Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Plasma Physics
Volume 57, Number 12
Monday–Friday, October 29–November 2 2012; Providence, Rhode Island
Session NO7: Particle Driven Wakefields and Laser Ion Acceleration |
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Chair: Stepan Bulanov, University of California, Berkeley Room: 556AB |
Wednesday, October 31, 2012 9:30AM - 9:42AM |
NO7.00001: The AWAKE Proton-driven Plasma Wakefield Acceleration Experiment at CERN Patric Muggli We are planning an experiment at CERN to accelerate externally injected electrons $e^-$ on the wake driven by a long, self-modulated proton $p^+$ bunch. In the plan the $12cm$-long bunch from the SPS with $10^{11}$ $p^+$ experiences a two-stream transverse instability that modulates the bunch radius at the plasma wake period. The bunch is focused to $200\mu m$ into a plasma with density in the $10^{14}-10^{15}cm^{-3}$ range. The modulation instability is seeded by co-propagating with the $p^+$ bunch a short laser pulse that ionizes a gas or vapor. The modulation resonantly drives wakefields to large amplitude. The low energy $e^-$ ($\approx5-20MeV$) produced by a rf-photoinjector gun are injected after the instability has saturated, $\approx3-5m$ into the plasma and is accelerated to the $GeV$ energy range. The $e^-$ energy spectrum is measured by a large energy acceptance magnetic spectrometer. Bunch modulation diagnostics such as time resolved OTR and electro-optic measurements are also included. The general plans for the experiment as well as the latest developments will be presented. [Preview Abstract] |
Wednesday, October 31, 2012 9:42AM - 9:54AM |
NO7.00002: Hosing and self-modulation competition in self-modulated plasma acceleration Jorge Vieira, Ricardo Fonseca, Warren Mori, Patric Muggli, Luis Silva It was recently proposed that large amplitude plasma waves could be resonantly excited by the self-modulation instability (SMI) of long particle bunches [Kumar, PRL 104 255003 (2010)]. Best conditions for particle acceleration are met after the saturation of the SMI when the driver and wake phase velocities are similar. It is therefore crucial to understand whether beam breakup due to the growth of the hosing instability (HI) can occur once the SMI has saturated. Here we show analytically and numerically that the HI is suppressed after the saturation of the SMI. We find that each self-modulated beamlet centroid performs harmonic betatron oscillations driven by the transverse wake associated with the preceding beamlets. Hence, resonances between beamlet centroids are avoided in the linear regime as the wake amplitude grows along the bunch, leading to different betatron frequencies for different beamlets. This suppression mechanism is analogous to the BNS damping [Balakin et al, Proc. 12th Int. Conf. High Energy Accel., Fermilab, 1983, p.119] used in conventional linear accelerators. These findings are confirmed by direct numerical solutions of the model. 3D particle-in-cell simulations confirm our predictions for a wide range of conditions. [Preview Abstract] |
Wednesday, October 31, 2012 9:54AM - 10:06AM |
NO7.00003: Long lepton bunch self-modulation experiment at SLAC Mark Hogan, Jorge Vieira, Nelson Lopes, Ricardo Fonseca, Olaf Reimann, Mike Litos, Selina Li, Spencer Gessner, Ken Marsh, Navid Vafaei, Chan Joshi, Warren Mori, Erik Adli, Yun Fang, Luis Silva, Patric Muggli The use of long particle bunches to drive ultra-relativistic, high amplitude plasma waves through the transverse self-modulation instability (SMI) has been recently investigated numerically. This has motivated proton driven plasma wakefield accelerator experiments currently being planned at CERN and Fermilab. We propose to explore the SMI using the 20 GeV, 500 microns long lepton bunches currently available at SLAC FACET. Full-scale PIC simulations show gradients greater than 20 GeV/m and up to 10 GeV energy gain/loss at the 1{\%} level in 1 meter plasmas using electron bunches. Simulations show that the blowout regime is reached at the saturation of the SMI. For the positron driven scenario, the blowout leads to the defocusing of most of the positrons and a gain/loss up to 5 GeV at the 1 {\%} energy level is reached. Simulation results as well as diagnostics to measure the SMI in the planned experiments are discussed. [Preview Abstract] |
Wednesday, October 31, 2012 10:06AM - 10:18AM |
