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Alfven eigenmodes (AEs) are routinely seen in present-day tokamaks and stellarators with energetic particles and they represent an attractive form of MHD spectroscopy that provides valuable information on background plasma and on the energetic particles. P ...

The kinetic code for plasma periphery (KIPP) was used to assess the importance of the kinetic effects of parallel electron transport in the scrape-off layer (SOL) and divertor of JET high radiative H-mode inter-ELM plasma conditions with the ITER-like wall ...

The Paxos part-time parliament protocol of Lamport provides a non trivial but very practical way to implement fault-tolerant deterministic services over a distributed message passing system. This paper deconstructs Paxos and modularly reconstructs more resilient and efficient variants of it, which can furthermore be customised for specific system configurations. The deconstruction consists in factoring out the key algorithmic principles of Paxos within three abstractions: round-based register, round-based c

Fast ions have recently been found to significantly impact and partially suppress plasma turbulence both in experimental and numerical studies in a number of scenarios. Understanding the underlying physics and identifying the range of their beneficial effe ...

The paper is dedicated to the characterisation of multi-strap ICRH antenna coupling to plasma. Relevance of traditional concept of coupling resistance to antennas with mutually coupled straps is revised and the importance of antenna port excitation consist ...

This paper presents the first application to real JET data of the new equilibrium code NICE which enables the consistent resolution of the inverse equilibrium reconstruction problem in the framework of non-linear free-boundary equilibrium coupled to the St ...

Reliable algorithms for disruption avoidance and prediction are foreseen to play a fundamental role in the JET control system for the successful operation of the machine in the upcoming deuterium-tritium campaigns. The integration of such algorithms is exp ...

This paper investigates the time-complexity of the non-blocking atomic commit (NBAC) problem in a synchronous distributed model where t out of n processes may fail by crashing. We exhibit for t > 3 an inherent trade-off between the fast abort property of NBAC, i.e., aborting a transaction as soon as possible if some process votes no,'' and the fast commit property, i.e., committing a transaction as soon as possible when all processes vote yes'' and no process crashes. We also give two algorithms: the fi

The electron temperature and density pedestals tend to vary in their relative radial positions, as observed in DIII-D (Beurskens et al 2011 Phys. Plasmas 18 056120) and ASDEX Upgrade (Dunne et al 2017 Plasma Phys. Control. Fusion 59 14017). This so-called ...

The impact of the finite grid size in SOLPS-ITER edge plasma simulations is assessed for JET H-mode discharges with a metal wall. For a semi-horizontal divertor configuration it is shown that the separatrix density is at least 30% higher when a narrow scra ...

Leasing is a very effective way to improve the performance of distributed algorithms without hampering their fault-tolerance. The notion of lease has traditionally been defined using a global notion of time and was hence strongly tied to synchronous system models. This paper introduces a new notion of lease devised for an asynchronous system model. We give the precise properties of our lease abstraction, we show how it can be implemented in an asynchronous system model, and we then illustrate its use by sig

This paper describes a new consensus algorithm for the asynchronous message passing system model augmented with an unreliable failure detector abstraction: channels are reliable, processes can fail by crashing, and the detection of crashes are not reliable. Our algorithm (a) matches all known consensus lower bounds on (1) failure detection, i.e., \Omega, (2) resilience, i.e., a majority of correct processes, and (3) latency, i.e., two communication steps for a global decision in nice runs (when no process c

We study efficient and robust implementations of an atomic read-write data structure over an asynchronous distributed message-passing system made of reader and writer processes, as well as failure prone server processes implementing the data structure. We determine the exact conditions under which every read operation involves one-round of communication with the servers. These conditions relate the number of readers to the tolerated number of faulty servers, in a general model with crash and arbitrary failu

Recent studies (Maggi et al 2015 Nucl. Fusion 55 113031; Maggi et al 2017 Nucl. Fusion 57 116012) have shown that on JET with the Be/W ITER-like wall (JET-ILW) in high beta discharges with high D-2 gas rates, the inter-ELM temperature pedestal growth is sa ...

Parallel heat flux calculations at the JET divertor have been based on the assumption that all incoming heat is due to the projection of the heat flux parallel to the magnetic line, q, plus a constant background. This simplification led to inconsistencies ...

A tritium imaging plate technique (TIPT) in combination with an electron-probe microscopic analysis (EPMA) were applied to examine tritium (T) retention characteristics in individual dust particles collected in the Joint European Torus with the ITER-like W ...

This paper analyses the final phase of hybrid scenario discharges at JET, the reduction of auxiliary heating towards finally the Ohmic phase. The here considered Ohmic phase is mostly still in the current flattop but may also be in the current ramp down. F ...

Fishbones are ubiquitous in high-performance JET plasmas and are typically considered to be unimportant for scenario design. However, during recent high-performance hybrid scenario experiments, sporadic and explosive fishbone oscillations with sawtooth rec ...

The analysis of the polarimetry measurements has the aim of validating models (De Marco and Segre 1972 Plasma Phys. 14 245), with a careful attention to the clarification of their limits of application. In this paper a new approximation method is introduce ...

In the last years, it has become apparent that detecting disruptions with sufficient anticipation time is an essential but not exclusive task of predictors. It is also important that the prediction is accompanied by appropriate qualifications of its reliab ...

Partha Dutta

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MHD spectroscopy of JET plasmas with pellets via Alfven eigenmodes

Assessment of the strength of kinetic effects of parallel electron transport in the SOL and divertor of JET high radiative H-mode plasmas using EDGE2D-EIRENE and KIPP codes

Deconstructing Paxos

Non-Maxwellian fast particle effects in gyrokinetic GENE simulations

ICRH antenna &ITS&IT-matrix measurements and plasma coupling characterisation at JET

Equilibrium reconstruction at JET using Stokes model for polarimetry

A First Analysis of JET Plasma Profile-Based Indicators for Disruption Prediction and Avoidance

Fast Non-Blocking Atomic Commit: An Inherent Trade-off

Effect of the relative shift between the electron density and temperature pedestal position on the pedestal stability in JET-ILW and comparison with JET-C

On the role of finite grid extent in SOLPS-ITER edge plasma simulations for JET H-mode discharges with metallic wall

Asynchronous Leasing

Fast Indulgent Consensus with Zero Degradation

How Fast can a Distributed Atomic Read be?

Inter-ELM evolution of the edge current density in JET-ILW type I ELMy H-mode plasmas

An improved model for the accurate calculation of parallel heat fluxes at the JET bulk tungsten outer divertor

Tritium retention characteristics in dust particles in JET with ITER-like wall

Analysis of plasma termination in the JET hybrid scenario

Full-orbit and drift calculations of fusion product losses due to explosive fishbones on JET

Approximate analytic expressions using Stokes model for tokamak polarimetry and their range of validity

On the potential of ruled-based machine learning for disruption prediction on JET