Publications de Richard Pitts | EPFL Graph Search

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The experimental method developed at ASDEX Upgrade for the determination of the intrinsic tungsten (W) density profile coupling data from the soft X-ray (SXR) diagnostic and vacuum-ultra-violet (VUV) spectroscopy has been upgraded for application to JET pl ...

The effect of ELMs on confinement in ohmic H-modes has been investigated by analysing the rates of change of global parameters such as the electron content and the stored energy as a function of ELM frequency. In double-null H-modes, ELMs are found to expel on average 2% of the electron content and 2.5% of the stored energy. In single-null discharges which are separated by more than 2.2 cm from the inner wall, larger ELMs are observed which expel on average 3-7% of the electron content and 3-12% of the stor

In noninductively driven discharges, 0.9 MW second harmonic (X2) off-axis co-electron cyclotron current drive deposition is combined with 0.45 MW X2 central heating to create an electron internal transport barrier (eITB) in steady plasma conditions resulting in a 1.6-fold increase of the confinement time (tau(Ee)) over ITER-98L-mode scaling. The eITB is associated with a reversed shear current profile enhanced by a large bootstrap current fraction (up to 80%) and is sustained for up to 10 current redistribu

A novel Shutdown dose rate benchmark experiment has been performed at Joint European Torus (JET) machine during the last high performance Deuterium-Deuterium (DD) campaign in preparation of future high Deuterium Tritium experiment (DTE2). On-line continuou ...

Sawtooth inversion radii and profile peaking factors of a large variety of ohmic and ECH heated L mode plasmas, including, elongations up to 2.6 and triangularities between -0.5 and 0.75, have been investigated in the TCV tokamak. In ohmic plasmas, normalized inversion radii and electron temperature profile peaking factors (corrected for sawtoothing effects) depend solely on the parameter (j)/q(0)j(0), irrespective of plasma shape. With ECH this parameter remains the main scaling parameter. Density profiles

We show for JET and ASDEX Upgrade, based on Thomson-scattering measurements, a clear correlation of the density limit of the tokamak H-mode high-confinement regime with the approach to the ideal ballooning instability threshold at the periphery of the plas ...

Micro/nanoscopic observations on the surface of the divertor tiles used in the first campaign (2011-2012) of the JET tokamak with ITER-like Wall (JET ILW) have been carried out by means of several material analysis techniques. Previous results from the inn ...

The phenomena of retention and de-trapping of deuterium (D) and tritium (T) in plasma facing components (PFC) and supporting structures must be understood in order to limit or control total T inventory in larger future fusion devices such as ITER, DEMO and ...

The transient pulses of heat and particles arriving at the divertor target plates as a consequence of upstream ELM activity have been characterised at JET using an array of target embedded Langmuir probes in the MkIIGB-SRP divertor. High temporal and spati ...

The Joint European Torus (JET), the largest magnetic confinement plasma physics experiment in operation, has a large amount of key diagnostics for physics exploration and machine operation, which include several Gamma Ray Diagnostics. The Gamma-Ray Spectro ...

Fully noninductive, steady-state electron cyclotron current drive (ECCD) has been demonstrated for the first time in experiments carried out in the tokamak a configuration variable (TCV) [O. Sauter , Phys. Rev. Lett. 84, 3322 (2000)]. By appropriately distributing six 0.45 MW ECCD sources over the discharge cross section, fully noninductive, stable, and stationary plasmas with I-p up to 210 kA were obtained for the full discharge duration of 1.9 s, corresponding to more than 900 energy confinement times and

A set of seven twin slit cameras, each containing two 20-element linear absolute extreme ultraviolet photodiode arrays, has been installed on the Tokamak a Configuration Variable. One array in each camera will operate as a bolometer and the second as a Lyman-alpha (L-alpha) emission monitor for estimating the recycled neutral flux. The camera configuration was optimized by simulations of tomographic reconstructions of the expected L-alpha emission. The diagnostic will provide spatial and temporal resolution

A calibration of the JET neutron detectors was carried out prior to the upcoming deuterium-tritium experimental campaign. Two Compact DT neutron generators (NGs) were purchased for this purpose from VNIIA, Russia. These generators are capable of producing ...

The design and operation of ITER experimental fusion reactor requires the development of neutron measurement techniques and numerical tools to derive the fusion power and the radiation field in the device and in the surrounding areas. Nuclear analyses prov ...

Analysis of the type-l ELM power load asymmetries using infra-red thermography and target current measurements is performed ASDEX Upgrade Upper Single Null and JET DOC-L type-I ELMy H-Mode discharges with 'normal' and,reversed' field direction, i.e. with t ...

The total emission of radiation is a crucial quantity to calculate the power balances and to understand the physics of any Tokamak. Bolometric systems are the main tool to measure this important physical quantity through quite sophisticated tomographic inv ...

Although ohmic H-modes have long been produced on TCV and the effects of ELMs at the divertor target studied in some detail, no attempt has yet been made to model the scrape-off layer (SOL) in these plasmas. This paper describes details of the first such e ...

The intensity of Be-9 + p nuclear fusion reactions was experimentally studied during second harmonic (2 omega CH) ion-cyclotron resonance heating (ICRH) and further analyzed during fundamental hydrogen minority ICRH of JET-ILW hydrogen and deuterium plasma ...

Compact DT neutron generators based on accelerators are often built on the principle of a mixed beam operation, meaning that deuterium (D) and tritium (T) are both present in the ion beam and in the target. Moreover, the beam consists of a mixture of ions ...

An effect due to fusion born triton production has been observed in JET high-performance deuterium plasma discharges with neutral beam injection (NBI) and H-minority ion cyclotron range of frequencies (ICRF) heating, using DD and deuterium tritium (DT) neu ...

Richard Pitts

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Determination of 2D poloidal maps of the intrinsic W density for transport studies in JET-ILW

Effect on confinement of edge-localized modes in TCV

Recent results from the electron cyclotron heated plasmas in Tokamak à Configuration Variable (TCV)

Shutdown dose rate neutronics experiment during high performances DD operations at JET

Shape dependence of sawtooth inversion radii and profile peaking factors in TCV L mode plasmas

Correlation of the tokamak H-mode density limit with ballooning stability at the separatrix

Plasma-wall interaction on the divertor tiles of JET ITER-like wall from the viewpoint of micro/nanoscopic observations

Thermal desorption spectrometry of beryllium plasma facing tiles exposed in the JET tokamak

Divertor particle and power deposition profiles in JET ELMy H-mode discharges

Control and data acquisition software upgrade for JET gamma-ray diagnostics

Steady-state fully noninductive operation with electron cyclotron current drive and current profile control in the tokamak a configuration variable (TCV)

AXUV bolometer and Lyman-alpha camera systems on the TCV tokamak

Characterisation of neutron generators and monitoring detectors for the in-vessel calibration of JET

Overview Of Neutron Measurements In Jet Fusion Device

Divertor power deposition and target current asymmetries during type-1 ELMS in ASDEX Upgrade and JET

Maximum likelihood bolometric tomography for the determination of the uncertainties in the radiation emission on JET TOKAMAK

SOLPS5 modelling of the type III ELMing H-mode on TCV

Evidence of Be-9 + p nuclear reactions during 2 omega(CH) and hydrogen minority ICRH in JET-ILW hydrogen and deuterium plasmas

Modelling of the neutron production in a mixed beam DT neutron generator

On a fusion born triton effect in JET deuterium discharges with H-minority ion cyclotron range of frequencies heating