# D. Kalupin's research while affiliated with Forschungszentrum Jülich and other places

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## Publications (61)

This paper is a written summary of an overview oral presentation given at the 1st Spanish Fusion High Performance Computer (HPC) Workshop that took place on the 27 November 2020 as an online event. Given that over the next few years ITER ²⁴ 24 ITER (‘The Way’ in Latin) is the world’s largest tokamak under construction in the south of France: a magn...

Relativistic runaway electrons are a major concern in tokamaks. The European framework for Integrated Modelling (EU-IM), facilitates the integration of different plasma simulation tools by providing a standard data structure for communication that enables relatively easy integration of different physics codes. A three-level modelling approach was a...

In this paper we present approach taken to run multiple Kepler sessions at the same time. This kind od execution is one of the requirements for the codes developed within EUROfusion. It allows to gain speed and resources. The choice of Integrated Modelling made by the former EFDA ITM-TF and pursued now under EUROfusion WPCD is unique and original:...

In this paper we present an approach taken to run multiple Kepler sessions at the same time. This kind of execution is one of the requirements for Integrated Tokamak Modelling (ITM) platform developed by the Nuclear Fusion community within the context of EUROFusion project [1]. The platform is unique and original: it entails the development of a co...

The European Transport Solver (ETS) has been
developed in the frame of Project 3 of EFDA’s Integrated
Tokamak Modeling Task Force. Several numerical methods have
been implemented in ETS. This paper presents a method of
verification of implemented numerical schemes for the case of
solutions with a transport barrier. A manufactured solution
method fo...

References [59–61] were incorrectly cited in Falchetto G.L. et al 2014 (Nucl. Fusion 54 043018), the corresponding paragraphs on page 14–15 should be replaced by the following:

A selection of achievements and first physics results are presented of the European Integrated Tokamak Modelling Task Force (EFDA ITM-TF) simulation framework, which aims to provide a standardized platform and an integrated modeling suite of validated numerical codes for the simulation and prediction of a complete plasma discharge of an arbitrary t...

The ‘European Transport Simulator’ (ETS) (Coster et al 2010
IEEE Trans. Plasma Sci. 38 2085-92,
Kalupin et al 2011 Proc. 38th EPS Conf. on Plasma Physics (Strasbourg,
France, 2011) vol 35G (ECA) P. 4.111) is the new modular package for 1D
discharge evolution developed within the EFDA Integrated Tokamak
Modelling (ITM) Task Force. It consists of pre...

The achievements and first physics results are presented of the European Integrated Tokamak Modelling Task Force (EFDA ITM-TF) effort, aiming at providing a standardized platform and an integrated modelling suite of validated numerical codes, for the simulation and prediction of a complete plasma discharge in arbitrary tokamaks. The framework devel...

Simulations of JET and AUG HS with the GLF23 model show that the observed core confinement improvement can be partly explained by the beneficial s/q effect on the ITG driven transport while the effect of the ExB shear stabilisation is weaker than in H-mode plasmas. Strong stabilising effect of βe on the ITG turbulence has been found, but the transp...

In order to reduce the heat load to the wall, in particular in the presence of a metallic wall, the radiated fraction is increased by means of impurity seeding. This paper aims at investigating qualitatively the balance between a degradation of the edge confinement and a potential reduction of the core turbulent transport due to the increase of eff...

Abstract
Since the last IAEA Conference JET has been in operation for one year with a programmatic focus on the qualification
of ITER operating scenarios, the consolidation of ITER design choices and preparation for plasma operation with
the ITER-like wall presently being installed in JET. Good progress has been achieved, including stationary ELMy...

The status of the European Transport Solver, a new 1-D core transport code that is being developed by the members of Integrated Modelling Project 3 (“Transport Code and Discharge Evolution”) of the EFDA Task Force on Integrated Tokamak Modelling (ITM), is described. The approach taken by the ITM is to couple codes so that the only exchange is via w...

The European Integrated Tokamak Modelling Task Force (ITM-TF) is developing a new type of fully modular and flexible integrated tokamak simulator, which will allow a large variety of simulation types. This ambitious goal requires new concepts of data structure and workflow organisation, which are described for the first time in this paper. The back...

a b s t r a c t In this contribution, we report on experimental results on edge transport in limiter H-mode plasmas in TEXTOR under the influence of the Dynamic Ergodic Divertor (DED). These plasmas are characterized by a pedestal structure mainly visible in the electron density, resulting in increased electron pressure gradi-ents of up to 30 kPa/m...