NO7.00004: Seeding of the Self-modulation of a Long Particle Bunch in a Plasma Yun Fang, Patric Muggli, Warren Mori, Jorge Vieira, Vitaly Yakimenko, Karl Kusche, Marcus Babzien, Christina Swinson, Mikhail Fedurin, Robert Malone We demonstrate experimentally for the first time the self-modulation seeding of a relativistic electron bunch in a plasma. The long ($\approx3.2~ps$) bunch available at BNL-ATF drives wakefields with periods one to one fifth the bunch length in plasmas in a $10^{15}\sim10^{16} cm^{-3}$ density range. The effect of the seeding is observed as a periodic modulation of the bunch correlated energy spectrum after the 2cm-long plasma. Although simulations and experimental results show that the self-modulation instability does not grow significantly over the $2~cm$-long plasma with a $50~pC$ bunch, its development is confirmed by the resulting large energy gain and loss observed with a higher charge bunch ($1~nC$). This demonstration serves as a proof -of -principle test for the mechanisms of seeding of the transverse self -modulation of particle bunches in plasmas, and indicates the possibility of using long electron or proton bunches as drivers for plasma based accelerators. Detailed experimental and simulation results will be presented. [Preview Abstract] |
Wednesday, October 31, 2012 10:18AM - 10:30AM |
NO7.00005: Beam-Driven Plasma Wakefield Acceleration of Electrons in Lithium and Rubidium Plasmas Navid Vafaei-Najafabadi, Kenneth Marsh, Christopher Clayton, Chandrasekhar Joshi, Erik Adli, Sebastien Corde, Michael Litos, Selina Li, Spencer Gessner, Joel Frederico, Mark Hogan, Dieter Walz, Joel England, Weiming An, Wei Lu, Warren Mori, Patric Muggli, Jean-Pierre Delahaye We report on the plasma wakefield experiments performed at the newly commissioned FACET facility at the SLAC National Laboratory. A beam of 2x10$^{10}$ 20.5 GeV electrons was focused through a 20-40 cm long vapor column of lithium or rubidium produced in a heat-pipe oven. The electron beam tunnel-ionized the metal vapor and then drove a large amplitude plasma wake. The resulting interaction was investigated for different plasma densities and beam parameters. The primary diagnostic was the energy gain and loss features observed using an imaging magnetic spectrometer. Preliminary data and a comparison between acceleration in rubidium and lithium plasmas will be presented. [Preview Abstract] |
Wednesday, October 31, 2012 10:30AM - 10:42AM |
NO7.00006: Frequency-Domain Interferometry of Electron Bunch Driven Wakefields Rafal Zgadzaj, M.C. Downer, Austin Yi, Gennady Shvets, Yun Fang, Patric Muggli, Vitaly Yakimenko, Marcus Babzien, Mikhail Fedurin, Karl Kusche Beam-driven plasma wakefield accelerators (PWFA), such as the ``plasma afterburner'' can potentially greatly increase the particle energies of conventional accelerators . Various schemes using single and multiple bunches of electrons, positrons and protons have been investigated. Appropriately delayed witness bunches have been the usual method to probe the fields of such wakes, and indirectly, the corresponding plasma wake structures. However, the wake structure has not been observed directly in the PWFA. We will report our progress in the development of direct, optical interferometric methods of measuring the plasma density modulation in electron beam driven wakefields. Frequency Domain Holography (FDH), employing two chirped laser pulses (probe and reference) co-propagating with the particle drive-beam and its plasma wake, permits single shot observation of an extended section of the wakefield behind a drive bunch. The chirped, temporally stretched, probe samples several periods of the wake, while the undisturbed reference pulse propagates ahead of the electron drive bunch. The technique is being developed in the Accelerator Test Facility at the Brookhaven National Laboratory as a probe for two and multibunch driven plasmawakefield experiments [Preview Abstract] |
Wednesday, October 31, 2012 10:42AM - 10:54AM |
NO7.00007: Ion acceleration beyond 100MeV/amu from relativistic laser-matter interactions Daniel Jung, Cort Gautier, Randall Johnson, Samuel Letzring, Rahul Shah, Sasikumar Palaniyappan, Tsutomu Shimada, Juan Fernandez, Manuel Hegelich, Lin Yin, Brian Albright, Dieter Habs In the past 10 years laser acceleration of protons and ions was mainly achieved by laser light interacting with micrometer scaled solid matter targets in the TNSA regime, favoring acceleration of protons. Ion acceleration based on this acceleration mechanism seems to have stagnated in terms of particle energy, remaining too low for most applications. The high contrast and relativistic intensities available at the Trident laser allow sub-micron solid matter laser interaction dominated by relativistic transparency of the target. This interaction efficiently couples laser