Chairs
Dr Mark J Hogan, SLAC National Accelerator Laboratory, USA
Dr Mark J Hogan, SLAC National Accelerator Laboratory, USA
Mark Hogan is the Plasma Group Leader and the FACET-II Project Scientist at the SLAC National Accelerator Laboratory. He earned his PhD in physics from UCLA in 1998 working on Self Amplified Spontaneous Emission free electron laser experiments at UCLA and Los Alamos National Laboratory. He joined SLAC as a postdoc in 1998 to work on the E-157 beam driven plasma wakefield accelerator experiment at the Final Focus Test Beam facility. He joined the SLAC staff in 2000 and was the spokesperson for the follow on experiments E-162/E-164/E-167. He is currently in charge of the science program for the FACET National User Facility and is developing ideas for the follow-on facility FACET-II. He leads the effort at the FACET facility to experimentally develop these ideas for plasma wakefield accelerator based linear colliders and free electron lasers.
09:05-09:35
Plasma wakefield acceleration experiments on FACET II and the DOE's Strategic Plan for Advanced Accelerator R&D
Professor Chandrashekhar Joshi, UCLA, USA
Abstract
A dense, ultra-relativistic electron bunch propagating through a uniform plasma can produce a highly nonlinear wake that can be employed for accelerating a second, trailing bunch in a scheme known as the Plasma Wakefield Accelerator (PWFA). Recent work has shown that a PWFA cavity can accelerate a low energy spread electron bunch containing a significant charge at both high gradients and high energy-extraction efficiency - necessary conditions for making future particle accelerators both compact and less expensive. The next important challenge that must be addressed is the high efficiency acceleration of a low emittance and narrow energy spread electron beam while pump depleting the drive beam. Professor Joshi will explain how such an ambitious experiment is well aligned with the U.S. Department of Energy-High Energy Physics Division’s long-range strategic plan for Advanced Accelerator Research and Development. A new facility, FACET II is being constructed at SLAC that will enable such an experiment. Professor Joshi will describe the plans and the progress for the upcoming experimental campaign on FACET II.
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Professor Chandrashekhar Joshi, UCLA, USA
Professor Chandrashekhar Joshi, UCLA, USA
Dr Chandrashekhar (Chan) Joshi is currently a Distinguished Chancellor’s Professor of Electrical Engineering at University of California Los Angeles. He has made fundamental contributions in the areas of nonlinear optical effects in plasmas, basic plasma physics and laser-matter interactions at ultra-high intensities. His research group is best known for work in the field of ultra-high gradient acceleration of charged particles using space charge density waves or wakes in plasmas using a laser or a particle beam pulse. Such wakes are being considered as accelerating structures for next generation of particle colliders and compact light sources to make these critical instruments of scientific discovery more compact and affordable. He is the recipient of APS’ Maxwell Prize, IEEE’s Marie Sklodowska Curie Prize and a member of the National Academy of Engineering.
09:50-10:15
Beam quality preservation challenges and strategies
Professor Michael Litos, University of Colorado Boulder, USA
Abstract
Plasma-based electron accelerators have now demonstrated the ability to reliably provide a large energy gain with a small final energy spread. Beam emittance preservation, however, remains an outstanding challenge for the field. If the beam size is appropriately matched to the plasma, the beam will not suffer chromatic emittance growth as it traverses the plasma source. Unfortunately, the typically small matched beam sizes present a serious problem for external beam injection and beam extraction. This makes it difficult for plasma accelerators to interface with conventional accelerator components, including electromagnetic beam transport systems and magnetic undulators. In this talk, a solution for beam matching into and out of a plasma accelerator is presented, based on the use of tailored plasma density ramps at the entrance and exit of the plasma source. A simple model for beam transport through the plasma will be discussed, and it will be shown that a plasma ramp of a practical length can perfectly match a high-energy electron beam into or out of a plasma source with experimentally realistic beam and plasma parameter tolerances. Further, empirical generalized scaling laws will be presented that give a prescription for the ideal plasma density profile as a function of the desired beam parameters entering or leaving the plasma source.
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Professor Michael Litos, University of Colorado Boulder, USA
Professor Michael Litos, University of Colorado Boulder, USA
Michael Litos received his PhD in experimental particle physics from Boston University in 2010, where he conducted research in neutrino physics and nucleon decay as a member of the Super-Kamiokande and T2K collaborations. He switched fields to advanced accelerator physics upon beginning his postdoctoral work as a member of the FACET research team at SLAC National Accelerator Laboratory, where he played a key role in experimental studies of plasma wakefield acceleration, culminating in the first high-energy acceleration of electron and positron bunches in a beam-driven plasma wakefield accelerator. He took a position as an Assistant Professor of Physics and became a Fellow of the Center for Integrated Plasma Studies at the University of Colorado Boulder in 2017 where he continues to study the physics of plasma wakefield acceleration and remains an active member of several international research collaborations focused on advanced accelerator concepts.
