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The first plasma with target values of the plasma current and the pulse duration was finally achieved on June 13, 2008 in the Korea Superconducting Tokamak Advanced Research (KSTAR). The diagnostic systems played an important role in achieving successful first plasma operation for the KSTAR tokamak. The employed plasma diagnostic systems for the KSTAR first plasma including the magnetic diagnostics, millimeter-wave interferometer, inspection illuminator, Hα, visible spectrometer, filterscope, and electron cyclotron emission (ECE) radiometer have provided the main plasma parameters, which are essential for the plasma generation, control, and physics understanding. Improvements to the first diagnostic systems and additional diagnostics including an x-ray imaging crystal spectrometer, reflectometer, ECE radiometer, resistive bolometer, and soft x-ray array are scheduled to be added for the next KSTAR experimental campaign in 2009. [ABSTRACT FROM AUTHOR]

A simple single-channel horizontal millimeter-wave interferometer has been designed for plasma electron density measurements on the Korea Superconducting Tokamak Advanced Research (KSTAR). To measure line integrated plasma densities of 2 × 10[sup 19] m[sup -2] in the initial phase of the KSTAR, Gunn oscillator frequency of 280 GHz has been chosen to optimize errors due to both vibration on the beam path and refraction in the plasma. To reduce the free propagation length of the probing beam and to obtain small beam width on the vacuum windows, a retractable cassette system for deep positioning of the diagnostic system has been designed, where microwave parts are located as close as possible to the tokamak with a shielding box. A beam focusing system with concave reflecting mirrors has been designed on the cassette and on the inner wall of the tokamak to reduce beam losses and to minimize beam width in the plasma. The estimated total transmission loss is about 25 dB, and beam widths are reduced significantly in the range of 20-50 mm. [ABSTRACT FROM AUTHOR]

The diamagnetic effect is measured by using the diamagnetic loop with a compensation loop in the central cell of the Hanbit magnetic mirror device. To ensure reliable measurement, the influence of nearby conductors on the diamagnetic loop signal is investigated, and the output voltages during a pulsed vacuum field are measured to calibrate the loops installed inside the central cell. The diamagnetic measurement is carried out during rf discharges with a frequency of 3.75 MHz and heating power of up to 150 kW. In the measurement, the vacuum field of 0.126 T is applied in the central cell. The results from the experimental measurements are presented. © 2001 American Institute of Physics. [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]

Describes a method of measuring Q of a two port cavity resonator by scattering parameters. Use of a lumped equivalent circuit model as a function of cavity parameters; Additional information such as the coupled power ratio provided by the two port measurement, which is one of the important parameters for the beam-accelerating cavities.

We report on the design and characterization of a cold atom source for strontium (Sr) based on a two-dimensional magneto-optical trap (MOT) that is directly loaded from the atom jet of a dispenser. We characterize the atom flux of the source by measuring the loading rate of a three-dimensional MOT. We find loading rates of up to 10 8 atoms per second. The setup is compact, easy to construct, and has low power consumption. It addresses the longstanding challenge of reducing the complexity of cold beam sources for Sr, which is relevant for optical atomic clocks, quantum simulation, and computing devices based on ultracold Sr.

The charge exchange spectroscopy (CES) system including collection assemblies, lens design, and cassettes for the KSTAR experiment was installed to obtain profiles of the ion temperature and the toroidal rotation velocity from charge exchange emission between plasma ions and beam neutrals near the plasma axis by using a modulated neutral beam and a background system. We can measure the charge exchange spectra of an impurity line such as the 529 nm line of carbon VI to get ion temperature and rotation profiles in KSTAR. The CES and background systems will have absolute intensity and spectral calibrations using a calibrated source and various spectral lamps. The calibration was done inside the tokamak after all CES systems are installed and the optical systems are slid into the cassettes. This requires that the diagnostic systems are installed near the vacuum vessel inside the cryostat maintaining the superconducting state of the superconducting coils. Repeated spectral calibrations of the spectrometer and charge coupled device for CES will be made in the diagnostic room during the experimental campaign. We show a detailed description of the KSTAR CES system, how to calibrate, and the results of calibration.

Plasma experiments on KSTAR are scheduled to start up this year (2008). We have developed an electron cyclotron emission (ECE) radiometer to measure the radial electron temperature profiles in KSTAR experiments. The radiometer system consists, briefly, of two downconversion stages, amplifiers, bandpass filter banks, and video detectors. These components are made commercially or developed in house. The system detects ECE power in the frequency range from 110 to 196 GHz, the detected signal being resolved by means of 48 frequency windows. Before installation of this system on KSTAR, we installed a part of this system on large helical device (LHD) to study the system under similar plasma conditions. In this experiment, the signal amplitude, considered to be proportional to the electron temperature, is measured. The time-dependent traces of the electron temperature measured by this radiometer are in good agreement with those provided by the LHD Michelson spectrometer. The system noise level which limits the minimum measurable temperature (converted to the electron temperature) is about 30 eV.

A Multi-Purpose Plasma (MP(2)) facility has been renovated from Hanbit mirror device [Kwon et al., Nucl. Fusion 43, 686 (2003)] by adopting the same philosophy of diversified plasma simulator (DiPS) [Chung et al., Contrib. Plasma Phys. 46, 354 (2006)] by installing two plasma sources: LaB(6) (dc) and helicon (rf) plasma sources; and making three distinct simulators: divertor plasma simulator, space propulsion simulator, and astrophysics simulator. During the first renovation stage, a honeycomblike large area LaB(6) (HLA-LaB(6)) cathode was developed for the divertor plasma simulator to improve the resistance against the thermal shock fragility for large and high density plasma generation. A HLA-LaB(6) cathode is composed of the one inner cathode with 4 in. diameter and the six outer cathodes with 2 in. diameter along with separate graphite heaters. The first plasma is generated with Ar gas and its properties are measured by the electric probes with various discharge currents and magnetic field configurations. Plasma density at the middle of central cell reaches up to 2.6 x 10(12) cm(-3), while the electron temperature remains around 3-3.5 eV at the low discharge current of less than 45 A, and the magnetic field intensity of 870 G. Unique features of electric property of heaters, plasma density profiles, is explained comparing with those of single LaB(6) cathode with 4 in. diameter in DiPS.