A5056367739- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Laser-Plasma Interactions and Diagnostics
- Particle Accelerators and Free-Electron Lasers
- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Particle Detector Development and Performance
- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Plasma Diagnostics and Applications
- Atomic and Molecular Physics
- Neutrino Physics Research
- Superconducting Materials and Applications
- Laser Design and Applications
- Laser-Matter Interactions and Applications
- Distributed and Parallel Computing Systems
- Pulsed Power Technology Applications
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Laser-induced spectroscopy and plasma
- Computational Physics and Python Applications
- Advanced X-ray Imaging Techniques
- Astrophysics and Cosmic Phenomena
- Fusion materials and technologies
Lawrence Berkeley National Laboratory
2021-2024
European Organization for Nuclear Research
2013-2024
Campbell Collaboration
2020-2023
Centre National de la Recherche Scientifique
2020
École Nationale Supérieure de Techniques Avancées
2020
École Polytechnique
2020
Google (United States)
2019
Brunel University of London
2012-2018
Institute of High Energy Physics
2012-2017
Graz University of Technology
2016-2017
In JET, both high density and low-q operation are limited by disruptions. The limit disruptions caused initially impurity radiation. This causes a contraction of the plasma temperature profile leads to an MHD unstable configuration. There is evidence magnetic island formation resulting in minor After several disruptions, major disruption with rapid energy quench occurs. event takes place two stages. first stage there loss from central region. second more drop very low temperature, apparently...
High energy particle accelerators have been crucial in providing a deeper understanding of fundamental particles and the forces that govern their interactions. In order to increase or reduce size accelerator, new acceleration schemes need be developed. Plasma wakefield acceleration, which electrons plasma are excited, leading strong electric fields, is one such promising novel technique. Pioneering experiments shown an intense laser pulse electron bunch traversing plasma, drives fields 10s...
The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) aims at studying plasma wakefield generation and electron acceleration driven by proton bunches. It is a proof-of-principle R&D experiment CERN the world׳s first experiment. AWAKE will be installed in former CNGS facility uses 400 GeV/c beam bunches from SPS. experiments focus on self-modulation instability of long (rms ~12 cm) bunch plasma. These are planned for end 2016. Later, 2017/2018, low energy (~15 MeV)...
The seeded self-modulation of a relativistic, charged particle bunch in plasma is shown to grow both along the and plasma, resulting transverse wakefield amplitudes that far exceed initial seed values.
Abstract Colliders are essential research tools for particle physics. Numerous future collider proposal were discussed in the course of US high energy physics community strategic planning exercise Snowmass'21 . The Implementation Task Force (ITF) has been established to evaluate proposed accelerator projects performance, technology readiness, schedule, cost, and environmental impact. Corresponding metrics developed uniform comparison proposals ranging from Higgs/EW factories multi-TeV...
Low aspect ratio tokamaks may provide a low cost route to developing magnetic fusion energy and offer simpler more economic reactors. The first test of this concept with hot plasmas has been conducted the Small Tight Aspect Ratio Tokamak (START) experiment now in operation at Culham Laboratory. novel method plasma formation is described observations ratios as 1.3 are presented, indicating high temperature discharges good global stability properties typical tokamak characteristics. This...
Plasma wakefield acceleration is a promising technology to reduce the size of particle accelerators. The use high energy protons drive wakefields in plasma has been demonstrated during Run 1 AWAKE programme at CERN. Protons 400 GeV drove that accelerated electrons 2 under 10 m plasma. collaboration now embarking on with main aims demonstrate stable accelerating gradients 0.5–1 GV/m, preserve emittance electron bunches and develop sources scalable 100s metres beyond. By end 2, scheme should...
We show in experiments that a long, underdense, relativistic proton bunch propagating plasma undergoes the oblique instability, which we observe as filamentation. determine threshold value for ratio between transverse size and skin depth instability to occur. At threshold, outcome of experiment alternates filamentation self-modulation (evidenced by longitudinal modulation into microbunches). Time-resolved images density distribution reveal grows an observable level late along bunch,...
Experimental results show that hosing of a long particle bunch in plasma can be induced by wakefields driven short, misaligned preceding bunch. Hosing develops the plane misalignment, self-modulation perpendicular plane, at frequencies close to electron frequency, and are reproducible. Development depends on misalignment direction, its growth extent proton charge. Results have main characteristics theoretical model, relevant other plasma-based accelerators represent first characterization...
Instabilities are governed by transport-determined plasma profiles and transport is in turn affected instabilities. A one-dimensional code has been developed which models this relationship. The dependence of magnetic island sizes on total current described. Above a critical current, there non-linea interaction between the m = 1 2 modes takes place through their effect profile. This leads to disruptive loss confinement. Inclusion impurity radiation repeated soft disruptions at lower current.
