Publications de Jean-Philippe Hogge

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The self-consistent simulation of the electron beam interaction was performed in the presence of a lossy dielectric layer in the smooth-wall beam duct of a gyrotron oscillator. For this purpose, the linear and spectral code TWANGlinspec was extended. In th ...

During initial studies of ECRH in the TCV tokamak, non-standard central MHD activities, such as humpbacks and saturated and inverted sawteeth, have been observed while changing the heating location, the ECRH power, the plasma shape and the safety factor. For edge safety factors q(alpha) > 4.5, safety factors on-axis q(0) < 1 and small plasmas, complete sawtooth stabilization was achieved with the present 1 MW gyrotron power, and it is likely that sawtooth stabilization can be achieved for all conditions at.

The development of high-power gyrotrons (118 GHz, 140 GHz) in continuous-wave (CW) operation for heating nuclear fusion plasmas has been in progress for several years in a joint collaboration between different European research institutes and industrial partners. The 140-GHz gyrotron being under development for the installation at the W7-X stellarator now under construction at the IPP Greifswald, Germany, operates in the TE28,8 mode and is equipped with a diode type magnetron injection electron gun, an impr

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

The future EC systems will consist of several gyrotron sources providing MW-level millimeter wave power at a frequency around or above 170 GHz. The development of matched loads is necessary to test the new sources, the components for the transmission lines ...

A high power radiation source in the THz range with long pulse and narrow line width is required for diagnosing fusion type plasmas by collective Thomson scattering. Gyrotrons currently meet the requirements concerning power, pulse length and line width when operating in the 50-150 GHz range. They may have the potential also to do this in the THz range. In this paper two methods based on harmonic operation are investigated. Both look promising, if high conversion efficiency can be attained. This, however, s

The European 1 MW, 170 GHz industrial CW prototype gyrotron has been designed within EGYC (European GYrotron Consortium) in collaboration with the industrial partner Thales Electron Devices (TED) and under the coordination of Fusion for Energy (F4E). This ...

Within the range of plasma shapes and plasma currents investigated, the electron confinement time, tau_Ee, increases with safety factor, density and negative triangularity similar to the Ohmic heating case. There is little dependence of tau_Ee on the heating location provided power deposition occurs inside the q=1 surface; as power deposition moves out of the inversion surface, tau_Ee decreases. The power-induced energy confinement degradation exponent (tau_Ee~PaP) is as usual: alpha_P ~-0.5. As a general t

In the Tokamak a Configuration Variable (TCV), the central electron temperature obtained in discharges with counter (CNTR) electron cyclotron current drive (ECCD) is larger than with CO-ECCD or electron cyclotron resonance heating (ECRH) alone. Comparison of experimental results with calculations by the transport code PRETOR [IAEA Technical Conference on Advances in Simulation and Models of Thermonuclear Plasmas. Montreal 142 (International Atomic Energy Agency, Vienna 1992)] indicates that sawtooth stabili

A significant effort has recently been initiated at ETHZ for the development of high frequency, high power, frequency-agile gyrotrons for DNP-NMR spectroscopy. In this context an in house cavity interaction code is under development. In this paper, some de ...

In the frame of the TCV Tokamak upgrade, two 84/126 GHz/2 s dual frequency gyrotrons designed by SPC and KIT and manufactured by THALES will be added to the existing EC-System. The first unit has been delivered to EPFL-SPC and tested. In the commissioning ...

In the foreseen upgrade of the Tokamak-a-Configuration-Variable (TCV) it is planned to add 3MW of additional RF power (3rd harmonic X-mode, X3, top-launch) to the present Electron Cyclotron (EC) system. With the upgrade of the EC-system, bringing the total EC power in X3-mode to 4.5MW, and the installation of 1 MW of neutral beam injection, a new avenue will be opened allowing the extensive study of H-mode physics in TCV. The envisaged new gyrotrons (lMW, 126GHz) are based on a minimum redesign of the 140 G

The development of high power gyrotrons in continuous wave (CW) operation for heating of plasmas used in nuclear fusion research has been in progress for several years in a joint collaboration between different European research institutes and industrial partners. A recent R&D program aims at the development of 140 GHz gyrotrons with an output power of 1 MW in CW operation for the 10 MW ECRH system of the new stellarator plasma physics experiment Wendelstein 7-X at IPP Greifswald, Germany. The work is perfo

We report the experimental results of the infrared measurements of output RF beam of the European 2-MW 170-GHz coaxial cavity gyrotron for ITER. The output beam profile is measured by the infrared thermographic technique using an infrared camera and a targ ...

