Edge electron density profiles and fluctuations measured by two-dimensional beam emission spectroscopy in the KSTAR

Journal Article · Sat Nov 15 00:00:00 EST 2014 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.4894839· OSTI ID:22303719

Wi, H. M. ^[1]; Zoletnik, S.; Lampert, M. ^[2]; Kovácsik, Ákos ^[3]

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1. National Fusion Research Institute, Daejeon (Korea, Republic of)
2. Wigner RCP Institute for Particle and Nuclear Physics, Budapest (Hungary)
3. Institute of Nuclear Techniques, Budapest Technical University, Budapest (Hungary)

Beam emission spectroscopy (BES) system in Korea Superconducting Tokamak Advanced Research (KSTAR) has recently been upgraded. The background intensity was reduced from 30% to 2% by suppressing the stray lights. This allows acquisition of the relative electron density profiles on the plasma edge without background subtraction from the beam power modulation signals. The KSTAR BES system has its spatial resolution of 1 cm, the temporal resolution of 2 MHz, and a total 32 channel (8 radial × 4 poloidal) avalanche photo diode array. Most measurements were done on the plasma edge, r/a ∼ 0.9, with 8 cm radial measurement width that covers the pedestal range. High speed density profile measurements reveal temporal behaviors of fast transient events, such as the precursors of edge localized modes and the transitions between confinement modes. Low background level also allows analysis of the edge density fluctuation patterns with reduced background fluctuations. Propagation of the density structures can be investigated by comparing the phase delays between the spatially distributed channels.

• OSTI ID: 22303719
• Journal Information: Review of Scientific Instruments, Vol. 85, Issue 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BEAMS
EDGE LOCALIZED MODES
ELECTRON DENSITY
EMISSION SPECTROSCOPY
FLUCTUATIONS
MHZ RANGE
MODULATION
PHOTODIODES
PLASMA
PLASMA CONFINEMENT
PRECURSOR
REPUBLIC OF KOREA
SIGNALS
SPATIAL RESOLUTION
TOKAMAK DEVICES
VISIBLE RADIATION