Publications by Jonathan Graves

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3D free boundary equilibrium computations have recently been used to model external kinks and edge harmonic oscillations (EHOs), comparing with linear MHD stability codes, and nonlinear analytic theory [Kleiner et al., Phys. Plasma Controlled Fusion 61, 08 ...

An extension of the SolEdge2D-EIRENE code package, named D-WEE, has been developed to add the dynamics of thermal desorption of hydrogen isotopes from the surface of plasma facing materials. To achieve this purpose, D-WEE models hydrogen isotopes implantat ...

We demonstrate for the first time that the nonlinear saturation of neoclassical tearing modes (NTMs) can be found directly using a variational principle based on Taylor relaxation, without needing to simulate the intermediate, resistivity-dependent dynamic ...

Good fast ion confinement in quasi-isodynamic stellarators still has to be demonstrated experimentally. In the absence of fusion alphas, auxiliary heating systems can be used to generate fast ions. For this purpose, W7-X has neutral beam injection and its ...

The erosion of tungsten (W), induced by the bombardment of plasma and impurity particles, determines the lifetime of plasma-facing components as well as impacting on plasma performance by the influx of W into the confined region. The screening of W by the ...

Sawtooth pacing with modulated ion-cyclotron resonance heating (ICRH) has been demonstrated to be very efficient in JET-ILW L-mode plasmas (Lerche et al 2017 Nucl. Fusion 57 036027, Lennholm et al 2017 Fusion Eng. Des. 123 535-40), where the main heat sour ...

Selected set of samples from JET ITER-Like Wall (JET-ILW) divertor tiles exposed in 2015-2016 has been analysed using Thermal Desorption Spectrometry (TDS). The deuterium (D) amounts obtained with TDS were compared with Nuclear Reaction Analysis (NRA). The ...

Beryllium limiter marker tiles were exposed to plasma in the Joint European Torus to diagnose the erosion of main chamber wall materials. A limiter marker tile consists of a beryllium coating layer (7-9 mu m) on the top of bulk beryllium, with a nickel int ...

Wendelstein 7-X (W7-X) is a large, superconducting, optimized stellarator being operated in Greifswald, Germany. One of the original optimization criteria (Grieger et al 1992 Phys. Fluids B: Plasma Physics 4 2081) is good fast-ion confinement, mainly at in ...

A Doppler shifted resonance minority species ion cyclotron range of frequency (ICRF) scheme for heating neutral beam ions has been identified and optimized for theWendelstein 7-X stellarator. Compared with more conventional methods, the synergetic scheme i ...

External kink modes, believed to be the drive of the 0-limiting resistive wall mode, are strongly stabilized by the presence of a separatrix. We thus propose a novel mechanism explaining the appearance of long-wavelength global instabilities in free bounda ...

The data of the H alpha high-resolution spectroscopy, collected on the multiple lines of sight, which cover the entire divertor space in poloidal cross-section, during the recent hydrogen-deuterium experiments in JET-ILW (ITER-like wall), are processed. A ...

The measurement of the energy spectra and densities of alpha-particles and other fast ions are part of the ITER measurement requirements, highlighting the importance of energy-resolved energetic-particle measurements for the mission of ITER. However, it ha ...

Observations of fishbone oscillations driven by energetic electrons have been reported in several tokamaks, but experimental evidence of the interaction between electrons and the mode has remained limited. In the TCV tokamak, a state-of-the-art multi-chann ...

This paper reports on impurity behavior in a set of hybrid discharges with Ne seeding-one of the techniques considered to reduce the power load on reactor walls. A series of experiments carried out with light gas injection on JET with the ITER-Like-Wall (I ...

Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create ne ...

Convolutional neural networks (CNNs) have found applications in many image processing tasks, such as feature extraction, image classification, and object recognition. It has also been shown that the inverse of CNNs, so-called deconvolutional neural network ...

The stepped-pressure equilibrium code (SPEC) (Hudson et al., Phys. Plasmas, vol. 19, issue 11, 2012, 112502) is extended to allow the computation of multi-region, relaxed magnetohydrodynamics (MRxMHD) equilibria at prescribed toroidal current profile. Toro ...

Strongly peaked tungsten accumulation is a common feature of high performance plasma scenarios in JET with the ITER-like wall, particularly during MHD activity induced by m/n = 1/1 continuous modes. This study investigates the effect of 1/1 long living int ...

The First Mirror Test for ITER has been carried out in JET with mirrors exposed during: (i) the third ILW campaign (ILW-3, 2015-2016, 23.33 h plasma) and (ii) all three campaigns, i.e. ILW-1 to ILW-3: 2011-2016, 63,52 h in total. All mirrors from main cham ...

Jonathan Graves

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Modeling of saturated external MHD instabilities in tokamaks: A comparison of 3D free boundary equilibria and nonlinear stability calculations

Dynamic modelling of local fuel inventory and desorption in the whole tokamak vacuum vessel for auto-consistent plasma-wall interaction simulations

Direct prediction of saturated neoclassical tearing modes in slab using an equilibrium approach

Fast ion generation by combined RF-NBI heating in W7-X

Erosion, screening, and migration of tungsten in the JET divertor

Sawtooth control with modulated ICRH in JET-ILW H-mode plasmas

Investigation of deuterium trapping and release in the JET divertor during the third ILW campaign using TDS

Micro ion beam analysis for the erosion of beryllium marker tiles in a tokamak limiter

Schemes for Generating Deeply Trapped Fast Ions Via Ion-cyclotron-resonance Heating in Wendelstein 7-x

Identification of an Optimized Heating and Fast Ion Generation Scheme for the Wendelstein 7-X Stellarator

Occam's razor on the mechanism of resistive-wall-mode-induced beta limits in diverted tokamaks

Determination of isotope ratio in the divertor of JET-ILW by high-resolution H alpha spectroscopy: H-D experiment and implications for D-T experiment

Diagnostic of fast-ion energy spectra and densities in magnetized plasmas

Suprathermal electron driven fishbone instability in the TCV tokamak

Application of the VUV and the soft x-ray systems on JET for the study of intrinsic impurity behavior in neon seeded hybrid discharges

Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

Deep neural networks for plasma tomography with applications to JET and COMPASS

Computation of multi-region, relaxed magnetohydrodynamic equilibria with prescribed toroidal current profile

Heavy impurity transport in tokamaks subject to plasma rotation, NTV and the influence of saturated ideal MHD perturbations

First mirror test in JET for ITER: Complete overview after three ILW campaigns