M. Hron

6701340372

Publications - 16

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

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

Results of Joint Experiments and other IAEA activities on research using small tokamaks

N. Kirneva V. Vershkov M. Sokolov C. Silva D. Valcrcel R. Gonzales A. Fonseca B. Kuteev L. Petrov M. Kolokoltsov J. Herrera M. Nieto-Perez A. Czarnecka A. Talebitaher A. Melnikov P. Khorshid V. Soldatov C. R. Gutierrez Tapia R. Dejarnac P. Balan M. Hron H. Fernandes I. Ďuran D. Dunai J. Stockel J. Brotankova L. A. Berni E. Del Bosco J. Sentkerestiova M. Gryaznevich G. Van Oost E. Dufkova P. Peleman A. Sharnin V. Pavlov J. Ferreira R. Gomes M. Berta V. Weinzettl A. Malaquias B. Tl J. Zajac G. Mank F. J.R. Simes I. El Chama Neto H. Figueiredo N. Dreval D. Nurov A. W. Kraemer-Flecken B. Brotas P. Carvalho S. Zoletnik Y. Kuznetsov L. Ruchko H. Hegazy A. Ovsyannikov R. Coelho A. Duarte J. Santos H. Hegazy G. M. Vorobjev E. Sukhov A. Singh G. Kirnev V. Budaev J. Figueiredo G. Ramos L. I. Krupnik I. Nedzelski A. Neto

Publication Name: Nuclear Fusion

Publication Date: 2009-09-21

Volume: 49

Issue: 10

Page Range: Unknown

Description:

This paper presents an overview of the results obtained during the Joint Experiments organized in the framework of the IAEA Coordinated Research Project on 'Joint Research Using Small Tokamaks' that have been carried out on the tokamaks CASTOR at IPP Prague, Czech Republic (2005), T-10 at RRC 'Kurchatov Institute', Moscow, Russia (2006), and the most recent one at ISTTOK at IST, Lisbon, Portugal, in 2007. Experimental programmes were aimed at diagnosing and characterizing the core and the edge plasma turbulence in a tokamak in order to investigate correlations between the occurrence of transport barriers, improved confinement, electric fields and electrostatic turbulence using advanced diagnostics with high spatial and temporal resolution. On CASTOR and ISTTOK, electric fields were generated by biasing an electrode inserted into the edge plasma and an improvement of the global particle confinement induced by the electrode positive biasing has been observed. Geodesic acoustic modes were studied using heavy ion beam diagnostics on T-10 and ISTTOK and correlation reflectometry on T-10. ISTTOK is equipped with a gallium jet injector and the technical feasibility of gallium jets interacting with plasmas has been investigated in pulsed and ac operation. The first Joint Experiments have clearly demonstrated that small tokamaks are suitable for broad international cooperation to conduct dedicated joint research programmes. Other activities within the IAEA Coordinated Research Project on Joint Research Using Small Tokamaks are also overviewed. © 2009 IAEA, Vienna.

Open Access: Yes

DOI: 10.1088/0029-5515/49/10/104026

Joint experiments on the Tokamaks CASTOR and Ta10

E. Dufkova J. Brotankova M. Berta R. Dejarnac A. Fonseca G. M. Vorobjev A. Talebitaher J. Sentkerestiova B. Tál R. Gonzales V. Soldatov E. Sukhov I. Ďuran I. El Chama Neto C. R.Gutierrez Tapia A. W. Kraemeraflecken J. Ferreira A. Singh H. Hegazy H. Hegazy P. Khorshid L. Ruchko G. Kirnev N. Kirneva E. Del Bosco V. Vershkov A. Malaquias M. Hron B. Kuteev G. Mank M. Gryaznevich L. I. Krupnik V. Budaev A. Ovsyannikov A. Melnikov G. Van Oost M. Sokolov Y. Kuznetsov P. Peleman J. Zajac S. Zoletnik V. Weinzettl J. Stockel

Publication Name: Aip Conference Proceedings

Publication Date: 2008-12-01

Volume: 996

Issue: Unknown

Page Range: 24-33

Description:

Small tokamaks may significantly contribute to the better understanding of phenomena in a wide range of fields such as plasma confiement and energy transport; plasma stability in different magnetic configurations; plasma turbulence and its impact on local and global plasma parameters; processes at the plasma edge and plasmaawall interaction; scenarios of additional heating and nonainductive current drive; new methods of plasma profile and parameter control; development of novel plasma diagnostics; benchmarking of new numerical codes and so on. Furthermore, due to the compactness, flexibility, low operation costs and high skill of their personnel small tokamaks are very convenient to develop and test new materials and technologies. Small tokamaks are suitable and important for broad international cooperation, providing the necessary environment and manpower to conduct dedicated joint research programmes. In addition, the experimental work on small tokamaks is very appropriate for the education of students, scientific activities of postagraduate students and for the training of personnel for large tokamaks. The first Joint (Host Laboratory) Experiment (JE1) has been carried out in 2005 on the CASTOR tokamak at the IPP Prague, Czech Republic. It was jointly organized by the IPPaASCR and KFKI HAC, Budapest, involved 20 scientists from 7 countries and was supported through the IAEA and the ICTP, Trieste. The objective of JE1 was to perform studies of plasma edge turbulence and plasma confinement. Following the success of JE1, JE2 has been performed on Ta10 at RRC "Kurchatov Institute" in Moscow; 30 scientists from 13 countries participated in this experiment. This experiment aimed to continue JE1 turbulence studies, now extending them to the plasma core. Results of JE1 and JE2 will be overviewed and compared. © 2008 American Institute of Physics.

