Wide-field turbulence imaging with beam emission spectroscopy

McKee, G. R.
Fonck, R. J.
Shafer, M. W.
Uzun Kaymak, İlker Ümit
Yan, Z.
Imaging of the size, shape, time-averaged, and time-resolved dynamics of long-wavelength density turbulence structures is accomplished with an expanded, high-sensitivity, wide-field beam emission spectroscopy (BES) diagnostic on DIII-D. A 64-channel BES system is configured with an 8 X 8 grid of discrete channels that image an approximately 7 X 9 cm region at the outboard midplane. The grid covers multiple correlation lengths and each channel shape matches the measured radial-poloidal correlation length asymmetry of turbulent eddies. The wide field 8 X 8 imaging capability allows for sampling of essentially the full two-dimensional spatial correlation function for typical plasma conditions. The sampled area can be radially scanned over 0.4 < r/a < 1, including the core ((n) over tilde /n < 1% ), pedestal, and scrape-off-layer. The resulting time-resolved visualizations of turbulence and flows provide critical data on turbulence dynamics. (C) 2010 American Institute of Physics. [doi:10.1063/1.3495788]


Apertureless scanning near field optical microscope with sub-10 nm resolution
Bek, Alpan; KERN, KLAUS (AIP Publishing, 2006-04-01)
We report on the implementation of a versatile dynamic mode apertureless scanning near field optical microscope (aSNOM) for nanoscopic investigations of optical properties at surfaces and interfaces. The newly developed modular aSNOM optomechanical unit is essentially integrable with a multitude of laser sources, homemade scanning probe microscopes (SPMs) as well as commercially available SPMs as demonstrated here. The instrument is especially designed to image opaque surfaces without a restriction to trans...
Overview of the beam emission spectroscopy diagnostic system on the National Spherical Torus Experiment
Smith, D. R.; Feder, H.; Feder, R.; Fonck, R. J.; Labik, G.; McKee, G. R.; Schoenbeck, N.; Stratton, B. C.; Uzun Kaymak, İlker Ümit; Winz, G. (AIP Publishing, 2010-10-01)
A beam emission spectroscopy (BES) system has been installed on the National Spherical Torus Experiment (NSTX) to study ion gyroscale fluctuations. The BES system measures D-alpha emission from a deuterium neutral heating beam. The system includes two optical views centered at r/a approximate to 0.45 and 0.85 and aligned to magnetic field pitch angles at the neutral beam. f/1.5 collection optics produce 2-3 cm spot sizes at the neutral beam. The initial channel layout includes radial arrays, poloidal arrays...
A highly sensitive atomic force microscope for linear measurements of molecular forces in liquids
PATİL, S; MATEİ, G; DONG, H; HOFFMANN, PM; Karakose, M; Oral, Ahmet (AIP Publishing, 2005-10-01)
We describe a highly improved atomic force microscope for quantitative nanomechanical measurements in liquids. The main feature of this microscope is a modified fiber interferometer mounted on a five axis inertial slider which provides a deflection sensitivity that is significantly better than conventional laser deflection based systems. The measured low noise floor of 572.0 fm/root Hz provides excellent cantilever amplitude resolution. This allows us to operate the instrument far below resonance at extreme...
Ultrafast spectroscopy diagnostic to measure localized ion temperature and toroidal velocity fluctuations
Uzun Kaymak, İlker Ümit; McKee, G. R.; Schoenbeck, N.; Smith, D.; Winz, G.; Yan, Z. (AIP Publishing, 2010-10-01)
A dual-channel high-efficiency, high-throughput custom spectroscopic system has been designed and implemented at DIII-D to measure localized ion thermal fluctuations associated with drift wave turbulence. A large-area prism-coupled transmission grating and high-throughput collection optics are employed to observe C VI emission centered near lambda = 529 nm. The diagnostic achieves 0.25 nm resolution over a 2.0 nm spectral band via eight discrete spectral channels. A turbulence-relevant time resolution of 1 ...
Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at root s=8TeV
Khachatryan, V.; et. al. (IOP Publishing, 2015-08-01)
A description is provided of the performance of the CMS detector for photon reconstruction and identification in proton-proton collisions at a centre-of-mass energy of 8 TeV at the CERN LHC. Details are given on the reconstruction of photons from energy deposits in the electromagnetic calorimeter (ECAL) and the extraction of photon energy estimates. The reconstruction of electron tracks from photons that convert to electrons in the CMS tracker is also described, as is the optimization of the photon energy r...
Citation Formats
G. R. McKee, R. J. Fonck, M. W. Shafer, İ. Ü. Uzun Kaymak, and Z. Yan, “Wide-field turbulence imaging with beam emission spectroscopy,” REVIEW OF SCIENTIFIC INSTRUMENTS, pp. 0–0, 2010, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/34415.