momentum into all target ion species, making it a promising alternative to conventional accelerators. However, little experimental research has up to now studied conversion efficiency or beam distributions, which are essential for application, such as ion based fast ignition (IFI) or hadron cancer therapy. We here present experimental data addressing these aspects for C$^{6+}$ ions and protons in comparison with the TNSA regime. Unique measurements of angularly resolved ion energy spectra for targets ranging from 30 nm to 25 micron are presented. While the measured conversion efficiency for C$^{6+}$ reaches up to $\sim $7{\%}, peak energies of 1 GeV and 120 MeV have been measured for C$^{6+}$ and protons, respectively. [Preview Abstract] |
Wednesday, October 31, 2012 10:54AM - 11:06AM |
NO7.00008: Laser-Driven Ion Beams for Fast Ignition Juan C. Fernandez, B.J. Albright, D.C. Gautier, B.M. Hegelich, C. Huang, D. Jung, S. Letzring, S. Palaniyappan, R. Shah, L. Yin, H. Wu, J.J. Honrubia, M. Roth We have been developing laser-driven Carbon ion beams for fusion fast ignition (FI). We present our latest understanding on the mechanisms capable of producing the required quasi-monoenergetic C-ion beams with an ion energy of about 0.5 GeV, which is necessary to penetrate to the core of the compressed DT fuel. We discuss how our understanding is informed by the results from our Trident laser experiments, including the geometry of the resulting C beam, its energy spectrum (extending up to 1 GeV), and the plasma conditions where the beam is produced. We present our progress and experimental plans towards achieving the beam parameters required for FI. [Preview Abstract] |
Wednesday, October 31, 2012 11:06AM - 11:18AM |
NO7.00009: Shock Wave Acceleration of Ions on Omega EP D. Haberberger, S. Tochitsky, C. Gong, W.B. Mori, C. Joshi, F. Fiuza, R.A. Fonseca, L.O. Silva For the past decade, laser-driven ion acceleration (LDIA) has typically produced ion beams with continuous energy spread and poor peak ion energy scaling with laser power. Recent experimental results using shock-wave acceleration (SWA) driven by a CO$_{2}$ laser in an H$_{2}$ gas-jet plasma have shown the possibility of producing proton beams with energy spreads down to 1{\%} and energies of up to 20 MeV using a modest peak laser power of 4 TW.\footnote{D. Haberberger \textit{et al}., Nature Phys. \textbf{8}, 95 (2012).} Here we propose to investigate the scaling of the SWA mechanism to higher laser powers using the 1-\textit{$\mu $}m OMEGA EP Laser System at LLE. UV nanosecond laser beams will be used to ionize a thin plastic target with a fixed delay from the main pulse such that the desired characteristics optimal for SWA are met---peak plasma density is overdense for the 1-\textit{$\mu $}m main pulse and the plasma profile exponentially decays over a long scale length on the rear side. A 4\textit{$\omega $} probe will be used to experimentally characterize the plasma density profile. Scaling from simulations of the SWA mechanism shows that ion energies in the range of 100 MeV/amu are achievable with a focused $a_{o}$ of 5 from the OMEGA EP Laser System, surpassing the current scaling in LDIA results. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302. [Preview Abstract] |
Wednesday, October 31, 2012 11:18AM - 11:30AM |
NO7.00010: Laser Radiation Pressure Acceleration of Ions by a Slow Electromagnetic Wave and Ion Beam Instabilities S.S. Bulanov, C.G.R. Geddes, C.B. Schroeder, E. Esarey, W.P. Leemans, S.V. Bulanov, T. Zh. Esirkepov, M. Kando, F. Pegoraro When the radiation pressure of a laser pulse accelerates the ions in a plasma, the ion velocity cannot exceed the pulse group velocity, which can be considerably smaller than the speed of light in vacuum. This is demonstrated in two cases: (1) a thin foil target irradiated by high intensity laser light and (2) the hole boring produced in an extended plasma by a laser pulse that is accompanied by the formation of a collisionless shock wave. It is found that the beams of ions accelerated at the collisionless shock wave front are unstable against Buneman-like and Weibel-like instabilities, which result in the broadening of the ion energy spectrum. [Preview Abstract] |
Wednesday, October 31, 2012 11:30AM - 11:42AM |
