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2026 Articolo in rivista open access

Towards large databases analysis for reactors-relevant studies on high electron temperature measurement discrepancy

Senni L. ; Orsitto F. P. ; Giruzzi G. ; Mazon D. ; Mazzi S. ; Fontana M. ; Giovannozzi E. ; Kos D. ; Maslov M. ; Challis C. ; Frigione D. ; Garzotti L. ; Hobirk J. ; Kappatou A. ; Keeling D. ; Lerche E. ; Maggi C. ; Mailloux J. ; Rimini F. ; Van Eester D. ; contributors J.

Accurate electron temperature (Te) measurements are critical for future reactors such as ITER, CFETR, and DEMO, where core T e is expected to exceed 25 keV [1-3]. However, in current tokamaks, core electron temperature measurements become increasingly challenging at high values (typically above 6–7 keV), where discrepancies frequently arise between diagnostics such as Thomson Scattering (TS) and Electron cyclotron emission (ECE). These discrepancies highlight both a diagnostic challenge and an opportunity to deepen the understanding of core plasma physics. Recent studies have provided further insights into these phenomena, clarifying key physical aspects, and yielding more substantial results [4-8]. Nevertheless, a broader experimental database remains essential to validate and support the physical hypotheses developed in recent years. This contribution reports on preliminary results obtained from the analysis of the entire JET-DTE3 dataset, providing a status update on our ongoing research. Specifically, we focus on the methodological advancements and the analytical tools recently developed to manage the unprecedented volume of data within the DTE3 database. This framework enables a deep investigation into the T e discrepancy, marking the first time this phenomenon has been systematically studied across such an extensive and statistically significant dataset. This work is conducted within the framework of the International Tokamak Physics Activity (ITPA) JEX#17 on `High Electron Temperature Measurements', which aims to compare data collected across multiple fusion devices to systematically identify the origin of the observed Te discrepancy.

Analysis and statistical methods Data processing methods Nuclear instruments and methods for hot plasma diagnostics Plasma diagnostics - charged-particle spectroscopy
CNR IRIS
2025 Articolo in rivista metadata only access

Standardizing high electron temperature measurement comparisons: a method for cross-diagnostic and cross-machine analysis

L. Senni ; F. P. Orsitto ; M. Fontana ; S. Mazzi ; E. Giovannozzi ; G. Giruzzi

In tokamaks, measuring electron temperatures in the plasma core may be quite challenging, especially when they exceed 6-8 keV [1]. Discrepancies are detected between the values measured by different diagnostics, such as Thomson Scattering (TS) and Electron Cyclotron Emission (ECE), which are expected to agree. Accurate and reliable determination of electron temperature in high-temperature scenarios, is crucial for the development of future reactors like ITER and Demo (with ITER's core plasma expected to have an electron temperature of about 25 keV) [2], as well as for the Chinese Fusion Engineering Test Reactor (CFETR) [3]), in which discrepancies in electron temperature measurements could be even more pronounced. Resolving this diagnostic issue is crucial because it implies a deep understanding of important aspects of plasma physics in the core and beyond. Recently, further studies on this topic have yielded substantial results and clarified several aspects [9,10,11,12]. Current research focuses on the possible causes of the local non-Maxwellian shape of the electron energy distribution function, which is at the root of these discrepancies [1,4,5,6,7,8,9,10,11,12]. Ongoing research by various groups working on magnetic confinement machines worldwide aims to address this long-standing issue within the framework of an ITPA (International Tokamak Physics Activity) initiative. This paper proposes a method to compare data collected by ECE and TS, which is based upon previously developed techniques for analyzing JET data [1], and is implemented in a dedicated Python code, to tackle issues identified in recent years, while also ensuring the output is comparable across different machines. The goal is to perform comparisons under consistent conditions, irrespective of machine-specific factors such as dimensions, fields, and coordinates. The methods developed and the corresponding implementations in a code, addresses several critical aspects, including the positions of measurements, i.e. the plasma position relative to the diagnostics' lines of sight (LoS), the involved volumes, and other controls to ensure uniformity of results during multi-shot analyses. These controls encompass acquisition rate, data interpolation, and the equilibrium reconstruction codes employed, with the objective of obtaining the best possible comparison between the two diagnostics.

