Prof.
Young-chul Ghim
(Korea Advanced Institute of Science and Technology)
25/09/2017, 15:20
High-temperature plasmas
POSTER
Reliabilities of electron temperature measurements based on Thomson scattering (TS) systems depend on transmittance of the optical band-pass filters in polychromators. We investigate the system performance as a function of electron temperature to determine reliable range of measurements. To achieve the objective, we build a forward model of the KSTAR TS system, and generate synthetic TS data...
Dr
Hanif Muhammad
(National University of Sciences & Technology, Islamabad, Pakistan)
25/09/2017, 15:22
Low-temperature plasmas
POSTER
Spectroscopic studies of silicon (Si) plasma produced by the fundamental (1064 nm) and second (532 nm) harmonics of an Nd: YAG laser by placing the target material in open air at atmospheric pressure are presented.. The electron temperature measurements have been estimated using the Boltzmann plot method. The electron temperature as a function of laser irradiance (2 x $10^{10}$ to 6.5 x...
Mr
Miroslav Šos
(Institute of Plasma Physics of the CAS, Czech Republic)
25/09/2017, 15:24
High-temperature plasmas
POSTER
Due to the character of the Thomson scattering (TS) process the intensity of the effective
collected signal is reduced by several orders of magnitudes against the probing light source
intensity. Thus, precise spectral and absolute calibrations together with optimised data
processing are indispensable in order to provide reliable and accurate plasma diagnostic.
Since the installation of the...
Dr
Yuan Huang
(Southwestern Institute of Physics)
25/09/2017, 15:26
High-temperature plasmas
POSTER
In recent two years, some efforts have been made to promote the performance of incoherent Thomson scattering (TS) diagnostic on HL-2A tokamak. Step motors are used to adjust the reflecting mirrors and focusing lens of the input laser beam optics, by which it is easy to control the laser beam pass through the narrow throats of the lower and upper closed divertors. Spectral calibration has been...
Prof.
Daniel Den Hartog
(University of Wisconsin-Madison)
25/09/2017, 15:28
High-temperature plasmas
POSTER
A pulse-burst laser system has been built for Thomson scattering on NSTX-U, and is currently being integrated into the NSTX-U Thomson scattering diagnostic system. The laser is Nd:YAG operated at 1064 nm, *q*-switched to produce ≥1.5 J pulses with $\sim$20 ns FWHM. It is flashlamp pumped, with dual-rod oscillator (9 mm) and dual-rod amplifier (12 mm). Variable pulse-width drive of the...
Dr
Joshua Hawke
(Swiss Federal Institute of Technology (Swiss Plasma Center))
25/09/2017, 15:30
High-temperature plasmas
POSTER
The recently completed MST2 upgrade to the Thomson scattering (TS) system on the TCV Tokamak at the Swiss Plasma Center at EPFL was performed. This upgrades aim was to provide an enhanced spatial and spectral resolution while maintaining the high level of diagnostic stability that is required for physics studies of TCV plasmas. In order to improve the spatial resolution of the system, there...
Mr
Young-Gi Kim
(Seoul National University)
25/09/2017, 15:32
Instrumentation development
POSTER
A Nd:YAG laser Thomson scattering (TS) system has been developed on Versatile Experiment Spherical Torus (VEST) for measurement of the electron temperature and density of the core plasmas. To overcome the limitations of relatively low laser energy of 0.6 J/pulse for measuring low electron density of $\sim10^{18}$ m$^{-3}$, the system is delicately designed to improve a signal-to-noise ratio by...
Petr Böhm
25/09/2017, 15:34
High-temperature plasmas
POSTER
The Thomson scattering (TS) diagnostic system on the COMPASS tokamak consists of separate collection optics for core and edge plasma. Till now, the adverse orientation of the viewport available for the edge TS limited the investigated plasma scenarios to those, where H-mode plasma pedestal was possible to be observed. The vacuum vessel port has been recently modified and directed more to the...
Dr
Jong-ha Lee
(NFRI)
25/09/2017, 15:36
High-temperature plasmas
POSTER
Thomson scattering diagnostic is most important diagnostic system in fusion plasma research. This diagnostic system gives reliable electron temperature and density profiles in magnetically confined plasma. In KSTAR tokamak, Q-switched Nd:YAG Thomson system was installed several years ago to measure the electron temperature and density profiles. For the KSTAR Thomson scattering system, a...
Mr
Chris Gowers
(Retired from JET, CCFE, Culham, Oxon, UK), Dr
Hans Salzmann
(Retired from MPI f. Plasmaphysik), Dr
Per Nielsen
(Retired: Consorzio RFX, Padova Italy)
25/09/2017, 15:38
High-temperature plasmas
POSTER
We have shown recently, and in more detail at this conference (Salzmann et al) that the LIDAR approach to ITER core TS measurements requires only two mirrors in the inaccessible port plug area of the machine. This leads to simplified and robust alignment, lower risk of mirror damage by plasma contamination and a much simpler calibration procedure, compared with the awkward and vulnerable...
