R. Pánek

7006809441

Publications - 12

Overview of the COMPASS results

W. Bin K. Bogár P. Bilkova P. Bohm O. Bogár I. Borodkina E. Gauthier S. Brezinsek P. Buratti J. Čaloud None Fuková J. Gerardin K. Kovarik J. P. Gunn M. Jirsa P. Junek A. Kallenbach O. Kovanda M. Gobbin G. Grenfell Y. Gribov N. Lemoine X. Litaudon Y. Q. Liu I. Mysiura D. I. Naydenkova F. Napoli J. K. Park N. Patel P. Pavlo M. Poradzinski J. Preinhaelter A. Prishvitsin A. Podolnik D. Réfy R. A. Pitts R. Roccella N. C. Logan T. Loarer A. Loarte P. Lourenco A. Casolari J. Adámek J. Horacek O. Grover R. Dejarnac J. Cavalier O. Ficker M. Hron M. Komm E. Macúšová C. Castaldo J. Čečrdle J. Čeřovský E. Matveeva R. Pánek M. Peterka J. Seidl D. Cipciar S. Entler M. Farník H. Fernandes M. Dimitrova I. Ďuran D. Fridrich M. Grof L. Kripner A. Devitre L. Krlín P. Kulhánek M. Lehnen S. Lukes T. Markovic P. Mácha A. Marin Roldan M. Rabinski J. Matějíček J. Mlynar D. Sestak G. Mazzitelli P. Hacek J. Krbec F. Brochard M. Berta A. Bencze D. Tskhakaya V. Yanovskiy F. J. Artola S. Atikukke P. Barton J. Havlicek A. Havranek C. Hidalgo K. Hromasová O. Hronova M. Iafrati N. Isernia F. Jaulmes M. Imrišek M. Jeřáb

Publication Name: Nuclear Fusion

Publication Date: 2022-04-01

Volume: 62

Issue: 4

Page Range: Unknown

Description:

COMPASS addressed several physical processes that may explain the behaviour of important phenomena. This paper presents results related to the main fields of COMPASS research obtained in the recent two years, including studies of turbulence, L-H transition, plasma material interaction, runaway electron, and disruption physics: Tomographic reconstruction of the edge/SOL turbulence observed by a fast visible camera allowed to visualize turbulent structures without perturbing the plasma. Dependence of the power threshold on the X-point height was studied and related role of radial electric field in the edge/SOL plasma was identified. The effect of high-field-side error fields on the L-H transition was investigated in order to assess the influence of the central solenoid misalignment and the possibility to compensate these error fields by low-field-side coils. Results of fast measurements of electron temperature during ELMs show the ELM peak values at the divertor are around 80% of the initial temperature at the pedestal. Liquid metals were used for the first time as plasma facing material in ELMy H-mode in the tokamak divertor. Good power handling capability was observed for heat fluxes up to 12 MW m-2 and no direct droplet ejection was observed. Partial detachment regime was achieved by impurity seeding in the divertor. The evolution of the heat flux footprint at the outer target was studied. Runaway electrons were studied using new unique systems - impact calorimetry, carbon pellet injection technique, wide variety of magnetic perturbations. Radial feedback control was imposed on the beam. Forces during plasma disruptions were monitored by a number of new diagnostics for vacuum vessel (VV) motion in order to contribute to the scaling laws of sideways disruption forces for ITER. Current flows towards the divertor tiles, incl. possible short-circuiting through PFCs, were investigated during the VDE experiments. The results support ATEC model and improve understanding of disruption loads.

Open Access: Yes

DOI: 10.1088/1741-4326/ac301f

Automatic ELM detection and study of statistical ELM properties by Li-BES on COMPASS

M. Berta P. Hacek J. Krbec M. Szutyányi R. Somers M. Hron R. Pánek A. Bencze V. Weinzettl

Publication Name: 46th Eps Conference on Plasma Physics Eps 2019

Publication Date: 2019-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

No description provided

Open Access: Yes

DOI: DOI not available

Fast density reconstruction of Li-BES signal on the COMPASS tokamak

M. Berta J. Seidl P. Hacek J. Krbec M. Hron R. Pánek

Publication Name: Review of Scientific Instruments

Publication Date: 2018-11-01

Volume: 89

Issue: 11

Page Range: Unknown

Description:

