Atomic spectroscopy is carried out in the Lasers, Optics & Spectroscopy Group, which is formally a section of the Plasma Physics Research Institute at the University of Natal. Our research programme is at present being developed within the framework of the project “Spectroscopic Data for Fusion Plasmas,” which is part of a German (WTZ) – South African (NRF) scientific cooperation programme.

International Cooperation Activities

Funding from this programme enables regular visits to be made to the TEXTOR tokamak (toroidal fusion device) at the Research Centre in Juelich, Germany  (http://www.kfa-juelich.de/ipp).  And German sponsorship is also available for postgraduate research at the University of Natal to be carried out partly in Juelich, where excellent laser and spectroscopic facilities are available for this purpose.

In November 1998, Dr. Philippe Mertens, an expert in laser-induced fluorescence (LIF-) spectroscopy, visited us from Juelich, and we expect another visit to be made to our research group within the next few months.

	Advertisement   We are particularly interested in attracting Honours graduates for M.Sc. and Ph. D. research to join our research group, who already have a good background in one or more of the following: quantum mechanics, atomic physics, optics and spectroscopy.

 

Theoretical and Experimental Background

Full calculations are carried out of the Zeeman effect (component positions and line strengths), and from the fits to measured profiles, kinetic temperatures of atomic species can be deduced. A number of Hamamatsu photomultipliers of high dynamic range are available, especially for scans towards the red and near infra-red spectral regions.

Our major subject of current research is an investigation of the production of cold hydrogen and deuterium atoms from electron impact-induced molecular dissociation, and the heating of these cold atoms by collisions with hot protons and deuterons. A number of interesting conclusions have been drawn regarding the polarisability of atoms in excited states, and the influence of polarisability on the atomic heating. Simple models have been developed and are being improved, to explain these effects and to produce atomic data for further measurements.

	Experimental Arrangement

 

EXPERIMENTAL SET-UP

We investigate properties of atoms in magnetic fields typical of magnetically confined fusion plasmas, by examining atomic spectra with the aid of spectrometers of moderate to high resolution. Our major pieces of laboratory equipment are listed as follows:

                                                                                     Best resolution [Å]

Scanning monochromators                                        1^st order at l~ 6000 Å

(1)  A Jarrell-Ash model 82-010 (f/8.6) half-metre

      Ebert-Fastie type                                                            ~ 0.50

(2)  A McPherson model 2035 (f/4.8) 0.35 metre

      Czerny-Turner type.                                                       ~0.35

(3)  A McPherson model 209 (f/9.4) 1.33 metre

      Czerny-Turner type                                                        ~0.07

Detectors fitted to the spectrometers:

(1)  EMI 9893B/350 End-On Photomultiplier (300-650 nm)

(2)  Hamamatsu R3896 Side-On Photomultiplier (185-900 nm)

(3)  Hamamatsu R2658 Side-On Photomultiplier (185-1010 nm)

(4)  Linear CCD Array Detectors (UniData Beam Profiler) with Lens-coupling system

(5)  High Sensitivity Cooled 2-d CCD Detector (Hamamatsu C7041) with Lens-coupling system

(6)  Image Intensifier (DEP) with Super S-25 Cathode

Other laboratory Accessories:

(1)  Electromagnets up to 1.6 T

(2)  Gaussmeter, accuracy within 1% (F.W. Bell)

(3)  Calibrated Tungsten Lamp (Phototronics) at 2865 K for the absolute calibration on the optic system.

(4)  4 Inch Integrating Sphere (Labsphere)

(5)  High Precision 7 ½ Digit Multimeter (Prema)

(6)  High Precision Power Supply (Fug), current stability better than 1×10^-4

(7)  Optical Components such as lenses, filters, polarizers, waveplates, He-Ne lasers (in green, yellow and red) and diode lasers

Publications in 1999

1.     M.N.A. Beurskens, C.J. Barth, C.C. Chu, and N.J. Lopes Cardoso, “Error analysis of Rijnhuizen tokamak project Thomson scattering data”, Review of Scientific Instruments Vol. 70 No. 4, pp. 1999 – 2011 (April 1999).

2.     J.D. Hey, C.C. Chu, and J.P.S. Rash, “Partial local thermal equilibrium in a low-temperature hydrogen plasma,” Journal of Quantitative Spectroscopy and Radiative Transfer Vol. 62 No. 3, pp. 371 – 387 (June 1999).

3.     J.D. Hey, C.C. Chu, and E. Hintz, “On a heating mechanism for cold hydrogen and deuterium atoms produced at the edge of a tokamak plasma,” Journal of Physics B: Atomic, Molecular & Optical Physics (in press).

	Please contact us at:   Hey@scifs1.und.ac.za (tel.: ( 27)-31-260-3164) Chu@scifs1.und.ac.za (tel.: ( 27)-31-260-1355) Krumm@scifs1.und.ac.za (tel.: ( 27)-31-260-1317)   Fax: ( 27)-31-261-6550