Data processing methods Nuclear instruments and methods for hot plasma diagnostics
CNR IRIS
2025 Articolo in rivista open access

Effects of Kinetic Ballooning Modes on the electron distribution function in the core of high-performance tokamak plasmas

Mazzi S. ; Giruzzi G. ; Camenen Y. ; Dumont R. ; Fontana M. ; de la Luna E. ; Orsitto F. P. ; Senni L. ; Aleynikova K. ; Brunner S. ; Frei B. J. ; Garcia J. ; Zocco A. ; Frigione D. ; Garzotti L. ; Rimini F. ; van Eester D.

This article is dedicated to study the physical causes of a long-standing issue experienced in different tokamak devices throughout the last decades: the observed discrepancies between electron cyclotron emission (ECE) and Thomson Scattering (TS) diagnostic measurements at high temperature in the core tokamak plasmas. A recently developed heuristic model (Fontana et al 2023 Phys. Plasmas 30 122503), tested on an extensive data set from multiple pulses in the frame of recent JET campaigns, showed that such ECE-TS discrepancy could be reconciled by introducing a bipolar perturbation in the electron distribution function. Such a perturbation indeed modifies the EC emission and absorption spectra. Nonetheless, the heuristic model does not provide the physical mechanisms causing such a bipolar perturbation. In this work, detailed gyrokinetic analyses unveil the unexplored wave-particle interaction between electrons and the Kinetic Ballooning Modes (KBMs) in tokamak plasmas. The numerical studies of the core of a selected high-temperature pulse of the JET device revealed that the electron-β was large enough to destabilize KBMs. Such KBMs affect the electron distribution function in momentum space with a characteristic bipolar structure. The position of the bipolar structure in the velocity space is intimately linked to the electron diamagnetic frequency. The amplitude of the perturbation, assessed through nonlinear computations, is shown to be dependent on the amplitude of the KBM-induced turbulent fluxes. Thus, this study demonstrates that KBMs, destabilized by the high-β plasma conditions achieved in the core of high-temperature scenarios, perturb the electron distribution function forming bipolar structures in momentum space and, thereby, modifying the EC spectrum. Therefore, the reported mechanism may represent an intriguing explanation of the ECE-TS measurement discrepancy in the deep core of high-temperature plasmas.

discrepancy ECE-Thomson electron distribution function high-performance fusion plasmas Kinetic Ballooning modes
CNR IRIS
2024 Articolo in rivista open access

