«Association EURATOM / IPP.CR I N S T I T U T E O F P L A S M A P H Y S I C S, v.v. i. ACADEMY OF SCIENCES OF THE CZECH REPUBLIC ANNUAL REPORT ...»
5.3 Spectroscopic diagnostics – a poloidal section of the diagnostic ports of COMPASS suitable for fast spectroscopic detectors such as fast AXUV-based bolometers, semiconductor SXR detectors and visible radiation monitors was chosen with regard to the presence of the two NBI heating systems in the vacuum vessel and a possibility to realize tomographic reconstructions of the selected radiation ranges. The small size of the allocated ports, a large number of the detectors inside them and requirements for cooling during a vessel baking led to an optimization in a choice of the detectors and to an integrated port design. The design including a placement of necessary multi-pin feed-through will be finalized after an access to the COMPASS planned to spring 2008 will be reached and information on available space around the ports will be known. High temporal resolution in combination with good spatial resolution, namely in the pedestal region, will be attained by the recently purchased 6 AXUV20-ELM (IRD Inc.) based arrays of bolometers and 4 LD35-5T-JET-Windowless (Centronic) arrays of the SXR detectors (in a cooperation with V.Igochine, IPP Garching) located inside the diagnostic ports, see Fig. 5.3.1. Visible light will be observed using optical fibers and a spectrometer/photomultipliers located in a diagnostic room.
Appendix – Tokamak COMPASS reinstallation in IPP Prague Fig. 5.3.1 On the left, there are the six AXUV20-ELM (IRD Inc.) based 20-channel arrays of fast bolometers equipped with the ceramic sockets. On the right, there are the four LD35-5TJET-Windowless (Centronic) 35-channel arrays of the soft X-ray detectors.
5.4 Fast visible camera - a cooperation with HAS Association (M.Berta, A.Szappanos) on the implementation of the fast visible camera on COMPASS has been started and the first model of the EDICAM camera with an exposure time up to 20 microseconds was tested on the CASTOR tokamak, according to the contract between IPP Prague and KFKI-RMKI Budapest signed in July
2007. The final hardware design and implementation of the sensor module and the Image Processing and Control Unit (IPCU) together with final tests are planned on 2008.
Fig. 5.4.1 Sequences of the 1280x1024 pixel frames taken by the EDICAM camera during CASTOR tokamak shots with 500 µs (upper frames, original colors) and 20 µs (lower frames, rescaled colormap) exposition time. Dynamically rescaled colormaps are used to visualize details, namely for exposition time shorter than 100 µs.
5.5 Thomson Scattering – the High Resolution Thomson scattering for COMPASS is under design.
Calculations of plasma background contribution to a scattered radiation signal were done and taken into account for selecting the laser parameters. In autumn 2007, an exchange of experts with the TEXTOR tokamak, Forschungszentrum Jϋlich, Germany was organized.
ANNUAL REPORT 2007 ASSOCIATION EURATOM/IPP.CR System parameters relevant to the TS layout on the reinstalled COMPASS tokamak were discussed in detail. Work on a design of the diagnostic set-up is in progress. Namely, the laser part of the
system was specified after calculations and discussions as follows:
• Nd:YAG laser system used at the second harmonic frequency
• energy about 2.5 J per pulse on 532 nm
• pulse length in the range of 10-20 ns
• repetition rate at least 30 Hz Contacts to possible suppliers of the laser system itself were arranged and negotiations will continue in spring 2008. The detection part of TS diagnostics will consist of focusing optics, optical fibers, a spectrometer in Littrow arrangement and ICCD camera, see Fig. 5.5.1. Detailed specifications are on the way in conjunction with experts from the optical workshop of IPP in Turnov.
Fig. 5.5.1 The detection scheme of TS for the COMPASS tokamak.
