Slide 1

Measurements with the KSTAR Beam Emission Spectroscopy diagnostic system Mt Lampert Wigner Research Centre for Physics Hungarian Academy of Sciences Budapest, Hungary E-mail: lampert.mate@wigner.mta.hu 3rd FUSENET PhD event - 2013. 06. 25. Mt Lampert Overview of the final Beam Emission Spectroscopy Diagnosic on KSTAR

Slide 2

Introduction to BES 2 Plasma transport is dominated by turbulence causing fluctuations in plasma parameters Beam Emission Spectroscopy (BES) is a suitable method for measuring fluctuations: The plasma is being heated by the Neutral Beam Injection (NBI) The particles of the beam are excited and emit light The intensity of the light is roughly proportional to the plasma density By measuring the light intensity, one can get information about turbulence From the movement of turbulence eddies, flow velocity can be determined Two important design constraints: Sufficient Doppler-shift (separation from edge D ) View along field lines (spatial resolution) 3rd FUSENET PhD event - 2013. 06. 25. Mt Lampert Overview of the final Beam Emission Spectroscopy Diagnosic on KSTAR Schematic view of a BES system

Slide 3

BES diagnostic setup 3 Design aspects: Direct imaging from plasma to multi-channel detector Combined system for HBES and LiBES measurements Wavelength: H: ~662nm (Doppler shifted H ), Li:~670nm APDCAM (Avalanche Photo Diode Camera): 4 x 8 channel array @ 2.000.000 frame/sec 1cm by 1cm per channel spatial resolution 4cm x 8cm of the plasma is measured at one shot Continuously adjustable from r/a = 0.1 to r/a = 1 CCD camera: inter-shot spatial calibration, 100Hz beam imaging, full minor radius, 640x480 Lithium beam density profile measurements Novel design features of the system: Heatable and rotateable filter for Wavelength tuning Filter changer for Lithium and Deuterium beam measurements Rotateable APDCAM for horizontal (4x8) and vertical (8x4) measurement Deuterium Beam APDCAM Periscope in M-port Tilting mirror at two angles CCD camera 3rd FUSENET PhD event - 2013. 06. 25. Mt Lampert Overview of the final Beam Emission Spectroscopy Diagnosic on KSTAR

Slide 4

The BES system Rotatable mirror CCD arm Inside M port Outside Filter APDCAM Plasma Prism Front mirror APDCAM Stepmotor for mirror rotation To CCD 3rd FUSENET PhD event - 2013. 06. 25. Mt Lampert Overview of the final Beam Emission Spectroscopy Diagnosic on KSTAR 4 BES tower BES installed in M port

Slide 5

Measurement possibilities 5 The BES system was operated by me during the 1000 shots of the 2012 campaign The system is capable of measuring: Turbulence Amplitude, wavelength Poloidal velocity 3D fluctuation together with Electron Cyclotron Emission imaging Signals are analyzed through Fourier / correlation methods During steady state plasma Radial density profile measurement (when NBI is modulated) Measured signal for shot 7177 3rd FUSENET PhD event - 2013. 06. 25. Mt Lampert Overview of the final Beam Emission Spectroscopy Diagnosic on KSTAR

Slide 6

Turbulence detection 6 Fluctuation level and noise level r/a=0.65 r/a=0.8 r/a=0.85r/a=1 Separatrix Core measurement: (r/a~0.7-0.8) SNR 60 Fluctuation amplitude is low Around 1 - 1.5% Noise level is 1.5 times higher then fluctuation Turbulence is hard to detect Edge measurement: (r/a ~ 0.9-1) SNR 45 Fluctuation amplitude is higher Around 3 - 4% Noise level is around the fluctuation level at channel 3 Turbulence can be detected Background fluctuation (