بسمه تعالی. Fast Imaging of turbulent plasmas in the GyM device D.Iraji , D.Ricci , G.Granucci , S.Garavaglia , A.Cremona IFP-CNR-Milan 7 th Workshop on Fusion Data Processing Validation and Analysis Frascati -March 2012. Outlines. Motivations Fast imaging of GyM plasmas
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Fast Imaging of turbulent plasmas in the GyM device
D.Iraji, D.Ricci, G.Granucci, S.Garavaglia, A.Cremona
7th Workshop on Fusion Data Processing Validation and Analysis
Fastimaging of GyM plasmas
Reconstruction of the emissivity profiles
CAS for detection and visualization of plasma structures (a comparisonwith probe measurements)
Basic understanding of fluctuations and turbulence in magnetized plasmas is an important issue for magnetic fusion, as they cause a high degree of particle and energy losses.
A full spatio-temporal imaging system with reasonable resolution in time and space is needed to study plasma turbulence .
A non perturbative approach is fast visible imaging of plasma turbulence. An ultimate goal of plasma imaging is extracting plasma turbulence characteristics from images.
Fast imaging is often used in fusion devices however detailed comparisons with other diagnostics are needed for justification.
Photron ultima APX-RS
Full, 1024 by 1024 pixel resolution, up to 3,000 fps, 10-bit monochrome CMOS sensor with pixels in dimension of 17×17µm
Top recording speed is 250,000 fps
Image memory can be expanded to
facilitate 6 second recordings at 1,000 fps
And 4.2 seconds at 250,000 fps.
Capability of synchronization with the
Other diagnostics such as probes
(error < 100nsec)
Max. gain 10000
Spectral response 185-900 nm
Repetition rate 200kHz
Resolution 38 lp/mm
Electron density profile
Electron Temperature profile
Modular device in which the magnetic
field configuration can be easily modified.
# of Coils 10
Max current 1000 A
Max magnetic field 0.13 T
Cooling water rate 22 l/min
Power supply (d.c.) 1000A/50V
Vacuum chamber (m):
B average ~ 80 mT
2.45 GHz source
Hot filament source
Camera image frame at time t
75000 fps, 4 us exposure time
Reconstructed emissivity profile at time t
U*U =V*V = unitary
V*S *U *I=g
75000 fps, 4 us exposure time
Fluctuation profile of reconstructed emissivity at time t
PSD of the MFL signal
Maximum fluctuations level (MFL)
Z-Scan of PSD
r-Scan of PSD
E×B rotation and Te
2 L = FWHM
V E×B ~ 1km/s, B~80 mT: E~80 V/m
L ~5.5cm, Te~ E L ~ 4.4 eV
E×B is responsible for the rotation of the plasma column
The intensified fast camera is able to image plasma with spatial resolution of 2cm and temporal resolution of 4µs.
.Plasma emissivity profiles are reconstructed using pixel methode and singular value decomposition approach.
Fourier analysis of the reconstructed images show presence of a distinct mode at ~4 kHz which is radially extended between -3cm<r<2 cm and vertically located at the bottom.
CASed images show rotation of the structures associated with the mode due to E×B drift.
Structural analysis of the reconstructed emissivity profiles to estimate plasma transport.
The establishment of comparisons between the experimental plasma transport related to the plasma structures with theoretical predictions and confirmation using probe data.