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We report the growth of SiC layers on low cost p-type silicon (100 and/or 111) substrates maintained at constant temperature (1050 - 1350oC, ∆T=50oC) in a low pressure chemical vapor deposition reactor. Typical Fourier transform infrared spectrum showed a dominant peak at 800 cm-1 due to Si-C bond excitation. Large area x-ray diffraction spectra revealed single crystalline cubic structures of 3C-SiC(111) and 3C-SiC(200) on Si(111) and Si(100) substrates, respectively. Cross-sectional views exposed by scanning electron microscopy display upto 104 µm thick SiC layer. Energy dispersive spectroscopy of the layers demonstrated stiochiometric growth of SiC. Surface roughness and morphology of the films were also checked with the help of atomic force microscopy. Resistivity of the as-grown layers increases with increasing substrate temperature due to decrease of isolated intrinsic defects such as silicon and/or carbon vacanies having activation energy 0.59 ±0.02 eV.

The extensive design effort for KSTAR has been focused on two major aspects of the KSTAR project mission - steady-state-operation capability and advanced tokamak physics. The steady state aspect of the mission is reflected in the choice of superconducting magnets, provision of actively cooled in-vessel components, and long pulse current drive and heating systems. The advanced tokamak aspect of the mission is incorporated in the design features associated with flexible plasma shaping, double null divertor and passive stabilizers, internal control coils and a comprehensive set of diagnostics. Substantial progress in engineering has been made on superconducting magnets, the vacuum vessel, plasma facing components and power supplies. The new KSTAR experimental facility with cryogenic system and deionized water cooling and main power systems has been designed, and the construction work is under way for completion in 2004.

The Korea Superconducting Tokamak Advanced Research (KSTAR) project is the major effort of the national fusion programme of the Republic of Korea. Its aim is to develop a steady state capable advanced superconducting tokamak to establish a scientific and technological basis for an attractive fusion reactor. The major parameters of the tokamak are: major radius 1.8 m, minor radius 0.5 m, toroidal field 3.5 T and plasma current 2 MA, with a strongly shaped plasma cross-section and double null divertor. The initial pulse length provided by the poloidal magnet system is 20 s, but the pulse length can be increased to 300 s through non-inductive current drive. The plasma heating and current drive system consists of neutral beams, ion cyclotron waves, lower hybrid waves and electron cyclotron waves for flexible profile control in advanced tokamak operating modes. A comprehensive set of diagnostics is planned for plasma control, performance evaluation and physics understanding. The project has completed its conceptual design and moved to the engineering design and construction phase. The target date for the first plasma is 2002.

Reflectometry is currently used to monitor density fluctuations and turbulent correlation lengths in fusion plasmas. Various models have been used to interpret the experimental data and to determine the regimes of validity of the reflectometer fluctuation measurements. Heretofore, these models have not been validated by direct comparison with experiment. In this paper the first comparison between a controlled laboratory experiment and a one‐dimensional numerical model is presented. It is found that the model is unable to predict the observed high degree of spatial localization and dependence on perturbation wave number. The implications of these disagreements are discussed, together with suggestions for their resolution.

Anomalous transport in fusion plasmas remains an enigma requiring explanation. A predictive capability is highly desirable if confinement enhancement regimes such as H mode or super shots are to be extrapolated to the next phase in development of the International Fusion program, epitomized, for example in ITER. Therefore, identification of the role that electrostatic turbulence plays in confinement is a critical issue requiring detailed experimental data capable of testing and challenging existing theoretical models. This article presents microturbulence measurements obtained on the DIII‐D and TEXT tokamaks utilizing heterodyne, far‐infrared collective scattering, and reflectometry techniques. The experimental systems are described on both machines and emphasis placed on results obtained during the L‐H transition, ELM activity, and saturated ohmic operation where ion temperature gradient driven (ITGD) turbulence is theoretically predicted to exist.