In this contribution, we report on experimental results on edge transport in limiter H-mode plasmas in TEXTOR under the influence of the Dynamic Ergodic Divertor (DED). These plasmas are characterized by a pedestal structure mainly visible in the electron density, resulting in increased electron pressure gradients of up to 30 kPa/m over a pedestal...

The 1.5D transport code JETTO (Cenacchi G. and Taroni A. 1988 Rapporto ENEA RT/TIB (88)5) has been applied to model the transition from the low (L) to the high confinement mode (H-mode) in the JET tokamak. Computed values of the critical power, P th , required for the L–H transition on JET are directly compared with experiment (Andrew Y. et al 2006...

Particle and energy transport in the edge transport barrier is analysed in the presence of magnetic field perturbations from external resonant coils successfully used recently for the mitigation of type I edge localized modes (ELMs). The modification of transport due to charged particle and heat flows along perturbed field lines in a small region n...

Argon and neon seeded ITER discharges are numerically simulated by coupling a 1D multifluid model for the plasma core with a 2D model for the SOL-divertor region. The model is fully self-consistent with respect to both the effects of impurities on the α-power level and the interaction between seeded and intrinsic impurities. This interaction leads...

A model to estimate the particle and energy losses caused in tokamaks by type I edge localized modes (ELMs) is proposed. This model is based on the assumption that the increase in transport by ELM is due to flows along magnetic field lines perturbed by ballooning–peeling MHD modes. The model reproduces well the experimentally found variation of los...

Edge pressure profiles can be controlled by the DED in limiter H-mode plasmas. However, no operational window could be found so far where the H-mode pedestal is maintained but the ELMs are suppressed. In the 6/2 base mode configuration the edge pedestal is steadily reduced with increasing perturbation together with ELM size until the plasma is fina...

The RITM transport model allowing for the self-consistent modeling of plasmas with the edge transport barrier has been introduced into the 1.5-D transport code JETTO. The model was calibrated on experimental plasma profiles for the L-mode conditions, when free normalization constants used in the model have been tuned and fixed. Computations done fo...

The measured K α spectra of He-like argon were used to determine the densities of H-, He-and Li-like argon ions in ohmically heated plasmas in the tokamak TEXTOR. The obtained ratio of the densities for the Li-and He-like ions shows a significant deviation from coronal equilibrium. In order to interpret these results numerical modelling of the impu...

A deliberate stochastization of the magnetic field in tokamaks with Ergodic Divertors (ED) modi.es essentially the transport properties at the plasma edge by permitting a radial transfer of particles and heat along stochastic field lines and affecting anomalous transport perpendicular to them. A model for the effective transport coefficients in a s...

Conditions for the formation of the edge transport barrier (ETB) in tokamaks are investigated by means of one-dimensional transport modeling performed for the characteristic parameter range of the TEXTOR tokamak. The computations predict the formation of the ETB at the heating power given by the multi-machine scaling if the fraction of convective h...

An approach to solve numerically transport equations for plasmas with spontaneously arising and arbitrarily located transport barriers, regions with a strongly reduced transfer of energy, is proposed. The transport equations are written in a form conserving heat flux and solved numerically by using piecewisely exact analytical solutions of linear d...

The difference in the H-mode power threshold in divertor and limiter configurations is numerically investigated by analysing the effect of boundary conditions imposed on the last closed magnetic surface (LCMS) and given by prescribed density and temperature e-folding lengths, δ n and δ T , respectively. It is demonstrated that the variation of δ n...

The effect of boundary conditions at the last closed magnetic surface LCMS on the formation of the edge transport barrier ETB in tokamaks is investigated by one-dimensional transport calculations for the radial profiles of plasma parameters. For a given heating power the transition from the low confinement mode L mode to the high confinement mode H...

Calculations done with 1-D transport code RITM show the strong dependence of the L-H threshold power on the dominant mechanism for the heat losses at the edge. Whereas, in the situation when the fraction of the convective heat losses in the total one does not exceed 50%, the computed threshold power coincides with the scaling prediction. An increas...

The results of predictive self-consistent modelling of plasma parameters in low (L) and high (H) confinement modes by the one-dimensional transport code RITM, with particular emphasis on the properties of the edge transport barrier, are presented and discussed. The same transport model is used under both L- and H-mode conditions and includes contri...

Deuterium fuelling through a carbon test limiter has been applied to maximize the plasma density in the Radiative Improved Mode. The impact of the fuelling on the local plasma edge properties has been investigated, by analyzing the spectral emission of both deuterium atoms and molecules, which indicates the creation of a cold and dense plasma cloud...