Experimental research on the TCV tokamak

Duval B. P. ; Abdolmaleki A. ; Agostini M. ; Ajay C. J. ; Alberti S. ; Alessi E. ; Anastasiou G. ; Andrebe Y. ; Apruzzese G. M. ; Auriemma F. ; Ayllon-Guerola J. ; Bagnato F. ; Baillod A. ; Bairaktaris F. ; Balbinot L. ; Balestri A. ; Baquero-Ruiz M. ; Barcellona C. ; Bernert M. ; Bin W. ; Blanchard P. ; Boedo J. ; Bolzonella T. ; Bombarda F. ; Boncagni L. ; Bonotto M. ; Bosman T. O. S. J. ; Brida D. ; Brunetti D. ; Buchli J. ; Buerman J. ; Buratti P. ; Burckhart A. ; Busil D. ; Caloud J. ; Camenen Y. ; Cardinali A. ; Carli S. ; Carnevale D. ; Carpanese F. ; Carpita M. ; Castaldo C. ; Causa F. ; Cavalier J. ; Cavedon M. ; Cazabonne J. A. ; Cerovsky J. ; Chapman B. ; Chernyshova M. ; Chmielewski P. ; Chomiczewska A. ; Ciraolo G. ; Coda S. ; Colandrea C. ; Contre C. ; Coosemans R. ; Cordaro L. ; Costea S. ; Craciunescu T. ; Crombe K. ; Dal Molin A. ; D'Arcangelo O. ; de Las Casas D. ; Decker J. ; Degrave J. ; de Oliveira H. ; Derks G. L. ; di Grazia L. E. ; Donner C. ; Dreval M. ; Dunne M. G. ; Durr-Legoupil-Nicoud G. ; Esposito B. ; Ewalds T. ; Faitsch M. ; Farnik M. ; Fasoli A. ; Felici F. ; Ferreira J. ; Fevrier O. ; Ficker O. ; Frank A. ; Fransson E. ; Frassinetti L. ; Fritz L. ; Furno I. ; Galassi D. ; Galazka K. ; Galdon-Quiroga J. ; Galeani S. ; Galperti C. ; Garavaglia S. ; Garcia-Munoz M. ; Gaudio P. ; Gelfusa M. ; Genoud J. ; Gerru Miguelanez R. ; Ghillardi G. ; Giacomin M. ; Gil L. ; Gillgren A. ; Giroud C. ; Golfinopoulos T. ; Goodman T. ; Gorini G. ; Gorno S. ; Grenfell G. ; Griener M. ; Gruca M. ; Gyergyek T. ; Hafner R. ; Hamed M. ; Hamm D. ; Han W. ; Harrer G. ; Harrison J. R. ; Hassabis D. ; Henderson S. ; Hennequin P. ; Hidalgo-Salaverri J. ; Hogge J. -P. ; Hoppe M. ; Horacek J. ; Huber A. ; Huett E. ; Iantchenko A. ; Innocente P. ; Ionita-Schrittwieser C. ; Ivanova Stanik I. ; Jablczynska M. ; van Vuuren A. J. ; Jardin A. ; Jarleblad H. ; Jarvinen A. E. ; Kalis J. ; Karimov R. ; Karpushov A. N. ; Kavukcuoglu K. ; Kay J. ; Kazakov Y. ; Keeling J. ; Kirjasuo A. ; Koenders J. T. W. ; Kohli P. ; Komm M. ; Kong M. ; Kovacic J. ; Kowalska-Strzeciwilk E. ; Krutkin O. ; Kudlacek O. ; Kumar U. ; Kwiatkowski R. ; Labit B. ; Laguardia L. ; Laszynska E. ; Lazaros A. ; Lee K. ; Lerche E. ; Linehan B. ; Liuzza D. ; Lunt T. ; Macusova E. ; Mancini D. ; Mantica P. ; Maraschek M. ; Marceca G. ; Marchioni S. ; Mariani A. ; Marin M. ; Marinoni A. ; Martellucci L. ; Martin Y. ; Martin P. ; Martinelli L. ; Martinelli F. ; Martin-Solis J. R. ; Masillo S. ; Masocco R. ; Masson V. ; Mathews A. ; Mattei M. ; Mazon D. ; Mazzi S. ; Mazzi S. ; Medvedev S. Y. ; Meineri C. ; Mele A. ; Menkovski V. ; Merle A. ; Meyer H. ; Mikszuta-Michalik K. ; Miron I. G. ; Molina Cabrera P. A. ; Moro A. ; Murari A. ; Muscente P. ; Mykytchuk D. ; Nabais F. ; Napoli F. ; Nem R. D. ; Neunert M. ; Nielsen S. K. ; Nielsen A. ; Nocente M. ; Noury S. ; Nowak S. ; Nystrom H. ; Offeddu N. ; Olasz S. ; Oliva F. ; Oliveira D. S. ; Orsitto F. P. ; Osborne N. ; Dominguez P. O. ; Pan O. ; Panontin E. ; Papadopoulos A. D. ; Papagiannis P. ; Papp G. ; Passoni M. ; Pastore F. ; Pau A. ; Pavlichenko R. O. ; Pedersen A. C. ; Pedrini M. ; Pelka G. ; Peluso E. ; Perek A. ; Von Thun C. P. ; Pesamosca F. ; Pfau D. ; Piergotti V. ; Pigatto L. ; Piron C. ; Piron L. ; Pironti A. ; Plank U. ; Plyusnin V. ; Poels Y. R. J. ; Pokol G. I. ; Poley-Sanjuan J. ; Poradzinski M. ; Porte L. ; Possieri C. ; Poulsen A. ; Pueschel M. J. ; Putterich T. ; Quadri V. ; Rabinski M. ; Ragona R. ; Raj H. ; Redl A. ; Reimerdes H. ; Reux C. ; Riedmiller M. ; Rienacker S. ; Rigamonti D. ; Rispoli N. ; Rivero-Rodriguez J. F. ; Madrid C. F. R. ; Rueda J. R. ; Ryan P. J. ; Salewski M. ; Salmi A. ; Sassano M. ; Sauter O. ; Schoonheere N. ; Schrittwieser R. W. ; Sciortino F. ; Selce A. ; Senni L. ; Sharapov S. ; Sheikh U. A. ; Sieglin B. ; Silva M. ; Silvagni D. ; Schmidt B. S. ; Simons L. ; Solano E. R. ; Sozzi C. ; Spolaore M. ; Spolladore L. ; Stagni A. ; Strand P. ; Sun G. ; Suttrop W. ; Svoboda J. ; Tal B. ; Tala T. ; Tamain P. ; Tardocchi M. ; Biwole A. T. ; Tenaglia A. ; Terranova D. ; Testa D. ; Theiler C. ; Thornton A. ; Thrysoe A. S. ; Tomes M. ; Tonello E. ; Torreblanca H. ; Tracey B. ; Tsimpoukelli M. ; Tsironis C. ; Tsui C. K. ; Ugoletti M. ; Vallar M. ; van Berkel M. ; van Mulders S. ; van Rossem M. ; Venturini C. ; Veranda M. ; Verdier T. ; Verhaegh K. ; Vermare L. ; Vianello N. ; Viezzer E. ; Villone F. ; Vincent B. ; Vincenzi P. ; Voitsekhovitch I. ; Votta L. ; Vu N. M. T. ; Wang Y. ; Wang E. ; Wauters T. ; Weiland M. ; Weisen H. ; Wendler N. ; Wiesen S. ; Wiesenberger M. ; Wijkamp T. ; Wuthrich C. ; Yadykin D. ; Yang H. ; Yanovskiy V. ; Zebrowski J. ; Zestanakis P. ; Zuin M. ; Zurita M. ; Ricci D.