5.6 Microwave reflectometer - the millimetre-wavelength reflectometer will be constructed for the pedestal electron density measurements on COMPASS in close collaboration with the Associação EURATOM / IST as specified by the contract between Institute of Plasma Physics AS CR, v.v.i.
and CFN/IST on the design and construction of the system consisting of 5 reflectometers in 4 frequency bands. The total frequency range 18-90 GHz will allow measurements of the edge plasma density profile. The reflectometers will have O-mode polarizatiton with the exception of the Kaband (26.5 – 40 GHz), in which both O and X-mode polarizations will be used because of their complementary functions. The scientific exchange between IPP and CFN/IST to accelerate the design phase was realized in autumn 2007. The agreed design of the system includes the technical aspects of the block scheme of the reflectometry electronics, quasi-optical band-combiner and antenna including the positioning in front of the tokamak port – see Fig. 5.6.1 and Fig. 5.6.2. All parts of the reflectometric system will be constructed, assembled and tested by CFN/IST in Lisboa in 2008/09, with the support of microwave engineers from IPP.CR. The deadline for the work is pending on the reply of the manufactures, in particular concerning the development of special Appendix – Tokamak COMPASS reinstallation in IPP Prague components such as the band-combiners/decombiners. By the end of 2007, the offer to collaborate on the project was addressed to the Usikov’s Institute for Radiophysics and Electronics NAS of Ukraine (IRE NASU, Kharkov). At the begining of 2008, the decision regarding which parts of the system would be developed at IRE NASU, will be taken.
5.7 Diagnostic neutral beam – is developed by the Association EURATOM/HAS under the Contract on collaboration signed on July 2007. Modeling of beam-plasma interaction for edge plasma parameters of COMPASS was performed. A design of the atomic beam system - optical layout, detector type, vacuum and control system and the design of the detection system for beam emission spectroscopy is planned on 2008.
5.8 Neutral particle analyser – existing NPA was transported from Culham. The status of key elements (in particular detectors) was checked and found to be satisfactory. The NPA will be put in operation in collaboration with Ioffe Institute, St Petersburg at the end of 2009.
Appendix – Tokamak COMPASS reinstallation in IPP Prague
6. CODAC, INTERLOCK AND IT INFRASTRUCTURE
6.1 CONTROL, DATA ACQUISITION, AND COMMUNICATION SYSTEM (CODAC)A completely new COMPASS CODAC system is being built in close collaboration with the Association Euratom/ IST. The CODAC tasks cover the experiment control, data acquisition and data handling, and operator / user communication environment.
The following CODAC interface will be used: “FireSignal“ [A. Neto et al.: Fusion Engineering and Design 82 (2007) 1359–1364]. Data access will be managed by the “SDAS“ layer [A. Neto: Fusion Engineering and Design 82 (2007) 1315–1320].
The control of slow and long-lasting processes („24 hours / day control“) is ensured by individual
! Control of energetics will be managed by its own control system, which was developed and will be provided by the supplier (ČKD). A communication link with CODAC will secure the exchange of requested and actual values of currents, respectively.
! Cooling water control will be a part of „Measurement and regulation system“, which controls the building systems operation – including the cooling water conditioning and also heating and cooling of the building.
6.1.1 Tasks achieved:
1. CODAC design was evaluated;
2. HW platform for the CODAC nodes was selected, namely the ATCA system [A.J.N. Batista et al.: Rev. Sci. Instrum. 77, 10F527 (2006)] developed at IST Lisbon.
3. We specified the communication protocol to be used between the CODAC and the power supplies, which are delivered together with the Energetics (toroidal field, equilibrium field, magnetizing field, and shaping field power supplies). A controller for the tests of Energetics was designed.
