A5035402935- Laser-Plasma Interactions and Diagnostics
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
- Laser-Matter Interactions and Applications
- Electrohydrodynamics and Fluid Dynamics
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Magnetic Field Sensors Techniques
- Atomic and Molecular Physics
- Dust and Plasma Wave Phenomena
- Solar and Space Plasma Dynamics
- Fusion materials and technologies
- Advanced Fiber Laser Technologies
- Cold Atom Physics and Bose-Einstein Condensates
- Laser Design and Applications
- Quantum chaos and dynamical systems
- Advanced Data Storage Technologies
- Spectroscopy Techniques in Biomedical and Chemical Research
- Plasma Applications and Diagnostics
- Quantum optics and atomic interactions
- High-pressure geophysics and materials
- Nuclear Physics and Applications
- Cold Fusion and Nuclear Reactions
- Atomic and Subatomic Physics Research
Princeton University
2016-2025
Princeton Plasma Physics Laboratory
2015-2025
Laboratoire Plasma et Conversion d'Energie
2018-2023
Institut National Polytechnique de Toulouse
2017-2023
Université Toulouse III - Paul Sabatier
2017-2023
Centre National de la Recherche Scientifique
2017-2023
Université de Toulouse
2017-2023
Université Paris-Saclay
2023
Université Paris Cité
2023
Laboratoire de Physique des 2 Infinis Irène Joliot-Curie
2023
The continuous operation of a tokamak fusion reactor requires, among other things, means providing continuously the toroidal current. Such is preferred to conventional pulsed operation, where plasma current induced by time-varying magnetic field. A variety methods have been proposed provide current, including that utilize particle beams or radio-frequency waves in any several frequency regimes. Currents as large half mega-amp now produced laboratory such means, and experimentation these...
Continuous toroidal electron currents, which sustain the poloidal magnetic field in tokamaks, may be generated by injecting waves with net parallel momentum into plasma via phased waveguide arrays. Waves high phase velocity can produce a current capable of confining reactor so that steady-state tokamak operation acceptable power dissipation becomes possible.
Preferential heating of electrons traveling in one direction can support a current even the absence dc electric field. An immediate implication is that waves which carry little toriodal momentum, such as electron cyclotron waves, may be attractive means for generating steady-state toroidal tokamak. analytical expression derived generated per power dissipated, agrees remarkably well with numerical calculations.
Laser beams can be strongly compressed in a plasma by stimulated Raman backscattering time short compared to the scale for filamentation instabilities develop. Such compression should make feasible multi-MJ multi-exawatt-laser pulses technologically challenging other means. The efficiency reach nearly $100%$ at Langmuir wave breaking limit.
Lower hybrid waves are a demonstrated, continuous means of driving toroidal current in tokamak. When these propagate tokamak fusion reactor, which there energetic \ensuremath{\alpha} particles, conditions under the particles do not appreciably damp, and may even amplify, wave, thereby enhancing current-drive effect. Waves traveling one poloidal direction, addition to being directed shown be most efficient drivers presence particles.
By injecting radio-frequency traveling waves into a tokamak, continuous toroidal electron currents may be generated. This process is studied by numerically solving the two-dimensional Fokker–Planck equation with an added quasi-linear term. The results are compared one-dimensional analytic treatment of Fisch, which predicted reduced plasma resistivity when high-phase-velocity employed. It shown that velocity space effects, while retaining scaling, further reduce ratio power dissipated to...
Hall thrusters might better scale to low power with nonconventional geometry. A 9 cm cylindrical, ceramic-channel, thruster a cusp-type magnetic field distribution has been investigated. It exhibits discharge characteristics similar conventional coaxial thrusters, but does not expose as much channel surface. Significantly, its operation is accompanied by large amplitude frequency oscillations.
An initially short ( $<1/{\ensuremath{\omega}}_{p}$) laser pulse can be superradiantly amplified by a counterpropagating long low-intensity pump while remaining ultrashort. This superradiant amplification occurs if the frequency of is lower than that pump, and initial intensity sufficiently high. Numerical simulations indicate to an hundreds times intensity, with depletion as high $40%$. implies efficiently time compressed without chirping stretching, making interesting alternative...
Various types of traveling waves may be injected into a tokamak to continuously sustain the toroidal current. Interest in this problem arises from possibility operating reactors steady state. The low-frequency most suitable for task are identified terms power cost deployment reactor. Means exciting these and tradeoffs with design criteria discussed. A comparison is made alternative attractive regime high-frequency waves. Conclusions based, part, on numerical solution two-dimensional...
The Rosenbluth form for the collision operator a weakly relativistic plasma is derived. formalism adopted by Antonsen and Chu can then be used to calculate efficiency of current drive fast waves in plasma. Accurate numerical results analytic asymptotic limits efficiencies are given.