Tokamak à configuration variable (TCV), recently celebrating 30 years of near-continual operation, continues in its missions to advance outstanding key physics and operational scenario issues for ITER and the design of future power plants such as DEMO. The main machine heating systems and operational changes are first described. Then follow five sections: plasma scenarios. ITER Base-Line (IBL) discharges, triangularity studies together with X3 heating and N2 seeding. Edge localised mode suppression, with a high radiation region near the X-point is reported with N2 injection with and without divertor baffles in a snowflake configuration. Negative triangularity (NT) discharges attained record, albeit transient, βN ∼ 3 with lower turbulence, higher low-Z impurity transport, vertical stability and density limits and core transport better than the IBL. Positive triangularity L-Mode linear and saturated ohmic confinement confinement saturation, often-correlated with intrinsic toroidal rotation reversals, was probed for D, H and He working gases. H-mode confinement and pedestal studies were extended to low collisionality with electron cyclotron heating obtaining steady state electron iternal transport barrier with neutral beam heating (NBH), and NBH driven H-mode configurations with off-axis co-electron cyclotron current drive. Fast particle physics. The physics of disruptions, runaway electrons and fast ions (FIs) was developed using near-full current conversion at disruption with recombination thresholds characterised for impurity species (Ne, Ar, Kr). Different flushing gases (D2, H2) and pathways to trigger a benign disruption were explored. The 55 kV NBH II generated a rich Alfvénic spectrum modulating the FI fas ion loss detector signal. NT configurations showed less toroidal Alfvén excitation activity preferentially affecting higher FI pitch angles. Scrape-off layer and edge physics. gas puff imaging systems characterised turbulent plasma ejection for several advanced divertor configurations, including NT. Combined diagnostic array divertor state analysis in detachment conditions was compared to modelling revealing an importance for molecular processes. Divertor physics. Internal gas baffles diversified to include shorter/longer structures on the high and/or low field side to probe compressive efficiency. Divertor studies concentrated upon mitigating target power, facilitating detachment and increasing the radiated power fraction employing alternative divertor geometries, optimised X-point radiator regimes and long-legged configurations. Smaller-than-expected improvements with total flux expansion were better modelled when including parallel flows. Peak outer target heat flux reduction was achieved (>50%) for high flux-expansion geometries, maintaining core performance (H98 > 1). A reduction in target heat loads and facilitated detachment access at lower core densities is reported. Real-time control. TCV’s real-time control upgrades employed MIMO gas injector control of stable, robust, partial detachment and plasma β feedback control avoiding neoclassical tearing modes with plasma confinement changes. Machine-learning enhancements include trajectory tracking disruption proximity and avoidance as well as a first-of-its-kind reinforcement learning-based controller for the plasma equilibrium trained entirely on a free-boundary simulator. Finally, a short description of TCV’s immediate future plans will be given.

