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Beginning the first plasma discharging experiment of KSTAR since 2008, KSTAR performed the third plasma discharging experiment by 2010. During the experiment of three times, KSTAR OPerator Interface (OPI) programs have been developed for KSTAR operation by itself. OPI programs used in KSTAR were implemented by KSTAR widget plug-in Toolkit (KWT). The KWT means the plug-in library implemented by Qt-based user interface development software. The main purpose of developing the KWT library is to implement full automation libraries having interface with the automated EPICS channel access (CA) guaranteeing the flexibility for requirements of operators. In addition, it has advantages in minimizing human code error and maximizing utilization of the limited human resource. According to the increasing of control systems, a number of OPI servers connected to one EPICS gateway server caused the connection problem and increased the amount of the network data packets. To solve these problems, an algorithm of “CachedChannelAccess” for shared memory base was implemented into an inner logic of the KWT library. KSTAR control system monitoring (CSM) program is one of applications developed by using KWT library. The function of CSM program is to notify alarm to operators by checking health status of every server's network health status and resource (cpu, memory, network packets, disk usage rate and system/user defined process) usage state. Another application is a post-shot sequencing program which is activated after every shot is completed. This application is to display major plasma parameters and diagnostic data in chart form, to save this data to database, and to transfer a chart image file to a web server. This paper describes the technical details how to develop OPI applications which have high productivity using Qt on the EPICS-based control system.

KSTAR is a fully superconducting (SC) tokamak consisting of 30 magnet coils made of Nb 3 Sn and NbTi. To keep the SC magnets at proper operating conditions, all cold components of KSTAR such as the SC bus-lines, current leads, and thermal shields must be maintained at the respective cryogenic temperatures by using a helium refrigeration system (HRS). The main components of the HRS can be classified into the warm compression system (WCS) and the cryogenic systems according to their operating temperature levels. The HRS had been manufactured, installed and commissioned until March 2008 and has been operated for KSTAR campaign since then. In this paper, the result of the commissioning, operation and reliability record of the KSTAR HRS will be presented.

Since the first campaign of KSTAR in 2008, the home-made timing system had run for the synchronized operation of tokamak. The timing board which featured PMC-form factor, giga-bit optical communication, home-made protocol, multi-triggering capability, using GPS time and being integrated to EPICS (Experimental Physics and Industrial Control System), had advantages of compactness, modularity, platform independency and full functionality for the synchronized tokamak operation. However, there was deficiency in timing accuracy resulting from the engagement of software in realization of timing function and timing jitter due to poor isolation in output ports. Moreover, new requirements were on the rise as the plasma pulse length was getting longer and diagnostics operating at the higher frequency were newly installed. In order to meet new requirements and overcome the problems, the new timing board has been developed. As a result, the performance is remarkably enhanced: timing accuracy less than 5 ns, jitter less than 100 ps, 8 configurable multi-triggering sections, provision of maximum 100 MHz sampling clock. The KSTAR timing system upgraded by introducing the new timing board is participating in the 2011 campaign after calibration and consolidating the established timing system. This paper describes design, development and commissioning results of the new KSTAR timing system.

First boronization was performed in KSTAR tokamak during 2009 campaign in order to reduce oxygen impurities and to lower the power loss due to radiation. We report the results from the experiences on carborane during the first boronization in KSTAR. After the boronization, H2O and O2 level in the vacuum vessel are reduced significantly. The characteristics of the deposited thin films were analyzed by variable angle spectroscopic ellipsometry, XPS, and AES. ∼1.78 × 1016 cm−2 s−1 of carbon flux on the wall is estimated by using cavity technique.

First boronization in KSTAR is reported. KSTAR boronization system is based on a carborane (C2B10H12) injection system. The design, construction, and test of the system are accomplished and it is tested by using a small vacuum vessel before it is mounted to a KSTAR port. After the boronization in KSTAR, impurity levels are significantly reduced by factor of 3 (oxygen) and by 10 (carbon). Characteristics of a-C/B:H thin films deposited by carborane vapor are investigated. Re-condensation of carborane vapor during the test phase has been reported.

