Premium
Electric Probe Measurements at Edge Region During H‐Mode Discharges in KSTAR
Author(s) -
Bak J.G.,
Oh Y.S.,
Kim H.S.,
Hahn S.H.,
Yoon S.W.,
Jeon Y.M.,
Xiao W.W.,
Ko W.H.,
Kim W.C.,
Kwak J.G.,
Woo H.J.,
Chung K.S.
Publication year - 2013
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.201310012
Subject(s) - kstar , langmuir probe , divertor , atomic physics , plasma , saturation current , electron temperature , plasma diagnostics , ion , tokamak , electron density , saturation (graph theory) , materials science , physics , spectral line , plasma parameters , voltage , nuclear physics , mathematics , quantum mechanics , combinatorics , astronomy
Electrical probe measurements are carried out at the scrape‐off‐layer (SOL) and divertor regions in order to investigate the characteristics of edge plasmas during H‐mode discharges in the Korea Superconducting Tokamak Advanced Research (KSTAR) device. Radial profiles of plasma parameters such as electron temperature T e , plasma density n e , and parallel flow velocity v ‖ are measured by using a fast reciprocating Langmuir probe assembly (FRLPA) at the SOL region. From the FRLPA measurements, it is found that the decay length of temperature λ Te and that of density λ ne are 2 ∼ 4 cm and 1 ∼ 3 cm, respectively. The magnitude of v ‖ near the last closed flux surface (LCFS) is 4 ∼ 15 km/s. The radial flux due to edge turbulence at the SOL region is investigated by using spectra analysis on electrostatic fluctuation levels such as ion saturation current Ĩ is and floating potential $ \tilde{\rm V}_f$ obtained from the FRLPA measurement. The value of the flux is estimated as ∼ 10 20 particle m −2 s −1 near the LCFS. The poloidal distribution of the ion saturation current density j is is measured by fixed edge Langmuir probe array (ELPA) at the divertor region, and it is found that the positions of strike points from the ELPA measurement agree well with those reconstructed from the EFIT result using magnetic diagnostic data. From the spectrum analysis on the ELPA measurements at the divertor region during edge localized modes (ELMs) control in the H‐mode discharges, it is observed that the magnitude of $ \tilde{\rm j}_{is}$ ( ω ) near strike point decreases when the ELMs are suppressed or mitigated (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)