EPFL plasma review SPC TCV
CNR IRIS
2024 Contributo in Atti di convegno restricted access

High beta experiments on JET in preparation of JT60SA

Orsitto F. P. ; Garzotti L. ; Pucella G. ; Gabriellini S. ; Auriemma F. ; Baruzzo M. ; Burckhart A. ; Bernardo J. ; Challis C. ; Dumont R. ; Hawkes N. ; Keeling D. ; King D. ; Mailloux J. ; Patel A. ; Piron C. ; Sozzi C. ; Zotta V. K. ; Senni L.

High beta discharges with dimensionless parameters collisionality (ν*), normalized toroidal Larmor radius (ρ*), and normalized beta (βN) relatively close to the JT-60SA scenarios hybrid and advanced were realized on JET: the JET ρ*=0.04 and bootstrap fraction fBS=0.4 were close to JT60SA values. So the discharges realized on JET are expected having comparable confinement properties as in JT60SA[1]. Since the maximum normalized beta βN_MAX≈ A-1/2 , is slowly dependent on the aspect ratio A, the equilibrium properties at high beta on JET (A=3.1) would not differ in JT60SA(A=2.5). Using the similarity scaling laws [1], JET pulses at BT/Ip (magnetic field/current)=2.4T/1.4MA are ‘similar’, i.e. share confinement and beta behaviour with the JT60SA scenario 5-1 with parameters BT=1.62T, Ip=1.4MA, and auxiliary heating power PAUX_JT60SA >10MW. The JET60SA high beta program can take profit of the high beta JET experiments in particular: i) in the phase of program development at BT=1.6-1.7T at low power to optimize the JT60SA current drive capabilities to get the full current drive , and ii) as a database for the validation of transport models. Strategy of JET experiments was to explore high normalized beta (βN) values, MHD effects at different Ip/BT and find parameters for discharges with mild MHD. Deuterium plasmas were realized in a variant of the hybrid-advanced scenario at toroidal magnetic field BT = 1.7, 2, 2.4 T, plasma current Ip = 1.4 MA, elongation k = 1.6, and high triangularity δ ≈ 0.4, q95=3.5-4.5, and central safety factor q0>1.2 at NBI start, with NBI power PNBI = 16-25 MW, no ICRH. Shots at BT=2.4T were realized in third Deuterium-Tritium (DTE3) campaign. The deuterium dataset is new. Pulses at BT=1.7/Ip=1.4MA are similar to 2014 Hybrid power scan at high δ[2], but there is an extension in the range of NBI power to PNBI=25MW. While pulses at BT=2.4T[3]. are executed at higher q95 with respect to the yr 2014 advanced pulses. Two scans were executed : i) a NBI power scan, affecting βN and ii) a NBI start time scan, affecting the central safety factor q0, which is a key ingredient for MHD stability of the high beta phase. Results of the experiments were: i) Good confinement properties and relatively high βN values; the betaN achievable increases with input power, βN>3.5 for BT/Ip=1.7T/ 1.4MA ; ii) Good control of q0 at start of main heating phase with NBI starting time t0_NBI depending on the toroidal magnetic field value, as investigated in JET hybrid and advanced scenarios; iii) Maximum βN≈ 2.5-2.7 with mild MHD at BT = 2.4 T and q0 > 1 (pulse#103116). Preliminary transport analysis has been done using Bohm-gyroBohm , QuaLiKiz , CDBM codes . The measured ion and electron temperature profiles and neutron fluxes are reproduced by CDBM code at all the magnetic fields. 1.Michele Romanelli and Francesco Paolo Orsitto PPCF 63(2021)125004 2.C Challis et al., Nucl. Fusion 55(2015) 053031 3.J Mailloux et al , 41st EPS Conf. Plasma Physics Berlin 2014 , O4.127. (*) see the author list of ‘Overview of T and D-T results JET with ITER-like wall’ by C Maggi et al. to be published in Nuclear Fusion Special Issue for IAEA FEC23 London 19-21 oct.2023.

Fusion, High Beta, JET, JT60SA
CNR IRIS
2023 Contributo in Atti di convegno restricted access

Study on Differences of ECE and High-Resolution Thomson Scattering temperature measurements in DT (Deuterium-Tritium) plasmas on JET

Orsitto F. P. ; Fontana M. ; Giruzzi G. ; Senni L. ; Dumont R. ; Figini L. ; Kos D. ; Maslov M. ; Mazzi S. ; Schmuck S. ; Sozzi C. ; Challis C. ; Frigione D. ; Garcia J. ; Garzotti L. ; Hobirk J. ; Kappatou A. ; Keeling D. ; Lerche E. ; Maggi C. ; Mailloux J. ; Rimini F. ; van Eester D.