4. communication module between the CODAC and fast amplifiers (feedback) was designed;
5. vacuum system control was designed, incl. a vessel baking module;
6. NBI control requirements were specified for the Call for Tender.
6.1.2 Present status:
1. production of the CODAC node's HW is under way
2. production of the vacuum system controller is under way
3. production of the controller of the fast amplifiers is under way
4. preparation of a controller for tests of the CODAC – Energetics communication is under way 6.1.3 Next activities:
1. installation of the vacuum control system (March 2008)
2. tests of the Energetics system including the communication with CODAC (March 2008)
3. installation and tests of the CODAC nodes (April – June 2008)
4. programming of the control nodes (July – August 2008)
6.2 Interlock 6.2.1 Activities done:
1. control of the access of personnel to the experimental area has been designed;
2. principle design of the central interlock was prepared;
3. interfaces of local interlocks of individual systems were defined;
6.2.2 Present status:
1. the experimental area access system is installed in the building
2. design of the central interlock, connecting the individual systems, is being updated and finalized in details 6.2.3 Next activities:
1. tests of the experimental area access system and adjustment of the access control (February 2008)
2. installation of the central interlock system (April – May 2008)
3. test of the interlock (June 2008)
6.3 IT infrastructure The COMPASS installation and its putting in operation in the new building requests a new IT infrastructure. This task covers the building's network installation, data storage, computational power, and client stations for individual users.
6.3.1 Activities done:
1. design of the IT networks in the new building;
2. specifications for servers for data storage and for user's computation and data evaluation were fixed; a supplier was selected and the HW was ordered.
6.3.2 Present status:
1. installation of the IT networks is close to completion;
2. specifications for the data storage media (hard drives) are fixed, ready for a call for offers of possible suppliers;
3. specifications for the client stations are fixed, request for offers was placed.
6.3.3 Next activities:
1. purchase of the remaining server HW (January 2008);
2. installation and configuration of the servers (January – March 2008);
3. purchase and tests of the client stations (February – April 2008);
4. tests (since March 2008) and full operation of the new IT infrastructure (since May 2008).
Appendix – Tokamak COMPASS reinstallation in IPP Prague
7. FEEDBACK CONTROL A new feedback system is under construction for the plasma control. From the original COMPASSD systems from Culham, only the analog signal integrators will be used. The remaining part of the feedback is being built newly and it is based on a digital approach.
A modelling of the feedback is performed in order to create the algorithms for feedback system. A dynamic simulation of the evolution of the magnetic configuration during a discharge is performed using a non-linear FEM code MAXFEA.
The output of the modelling will be converted to algorithms, which will be programmed to the CODAC nodes. These nodes include ATCA modules, each one with 32 analog input channels, 4 analog output channels, and 8 digital input/output channels connected to a processor. Such set-up allows the implementation of MIMO controllers.
Three identical fast amplifiers are being built in the IPP for the feedback stabilization of the horizontal (1 piece) and vertical (2 pieces in a bridge) plasma positions. The amplifiers are based on MOS transistors, each amplifier has maximum current of 5kA, ±50V voltage, frequency range DCkHz and output impedance of 5 mΩ - 274 mH.
The circuit safety is designed for overcurrent, overvoltage and optical isolation protection inside the energizer that determines the amplifiers inputs. In addition, amplifier zero-output-voltage pre-shot check and another delayed overcurrent protection is put in.
7.1 Activities done:
1. analog integrators were tested (see also Diagnostics section)
2. COMPASS geometry was implemented to MAXFEA and mesh files were created in the feedback modelling;
3. fast amplifiers for the feedback control were designed;
4. cooling of the transistors is designed as passive cooling through heat absorption in attached mass of aluminium blocks;
5. digital PID controller was designed for the control of the fast amplifiers;
6. three energizers for the fast amplifiers (containing pre-amplifier, optical decoupling and protection circuits) were designed.
7.2 Present status:
1. in modelling of the feedback, material description files are being created currently;
2. 3 amplifiers are under construction in IPP: one for the horizontal plasma position stabilization and two (in a bridge) for the vertical stabilization;
3. the energizers are built and ready for testing.
7.3 Next activities:
1. compilation of the magnetising circuit current profile to the MAXFEA code (February 2008);
2. calculation of the feedback model using MAXFEA (February – March 2008);
3. creation of the algorithms from the results of the model (April – June 2008);
4. programming of the model to the control CODAC node (June – July 2008);
5. construction of the amplifiers (till May 2008);
6. tests of the fast amplifiers (May – June 2008);
7. tests debugging of the whole feedback system (July – September 2008).