This article describes a fast and automatic reconstruction of the edge plasma electron density from the radiation of energetic Li atoms of the diagnostic beam on the COMPASS tokamak. Radiation is detected by using a CCD camera and by using an avalanche photo-diode system with a temporal resolution of 20 ms and 2 μs, respectively. Both systems are equipped with a 670.8 nm optical filter which corresponds to the lithium 1s22s1-1s22p1 transition. A theoretical model and a data processing procedure of a raw signal to obtain the density profile are described. The reconstruction algorithm provides the absolutely calibrated electron density profiles together with the measurement error estimated from relatively calibrated light profiles; the implementation is performed in Python. Time demanding operations of the code were optimized to provide reconstruction of a single profile within less than 10 ms which makes the code applicable for processing of a large amount of data. Thanks to this calculation speed, it is possible to reconstruct electron density profiles between two consecutive shots on the COMPASS tokamak with 2 μs time resolution.

Open Access: Yes

DOI: 10.1063/1.5049894

Development of an ion beam detector for the atomic beam probe diagnostic

M. Berta G. Anda D. Dunai P. Hacek D. Réfy M. Aradi J. Krbec R. Pánek S. Zoletnik A. Bencze V. Weinzettl J. Stockel

Publication Name: Review of Scientific Instruments

Publication Date: 2018-11-01

Volume: 89

Issue: 11

Page Range: Unknown

Description:

The atomic beam probe diagnostic concept aims at measuring the edge magnetic field and through that edge current distribution in fusion plasmas by observing trajectories of an ion beam stemming from a diagnostic neutral beam. The diagnostic potentially has microsecond scale time resolution and can thus prove to be a powerful option to study fast changes in the edge plasma. A test detector has been installed on the COMPASS tokamak as an extension of the existing lithium beam diagnostic system. It employs a relatively simple concept of an array of conductive detection plates measuring the incident ion current, which is then amplified and converted to a voltage signal. The aim of the test detector is to experimentally examine the idea of the diagnostic and provide background data for design and installation of a final detector. Also, a numerical code based on the CUDA parallel computing platform has been developed for modeling lithium ion trajectories in the given COMPASS plasma discharges. We present the developments of the detector design and test measurements of the diagnostic performed both in a laboratory beam system and on the COMPASS tokamak.

Open Access: Yes

DOI: 10.1063/1.5044529

Statistical analysis of SOL fluctuations on COMPASS tokamak as measured by the Li-BES diagnostic

M. Berta J. Seidl P. Hacek J. Krbec A. Buzás R. Pánek A. Bencze

Publication Name: 45th Eps Conference on Plasma Physics Eps 2018

Publication Date: 2018-01-01

Volume: 2018-July

Issue: Unknown

Page Range: 849-852

Description:

No description provided

Open Access: Yes

DOI: DOI not available

Atomic Beam Probe diagnostic for plasma edge current measurements at COMPASS

M. Berta G. Anda D. Dunai P. Hacek D. Réfy M. Aradi M. Lampert J. Krbec M. Palánkai S. Hegedus B. Leskó J. Kádi D. Nagy R. Pánek S. Zoletnik A. Bencze V. Weinzettl

Publication Name: 45th Eps Conference on Plasma Physics Eps 2018

Publication Date: 2018-01-01

Volume: 2018-July

Issue: Unknown

Page Range: 1028-1031

Description:

No description provided

Open Access: Yes

DOI: DOI not available

Progress in diagnostics of the COMPASS tokamak

P. Bilkova P. Bohm O. Bogár E. Gauthier K. Kovarik J. P. Gunn D. I. Naydenkova A. Podolnik D. Réfy N. Vianello J. Adámek J. Horacek O. Grover R. Dejarnac J. Cavalier O. Ficker M. Hron M. Komm E. Matveeva R. Pánek M. Peterka J. Seidl M. Dimitrova D. Fridrich A. Devitre T. Markovic G. Anda D. Dunai M. Rabinski J. Stockel J. Mlynar R. Paprok K. Mitošinková M. Sos J. Varju M. Tomes M. Varavin P. Hacek J. Krbec R. Gomes M. Berta J. Havlicek A. Havranek T. Krizsanóczi V. Weinzettl P. Vondráček F. Zacek M. Vlainic M. Stano T. Pereira G. P. Ermak J. Zebrowski M. Jakubowski K. Malinowski M. Spolaore J. Zajac A. Silva S. Zoletnik Tsv Popov D. Sarychev M. Imrišek S. Nanobashvili

