A5027570828- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Plasma Diagnostics and Applications
- Gyrotron and Vacuum Electronics Research
- Physics of Superconductivity and Magnetism
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Magnetic Field Sensors Techniques
- Dust and Plasma Wave Phenomena
- Solar and Space Plasma Dynamics
- Nuclear reactor physics and engineering
- Magneto-Optical Properties and Applications
- Mass Spectrometry Techniques and Applications
- Particle Accelerators and Free-Electron Lasers
- Advanced X-ray Imaging Techniques
- Analytical Chemistry and Chromatography
- Transition Metal Oxide Nanomaterials
- Mobile Agent-Based Network Management
- Pulsars and Gravitational Waves Research
- Analytical Chemistry and Sensors
- Maritime and Coastal Archaeology
École Polytechnique Fédérale de Lausanne
2005-2019
ITER
2019
Max Planck Institute for Plasma Physics
2016
Max Planck Society
2016
Los Alamos National Laboratory
2002
Joint European Torus
1995
École Polytechnique
1990
The TCV tokamak offers outstanding variability of the plasma shape. Using x-ray tomography, shape inner flux surfaces a poloidal cross section can be reconstructed, including fast variations due to MHD activity. Both hardware and software 200 channel system developed for are described.
During the first year of operation, TCV tokamak has produced a large variety plasma shapes and magnetic configurations, with 1.0<or=Btor<or=1.46 T, Ip<or=800 kA, kappa <or=2.05, -0.7<or= delta <or=0.7. A new shape control algorithm, based on finite element reconstruction current in real time, been implemented. Vertical growth rates 800 sec-1 corresponding to stability margin f=1.15, have stabilized. Ohmic H-modes, energy confinement times reaching 80 ms, normalized beta ( toraB/Ip) 1.9 tau...
This Letter presents the first direct experimental measurements of damping toroidicity-induced Alfv\'en eigenmodes (TAE), carried out in JET tokamak. These were obtained during experiments to drive these modes with antennas external a tokamak plasma. Different regimes corresponding different dominant TAE absorption mechanisms wide range rates, ${10}^{\ensuremath{-}3}\ensuremath{\le}\ensuremath{\gamma}/\ensuremath{\omega}\ensuremath{\le}{10}^{\ensuremath{-}1}$, have been identified Ohmically...
The European Union is working toward providing 2-MW, coaxial-cavity, continuous-wave (cw) 170-GHz gyrotrons for ITER. Their design based on results from an experimental preprototype tube having a pulse length of several milliseconds, in operation at Forschungszentrum Karlsruhe (FZK) years now. first industrial prototype was designed cw but, phase, aimed 1 s the Gyrotron Test Facility Lausanne, Switzerland, as part phased testing/development program (1 s, 60 cw). this gyrotron are reported...
A steady-state, fully noninductive plasma current has been sustained for the first time in a tokamak using electron cyclotron drive only. In this discharge, 123 kA of have entire gyrotron pulse duration 2 s. Careful distribution across minor radius power deposited from three 0. 5-MW gyrotrons was essential reaching steady-state conditions. With central drive, up to 153 replaced transiently 100 ms. The scenario is confirmed by ability recharge Ohmic transformer. dependence efficiency on also...
Confinement in TCV electron cyclotron heated discharges was studied as a function of plasma shape, i.e. elongation, 1.1 < κ< 2.15, and triangularity, -0.65 ⩽ δ 0.55. The energy confinement time found to increase with owing part the current elongation. beneficial effect negative triangularities most effective at low power tended decrease higher powers used. large variety sawtooth types observed for different deposition locations, from on-axis q = 1 region, simulated model that included local...
The triple probe method to obtain local, time-resolved measurements of density, electron temperature and plasma potential is investigated in detail. difficulties obtaining reliable with this technique are discussed overcome. These include phase delay errors, ion sheath expansion limited bandwidth due stray capacitance ground. In particular, a relatively simple electronic circuit described strongly reduce capacitance. Measurements the presented characterized by interchange-driven turbulence...
A detailed description of the Langmuir probe electronics upgrade for TCV (Tokamak à Configuration Variable) is presented. The number amplifiers and corresponding has been increased from 48 to 120 in order simultaneously connect all 114 probes currently mounted divertor main-wall tiles. Another set 108 ready be installed 80 new probes, built frame upgrade. Technical details amplifier circuitry are discussed as well improvements over first generation developed at SPC (formerly CRPP) 1993/1994...
The general control of tokamak plasmas has evolved considerably over the past few years with an increase in plasma pulse length, additional heating and fueling, degree to which shape can be varied. Tokamak Configuration Variable (TCV) is specifically designed explore operational benefits shaping a wide variety shapes. Consequently, considerable attention been given poloidal field coil currents that impose desired shape. All aspects TCV plasmas, from diagnostic measurements power supplies,...
This work reports developments of the incoherent TS diagnostic capabilities in Tokamak à Configuration Variable (TCV). Their goals are to (i) diagnose TCV divertor region, and (ii) provide Te ne profiles plasma bulk real-time. These two new implemented within framework a upgrade that will insert baffles lower region. 20 spectrometers being installed access electron temperatures down ~1 eV, for densities above ~1.5×1019m−3 They measure Thomson light scattered along vertical propagation path...
