Publications de Damien Fasel | EPFL Graph Search

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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 ...

Basic wave-particle interaction dynamics from linear to chaotic regimes is experimentally studied on a frequency tunable gyrotron generating THz radiation in continuous mode (200W) at 263GHz which will be used for dynamic nuclear polarization nuclear magnetic resonance spectroscopy applications. In the studied system, the nonlinear dynamics associated to the waveparticle interaction is dominated by longitudinal mode competition of a given transverse TEm;p cavity-mode. This study covers a wide range of contr

During the first two years of operation, the TCV tokamak has produced a large variety of plasma shapes and magnetic configurations, with 1.0 less than or equal to B-tor less than or equal to 1.46T, I-p less than or equal to 800kA, kappa less than or equal to 2.05, -0.7 less than or equal to delta less than or equal to 1. A new shape control algorithm, based on a finite element reconstruction of the plasma current in real time, has been implemented. Vertical growth rates up to 1000 s(-1) have been stabilized

A future fusion reactor will use deuterium and tritium as fuel. The former is found in abundance in seawater, while the latter is not available naturally due to its short lifetime. Present developments in the context of fusion propose generating tritium in ...

EC RF power sources will play a major role in the future operation of large scale tokamaks (ITER, DEMO). A 1MW/170GHz gyrotron is the standard RF power unit considered for ITER. Even though the efficiency of such devices has been significantly increased th ...

An 1 MW long-pulse (2s), 84/126 GHz dual frequency gyrotron has been produced by THALES MSI, France responding to the needs for upgrading the ECH system of the TCV tokamak The initial tests of the prototype carried out at EPFL, Switzerland, have verified a ...

A steady-state, fully noninductive plasma current has been sustained for the first time in a tokamak using electron cyclotron current drive only. In this discharge, 123 kA of current have been sustained for the entire gyrotron pulse duration of 2 s. Careful distribution across the plasma miner radius of the power deposited from three 0.5-MW gyrotrons was essential for reaching steady-state conditions. With central current drive, up to 153 kA of current have been fully replaced transiently for 100 ms. The no

The EU is working towards providing 2 MW, coaxial-cavity, CW, 170 GHz gyrotrons for ITER. Their design is based on results from an experimental pre-prototype tube in operation at FZK for several years, having a pulse length of several milliseconds. The fir ...

The Tokamak Configuration Variable (TCV) tokamak (R = 0.88 m, a < 0.25 m, B < 1.54 T) programme is based on flexible plasma shaping and heating for studies of confinement, transport, control and power exhaust. Recent advances in fully sustained off-axis electron cyclotron current drive (ECCD) scenarios have allowed the creation of plasmas with high bootstrap fraction, steady-state reversed central shear and an electron internal transport barrier. High elongation plasmas, kappa = 2.5, are produced at low nor

The European Union is working toward providing 2-MW, coaxial-cavity, continuous-wave (cw) 170-GHz gyrotrons for ITER. Their design is based on results,from an experimental preprototype tube having a pulse length of several milliseconds, in operation at For ...

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

The general control of tokamak plasmas has evolved considerably over the past few years with an increase in the plasma pulse length, an increase in the control of additional heating and fueling, and an increase in the degree to which the shape of the plasma can be varied. The Tokamak Configuration Variable (TCV) is specifically designed to explore the operational benefits of plasma shaping over a wide variety of plasma shapes. Consequently, considerable attention has been given to the control of the poloida

A Diagnostic Neutral Beam Injector (DNBI) is operated on the TCV Tokamak since 2000. Over the years, the plasma source and the ion optical system have benefited from several upgrades, whereas the power supply system remained almost unchanged. DNBI operation is now compromised by the obsolescence of both the power components and the control infrastructure. To allow for a long-term reliable operation, a complete renew of the power supplies set is ongoing. It includes a high-speed current source rated 500A/100

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 ...

The present status of operation and upgrades of the 50 keV / 3 A Diagnostic Neutral Beam Injector (DNBI) at TCV tokamak are described. The plasma grid was replaced by a new re-manufactured one with its existing design. The technology and production were performed within SPC-EPFL. The further redesign of the plasma grid was done to improve the strength and stability, accounting for the results of grid deformation measurements, and considering ANSYS thermomechanical analysis in combination with IBSimu beam si

A Diagnostic Neutral Beam Injector (DNBI) is operated on the TCV Tokamak since 2000. Over the years, the plasma source and the ion optical system have benefited from several upgrades, whereas the power supply system remained almost unchanged. DNBI operation is now compromised by the obsolescence of both the power components and the control infrastructure. To allow for a long term reliable operation, a complete renew of the power supplies set is ongoing. It includes a high-speed current source rated 500 A/10

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 ...

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 ...

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 ...

Damien Fasel

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

Experimental study from linear to chaotic regimes on a terahertz-frequency gyrotron oscillator

Recent Results from the Tcv Tokamak

Availability of lithium in the context of future D-T fusion reactors

Homogenous power distribution along gyrotron collector walls

Manufacturing and Test of the 1 MW Long-Pulse 84/126 GHz Dual-Frequency Gyrotron for TCV

Steady-state fully noninductive current driven by electron cyclotron waves in a magnetically confined plasma

First experimental results from the EU 2 MW coaxial cavity ITER gyrotron prototype

An overview of results from the TCV tokamak

First experimental results from the European Union 2 MW coaxial cavity ITER gyrotron prototype

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

The control of tokamak configuration variable plasmas

New ARC Power Supply for the TCV Diagnostic Neutral Beam Injector

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

Recent progress with Diagnostic Neutral Beam Injector at TCV tokamak

High Voltage Modulator for the TCV Diagnostic Neutral Beam Injector

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

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

Enhanced operation of the Eu Ec test facility