Open Access: Yes

DOI: 10.1063/1.2917019

Joint experiments on small tokamaks: Edge plasma studies on CASTOR

E. Dufkova J. Brotankova M. Berta R. Dejarnac A. Fonseca A. Talebitaher J. Sentkerestiova B. Tál J. Horacek J. Ferrera A. Ossyannikov M. Sokholov I. Ďuran A. Singh H. Hegazy H. Hegazy E. Del Bosco A. Malaquias M. Hron G. Mank M. Gryaznevich G. Van Oost Y. Kuznetsov P. Peleman S. Zoletnik V. Weinzettl J. Stockel

Publication Name: Nuclear Fusion

Publication Date: 2007-12-01

Volume: 47

Issue: 5

Page Range: 378-386

Description:

The 1st Joint (Host Laboratory) Experiment on 'joint research using small tokamaks' was carried out using the IPP Prague experimental facility 'CASTOR tokamak'. The main experimental programme was aimed at characterizing the edge plasma in a tokamak by using different advanced diagnostic techniques. It is widely recognized that characterization of phenomena occurring at the plasma edge is essential for understanding the plasma confinement in a tokamak. The edge plasma in small and large scale experiments has many similar features, and the results obtained through detailed measurements in a small flexible device such as CASTOR are in many aspects still relevant to those in large tokamaks. Therefore, it is expected that the results of this joint experiment will have general validity. The radial and poloidal structure of electrostatic turbulence was characterized. The effects of edge biasing were analysed. Radiation fluctuations and profile measurements were performed using fast bolometry. Plasma position measurements were performed using novel Hall sensors. © 2007 IAEA, Vienna.

Open Access: Yes

DOI: 10.1088/0029-5515/47/5/002

Progress on joint experiments on small tokamaks

E. Dufkova J. Brotankova M. Berta R. Dejarnac A. Fonseca G. Ramos G. M. Vorobjev A. Talebitaher J. Sentkerestiova B. Tál I. El Chama Neto V. Soldatov E. Sukhov I. Ďuran A. W. Kraemer-Flecken J. Ferreira A. Singh H. Hegazy H. Hegazy A. M. Marques Fonseca P. Khorshid C. R. Gutierrez Tapia L. Ruchko G. Kirnev N. Kirneva E. Del Bosco V. Vershkov A. Malaquias M. Hron B. Kuteev G. Mank M. Gryaznevich L. I. Krupnik V. Budaev A. Ovsyannikov A. Melnikov G. Van Oost M. Sokolov Y. Kuznetsov P. Peleman J. Zajac S. Zoletnik V. Weinzettl J. Stockel

Publication Name: 34th Eps Conference on Plasma Physics 2007 Eps 2007 Europhysics Conference Abstracts

Publication Date: 2007-12-01

Volume: 31

Issue: 1

Page Range: 435-438

Description:

No description provided

Open Access: Yes

DOI: DOI not available

The spatial structure of flows, Reynolds stress and turbulence in the CASTOR tokamak

M. Berta R. Dejarnac B. Tál M. Hron J. Zajac S. Zoletnik A. Bencze J. Stockel

Publication Name: 33rd Eps Conference on Plasma Physics 2006 Eps 2006

Publication Date: 2006-12-01

Volume: 2

Issue: Unknown

Page Range: 1452-1455

Description:

No description provided

Open Access: Yes

DOI: DOI not available

Observation of zonal flow-like structures using the autocorrelation-width technique

M. Berta J. Adámek M. Hron S. Zoletnik A. Bencze J. Stockel

Publication Name: Plasma Physics and Controlled Fusion

Publication Date: 2006-04-01

Volume: 48

Issue: 4

Page Range: S137-S153

Description:

This paper presents the first application of the autocorrelation-width technique (Bencze A and Zoletnik S 2005 Phys. Plasmas 12 052323) to detect and characterize the microturbulence-zonal flow system using fluctuating signals ( , ) measured by arrays of single-tip Langmuir probes in the CASTOR tokamak. Radially localized (≈1 cm) random flow structures have been clearly observed with a lifetime of ≈1 ms and a long-range poloidal correlation, extending over at least one-fourth of the poloidal circumference. © 2006 IOP Publishing Ltd.

Open Access: Yes

DOI: 10.1088/0741-3335/48/4/S10

Detection of radially localized and poloidally symmetric structures in the poloidal flow of tokamak plasmas

M. Berta J. Adámek M. Hron S. Zoletnik A. Bencze J. Stockel

Publication Name: 32nd Eps Conference on Plasma Physics 2005 Eps 2005 Held with the 8th International Workshop on Fast Ignition of Fusion Targets Europhysics Conference Abstracts

Publication Date: 2005-12-01

Volume: 3

Issue: Unknown

Page Range: 1994-1997

Description:

No description provided

Open Access: Yes

DOI: DOI not available