TEXTOR is equipped with two gyrotrons at 110 and 140 GHz, respectively. Both share a single power supply and a confocal quasi-optical transmission line. They cannot be operated simultaneously. The 110-GHz gyrotron with limited power and pulse length (300 kW; 200 ms) has been used in a first series of experiments on electron cyclotron resonance heat...

The first results of the Dynamic Ergodic Divertor in TEXTOR, when operating in the m/n=3/1 mode configuration, are presented. The deeply penetrating external magnetic field perturbation of this configuration increases the toroidal plasma rotation. Staying below the excitation threshold for the m/n=2/1 tearing mode, this toroidal rotation is always...

Recently, the dynamic ergodic divertor (DED) of TEXTOR has been studied in an m/n = 3/1 set-up which is characterized by a relatively deep penetration of the perturbation ﬁeld. The perturbation ﬁeld creates (a) a helical divertor, (b) an ergodic pattern and/or (c) excitation of tearing modes, depending on whether the DED current is static, rotating...

The reduction of energy and particle losses with the increasing mass of the hydrogen isotope is more pronounced under conditions of improved confinement when the dominant ion temperature gradient instability is suppressed and other channels of anomalous transport are of importance. In this Letter, we reconsider the dissipative trapped electron (DTE...

Self-consistent modelling of energy and particle transport of the plasma background and impurities has been performed with the code RITM for argon seeded high density H-mode plasmas in JET The code can reproduce both the profiles in the plasma core and the structure of the edge pedestal. The impact of argon on core transport is found to be small; i...

This paper reports on experiments in TEXTOR with electron cyclotron resonance heating (ECRH) of radiatively improved (RI) mode discharges. With ECRH the energy content of RI-mode discharges can be increased without the normally observed power degradation in confinement time. The experiments are described and the effects of ECRH on global confinemen...

The 110 GHz and the new 140 GHz gyrotron systems for electron cyclotron resonance heating (ECRH) and ECCD on TEXTOR are described and results of ECRH experiments with the 110 GHz system are reported. Central ECRH on Ohmic plasmas shows the presence of an internal electron transport barrier near q = 1. This is confirmed by modulated ECRH experiments...

The radiative improved (RI) mode at TEXTOR is a high confinement regime, which is obtained by the seeding of neon into deuterium plasmas. Recent experiments were aimed to study the influence of external gas fuelling on the confinement properties of the RI mode. In particular, it was found that a hydrogen puff into such plasmas leads to lower confin...

A 110 GHz, 400 kW, 200 ms gyrotron has been employed on TEXTOR for ECRH. The highly localised electron heating allowed the identification of (multiple) electron transport barriers. The RTP q-comb model for the electron heat conductivity gives a good description of TEXTOR results with ECRH in Ohmic discharges. Central ECRH in the current ramp phase...

Confinement deterioration and rollover from the radiative improved (RI) mode to the low (L) confinement mode in plasmas with a strong gas puff in the tokamak TEXTOR-94 are modelled by the one-dimensional transport code RITM (radiation from impurities in the transport model). The anomalous transport coefficients in the plasma core include contributi...

The results of self-consistent modelling by the one-dimensional transport code RITM of plasma parameters in Low (L) and High (H) confinement modes, with particular stress on the edge transport barrier in the H-mode, are presented and discussed. The transport model used under both L and H-mode conditions includes contributions from Ion Temperature G...

An actual subject of experimental and theoretical studies in present day fusion research is the development of an operational scenario combining simultaneously high confinement, with at least H-mode quality, and high densities, around or above the empirical Greenwald limit. Recently, this subject was cared by TEXTOR experimental program in Radiativ...

Gas puff is a standard method for density control in fusion devices. However, a too intensive puffing applied in order to achieve high densities leads often to a degradation of the energy confinement and transitions from the regimes with good performance (linear ohmic confinement, H-mode in divertor machines, radiative improved (R I) mode under imp...

1) The stability of ideal ballooning-peeling MHD modes is examined in the presence of external magnetic field perturbations. It is demonstrated that external field perturbation can increase the threshold of MHD modes. It is also shown that this effect should be much more important under ITER conditions than in the present devices like D-III D. (2)...

A strong correlation is found between the edge neutral pressure pn and the confinement degradation with respect to the RI-mode scaling (tau_RIalphan P-2/3). Consequently, for any density the confinement can be found by multiplying tau_RI by a degrading function f(p_n). The increase of pn is also well correlated with the rise of the recycling flux a...

Radiative Improved (RI) mode is a tokamak operation regime with the energy and particle confinement improved by a deliberate seeding of impurities. The reduction of anomalous transport takes place not in thin transport barriers but in a significant part of the plasma volume. A firm transport modelling of such states requires a coherent description...