The supervisory interlock system (SIS), the personal safety interlock (PSI) and the radiation monitoring system (RMS) are the safety and protection system for the KSTAR operations. The supervisory interlock system prevents men and devices from an accident and it protects auxiliary systems and the superconducting tokamak against the propagation hazardous events. SIS is collecting events of the tokamak and auxiliary systems and decides a level of the event and command to stop the actions of local I&C for the KSTAR operation. The local interlock system is self-protecting from local accidents and executing orders from supervisory interlock system. SIS had accomplished its own functions at the first campaign of the KSTAR. Even though several unexpected incidents and mismanagement had occurred, the interlock function had been properly responding. We have test result of the emergency stop function for the superconducting magnet power supplies against accidents. We measured different shutdown time of each magnet power supply, which is about 1 min, but we need to more analysis to the source of delay. We had inserted the current and density fault protection logics to stop the ECH and the ICRF at central control system through the first campaign. The short message system (SMS) had helped to restore fast of faults in local and KSTAR integrated control system (ICS). The processor regular scanning time is about 75 ms that is longer than recommended scanning time of the redundancy system. We had reduced it

During the commissioning of the KSTAR device, electronic logbook has been developed to record participant's opinions regarding experimental procedures and results. The experimental logbook, a kind of the electronic logbooks inserts principal experimental parameters by itself and gets the experimenter's comments. Since it usually takes long time to surf around raw experimental data, a summarized comment on the experimental logbook helps physicists to analyze the results. The operation logbook, the other part of electronic logbook records history about system's abnormality, including their management history. Records on the operation logbook for components provide the criteria to validate the device's stability and the basis to complement the device operation procedure. Since a large majority of readers is interested in the information on the electronic logbook, the data is manipulated to be searched and read on the web-site which is accessible by the authenticated users. The web-site also includes a formatting function to report the logbook data as a document using Java Document Object Model (DOM) and Java Simple API for XML (SAX) API. Because there were difficulties to make an action scenario on the events due to insufficient experience of tokamak operation, it was developed in parallel during the commissioning. By training operators to write comments on every detail of the experimental results and operation events, it could be more valuable data source for the next experiments.

For the 1st plasma operation of the Korea Superconducting Tokamak Advanced Research (KSTAR) in 2008, 11 diagnostic systems had been developed such as five types of magnetic diagnostics, millimeter-wave interferometer, ECE radiometer, visible survey spectrometer, H_alpha monitor, filter scope and visible/H-alpha TVs to measure basic physics data; plasma current, electron density, temperature, plasma image, impurity, and so on. Data acquisition (DAQ) systems for those diagnostics performed signal conditioning, conversion from analog signal to digital signal with specific bit resolution, and data transmission in synchronized manner. A feature of the KSTAR diagnostic DAQ systems is that the systems have been implemented with various platforms for maximum hardware efficiency, future extendibility and adaptability to diagnostic systems. Another feature is that all diagnostic DAQ systems have been integrated into KSTAR central control system with EPICS (Experimental Physics and Industrial Control System) to configure and monitor them. In addition, all diagnostic DAQ systems operate in a synchronized manner by using local timing units (LTU) which are connected to a central timing unit (CTU) in the KSTAR time & synchronization system (TSS) via a dedicated timing network. Finally, diagnostic data generated during a shot are transferred to a centralized storage system using MDSplus (Model Driven System plus) which is an open source tool to be used widely in fusion environment. This paper will present the implementation of heterogeneous KSTAR diagnostic DAQ systems and their operation results.

The construction of the Korea Superconducting Tokamak Advanced Research (KSTAR) device has been completed by August 2007. Key achievements in the KSTAR construction are (i) fabrication process establishment in the Nb3Sn superconducting coils including interface components, (ii) development of magnet structures to resist high magnetic force and thermal loads of TF and PF coils, (iii) accurate assembling of all components using special assembly tools, and (iv) development of ancillary systems including a control system, magnet power supplies, diagnostic systems, heating systems, and cryogenic facility. Device commissioning has been started and the milestone for first plasma discharge is by the end of 2008. The KSTAR operation plan is targeted on the high performance plasma confinement research and long pulse operation achievement using the fully superconducting tokamak device. There is a lot of engineering similarity between KSTAR and ITER, such as using Nb3Sn superconductor for TF and CS magnets. The experience of the KSTAR device could be an important technical basis for the design, procurement, and initial operation of the ITER device, as a role of a ITER pilot device.

