coverage, nm

145 34 14

CCD resolution (FWHM), nm

0.35 0.08 0.035

Experimental set-up

I. Usage of camera for plasma observation in visible region

II. Diagnostic system to measure spectra

Scientific problems that can be solved with the help of the spectroscopic

diagnostic complex1. Monitoring the Tokamak plasma parameters to influence

on its operation. This task is very important, because such problems are possibly identical for all types of Tokamaks.

2. Study of Tokamak plasma near walls where plasma reacts with wall material.

3. Study of different materials introducing into Tokamak camera. These materials can be in gas phase – investigation of hot plasma of different composition, – and in solid state – investigation of interaction between plasma and solid bodies.

4. Developing diagnostics methods.

5. Teaching young scientists and engineers to operate with

Tokamak and hot plasma and carry out its diagnostics.