Publications by Jean-Philippe Hogge

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An over-moded evacuated waveguide line was chosen for use in the transmission system for the proposed JET enhanced performance project (JET-EP) electron cyclotron resonance heating (ECRH) system. A comparison between the quasi-optical, atmospheric waveguide and evacuated waveguide systems was performed for the project with a strong emphasis placed on the technical and financial aspects. The evacuated waveguide line was chosen as the optimal system in light of the above criteria. The system includes six line

Gyrotrons are high-power microwave sources, readily applied in diverse fields ranging from fusion research and thermal treatment of materials to advanced spectroscopic techniques. Here, we provide the cavity design of a 198 GHz gyrotron to generate microwa ...

Computer aided design of powerful gyrotrons for electron cyclotron resonance heating and current drive of fusion plasmas requires adequate physical models and efficient software packages for analysis, comparison and optimization of their electron-optical s ...

The EC-system of the TCV tokamak is progressively being upgraded with the addition of two MW-class dual-frequency gyrotrons (84 and 126 GHz/2s/1MW). In order to connect the two gyrotrons to the existing low field side and top launchers, new waveguide routi ...

The upgraded European 1-MW, 170-GHz continuous wave (CW) industrial prototype gyrotron (TH1509U) for electron cyclotron resonance heating and current drive in ITER was tested at the Karlsruhe Institute of Technology (KIT). In this work, we report on the ma ...

Confinement in TCV electron cyclotron heated discharges was studied as a function of plasma shape, i.e. as a function of elongation, 1.1 < kappa < 2.15, and triangularity, -0.65 less than or equal to delta less than or equal to 0.55. The electron energy confinement time was found to increase with elongation, owing in part to the increase of plasma current with elongation. The beneficial effect of negative triangularities was most effective at low power and tended to decrease at the higher powers used. The l

The design of a diffration grating used as an output coupler for a Fabry-Perot resonator is presented. We then consider the problem of determining the distortion and the cross-polarization of the incident Gaussian beam. Different types of gratings and planes with straight or curvilinear grooves and elliptical, have been designed and built. The output pattern from a resonator using such a grating has been measured experimentally. We found that the elliptical grating generates the least distortion and cross-p

The TCV tokamak (R = 0.88 in, a < 0.25 in, BT < 1.54 T) is equipped with six 0.5 MW gyrotron sources operating at 82.7 GHz for second harmonic X mode ECH. By distributing the ECCD current sources over the discharge cross section, fully driven stationary plasmas with I-p = 210 kA, n(e0) = 2 x 10(19) m(-3), T-e0 approximate to 4 keV, were obtained for the full discharge duration of 2 s. Highly peaked electron temperature profiles with T-e0 up to 12 keV were obtained in central counter-current drive scenarios

A research activity in the Institute for Plasma Science and Technology of National Research Council (ISTP-CNR, Italy, former IFP-CNR) and in L.T. Calcoli (LTC, Italy) is aimed at the design and construction of calorimetric loads for absorption and measurem ...

The electron cyclotron heating (ECH) system in TCV has recently been upgraded to a total of 4.5 MW of installed power. In order to extend the density range of ECH-heated plasmas up to electron densities of 1.2 x 10(20) m(-3), three 0.5 MW gyrotrons at a frequency of 118 GHz have been added to the existing 3 MW second harmonic system operating at a frequency of 82.7 GHz. The launcher consists of a mirror placed at the top of the vessel that collects the power of the three microwave sources and can be steered

A numerical model is presented to describe the electron beam neutralization during long-pulse and continuous-wave operation in gyrotrons. This model has been implemented in the electrostatic, self-consistent electron optics code Ariadne. Using this model, ...

The operating space of the TCV tokamak has been extended to higher elongation, kappa = 2.8, and higher normalized current, I-N = I-p/aB = 3.6MA/mT, than were previously attainable. This has been achieved by optimizing the parameters of the vertical position control system and by optimizing the plasma shape. Experimental current and beta limits were found to be consistent with ideal MHD stability calculations, using measured plasma shapes and profiles. The sawtooth period was measured as a function of elonga