Publication Name: Journal of Instrumentation

Publication Date: 2017-12-07

Volume: 12

Issue: 12

Page Range: Unknown

Description:

The COMPASS tokamak at IPP Prague is a small-size device with an ITER-relevant plasma geometry and operating in both the Ohmic as well as neutral beam assisted H-modes since 2012. A basic set of diagnostics installed at the beginning of the COMPASS operation has been gradually broadened in type of diagnostics, extended in number of detectors and collected channels and improved by an increased data acquisition speed. In recent years, a significant progress in diagnostic development has been motivated by the improved COMPASS plasma performance and broadening of its scientific programme (L-H transition and pedestal scaling studies, magnetic perturbations, runaway electron control and mitigation, plasma-surface interaction and corresponding heat fluxes, Alfvenic and edge localized mode observations, disruptions, etc.). In this contribution, we describe major upgrades of a broad spectrum of the COMPASS diagnostics and discuss their potential for physical studies. In particular, scrape-off layer plasma diagnostics will be represented by a new concept for microsecond electron temperature and heat flux measurements - we introduce a new set of divertor Langmuir and ball-pen probe arrays, newly constructed probe heads for reciprocating manipulators as well as several types of standalone probes. Among optical tools, an upgraded high-resolution edge Thomson scattering diagnostic for pedestal studies and a set of new visible light and infrared (plasma-surface interaction investigations) cameras will be described. Particle and beam diagnostics will be covered by a neutral particle analyzer, diagnostics on a lithium beam, Cherenkov detectors (for a direct detection of runaway electrons) and neutron detectors. We also present new modifications of the microwave reflectometer for fast edge density profile measurements.

Open Access: Yes

DOI: 10.1088/1748-0221/12/12/C12015

Automatic ELM detection using gSPRT on the COMPASS tokamak

M. Berta M. Szutyányi M. Hron R. Pánek A. Bencze

Publication Name: Fusion Engineering and Design

Publication Date: 2017-11-01

Volume: 123

Issue: Unknown

Page Range: 950-954

Description:

This paper contains the description of the generalized Sequential Probability Ratio Test (gSPRT) method used for automatic ELM detection in different diagnostic signals collected on the COMPASS tokamak. After determination of H-mode region based on Dα signal in a given shot, ELMs are automatically detected in different diagnostic time traces (e.g. magnetic signals and also in Dα signals). The onset time, the maximum location and the peak value, and the duration of each detected ELM is determined. Analyzed diagnostic signals came from different radial positions of the studied plasma volume, thus from arrival times of given ELM into different detectors, the average radial propagation velocity of the ELM event can be also estimated. Comparison of results from gSPRT method with two different, commonly used automatic ELM detection method (threshold technique and correlation based technique) is also reported.

Open Access: Yes

DOI: 10.1016/j.fusengdes.2017.03.025

Contribution to the multi-machine pedestal scaling from the COMPASS tokamak

P. Bilkova P. Bohm O. Bogár D. I. Naydenkova O. Grover M. Hron M. Komm R. Pánek M. Peterka J. Stockel K. Mitošinková M. Sos J. Varju L. Frassinetti M. Aftanas P. B. Snyder E. Stefanikova P. Hacek J. Krbec M. Berta J. Havlicek V. Weinzettl J. Urban P. Vondráček M. Imrišek

Publication Name: Nuclear Fusion

Publication Date: 2017-04-06

Volume: 57

Issue: 5

Page Range: Unknown

Description:

First systematic measurements of pedestal structure during Ohmic and NBI-assisted Type I ELMy H-modes were performed on the COMPASS tokamak in two dedicated experimental campaigns during 2015 and 2016. By adjusting the NBI heating and a toroidal magnetic field, the electron pedestal temperature was increased from 200 eV up to 300 eV, which allowed reaching pedestal collisionality v∗ ped < 1 at q95 ∼3. COMPASS has approached conditions for the Identity experiment done at JET and DIII-D, complementing the range of scanned p∗ ped. The pedestal pressure was successfully reproduced by the EPED model. The dependence of pedestal pressure width on v∗ ped and βpol ped is discussed.