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 at second-harmonic frequency (82.7 GHz) X-mode. The power transmitted plasma by independent launchers, each equipped steerable mirrors that allow a wide variety of injection angles both poloidal toroidal directions. Fully non-inductive operation has been achieved steady state, for full 2 s gyrotron pulse duration, co-ECCD...
The recently completed MST2 upgrade to the Thomson scattering (TS) system on TCV (Tokamak à Configuration Variable) at Swiss Plasma Center aims provide an enhanced spatial and spectral resolution while maintaining high level of diagnostic flexibility for study plasmas. (Medium Sized Tokamak) is a work program within Eurofusion ITER physics department, aimed exploiting Europe's medium sized tokamak programs better understanding physics. This involved installation 40 new compact 5-channel...
Fully noninductive, steady-state electron cyclotron current drive (ECCD) has been demonstrated for the first time in experiments carried out tokamak à configuration variable (TCV) [O. Sauter et al., Phys. Rev. Lett. 84, 3322 (2000)]. By appropriately distributing six 0.45 MW ECCD sources over discharge cross section, fully stable, and stationary plasmas with Ip up to 210 kA were obtained full duration of 1.9 s, corresponding more than 900 energy confinement times 10 redistribution at an...
In ITER, EC heating and current drive (H&CD) is foreseen not only as a principal auxiliary system for plasma assist start-up, but considered essential in meeting the key requirement of neoclassical tearing mode (NTM) stabilisation, by localized drive. reference ECH design, ITER requires total 20 MW/CW power at 170 GHz using gyrotrons with unit 1 MW. A higher per (2 MW/gyrotron) would result strong reduction cost whole ECRH system, also relax room constraints on launcher antenna design. view...
In noninductively driven discharges, 0.9 MW second harmonic (X2) off-axis co-electron cyclotron current drive deposition is combined with 0.45 X2 central heating to create an electron internal transport barrier (eITB) in steady plasma conditions resulting a 1.6-fold increase of the confinement time (τEe) over ITER-98L-mode scaling. The eITB associated reversed shear profile enhanced by large bootstrap fraction (up 80%) and sustained for up 10 redistribution times. A linear dependence...
The Tokamak à Configuration Variable (TCV) tokamak (R = 0.88 m, a < 0.25 B 1.54 T) programme is based on flexible plasma shaping and heating for studies of confinement, transport, control power exhaust. Recent advances in fully sustained off-axis electron cyclotron current drive (ECCD) scenarios have allowed the creation plasmas with high bootstrap fraction, steady-state reversed central shear an internal transport barrier. High elongation plasmas, κ 2.5, are produced at low normalized using...
In the moderate magnetic field of TCV (1.5 T), recently installed X3 system (3 gyrotrons, 118 GHz, 0.45 MW each, 2 s) broadens operational space with possibility heating plasmas at high density, well above cutoff density X2 system. To compensate for significantly weaker absorption coefficient compared to X2, top-launch injection allows ray path maximize along resonance layer thereby maximizing optical depth. maintain maximum in plasma discharges a dynamic variation both (refraction) and...
On the TokamakConfiguration Variable (TCV), electron internal transport barriers (eITBs) can be formed during a gradual evolution from centrally peaked to hollow current profile while all external actuators are held constant. The formation occurs rapidly (<τeE) and locally and, according ASTRA modelling, is consistent with appearance of local minimum in safety factor (q) profile. eITB sustained by non-inductively driven currents (including off-axis bootstrap current) for many redistribution...
The TCV tokamak has obtained ohmic H-modes in virtually all diverted plasmas with the ion drift directed towards an X-point and several elongated limiter plasmas. Troyon factors up to 2 line average densities , corresponding Ithe Greenwald limit, have been ELM-free H-modes. Quasi-stationary lasting for entire current flat top (1.5 s) presence of regular ELMs. occurrence magnitude ELMs found depend on configurational parameters such as position `active' unbalanced double-null discharges...
The design and first results are presented from a bolometric diagnostic with high temporal resolution recently installed on the TCV tokamak. system consists of two pinhole cameras viewing plasma above below at same toroidal location. Each camera is equipped an AXUV-16ELO linear array 16 p–n junction photodiodes, characterized by flat spectral sensitivity ultraviolet to x-ray energies, response (&lt;0.5 μs), insensitivity low-energy neutral particles emitted plasma. This allows study...
Electron cyclotron emission (ECE) diagnostics on Tokamak à Configuration Variable (TCV) allow study of the electron temperature evolution in time with good spatial and temporal resolution at high field side low various lines sight. That is why ECE being widely used to obtain both qualitative quantitative information heat transport, magnetohydrodynamics (MHD) phenomena, fast dynamics. In this paper, a new regime TCV regular oscillations current drive (ECCD) driven fully noninductive...
A high sensitivity field asymmetric ion mobility spectrometer (FAIMS) was designed, fabricated, and tested. The main components of the system are a 10.6 eV UV photoionization source, an filter driven by voltage/high frequency n-MOS inverter circuit, low noise detector. electronics capable to generate square waveforms with peak-to-peak voltages up 1000 V at frequencies 1 MHz adjustable duty cycles. detector current amplifier has gain 1012 V/A effective equivalent input level down about...