Search

We developed and installed an electron cyclotron emission radiometer for taking measurements of Korea Superconducting Tokamak Advanced Research (KSTAR) plasma. In order to precisely measure the absolute value of electron temperatures, a calibration measurement of the whole radiometer system was performed, which confirmed that the radiometer has an acceptably linear output signal for changes in input temperature. It was also found that the output power level predicted by a theoretical calculation agrees with that obtained by the calibration measurement. We also showed that the system displays acceptable noise-temperature performance around 0.23 eV. [ABSTRACT FROM AUTHOR]

A new electron cyclotron emission (ECE) diagnostics system was installed for the Second Korea Superconducting Tokamak Advanced Research (KSTAR) campaign. The new ECE system consists of an ECE collecting optics system, an overmode circular corrugated waveguide system, and 48 channel heterodyne radiometer with the frequency range of 110-162 GHz. During the 2 T operation of the KSTAR tokamak, the electron temperatures as well as its radial profiles at the high field side were measured and sawtooth phenomena were also observed. We also discuss the effect of a window on in situ calibration. [ABSTRACT FROM AUTHOR]

A new probe set, called the Gundestrup-emissive-triple (GET) probe, is developed to measure the rotational velocity, plasma potential, electron temperature, and plasma density profiles simultaneously in Hanbit mirror device. The GET probe system is composed of the Gunderstrup, an emissive, and a triple probe installed in one boron nitride probe holder, which is attached on the fast scanning injection system. Rotational and parallel flow velocities are deduced from the measurement of Gundestrup probe by using fluid and kinetic theories for unmagnetized and magnetized plasmas. The E×B drift velocity is also deduced from the measurement of plasma potential by an emissive probe. Electron temperature and plasma density variations are measured by a triple probe. Applicability of various theories will be addressed. [ABSTRACT FROM AUTHOR]

The conceptual design and theory of diagnostics to measure electron temperature and density fluctuations using electron cyclotron emission (ECE) was proposed and a new, single-sightline ECE system with the heterodyne radiometer has been built for TEXT-U. This ECE system was designed to employ auto- and cross-correlation techniques. Calculations indicate that fluctuations as small as 0.2% in amplitude can be achieved from auto-correlation of the ECE signal. The cross-correlation technique, however, must be used to resolve the fluctuations in frequency. Auto- and cross-correlation between optically thick ECE channels will be used for our initial approach to electron temperature fluctuation measurement with the single-sightline ECE system. A description of the TEXT-U ECE system, investigation of the feasibility of this measurement, and the initial results of test, calibration, and operation are presented. [ABSTRACT FROM AUTHOR]

Abstract: The neutral beam injection (NBI) system was designed to provide plasma heating and current drive for high performance and long pulse operation of the Korean Superconducting Tokamak Advanced Research (KSTAR) device using two co-current beam injection systems. Each neutral beam injection system was designed to inject three beams using three ion sources and each ion source has been designed to deliver more than 2.0MW of deuterium neutral beam power for the 100-keV beam energy. Consequently, the final goal of the KSTAR NBI system aims to inject more than 12MW of deuterium beam power with the two NBI for the long pulse operation of the KSTAR. As an initial step toward the long pulse (∼300s) KSTAR NBI system development, the first neutral beam injection system equipped with one ion source was constructed for the KSTAR 2010 campaign and successfully commissioned. During the KSTAR 2010 campaign, a MW-deuterium neutral beam was successfully injected to the KSTAR plasma with maximum beam energy of 90keV and the L-H transition was observed with neutral beam heating. In recent 2011 campaign, the beam power of 1.5MW is injected with the beam energy of 95keV. With the beam injection, the ion and electron temperatures increased significantly, and increase of the toroidal rotation speed of the plasma was observed as well. This paper describes the design, construction, commissioning results of the first NBI system leading the successful heating experiments carried in the KSTAR 2010 and 2011 campaign and the trial of 300-s long pulse beam extraction. [Copyright &y& Elsevier]