The TCV tokamak (B-T < 1.5 T, R approximate to 0.88 m, a < 0.25 m) has produced a wide variety of plasma configurations, both diverted and limited, with elongations kappa(a), ranging from 0.9 to 2.58, triangularities delta(a) from -0.7 to 1 as well as discharges with nearly rectangular cross sections. Plasma currents of 1 MA have been obtained in elongated discharges (kappa(a) approximate to 2.3). Ohmic discharges with delta(a) < 0 have smaller sawteeth and higher levels of MHD mode activity than plasmas wi

In the frame of development of the ITER electron cyclotron wave (ECW) system, a two MW CW coaxial cavity gyrotron will be developed during the Sixth Framework Program (2003-2006). Such development relies on the availability of a test stand capable of providing the electrical energy and cooling capacity. This test stand will possibly be used, in a later stage, for the component test of the ITER ECW system. This paper will first present the main parameters of this new coaxial gyrotron. Then we describe the te

A small component of ECCD exists when heating off-axis with no toroidal injection due to the field helicity. The sign of the ECCD will change depending on the absorption location in a poloidal plane, the beam injection relative to delB(vac), and the direction of the toroidal magnetic field. The importance of the ECCD component can be confirmed by the behavior of the sawteeth when the ECH deposition crosses the q=1 surface. The sawtooth period is very sensitive to the local shear at q=1 and it is shown that

The demand for megawatt-class gyrotrons for Electron Cyclotron Resonance Heating (ECRH) of nuclear fusion devices is growing significantly. It goes hand in hand with growing requirements for output power, efficiency, operating flexibility, and reliability of gyrotrons used in nuclear fusion, as well as higher demanding of the manufacturability for serial production. In Europe research and development is ongoing to fulfil that future needs, particularly, with regards to output power and efficiency. It is com

The European DEMO (EU-DEMO) reactor studies within EUROfusion aim to develop a fusion power plant concept. The large tokamak device needs an auxiliary heating power which, at the present stage, is provided by the Electron Cyclotron (EC) heating system with ...

Efficiency is a key factor for high-power gyrotrons, particularly in future fusion power plants, where a large number of gyrotron units will be required for plasma heating. A single-stage depressed collector enhances efficiency from approximately 35% to 50 ...

We report the first three-dimensional kinetic simulations that self-consistently reproduce relaxation oscillations of high-density, strongly rotating electron clouds confined in Penning-like potential wells. Using the finite element non-neutral electron clouds simulator code, we model the Trapped Electrons eXperiment (T-REX), a dedicated setup designed to study electron cloud dynamics relevant to gyrotron electron guns. The simulations are in quantitative agreement with experiment and show that the observed

A dual-frequency gyrotron has been developed within the context of the recent Tokamak à Configuration Variable (TCV) upgrade. The gyrotron is designed to generate a 1 MW, 2 seconds RF wave at 84 or 126 GHz. Before integrating the gyrotrons in the TCV tokam ...

Jean-Philippe Hogge

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An ITER relevant evacuated waveguide transmission system for the JET-EP ECRH project

Cavity Design for a High-Power, Frequency-Agile 198 GHz Gyrotron

Recent evolution of the simulation tools for computer aided design of electron-optical systems for powerful gyrotrons

Design and implementation of quasi-optical components for the upgrade of the TCV EC-system

Experimental Testing of the European TH1509U 170-GHz 1-MW CW Industrial Gyrotron-Long Pulse Operation

Energy confinement and MHD activity in shaped TCV plasmas with localized electron cyclotron heating

Properties of Diffraction Gratings Used as Output Couplers in a Quasi-Optical Gyrotron

Overview of TCV results

Operations with Spherical Calorimetric Loads in Different Configurations at Gyrotron Test Stands at EPFL and QST

Preliminary results of top launch third harmonic X-mode electron cyclotron heating in the TCV tokamak

A model of electron beam neutralization for gyrotron simulations

Stability and energy confinement of highly elongated plasmas in TCV

Effect of plasma shape on confinement and MHD behaviour in TCV

Design study of a test stand for ITER gyrotron

Poloidally asymmetric plasma response with ECH deposition near q=1 in TCV

Megawatt-Class Sub-THz Gyrotrons for ECRH in Future High-Field Fusion Devices

Conceptual design of a modular EC heating system for EU-DEMO

Effects of reflected electrons on the efficiency of high-power gyrotrons

Relaxation oscillations driven by the diocotron instability in trapped electron clouds

Experimental characterization of the TCV dual-frequency gyrotron and validation of numerical codes including the effect of After Cavity Interaction