Jonathan Bryan Lister

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Analysis of magnetic fluctuations is important for understanding the magneto-hydrodynamic (MHD) properties of fusion plasmas. These properties affect nearly all aspects of behaviour of magnetic confinement, and thus are of interest in topics ranging from global plasma stability, control, and disruption avoidance, to more subtle areas such as MHD spectroscopy. Mode number analysis is generally accomplished by interpreting signals from a finite number of Mirnov coils, which typically are unevenly spaced in th

The original TCV control system was designed in the late 1980s to be inherently network based in that all control operations were performed from X-windows terminals and the control computers were networked. Using VMS-VAX technology, the acquisition system (CAMAC) and control system (BITBUS) were connected to controllers situated in the machine bus of these machines that were linked homogeneously by the VMS 'cluster' technology. Although the computing power and network bandwidth have improved considerably ov

Efficient, real-time and automated data analysis is one of the key elements for achieving scientific success in complex engineering and physical systems, of which two examples are the JET and ITER tokamaks. One problem which is common to these fields is th ...

The high-frequency (HF) magnetic sensors for ITER are currently based on a conventional, Mirnov-type, pick-up coil, with an effective area in the range 0.03

This contribution describes the results of impurity seeding experiments using neon gas injection into the private fl zone of an ohmically heated TCV single null lower, deuterium fuelled, open divertor configuration. In these first experiments, neon has been injected under feedback control on the intensity of the UV NeVIII line at 77 nm. Measurements of the dependence of edge temperature and density on ii, at the outboard divertor target show the divertor in the absence of neon to be operating in the low rec

Earthing of electrical installations is mainly governed by safety rules. Electromagnetic compatibility also deals with earthing, among other circuit characteristics. Tokamaks are large-scale electrical installations that are known to generate large and low frequency magnetic fields as well as large and high frequency electric fields. Four European Tokamak installations have been investigated, from the earthing point of view, to identify appropriate techniques to earth the electrical equipment and to provide

This paper presents experimental results on the accessibility and the properties of plasmas with improved confinement in TCV. First, the H-mode threshold power is measured in Ohmic plasmas. Above an Ohmic threshold density, the threshold power increases with the density. A lower threshold density is found when additional electron cyclotron heating (ECH) is applied. At these low densities, the threshold power increases dramatically with decreasing density. Only a small fraction of the wide operational domain

On the Tokamak a Configuration Variable (TCV), electron internal transport barriers (eITBs) can be formed during a gradual evolution from a centrally peaked to a hollow current profile while all external actuators are held constant. The formation occurs ra ...

Experiments with high-power electron cyclotron heating (ECH) and current drive (ECCD) in the TCV tokamak are discussed. Power up to 2.7 MW from six gyrotrons is delivered to the tokamak at the second-harmonic frequency (82.7 GHz) in X-mode. The power is transmitted to the plasma by six independent launchers, each equipped with steerable mirrors that allow a wide variety of injection angles in both the poloidal and toroidal directions. Fully non-inductive operation of the tokamak has been achieved in steady

A full tokamak discharge simulator has been developed by combining a free-boundary equilibrium evolution code, DINA-CH, and an advanced transport modelling code, CRONOS. The combined tokamak discharge simulator provides a full simulation of a whole tokamak ...

An integrated radiative high performance scenario has been established at ASDEX Upgrade based on simultaneous feedback control of the average divertor neutral particle and power flux in combination with a high, pellet induced frequency of edge localized mo ...

The ITER high-frequency (HF) magnetic sensor is currently intended to be a conventional, Mirnov-type, pickup coil, designed to provide measurements of magnetic instabilities with magnitude as low as |dB|~10e-4G at the position of the sensors and up to freq ...