Abstract Laser-plasma accelerators are capable of sustaining accelerating fields 10–100 GeV/m, 100–1000 times that conventional technology and the highest produced by any widely researched advanced accelerator concepts. also intrinsically accelerate short particle bunches, several orders magnitude shorter than technology, which leads to reductions in beamstrahlung and, hence, savings overall power consumption reach a desired luminosity. These properties make laser-plasma promising for more...
An international multi-tokamak profile database has been assembled, constituting a representative set of reference tokamak discharges for the purpose testing local transport models against well documented data. In particular, it will allow one to measure accuracy with which can reproduce experiments and draw confidence intervals predictions outside range covered in database. This is now available fusion community may be accessed by anonymous ftp iterphys.naka.go.jp; this article describe...
The sustainment of plasma discharges (current drive) using helicity injection and relaxation is discussed. It shown that toroidal plasmas may be sustained by applying only poloidal voltage current. Some the configurations which can maintained in this way are calculated.
We use a relativistic ionization front to provide various initial transverse wakefield amplitudes for the self-modulation of long proton bunch in plasma. show experimentally that, with sufficient amplitude [$\ensuremath{\ge}(4.1\ifmmode\pm\else\textpm\fi{}0.4)\text{ }\text{ }\mathrm{MV}/\mathrm{m}$], phase modulation along is reproducible from event event, 3%--7% (of $2\ensuremath{\pi}$) rms variations all bunch. The not lower amplitudes. observe transition between these two regimes. Phase...
This document outlines a community-driven Design Study for 10 TeV pCM Wakefield Accelerator Collider. The 2020 ESPP Report emphasized the need Advanced R\&D, and 2023 P5 calls ``delivery of an end-to-end design concept, including cost scales, with self-consistent parameters throughout." leverages recent experimental theoretical progress resulting from global R\&D program in order to deliver unified, Collider concept. Accelerators provide ultra-high accelerating gradients which enables...
We show experimentally that an effect of motion ions, observed in a plasma-based accelerator, depends inversely on the plasma ion mass. The appears within single wakefield event and manifests itself as bunch tail, occurring only when sufficient ions suppresses wakefields. Wakefields are driven resonantly by multiple bunches, simulation results indicate ponderomotive force causes ions. In this case, is also expected to depend amplitude wakefields, confirmed through variations drive charge.
The confinement time for an Ohmically heated, low-β tokamak is well described by the scaling law τ ∝ n. This implies that β should increase linearly with additional auxiliary heating power. In fact, much slower, and deteriorates increasing heating. possibility this deterioration due to localized onset of MHD ballooning instabilities, elsewhere continuing follow established Ohmic discharges, examined. It found overall effect instability indeed gradual resultant corresponds a in good agreement...
The START (Small Tight Aspect Ratio Tokamak) experiment became operational in January 1991 at AEA Fusion Culham Laboratory. It is the only tokamak producing hot plasmas aspect ratios as low A=R/a approximately 1.3, and providing valuable insight into physical processes (such toroidicity trapping) involved ratio. Three topics are discussed: equilibrium properties, including evidence of neo-classical bootstrap effects; energy confinement studies; MHD possible explanations for apparent absence...
We study experimentally the longitudinal and transverse wakefields driven by a highly relativistic proton bunch during self-modulation in plasma. show that wakefields' growth amplitude increase with increasing seed as well charge using maximum radius of distribution measured on screen downstream from externally injecting electrons measuring their final energy. Measurements agree trends predicted theory numerical simulations validate our understanding development self-modulation. Experiments...
Abstract We measured the parameter reproducibility and radial electron density profile of capillary discharge waveguides with diameters 650 $\mathrm{\mu} \mathrm{m}$ to 2 mm lengths 9 40 cm. To best authors’ knowledge, cm is longest plasma waveguide date. This length important for $\ge$ 10 GeV energy gain in a single laser-driven wakefield acceleration stage. Evaluation variations showed that their focusing strength was stable reproducible $<0.2$ % average on-axis $<1$ %. These explain...
In the theory of relaxed states toroidal plasmas certain eigenvalues equation ∇×B=μB play a crucial role. These are associated with vanishing flux and determine onset current limitation in discharge. axisymmetric systems there both periodic eigenfunctions it is important to know whether eigenmode lowest eigenvalue or axisymmetric. This depends on shape poloidal cross section determines nature current-limited The modes have been computed rectangular elliptical sections reentrant...