Five line integrated spectra are obtained from Hanbit mirror plasma using optical chords installed in the horizontal direction of central cell chamber.In this work, we describe the spectroscopic me...

IR and Raman spectra are measured to elucidate both the conformation and vibrational modes of bis(4,4-dimethyl-2,5-cyclohexadien-1-ylidene) in the fundamental state. It is found that the rule of mu...

The polarized Raman spectra of 9-methylfluoren-9-ol (MFOL) in crystal and in solution are measured and the frequencies and modes are reported along with the analysis procedure. A procedure of assigning the vibrational modes to the polarized Raman bands of a triclinic crystal of MFOL is presented. The assignments have been confirmed by measuring the depolarization ratios from the solution Raman scattering and the infrared spectra, and by the comparison with the Raman bands of fluorene. The frequencies and the intensities of Raman and IR bands are also compared to the fundamentals obtained with conventional ab initio Hartree-Fock and B3LYP density functional theory calculations using a 6-31G∗ basis set.

Cadmium telluride films were grown by an r.f. sputtering technique of deposition of p-type (1 1 1)InSb substrates in the growth temperature range between room temperature and 250°C. Typical thickness of the films was 0.5–1.5 μm. Raman spectra showed, however, that CdTe films deposited at a substrate temperature of about 200°C and an overlayer thickness of about 1 μm have an optimum crystal growth condition. In the case of a thick CdTe layer deposited on InSb substrate (t ≥ 0.5 μm), Raman spectroscopy showed the optical phonon mode of the CdTe films, whereas the mode did not occur for the films with t ≤ 0.5 μm. The formation of an indium telluride interfacial layer was observed. Furthermore, subsequent to annealing, Raman measurement showed that indium telluride interfacial layer was not found, whereas the modes related to the CdTe were observed. Greatest stable was found for t ≥ 0.8 μm at deposition temperatures in the range 150°C to 200°C.

The control of the ratio of hydrogen to the deuterium is one of the very important issues for ion cyclotron range of frequency (ICRF) minority heating as well as the plasma wall interaction in the tokamak. The ratio of hydrogen to deuterium during the tokamak shot was deduced from the emission spectroscopy measurements during the KSTAR 2009 experimental campaign. Graphite tiles were used for the plasma facing components (PFCs) at KSTAR and its surface area exposed to the plasma was about 11 m(2). The data showed that it remained as high as around 50% during the campaign period because graphite tiles were exposed to the air for about two months and the hydrogen contents at the tiles are not fully pumped out due to the lack of baking on the PFC in the 2009 campaign. The validation of the spectroscopy method was checked by using the Zeeman effects and the ratio of hydrogen to the deuterium is compared with results from the residual gas analysis. During the tokamak shot, the ratio is low below 10% initially and saturated after around 1 s. When there is a hydrogen injection to the vessel via ion cyclotron wall conditioning and the boronization process where the carbone is used, the ratio of the hydrogen to the deuterium is increased by up to 100% and it recovers to around 50% after one day of operation. However it does not decrease below 50% at the end of the experimental campaign. It was found that the full baking on the PFC (with a high temperature and sufficient vacuum pumping) is required for the ratio control which guarantees the efficient ICRF heating at the KSTAR 2010 experimental campaign.

Summary form only given, as follows. The Langmuir probe technique has some drawback in applying to electronegative plasma since it is difficult to determine both the positive ion current and negative charge saturation current. The planar probe ion current is modified due to the presence of negative ions. In this study, an inductively coupled oxygen RF plasma is employed as an example of electronegative discharge. Plasma parameters are obtained from Langmuir probe method based on modified Bohm flux theory and from the method based on electron energy distribution function (EEDF) integrals. The EEDF was measured by a double differentiation of the I-V characteristic according to the Druyvesteyn formula. The charged particle densities estimated based on both methods are compared. The effect of the ratio of electron temperature to negative ion temperature on the determination of the charged particle densities is also discussed. It is observed that at low pressure the EEDF is close to a Maxwellian Generally, as the pressure increases, the distributions switch to bi-Maxwellian and to Druyvesteyn, and suggest some depletion of electrons with larger energies.