In Deuterium Plasmas differences were detected in JET between electron temperature measurements (Te) made by Electron Cyclotron Emission - Te_ECE - and Thomson Scattering diagnostics systems (Te_TS) [1]. Similar behaviour was found in TFTR [2]. Plasmas heated by ECRH (Electron Cyclotron Heating) in Deuterium on FTU showed T_ECE < T_TS for 8 KeV ≤ Te ≤ 14 keV [3]. These differences can be due to the non-Maxwellian nature of the Electron velocity Distribution Function (EDF) [5,6]. The radiation temperature (Trad) measured by ECE is equal to the Te only for a Maxwellian plasma: being Trad dependent on the derivative of the EDF with respect to perpendicular velocity [5]. This paper describes differences of Te measured by ECE (ECE_MP, Martin-Puplett interferometer) and High-Resolution Thomson Scattering (HRTS) diagnostic. HRTS gives independent information on these differences, having shorter space resolution (2 cm), and faster repetition rate (20 Hz) on a different line of sight (16 cm from the magnetic centre): HRTS measurements confirm the trends observed using LIDAR TS [4,5]. Comparison between HRTS and ECE radiometer measurements is also reported (see sec.3).

CNR IRIS
2021 Articolo in rivista open access

Cherenkov probes and runaway electrons diagnostics

Kwiatkowski R. ; Rabinski M. ; Sadowski M. J. ; Zebrowski J. ; Karpinski P. ; Coda S. ; Agostini M. ; Albanese R. ; Alberti S. ; Alessi E. ; Allan S. ; Allcock J. ; Ambrosino R. ; Anand H. ; Andrebe Y. ; Arnichand H. ; Auriemma F. ; Ayllon-Guerola J. M. ; Bagnato F. ; Ball J. ; Baquero-Ruiz M. ; Beletskii A. A. ; Bernert M. ; Bin W. ; Blanchard P. ; Blanken T. C. ; Boedo J. A. ; Bogar O. ; Bolzonella T. ; Bombarda F. ; Bonanomi N. ; Bouquey F. ; Bowman C. ; Brida D. ; Bucalossi J. ; Buermans J. ; Bufferand H. ; Buratti P. ; Calabro G. ; Calacci L. ; Camenen Y. ; Carnevale D. ; Carpanese F. ; Carr M. ; Carraro L. ; Casolari A. ; Causa F. ; Cerovsky J. ; Chellai O. ; Chmielewski P. ; Choi D. ; Christen N. ; Ciraolo G. ; Cordaro L. ; Costea S. ; Cruz N. ; Czarnecka A. ; Molin A. D. ; David P. ; Decker J. ; De Oliveira H. ; Douai D. ; Dreval M. B. ; Dudson B. ; Dunne M. ; Duval B. P. ; Eich T. ; Elmore S. ; Embreus O. ; Esposito B. ; Faitsch M. ; Farnik M. ; Fasoli A. ; Fedorczak N. ; Felici F. ; Feng S. ; Feng X. ; Ferro G. ; Fevrier O. ; Ficker O. ; Fil A. ; Fontana M. ; Frassinetti L. ; Furno I. ; Gahle D. S. ; Galassi D. ; Galazka K. ; Gallo A. ; Galperti C. ; Garavaglia S. ; Garcia J. ; Garcia-Munoz M. ; Garrido A. J. ; Garrido I. ; Gath J. ; Geiger B. ; Giruzzi G. ; Gobbin M. ; Goodman T. P. ; Gorini G. ; Gospodarczyk M. ; Granucci G. ; Graves J. P. ; Gruca M. ; Gyergyek T. ; Hakola A. ; Happel T. ; Harrer G. F. ; Harrison J. ; Havlickova E. ; Hawke J. ; Henderson S. ; Hennequin P. ; Hesslow L. ; Hogeweij D. ; Hogge J. -P. ; Hopf C. ; Hoppe M. ; Horacek J. ; Huang Z. ; Hubbard A. ; Iantchenko A. ; Igochine V. ; Innocente P. ; Schrittwieser C. I. ; Isliker H. ; Jacquier R. ; Jardin A. ; Kappatou A. ; Karpushov A. ; Kazantzidis P. -V. ; Keeling D. ; Kirneva N. ; Komm M. ; Kong M. ; Kovacic J. ; Krawczyk N. ; Kudlacek O. ; Kurki-Suonio T. ; Kwiatkowski R. ; Labit B. ; Lazzaro E. ; Linehan B. ; Lipschultz