Summary form only given. A laser beam passing through plasma deflects due to a change in the line-integrated refractive index, which is attributed to an electron density gradient along the chord. By measuring the deflection angle of the laser beam, the electron density was obtained for an atmospheric pressure microwave-induced torch plasma generated in the ambient air. The diagnostic set-up, consisting of a low power He-Ne laser, a four channel segmented position-sensitive photodiode detector, and some relevant optical components, demands modest requirements of laser quality and optics alignments. The measured electron density was compared with that obtained by optical emission spectroscopy based on the measured Stark broadening width of the Balmer H-beta line emitted from the plasma. Both the multi channel deflection method and the optical emission method showed the same order of magnitude (~1015 cm-3) electron density values. Comparison of the detailed results will be presented.

The Korean Superconducting Tokamak Advanced Research (KSTAR) at the Korea Basic Science Institute in Taejon will be the first Tokamak with an advanced all superconducting magnet system, including toroidal field (TF), poloidal field (PF),and field error correction (FEC) coils. The conductors are all cable-in-conduit (CICC) superconductors with a single conduit similar to those in the International Thermonuclear Experimental Reactor (ITER).

The KSTAR (Korea Superconducting Tokamak Advanced Research) project is the major effort of the Korean National Fusion Program to design, construct, and operate a steady-state-capable superconducting tokamak. The project is led by Korea Basic Science Institute and shared by national laboratories, universities, and industry along with international collaboration. It is in the conceptual design phase and aims for the first plasma by mid 2002. The key design features of KSTAR are: major radius 1.8 m, minor radius 0.5 m, toroidal field 3.5 T, plasma current 2 MA, and flexible plasma shaping (elongation 2.0; triangularity 0.8; double-null poloidal divertor). Both the toroidal and the poloidal field magnets are superconducting coils. The device is configured to be initially capable of 20 s pulse operation and then to be upgraded for operation up to 300 s with non-inductive current drive. The auxiliary heating and current drive system consists of neutral beam, ICRF, lower hybrid, and ECRF. Deuterium operation is planned with a full radiation shielding.

The Korean Superconducting Tokamak Advanced Research device consists of 16 TF coils and 14 PF coils. All TF and PF coils are superconducting. Among them, 16 TF coils and 10 PF coils are made from Nb3Sn and the other 4 coils (PF 6 and 7, up/down) are made from NbTi. It is estimated that total 27 tons of Nb3Sn and 11 tons of NbTi are required for the fabrication of KSTAR magnets. The superconducting 8 mm rods are supplied by Mitsubishi Electric Corporation (MELCO) and Intermagnetics General Corporation (IGC) and processed to the final chromium plated 0.78 mm diameter strands by Nexans Korea and KISWIRE. Currently, about 6 tons of Nb3Sn strands have been produced, and the performance tests for them have been carried out. The specimens for the strand performance tests are taken from the both ends of the strand lot. In this paper, we present the latest test results of the current carrying capacity of non-copper volume, hysteresis loss of non-copper volume and residual resistivity ratio using statistical analysis.

Reflectometry is currently being used to investigate density fluctuations and turbulence in tokamak plasmas. However, there are unresolved questions about the spatial resolution and wave number sensitivity of this diagnostic method which impact the interpretation of the data. These questions are currently being addressed in a cylindrical, pulsed filament discharge plasma where ion acoustic waves (10–100 kHz) are launched toward the incident microwaves. Preliminary data supporting the spatially localized nature of reflectometry are presented. A computational model is also being developed to provide quantitative comparisons with experiment.

Theoretical and experimental studies of plasma diagnostic reflectometry have been undertaken as a collaborative research project between the Lawrence Livermore National Laboratory (LLNL) and the University of California Department of Applied Science Plasma Diagnostics Group under the auspices of the Laboratory Directed Research and Development Program at LLNL. Theoretical analyses have explored the basic principles of reflectometry to understand its limitations, to address specific gaps in the understanding of reflectometry measurements in laboratory experiments, and to explore extensions of reflectometry such as ultra-short-pulse reflectometry. The theory has supported basic laboratory reflectometry experiments where reflectometry measurements can be corroborated by independent diagnostic measurements.