Summary form only given, as follows. This report describes the engineering design of diagnostic cassette and its optical configuration for bay J for KSTAR. Bay J dedicates to a visible optical diagnostic including visible survey spectrometer, H/spl alpha/gonitor, visible Bremsstrahlung array and visible/H/spl alpha/ TV. This cassette design will be a model case as prototype for some other similar port and can be easily modified to a dedicated diagnostics. This report also describes the principal features of the optical lens design and provides some of the calculations for optical transmission made in defining the main components of the optical design.

The first comprehensive particle balance study is carried out in the KSTAR 2010 campaign with a full graphite first wall and diverted plasmas. The dominant retention is observed during the gas puffing into the plasmas. Statistical analysis shows that deuterium retention is increased with the number of injected particles. Particle balance analysis in the whole campaign shows that the long-term retention ratio is ~21%, and the retention via implantation can be partially recovered by He-glow discharge cleaning (GDC), while long-term retention via co-deposition. The wall pumping capability is decreased with the D2 plasma due to fuel accumulation in the first wall, and He-GDC is effective in recovering the wall pumping. Boronization assisted by the D2 glow discharge using C2B10H12 strongly enhances the wall puffing and leads to negative retentions, but the wall pumping capability is recovered in 2–3 days by He-GDCs. Electron cyclotron resonance heating enhances wall outgassing during the discharge. During a diverted H-mode discharge, the retention rate decreases to a very low value, and a high divertor particle flux of ~1.5 × 1023 D s−1 is observed indicating the strong recycling divertor. The amount of recovered deuterium after discharges mainly depends on the plasma–wall interaction when the plasma is terminated, and disruptive discharges release more particles from the first wall.

An electric resistance of lap joints assembled with Korea Superconducting Tokamak Advanced Research (KSTAR) poloidal field 1 (PF1) superconducting coils and bus lines was measured by 4-wire method with some improvements to reduce induced noise in measurements at cryogenic temperature. Generally, a large current has to flow through the joints in order to measure its resistance by electrical methods; however, an induced voltage generated by a DC power supply is much higher than a voltage drop on the joints. The improved method used a bypass resistor installed in parallel to the DC power supply and the coils in order to naturally reduce ripples of the coil current. Transitional waveforms of the coil current and tap voltages were approximated by non-linear curve fitting with constraints based on an electric circuit equation. The resistance and inductance were evaluated by solving simultaneous equations of an applied voltage on the conductors. The induced noise reduction by this method was helpful to evaluate the joint resistance.

The initial phase wall conditioning in KSTAR is depicted. The KSTAR wall conditioning procedure consists of vessel baking, glow discharge cleaning (GDC), ICRH wall conditioning (ICWC) and boronization (Bz). Vessel baking is performed for the initial vacuum conditioning in order to remove various kinds of impurities including H2O, carbon and oxygen and for the plasma operation. The total outgassing rates after vessel baking in three successive KSTAR campaigns are compared. GDC is regularly performed as a standard wall cleaning procedure. Another cleaning technique is ICWC, which is useful for inter-shot wall conditioning under a strong magnetic field. In order to optimize the operation time and removal efficiency of ICWC, a parameter scan is performed. Bz is a standard technique to remove oxygen impurity from a vacuum vessel. KSTAR has used carborane powder which is a non-toxic boron-containing material. The KSTAR Bz has been successfully performed through two campaigns: water and oxygen levels in the vacuum vessel are reduced significantly. As a result, KSTAR has achieved its first L–H mode transition, although the input power was marginal for the L–H transition threshold. The characteristics of boron-containing thin films deposited for boronization are investigated.

Hydrogen is the main constitute of plasmas in HANBIT magnetic mirror device, therefore, measurement of the emission from excited levels of hydrogen atoms is an important diagnostic tool. From the emissivity of Hα radiation one can derive quantities such as the neutral hydrogen density and the source rate, i.e., the rate at which the plasma protons are replenished by ionization of neutral atoms diffusing into the plasma. The reconstruction of emissivity profiles from Hα radiation measurement is a highly undetermined and ill-posed inversion problem, due to the restricted viewing access, number of chords and the increased noise level. An unbiased and consistent probability theory based approach within the framework of Bayesian inference is provided by the maximum entropy method which is independent of model assumptions, but allows any prior knowledge available to be incorporated. The formalism is applied to the reconstruction of Hα emissivity profiles in HANBIT magnetic mirror device.