## Citations

... The maximum plasma current was 800 kA [31]. Additional heating was available in the form of neutral beam injection (NBI) [32,33] and ion and electron cyclotron resonance heating (ICRH, ECRH) [34,35]. One of the two NBIs pointed in co-(NBI1) and one in counter-direction (NBI2) with respect to the usual plasma current direction, each with a heating power of maximum 1,7 MW. ...

... Caching has been supported by some workflow systems, e.g., Kepler [12], VisTrails [13] and OpenAlea [14]. In [15], we proposed an adaptive caching method for OpenAlea that automatically determines the most suited intermediate data to cache, but only for a single site. ...

... The approach described here is being used by several user communities that have been engaged within the project [1,11,14,19,20,41,53,68,72]. The developed solutions have also resulted in community and upstream code contributions to major open source solutions like OpenStack and OpenNebula. ...

... Given the quite positive results obtained with synthetic data, proving their better discriminatory capability, the proposed new versions of the selection criteria are expected to become useful in various fields. ey are already being deployed for the investigation of complex systems, ranging from high-temperature plasmas [16][17][18][19][20][21][22][23] to remote sensing of the atmosphere and radar [24][25][26]. Another promising application seems to be in support of the regularization of recent tomographic inversion methods [27][28][29]. ...

... Both plasmas have a similar high triangularity, up-down symmetric shape, β N = 2.7 and H IPB98(y,2) ≈ 1.2, but pulse #79635 has lower plasma current, magnetic field and NBI power, whereby the central densities and temperatures are approximately half in comparison with pulse #77922. The edge pedestal has been simulated assuming constant transport coefficients inside an external transport barrier (ETB), which are much higher than the inter-ELM values previously found in coupled TRANSP-EDGE2D simulations [7], thus compensating for the fact that ELM-driven transport is not considered here. For pulse #77922 the ETB has been set at ρ = 0.87 with D i = 0.02 m 2 s -1 , χ i = 1.0 m 2 s -1 and χ e = 1.7 m 2 s -1 . ...

... For example, an integrated modelling Python framework is established to take users' feedback and inputs to continually improve and broaden the multiscale physics model [8]. In particular, the European Integrated Tokamak Modelling [9] effort (EFDA-ITM) designed a generic platform for tokamak modelling and framework to aid the construction of complex workflows [10] that follow the component-based approach. This platform is currently sustained through the EUROfusion consortium, 2 which contributes extensively to the ITER Integrated Modelling and Analysis Suite (IMAS) [11]. ...

... The DEMO is based on a diverted magnetic configuration where plasma particles flowing in the scrape-off layer (SOL) are blocked by the divertor targets. The divertor is a key in-vessel component carrying out critical functions as follows [7][8][9][10]: ...

... Calculations with the code XGC incorporating neoclassical effects, neutral particles and X-point geometry [30] show a density pedestal developing in ~ 10ms, with a width ∆ ped ∝ (T -T c ) 1/2 /B T , where T c is a threshold temperature and the width depends on the toroidal field B T ; the temperature pedestal is somewhat wider. The drift-Alfven model for the L-H transition has been extended [31], emphasising the role of the density gradient length L n and finding ∆ ped ∝ n -1 . Since the transition and barrier formation is generally thought to be associated with plasma flows the time-dependent solutions of the coupled, non-linear system of equations for V θ and V φ in a neo-classical context with steep gradients have been investigated [32, 33]; chaotic oscillations can result. ...

Reference: Magnetic Confinement Theory Summary S/1-3

... The first workflows developed using the this technology have been the EQRECONSTRUCT, which couples magnetic fitting equilibrium codes to fixed-boundary high-resolution codes, and the MHD stability (EQSTABIL), which couples linear MHD stability codes to the high resolution equilibrium. Along with the EQRECONSTRUCT and EQSTABIL workflows, the ETS 18,19 is the most complex of all the workflows and encompasses several physics modules spanning from heating and current drive modules, first-principle Fig. 4). The core of ETS is a 1.5-d transport solver designed and implemented within the integrated modeling framework. ...

... As reported by Kalupin [194] the 'European Transport Solver' (ETS) is being developed as the new modular package for scenario simulations within the EFDA Integrated Tokamak Modelling (ITM) Task Force which was reported by Falchetto [195]. It incorporates a sophisticated module for synergy effects between heating schemes, several equilibrium modules, pellets, impurities, neutrals, sawteeth and NTM modules, a variety of simple transport modules and neoclassical modules. ...