The physics of tokamak plasmas, in which electrons are heated by electron cyclotron heating (ECH) and whose current is driven by electron cyclotron current drive (ECCD), is investigated in this paper together with applications on tokamak A configuration variable (TCV) using modifications of the pressure and current profiles to improve the operational regimes. In order to explain the experimentally determined current drive efficiency and hard x-ray and electron cyclotron emission measurements, it is shown th

A variety of techniques are being tested on ASDEX Upgrade for avoiding or reducing the divertor energy load caused by ELMs. Quiescent H-mode operation has been improved by operation with recently boronized vessel walls. Z(eff) values in QH-modes are now similar to2.5, comparable with those found in ELMy H-modes of similar density. Type It ELM operation has been generated in discharges with ICRF additional heating alone, thus demonstrating its compatibility with reactor-relevant low core momentum and particl

Collective Thomson scattering, using a high-power pulsed D2O laser at 385-mu-m and a heterodyne receiver system, has provided local ion temperature (T(i)) measurements of the plasma in the tokamak chauffage Alfven (TCA) tokamak. Recent improvements in the noise-equivalent power of the Schottky barrier diode mixers permitted us to achieve a typical precision of +/- 12% for a single shot measurement at densities above 10(20) m-3. Even at densities of standard TCA discharges (5 x 10(19) m-3) the uncertainty is

A systematic procedure to identify the plasma equilibrium response to the poloidal field coil voltages has been applied to the JT-60U tokamak. The required response was predicted with a high accuracy by a state-space model derived from first principles. The ab initio derivation of linearized plasma equilibrium response models is re-examined using an approach standard in analytical mechanics. A symmetric formulation is naturally obtained, removing a previous weakness in such models. RZIP, a rigid current dis

The calculation of AC loss due to the control currents in ITER is a cumbersome task. The reason is that control transients require small field changes (0.1 T or less) at moderate frequency (up to 10 Hz), where effects of partial penetration of the filament ...

Research into neural networks has gained a large following in recent years. In spite of the long term timescale of this Artificial Intelligence research, the tools which the community is developing can already find useful applications to real practical problems in experimental research. One of the main advantages of the parallel algorithms being developed in Al is the structural simplicity of the required hardware implementation, and the simple nature of the calculations involved. This makes these technique

The DINA free-boundary equilibrium simulation code has been implemented for TCV, including the full TCV feedback and diagnostic systems. First results showed good agreement with control coil perturbations and correctly reproduced certain non-linear features in the experimental measurements. The latest DINA code simulations, presented in this paper, exploit discharges with different cross-sectional shapes and different vertical instability growth rates which were subjected to controlled vertical displacement

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 struc ...

Jonathan Bryan Lister

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Astrophysics and Fusion Plasmas: application of the SparSpec algorithm to the data analysis and design of the ITER high-frequency Mirnov coil diagnostic system

Evolution not revolution in the TCV tokamak control and acquisition system

Sparse representation of signals: from astrophysics to real-time data analysis for fusion plasmas and system optimization analysis for ITER and TCV

Prototyping Conventionally Wound High-Frequency Magnetic Sensors for ITER

Experimental investigation of the effects of neon injection in TCV

ITER-Earthing

Accessibility and properties of ELMy H-mode and ITB plasmas in TCV

Safety factor profile requirements for electron ITB formation in TCV

High-power ECH and fully non-inductive operation with ECCD in the TCV tokamak

Full tokamak discharge simulation of ITER by combining DINA-CH and CRONOS

Integrated exhaust scenarios with actively controlled ELMs

Prototyping a High-Frequency Inductive Magnetic Sensor Using the Nonconventional, Low-Temperature Co-Fired Ceramic Technology for Use in ITER

ECH physics and new operational regimes on TCV

ITER-relevant H-mode physics at ASDEX upgrade

Ion Temperature-Measurements in a Tokamak by Collective Thomson Scattering

Plasma equilibrium response modelling and validation on JT-60U

Computations of AC loss in the ITER magnets, during fast field transients

Neural Networks in Front-End Processing and Control

Comparing TCV experimental VDE responses with DINA code simulations

A generic data structure for integrated modelling of tokamak physics and subsystems