Rotating spoke phenomena have been observed in a variety of Hall thruster and other E × B devices. It has suggested that the may be associated with enhancement electron cross-field transport. In this paper, current conducted across magnetic field via rotating directly measured for first time discharge cylindrical thruster. The was using segmented anode. Synchronized measurements high speed camera four-segment anode allow observation as function azimuthal position. Upwards 50% total is...
This paper provides perspectives on recent progress in the understanding of physics devices where external magnetic field is applied perpendicularly to discharge current. configuration generates a strong electric field, which acts accelerates ions. The many applications this set up include generation thrust for spacecraft propulsion and separation species plasma mass devices. These ExB plasmas are subject plasma-wall interaction effects as well various micro macro instabilities, devices, we...
Recently, it has been shown that altering the natural collisional power flow of proton–boron 11 (pB11) fusion reaction can significantly reduce Lawson product ion density and confinement time required to achieve ignition. However, these products are still onerous—on order 7×1015 cm−3 s under most optimistic scenarios. Fortunately, a breakeven plant does not require an igniting plasma, but rather reactor produces more electrical than consumes. Here, we extend existing 0D balance analysis...
We describe the status of our effort to realize a first neutrino factory and progress made in understanding problems associated with collection cooling muons towards that end. summarize physics can be done factories as well intense cold beams muons. The potential muon colliders is reviewed, both Higgs Factories compact high energy lepton colliders. timescale research development reviewed latest designs channels including promise ring coolers achieving longitudinal transverse simultaneously....
The discharge parameters in Hall thrusters depend strongly on the yield of secondary electron emission from channel walls. Comparative measurements at low energies primary electrons were performed for several dielectric materials used with segmented electrodes. showed that actual energetic dependencies total could differ fits, which are usually theoretical models. observed differences might be caused by backscattering, is dominant lower and depends surface properties. Fits based power or...
Electron-wall interaction effects in Hall thrusters are studied through measurements of the plasma response to variations thruster channel width and discharge voltage. The voltage threshold is shown separate two regimes. Below this threshold, electron energy gain constant acceleration region therefore, secondary emission (SEE) from walls insufficient enhance losses at walls. Above maximum temperature saturates. This result seemingly agrees with predictions saturation, which recent models...
The recently proposed scheme of so-called "fast compression" laser pulses in plasma can increase peak intensities by 10(5) [Phys. Rev. Lett. 82, 4448 (1999)]. compression mechanism is the transient stimulated Raman backscattering, which outruns fastest filamentation instabilities pumped pulse even at highly overcritical powers. This Letter proposes a novel nonlinear filtering effect that suppresses premature backscattering pump noisy layer, while desired amplification sufficiently intense...
The intensity of a subpicosecond laser pulse was amplified by factor up to 1000 using the Raman backscatter interaction in 2 mm long gas jet plasma. process amplification reached nonlinear regime, with exceeding that pump more than an order magnitude. Features unique regime such as gain saturation, bandwidth broadening, and shortening were observed. Simulation theory are qualitative agreement measurements.
Raman amplification of subpicosecond laser pulses up to 95 times is demonstrated at corresponding frequencies in a gas-jet plasma. The larger accompanied by broader bandwidth and shorter pulse duration. Theoretical simulations show qualitative agreement with the measurements, effects plasma conditions intensities are discussed.
The Hall thruster is a mature electric propulsion device that holds considerable promise in terms of the propellant saving potential. annular design conventional thruster, however, does not naturally scale to low power. efficiency tends be lower and lifetime issues are more aggravated. Cylindrical geometry thrusters have surface-to-volume ratio than and, thus, seem promising for scaling down. cylindrical (CHT) fundamentally different from way electrons confined ion space charge neutralized....
Through the use of high-speed camera and Langmuir probe measurements in a cylindrical Hall thruster, we report discovery rotating spoke increased plasma density light emission which correlates with electron transport across magnetic field. As cathode is increased, sharp transition occurs where disappears decreases. This suggests that significant fraction current might be directed through spoke.
The major emissive probe techniques are compared to better understand the floating potential of an electron emitting surface in a plasma. An overview separation point technique, and inflection limit zero emission technique is given, addressing how each method works as well theoretical basis limitations each. It shown that while most popular, it expected yield value ∼1.5Te/e below plasma due virtual cathode forming around probe. predictions were checked with experiments performed 2 kW annular...
This paper reviews and discusses recent experimental, theoretical, numerical studies of plasma-wall interaction in a weakly collisional magnetized plasma bounded with channel walls made from different materials. A low-pressure <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> × xmlns:xlink="http://www.w3.org/1999/xlink">B</i> discharge the Hall thruster was used to characterize electron current across magnetic field its dependence on applied...