NO7.00011: Neutron Generation through Ultra-Intense Laser Plasma Interactions C. Zulick, F. Dollar, L. Willingale, V. Chvykov, G. Kalintchenko, A. Maksimchuk, A.G.R. Thomas, V. Yanovsky, K. Krushelnick, J. Davis, G.M. Petrov, V. Glebov, P.M. Nilson, T.C. Sangster, C. Stoeckl, R.S. Craxton, P.A. Norreys, J. Cobble, H. Chen Fast neutrons ($\textgreater$ 1 MeV) have important applications in biological imaging, materials testing, and active interrogation for homeland security. Experiments at the HERUCLES laser facility produced neutrons with energies up to 12 MeV in directional beams utilizing $^7_3$Li(p,n)$^7_4$Be, and $^7_3$Li(d,n)$^8_4$Be reactions. The neutrons were produced in a two-stage pitcher-catcher configuration by accelerating protons and deuterons from micron scale solid targets into bulk LiF. The neutron yield was measured to be up to $2.3 (\pm 1.4) \times 10^7$ neutrons/sr with a flux $6$ times higher in the forward direction than at $90^{\circ}$. Additionally, the kilojoule short-pulse OMEGA EP laser was used to investigate $^2_1$D(d,n)$^3_2$He reactions from an underdense deuterated plastic plume. Fast neutron spectra were observed via time-of-flight measurements as a result of deuteron acceleration during the channel formation. [Preview Abstract] |
Wednesday, October 31, 2012 11:42AM - 11:54AM |
NO7.00012: A table-top laser-based source of short, collimated, ultra-relativistic positron beams Gianluca Sarri, Brendan Dromey, Mark Dieckmann, Matthew Zepf, Antonino Di Piazza, Cristoph Keitel, William Schumaker, Mike Vargas, Vladimir Chvykov, Alexander Maksimchuk, Viktor Yanovsky, Zhaohan He, Alexander Thomas, Karl Krushelnick We present here the first experimental evidence of the generation of ultra-short (35 fs), highly collimated (3 mrad) and ultra relativistic (150 MeV) positron beams following the interaction of a laser-wakefield accelerated electron beam with high-Z solid targets. The modest laser parameters (25 TW) make this the first demonstration of a table top source of relativistic positron beams. We anticipate that these beams will be also of direct relevance to the laboratory study of astrophysical leptonic jets. [Preview Abstract] |
Wednesday, October 31, 2012 11:54AM - 12:06PM |
NO7.00013: Laser-driven proton acceleration in thin micro-structured foils Jiri Limpouch, Ondrej Klimo, Jan Psikal, Richard Liska, Jan Proska, Lucie Stolcova, Jiri Vyskocil, Daniele Margarone, Georg Korn, Daniel Kramer, Tomas Mocek, Jan Prokupek, Tae Moon Jeong, I. Jong Kim, Hyung Taek Kim, K.H. Nam, Il Woo Choi, Seong Ku Lee, Jae Hee Sung, Tae Jun Yu Proton acceleration enhancement by microstructures on the front side of a thin foil was studied both theoretically and experimentally. Microstructures of characteristic width comparable to the laser wavelength improve the absorption of high-contrast ultrashort intense laser pulses, hot electron temperature and number is enhanced and subsequently, the efficiency of ion acceleration in the TNSA regime is increased. We have proposed, prepared and tested targets with a monolayer of microspheres on the surface of 1-$\mu $m-thick plastic foil. These targets were irradiated by 100 TW laser beam reaching intensities up to 5$\times $10$^{19}$~W/cm$^{2}$. The cut-off proton energy was increased by 60{\%} for the optimal spheres' diameter of 535~nm compared to the pure planar foil. The total number of protons with energies higher than 1~MeV was increased approximately 5 times. Experimental results are interpreted by means of 2.5-dimensional Particle-In-Cell code. [Preview Abstract] |
Wednesday, October 31, 2012 12:06PM - 12:18PM |
NO7.00014: ABSTRACT WITHDRAWN |
Wednesday, October 31, 2012 12:18PM - 12:30PM |
NO7.00015: Positron and Gamma-Ray Creation using the Texas Petawatt Laser Irradiating Gold Targets Edison Liang, Devin Taylor, Taylor Clarke, Alexander Henderson, Petr Chaguine, Xin Wang, Gilliss Dyer, Kristina Serratto, Nathan Riley, Michael Donovan, Todd Ditmire We report preliminary results of the positron and gamma-ray creation experiment performed at the Texas Petawatt Laser (TPW) during the summer of 2012. Of the shots using gold targets, preliminary results suggest that positrons were detected in many of the shots. TPW was operating at around 100 J and 0.5 -- 0.8 PW during this experiment, and 25{\%} of the shots achieved peak intensity exceeding 10$^{21}$W.cm$^{-2}$. We will report the measured positron spectra, positron angular distribution and positron to hot electron ratio, inferred positron yield and in-situ positron density. The positron energy data will be compared to simultaneous TNSA proton energy data to model sheath acceleration mechanisms. We also measured the bremsstrahlung gamma-ray spectra and angular distributions from the gold targets, using a combination of dosimeters, filter stack spectrometers and forward Compton spectrometer. Target activation data will also be reported. [Preview Abstract] |
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