Supersonic helium beam diagnostic for fluctuation measurements of electron temperature and density at the Tokamak TEXTOR
- Institute of Energy and Climate Research, Plasma Physics, Forschungszentrum Juelich GmbH, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, Juelich (Germany)
A supersonic helium beam diagnostic, based on the line-ratio technique for high resolution electron density and temperature measurements in the plasma edge (r/a > 0.9) was designed, built, and optimised at TEXTOR (Torus Experiment for Technology Oriented Research). The supersonic injection system, based on the Campargue skimmer-nozzle concept, was developed and optimised in order to provide both a high neutral helium beam density of n{sub 0}= 1.5 Multiplication-Sign 10{sup 18} m{sup -3} and a low beam divergence of {+-}1 Degree-Sign simultaneously, achieving a poloidal resolution of {Delta}{sub poloidal}= 9 mm. The setup utilises a newly developed dead volume free piezo valve for operation in a high magnetic field environment of up to 2 T with a maximum repetition rate of 80 Hz. Gas injections are realised for a duration of 120 ms at a repetition rate of 2 Hz (duty cycle 1/3). In combination with a high sensitivity detection system, consisting of three 32 multi-channel photomultipliers (PMTs), measurements of edge electron temperature and density with a radial resolution of {Delta}{sub radial}= 2 mm and a maximum temporal resolution of {Delta}t Asymptotically-Equal-To 2 {mu}s (470 kHz) are possible for the first time. The diagnostic setup at TEXTOR is presented. The newly developed injection system and its theoretical bases are discussed. The applicability of the stationary collisional-radiative model as basis of the line-ratio technique is shown. Finally, an example of a fluctuation analysis demonstrating the unique high temporal and spatial resolution capabilities of this new diagnostic is presented.
- OSTI ID:
- 22093639
- Journal Information:
- Review of Scientific Instruments, Vol. 83, Issue 6; Other Information: (c) 2012 EURATOM; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
BEAMS
CONFINEMENT
DENSITY
ELECTRON DENSITY
ELECTRON TEMPERATURE
FLUCTUATIONS
GAS INJECTION
HELIUM
ION TEMPERATURE
MAGNETIC FIELDS
NOZZLES
PHOTOMULTIPLIERS
PLASMA
PLASMA DENSITY
PLASMA DIAGNOSTICS
SENSITIVITY
SPATIAL RESOLUTION
SUPERSONIC FLOW
TEMPERATURE MEASUREMENT
TEXTOR TOKAMAK