Open Access: Yes

DOI: 10.1088/1741-4326/aa6659

Li-BES detection system for plasma turbulence measurements on the COMPASS tokamak

M. Berta G. Anda D. Dunai P. Hacek D. Réfy A. Kovácsik J. Krbec M. Hron G. Veres R. Pánek S. Zoletnik A. Bencze V. Weinzettl

Publication Name: Fusion Engineering and Design

Publication Date: 2015-10-01

Volume: 96-97

Issue: Unknown

Page Range: 795-798

Description:

A new Li beam emission spectroscopy (Li-BES) diagnostic system with a ∼ cm spatial resolution, and with beam energy ranging from 10 keV up to 120 keV and a 18 channel Avalanche photo diode (APD) detector system sampled at 2 MHz has been recently installed and tested on the COMPASS tokamak. This diagnostic allows to reconstruct density profile based on directly measured light profiles, and to follow turbulent behaviour of the edge plasma. The paper reports technical capabilities of this new system designed for fine spatio-temporal measurements of plasma electron density. Focusing on turbulence-induced fluctuation measurements, we demonstrate how physically relevant information can be extracted using the COMPASS Li-BES system.

Open Access: Yes

DOI: 10.1016/j.fusengdes.2015.06.030

Overview of the COMPASS diagnostics

P. Bilkova P. Bohm D. I. Naydenkova J. Adámek J. Horacek R. Dejarnac M. Hron R. Pánek I. Ďuran G. Anda J. Stockel J. Mlynar D. Sestak M. Aftanas G. Veres F. Janky J. Brotankova R. Melich P. Hacek R. Gomes M. Berta J. Havlicek V. Weinzettl F. Zacek A. Szappanos J. Zajac D. Jares J. Ghosh V. F. Shevchenko R. Scannell M. Walsh H. W. Müller V. Igochine A. Silva M. Manso S. Zoletnik Tsv Popov D. Sarychev V. K. Kiselov S. Nanobashvili

Publication Name: Fusion Engineering and Design

Publication Date: 2011-10-01

Volume: 86

Issue: 6-8

Page Range: 1227-1231

Description:

The COMPASS tokamak, a divertor device with clear H-mode and ITER-relevant geometry, has been re-installed in IPP Prague after its transport from CCFE in UK. The first plasma was achieved in December 2008. Many new diagnostic tools with both high temporal and spatial resolutions have been developed to address the scientific programme of COMPASS focused on H-mode physics and pedestal investigations. In the paper, an overview of existing and in near future planned diagnostics (magnetic, spectroscopy, microwave, probe and beam/particle) on COMPASS is given including their basic technical specifications and achievements. © 2011 EURATOM. Published by Elsevier B.V. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.fusengdes.2010.12.024

EDICAM fast video diagnostic installation on the COMPASS tokamak

M. Berta S. Tulipán A. Szappanos M. Hron G. Veres R. Pánek S. Zoletnik V. Weinzettl J. Stockel

Publication Name: Fusion Engineering and Design

Publication Date: 2010-01-01

Volume: 85

Issue: 3-4

Page Range: 370-373

Description:

A new camera system event detection intelligent camera (EDICAM) is being developed by the Hungarian Association and has been installed on the COMPASS tokamak in the Institute of Plasma Physics AS CR in Prague, during February 2009. The standalone system contains a data acquisition PC and a prototype sensor module of EDICAM. Appropriate optical system have been designed and adjusted for the local requirements, and a mechanical holder keeps the camera out of the magnetic field. The fast camera contains a monochrome CMOS sensor with advanced control features and spectral sensitivity in the visible range. A special web based control interface has been implemented using Java spring framework to provide the control features in a graphical user environment. Java native interface (JNI) is used to reach the driver functions and to collect the data stored by direct memory access (DMA). Using a built in real-time streaming server one can see the live video from the camera through any web browser in the intranet. The live video is distributed in a Motion Jpeg format using real-time streaming protocol (RTSP) and a Java applet have been written to show the movie on the client side. The control system contains basic image processing features and the 3D wireframe of the tokamak can be projected to the selected frames. A MatLab interface is also presented with advanced post processing and analysis features to make the raw data available for high level computing programs. In this contribution all the concepts of EDICAM control center and the functions of the distinct software modules are described. © 2009 Elsevier B.V. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.fusengdes.2009.11.001