Back to Search
Start Over
Profile measurements in the plasma edge of mega amp spherical tokamak using a ball pen probe
- Source :
- Review of Scientific Instruments
- Publication Year :
- 2015
-
Abstract
- The ball pen probe (BPP) technique is used successfully to make profile measurements of plasma potential, electron temperature and radial electric field on the Mega Amp Spherical Tokamak (MAST). The potential profile measured by the BPP is shown to significantly differ from the floating potential both in polarity and profile shape. By combining the BPP potential and the floating potential the electron temperature can be measured, which is compared with the Thomson scattering (TS) diagnostic. Excellent agreement between the two diagnostics is obtained when secondary electron emission is accounted for in the floating potential. From the BPP profile an estimate of the radial electric field is extracted which is shown to be of the order ~1kV/m and increases with plasma current. Corrections to the BPP measurement, constrained by the TS comparison, introduce uncertainty into the ER measurements. The uncertainty is most significant in the electric field well inside the separatrix. The electric field is used to estimate toroidal and poloidal rotation velocities from ExB motion. This paper further demonstrates the ability of the ball pen probe to make valuable and important measurements in the boundary plasma of a tokamak.
- Subjects :
- Materials science
Tokamak
Thomson scattering
Plasma
Spherical tokamak
01 natural sciences
010305 fluids & plasmas
Computational physics
law.invention
Physics::Plasma Physics
law
Electric field
Secondary emission
0103 physical sciences
Electron temperature
Ball-pen probe
010306 general physics
Instrumentation
Subjects
Details
- ISSN :
- 10897623
- Volume :
- 86
- Issue :
- 2
- Database :
- OpenAIRE
- Journal :
- The Review of scientific instruments
- Accession number :
- edsair.doi.dedup.....c49971c7246944d01a1621a682bb6c5d