A way to determine the magnetic axis of gyrotron cryomagnets, and more generally magnets composed of coils wound around a single mandrel is presented. The method is based on measurements of the longitudinal component of the magnetic field performed at suitable locations with a high accuracy (100 ppm) Hall probe [1]. The tilt and the shift of the magnetic axis with respect to the mechanical axis can be determined with a typical accuracy of 0.01deg and 0.1 mm respectively.

The first unit of the dual-frequency gyrotron, 84-126GHz/lMW/2s, for the upgrade of the TCV ECH system has been delivered and is presently being commissioned. During a first phase, long-pulse operation (TRF>0.5s) has been achieved and powers in excess of 0 ...

The operation of a 92 GHz quasi-optical gyrotron having a resonator formed by a spherical mirror and a diffraction grating placed in -1 order Littrow mount is presented. A power of 150 kW with a Gaussian output pattern was measured. The Gaussian content in the output was 98% with less than 1% of depolarization. By optimizing the magnetic field al fixed frequency a maximum efficiency of 15% was reached. (C) 1996 American Institute of Physics.

The field pattern of the resonator used in a quasi-optical gyrotron operating in the millimetre wave range is measured. Two resonators are studied: one composed of a spherical mirror and an ellipsoidal grating and the other symmetric using two mirrors with annular slots. The measurements indicate that the electric field distribution is gaussian, in spite of the complex geometry of the resonator, and thus provide an experimental basis for the assumption often used to compute the efficiency of quasi-optical g

A Test Facility (TF) has been designed and installed at SPC to allow for the commissioning of the EU gyrotrons developed in view of their integration to the ITER EC system. The first phase of operation of this TF was dedicated to the development of the EU ...

The European Gyrotron Consortium (EGYC) is developing the European 1 MW, 170 GHz Continuous Wave (CW) industrial prototype gyrotron for ITER in cooperation with Thales Electron Devices (TED) and Fusion for Energy (F4E). This conventional, hollow-cavity gyr ...

Jean-Philippe Hogge

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Modeling of parasitic oscillations in smooth-wall circular symmetric dielectric-loaded gyrotron beam ducts

Behaviour of central plasma relaxation oscillations during localized electron cyclotron heating on the TCV tokamak

Development of a 140-GHz 1-MW continuous wave gyrotron for the W7-X stellarator

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

Tests and developments of a long-pulse high-power 170 GHz absorbing matched load

Development of a high-power THz radiation source for plasma diagnostics

Report of recent experiments with the European 1 MW, 170 GHz CW and SP prototype gyrotrons for ITER

EFFECT OF LOCALISED ELECTRON CYCLOTRON HEATING ON ENERGY CONFINEMENT AND MHD IN TCV

Central electron temperature enhancements due to sawtooth stabilization during counter electron cyclotron current drive in Tokamak a Configuration Variable

Development of Kilowatt THz Gyrotrons for Pulsed Dynamic Nuclear Polarization - Cavity Design Code Phaedra -

Megawatt power generation of the dual-frequency gyrotron for TCV at 84 and 126 GHz, in long pulses

Millimeter Wave System Upgrades On TCV: Additional X3 Power And Fast ECE Polarizers

Development of a 140 GHz, 1 MW, continuous wave gyrotron for the W7-X stellarator

Infrared Measurements of the RF Output of 170-GHz/2-MW Coaxial Cavity Gyrotron and Its Phase Retrieval Analysis

Accurate gyrotron magnetic axis determination

High-efficiency, long-pulse operation of MW-level dual-frequency gyrotron, 84/126GHz, for the TCV Tokamak

Operation of a quasi-optical gyrotron with a Gaussian output coupler

Measurement of the Electric-Field Pattern of a Fabry-Perot Resonator Used in Quasi-Optical Gyrotrons

Enhanced operation of the Eu Ec test facility

Recent experiments with the European 1MW, 170GHz industrial CW and short-pulse gyrotrons for ITER