Mr
Chris Gowers
(Retired from CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB, UK), Dr
Hans Salzmann
(Retired from MPI f. Plasmaphysik, Garching), Dr
Per Nielsen
(Retired: Conzorzio RFX, Padova Italy)
25/09/2017, 15:40
High-temperature plasmas
POSTER
Calibration, after initial installation, of the proposed LIDAR Thomson Scattering System requires no access to the front end and does not require a foreign gas fill for Raman scattering. As already described (Salzmann et al), the variation of solid angle of collection with scattering position is a simple geometrical variation over the unvignetted region. The additional loss over the vignetted...
Mr
Sehyun Kwak
(Korea Advanced Institute of Science and Technology)
25/09/2017, 15:42
High-temperature plasmas
POSTER
Thomson scattering systems to measure electron density and temperature for fusion-grade plasma have usually been based on a collection of polychromators. Such a polychromator-based system increases the number of detected Thomson scattered photons by integrating them in spectral domain, but this results in the loss of detailed spectral information. As the spectral information of Thomson...
Dr
Shinji Yoshimura
(National Institute for Fusion Science)
25/09/2017, 15:44
Low-temperature plasmas
POSTER
We have been developing a new laser spectroscopy technique using a Laguerre-Gaussian (LG) beam, which is known as an optical vortex. One of the characteristics of optical vortices is helical equiphase surfaces associated with orbital angular momentum of light. Existing techniques using a plan-wave laser beam are insensitive to perpendicularly crossing motion of atoms, since they rely on the...
Prof.
Masahiro Hasuo
(Kyoto University)
25/09/2017, 15:46
Low-temperature plasmas
POSTER
Atmospheric-pressure plasmas have been attracting much interest because of their possibility for various applications, such as surface treatment, nano-particle formation and pollution gas processing [1]. One of the methods to generate high-pressure plasmas at moderate voltage is a microhollow cathode discharge. The gas temperature and electron density of microhollow cathode plasmas have been...
Prof.
Kenji Tanaka
(National Institute for Fusion Science)
25/09/2017, 15:48
High-temperature plasmas
POSTER
Collective thomson scattering (CTS) is a powerful diagnostic to measure the bulk and fast ion tempertures, densities and ion density ratios A 77 GHZ CTS system has been developed in LHD with a 1 MW gyrotron for electron heating and succesful results have been obtaned [1,2,3]. Use of the frequency of 77 GHz has an advantage of strong signal but suffers from refraction, which makes adjustment of...
Mr
Oisin McCormack
(RFX - University of Padova)
25/09/2017, 15:50
High-temperature plasmas
POSTER
The depolarisation of the Thomson scattering (TS) radiation, a relativistic effect noticeable only in very high $T_e$ plasmas and never before observed in a fusion machine, is measured for the first time in JET. This depolarisation effect is at the basis of polarimetric TS, an alternative method for the measurement of the plasma electron temperature, suitable for high $T_e$ plasmas such as in...
Alessandro Fassina
(Consorzio RFX-CNR)
25/09/2017, 15:52
Instrumentation development
POSTER
RFX-mod RFP is now under shutdown and it is undergoing a deep modification in the plasma magnetic boundary, with changes in the vacuum vessel, first wall and stabilizing shell. A diagnostics upgrade is also foreseen; in particular, an improvement in the signal level of the main Thomson Scattering Diagnostics becomes crucial for the diagnostic operation in low density RFP and tokamak...
Dr
Yonggao Li
(Southwestern Institute of Physics)
25/09/2017, 15:54
High-temperature plasmas
POSTER
The novel dual-laser based Polarimeter-Interferometer (PIer) scheme, in which the Faraday angle (αF) and electron density (ne) can be simultaneously measured by utilizing two laser sources, has been successfully demonstrated on HL-2A tokamak through upgrading the present Faraday-effect polarimeter. Comparing to the conventional three-wave PIer, dual-laser PIer generates only one intermediate...
Mr
Bart Klarenaar
(Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands)
25/09/2017, 15:56
Low-temperature plasmas
POSTER
Efficient reduction of CO$_2$ to CO is a key step in the process of storing renewable energy in the form of hydrocarbon fuels. This process is believed to be most efficient when selectively exciting the asymmetric-stretch vibration of CO$_2$. We study the temperature dynamics of CO$_2$ by *in situ* rotational Raman spectroscopy in a pulsed glow discharge. The cylindrical plasma reactor (23 cm...
Prof.
Wonho Choe
(Korea Advanced Institute of Science and Technology (KAIST))
25/09/2017, 15:58
Low-temperature plasmas
POSTER
A Hall plasma thruster is a type of electric propulsion that generates thrust by accelerating unmagnetized ions through an electric potential gradient in the axial direction established by azimuthal Hall drift (ExB) electrons within crossed (axial) electric and (radial) magnetic fields. In the Hall thruster plasma study, accurate measurement of the plasma and the ion beam parameters is a key...