B. ; Llobet X. ; Lombroni R. ; Loschiavo V. P. ; Lunt T. ; Macusova E. ; Madsen J. ; Maljaars E. ; Mantica P. ; Maraschek M. ; Marchetto C. ; Marco A. ; Mariani A. ; Marini C. ; Martin Y. ; Matos F. ; Maurizio R. ; Mavkov B. ; Mazon D. ; McCarthy P. ; McDermott R. ; Menkovski V. ; Merle A. ; Meyer H. ; Micheletti D. ; Militello F. ; Mitosinkova K. ; Mlynar J. ; Moiseenko V. ; Cabrera P. A. M. ; Morales J. ; Moret J. -M. ; Moro A. ; Mumgaard R. T. ; Naulin V. ; Nem R. D. ; Nespoli F. ; Nielsen A. H. ; Nielsen S. K. ; Nocente M. ; Nowak S. ; Offeddu N. ; Orsitto F. P. ; Paccagnella R. ; Palha A. ; Papp G. ; Pau A. ; Pavlichenko R. O. ; Perek A. ; Pericoli Ridolfini V. ; Pesamosca F. ; Piergotti V. ; Pigatto L. ; Piovesan P. ; Piron C. ; Plyusnin V. ; Poli E. ; Porte L. ; Pucella G. ; Puiatti M. E. ; Putterich T. ; Rasmussen J. J. ; Ravensbergen T. ; Reich M. ; Reimerdes H. ; Reimold F. ; Reux C. ; Ricci D. ; Ricci P. ; Rispoli N. ; Rosato J. ; Saarelma S. ; Salewski M. ; Salmi A. ; Sauter O. ; Scheffer M. ; Schlatter C. ; Schneider B. S. ; Schrittwieser R. ; Sharapov S. ; Sheeba R. R. ; Sheikh U. ; Shousha R. ; Silva M. ; Sinha J. ; Sozzi C. ; Spolaore M. ; Stipani L. ; Strand P. ; Tala T. ; Biwole A. S. T. ; Teplukhina A. A. ; Testa D. ; Theiler C. ; Thornton A. ; Tomaz G. ; Tomes M. ; Tran M. Q. ; Tsironis C. ; Tsui C. K. ; Urban J. ; Valisa M. ; Vallar M. ; Van Vugt D. ; Vartanian S. ; Vasilovici O. ; Verhaegh K. ; Vermare L. ; Vianello N. ; Viezzer E. ; Vijvers W. A. J. ; Villone F. ; Voitsekhovitch I. ; Vu N. M. T. ; Walkden N. ; Wauters T. ; Weiland M. ; Weisen H. ; Wensing M. ; Wiesenberger M. ; Wilkie G. ; Wischmeier M. ; Wu K. ; Yoshida M. ; Zagorski R. ; Zanca P. ; Zisis A. ; Zuin M.

The beams of fast runaway electrons (RE), which are often produced during tokamak discharges, are particularly dangerous and can induce serious damages of the vacuum vessel and internal components of the machine. The proper and fast diagnostics of RE beams is essential for controlling the discharge, e.g., by early mitigation of disruptions and potentially dangerous RE beams. The diagnostics of RE beams is usually based on measurements of the radiation emitted either by these electrons, or as a result of their interactions with plasma and/or vessel walls. Such a radiation is usually recorded by the means of probes placed outside the vacuum vessel. The method developed by our team is based on the probe located inside the vacuum vessel. The probe can be used to detect highly localized RE bunches and to determine their spatial and temporal characteristics. During last few years, the NCBJ team have developed and used the RE diagnostics based on the Cherenkov effect observed in diamond radiators coupled with fast photomultipliers. During the investigated discharges, the probe was inserted into the vacuum vessel, and its head was placed at the plasma edge, where fast RE are expected. A correlation between signals recorded using our probes and other diagnostics, e.g., hard x-ray signals, was also studied. In this paper, we present recent results of the RE measurements by means of Cherenkov probes, which were performed in the COMPASS and TCV tokamaks.

runaways tokamak cherenkov
CNR IRIS