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WEP126 | Progress in Experimental Study of Current Filamentation Instability | 1719 |
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Funding: Work supported by Department of Energy and National Science Foundation Current Filamentation Instability, CFI, is of central importance for the propagation of relativistic electron beams in plasmas. CFI could play an important role in the generation of magnetic fields and radiation in the after-glow of gamma ray bursts and also in energy transport for the fast-igniter inertial confinement fusion concept. Simulations were conducted with the particle-in-cell code QuickPIC* for e- beam and plasma parameters at the Brookhaven National Laboratory – Accelerator Test Facility, BNL-ATF. Results show that for a 2cm plasma the instability reaches near saturation. An experimental program was proposed and accepted at the BNL-ATF and an experiment is currently underway. There are three components to the experimental program: 1) imaging of the beam density/filaments at the exit from the plasma, 2) measurement and imaging of the transverse plasma density gradient and measurement of the magnetic field and 3) identifying the radiation spectrum of the instability. Preliminary results from phase one will be presented along with the progress and diagnostic design for the following phases of the experiment. * C. Huang et. al. Journal of Computational Physics 217, 2(2006) |
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TUOBN1 | Laser Wakefield Acceleration Beyond 1 GeV using Ionization Induced Injection | 707 |
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Funding: Supported by DOE Grants No. DE-AC52-07NA27344, DE-FG03-92ER40727, DE-FG02-92ER40727, DE-FC02-07ER41500, DE-FG52-09NA29552, NSF Grants No. PHY-0936266, PHY-0904039 and FCT, Por., No. SFRH/BD/35749/2007 A series of laser wakefield accelerator experiments leading to electron energy exceeding 1 GeV are described. Theoretical concepts and experimental methods developed while conducting experiments using the 10 TW Ti:Sapphire laser at UCLA were implemented and transferred successfully to the 100 TW Calisto Laser System at the Jupiter Laser Facility at LLNL. To reach electron energies greater than 1 GeV with current laser systems, it is necessary to inject and trap electrons into the wake and to guide the laser for more than 1 cm of plasma. Using the 10 TW laser, the physics of self-guiding and the limitations in regards to pump depletion over cm-scale plasmas were demonstrated. Furthermore, a novel injection mechanism was explored which allows injection by ionization at conditions necessary for generating electron energies greater than a GeV. The 10 TW results were followed by self-guiding at the 100 TW scale over cm plasma lengths. The energy of the self-injected electrons, at 3x1018 cm-3 plasma density, was limited by dephasing to 720 MeV. Implementation of ionization injection allowed extending the acceleration well beyond a centimeter and 1.4 GeV electrons were measured. |
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Slides TUOBN1 [2.488 MB] | ||
TUOBN5 | A Proposed Experimental Test of Proton-Driven Plasma Wakefield Acceleration Based on CERN SPS | 718 |
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Proton-driven plasma wakefield acceleration (PDPWA) has been proposed as an approach to accelerate electron beam to TeV energy regime in a single passage of plasma channel. An experimental test is recently proposed to demonstrate the capability of PDPWA by using proton beams from the CERN SPS. The preparation of experiment is introduced. The particle-in-cell simulation results based on realistic beam parameters are presented. | ||
Slides TUOBN5 [2.208 MB] | ||
MOP101 | Numerical Study of Self and Controlled Injection in 3-Dimensional Laser-Driven Wakefields | 286 |
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Funding: DOE and NSF In plasma based accelerators (LWFA and PWFA), the methods of injecting high quality electron bunches into the accelerating wakefield is of utmost importance for various applications. Understanding how injection occurs in both self and controlled scenarios is therefore important. To simplify this understanding, we start from single particle motion in an arbitrary traveling wave wakefields, an electromagnetic structure with a fixed phase velocity(e.g., wakefields driven by non-evolving drivers), and obtain the general conditions for trapping to occur. We then compare this condition with high fidelity 3D PIC simulations through advanced particle and field tracking diagnostics. Numerous numerical convergence tests were performed to ensure the correctness of the simulations. The agreement between theory and simulations helps to clarify the role played by driver evolution on injection, and a physical picture of injection first proposed in * is confirmed through simulations. Several ideas, including ionization assisted injection, for achieving high quality controlled injection were also explored and some simulation results relevant to current and future experiments will be presented. *W. Lu et al., PRSTAB 10, 061301, 2007 |
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