10:50-11:15
FLASHForward – plasma wakefield accelerator science for high average power applications
Dr Jens Osterhoff, DESY, Germany
Abstract
The field of particle acceleration in plasma waves has seen remarkable progress in the last two decades. These days, acceleration gradients of more than 10 GV/m can be readily achieved using either ultra-short intense laser pulses or high-current density particle beams as plasma wakefield drivers. With the demonstration of first GeV electron beams and a trend towards improved reproducibility, beam quality and control over the involved plasma processes, plasma-acceleration techniques are drawing considerable interest in the traditional accelerator community. As a consequence, DESY, Germany's leading accelerator centre, has established a research programme for beam-driven plasma-based novel acceleration techniques with the goal to symbiotically combine conventional and new accelerator concepts for applications. This presentation will give an introduction into these emerging activities, show first theoretical and experimental results and outline the DESY PWFA flagship project, FLASHForward.
FLASHForward is a pioneering beam-driven plasma-wakefield experiment that aims to produce, in a few centimetres of ionized hydrogen, electron beams of energies exceeding 1.5 GeV that are of sufficient quality to demonstrate gain in a free-electron laser. The experimental beamline will allow for milestone studies assessing plasma-internal particle injection regimes, external injection, and controlled beam capturing and release for subsequent applications. The facility provides a unique combination of low-emittance GeV-class electrons from the superconducting MHz repetition rate, high-average power accelerator FLASH synchronized to a 25 TW laser interacting in a windowless, optically accessible, versatile plasma target. Experiments will commence in 2018 and are foreseen to run for the next decade, opening up new avenues in this highly dynamic research field.
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Dr Jens Osterhoff, DESY, Germany
Dr Jens Osterhoff, DESY, Germany
Jens Osterhoff is the initiator and leader of the beam-driven plasma accelerator project FLASHForward at DESY, Hamburg, Germany. He has been heading the plasma wakefield acceleration group within the DESY Particle Physics Division since 2013 and acts as the deputy spokesperson of Accelerator Research and Development in the Helmholtz Association of German Research Centers. Jens pioneered plasma accelerator science in Hamburg when he founded his research team at the University in 2010 after postdoctoral stays with Wim Leemans at Lawrence Berkeley National Lab and Stefan Karsch at LMU Munich. In 2009, he obtained his PhD in the field of laser-wakefield acceleration under the supervision of Ferenc Krausz at the Max-Planck-Institute of Quantum Optics. His general interest in laser-matter interaction dates back to 2003 when it received a critical spark at the University of Texas in Austin, where Jens investigated shock-wave dynamics in plasma under Todd Ditmire and Mike Downer.
11:30-11:55
On the phase space dynamics of high brightness injection and staging in plasma wakefield acceleration
Professor Wei Lu, Tsinghua University of Beijing, China
Abstract
In this talk, the current physics understanding of phase space dynamics for different injection methods and matching between stages in Plasma Wakefield Acceleration (PWFA) will be reviewed, with a focus on how to generate and maintain high quality electron beams of ultra-high brightness and low energy spread. Two major injection methods (plasma density modulation and ionization based injection) will be discussed in detail to show their potentials and limitations. Furthermore, phase space manipulation methods on staging and energy chirp reduction to 0.1% level will also be discussed.
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Professor Wei Lu, Tsinghua University of Beijing, China
Professor Wei Lu, Tsinghua University of Beijing, China
Dr Wei Lu has been a full professor of Tsinghua University since 2011, and currently he is leading a research team with a focus on high quality plasma based accelerator and light source. In 1998 and 2001, Dr Lu obtained his BS and MS degrees in Tsinghua University. In 2006, he obtained his PhD degree on plasma physics at UCLA. DrLu has received worldwide recognition for his contribution on plasma based accelerator research. He won several international awards, including the first edition of John Dawson prize of plasma accelerator community (2007), the IUPAP Young Scientist Prize on plasma physics (2014, as the first winner on laser plasma and high energy density physics), the first edition of Young Researcher Award of AAPPS on plasma physics (2016). Dr Lu has coauthored more than 100 papers in journals and conference proceedings, including 3 Nature, 1 Nature Physics, 3 Nat. Com. and 24 PRLs, with a total citation more than 4000 times. Since 2009, Dr Lu has been on board of program or advisory committee for all the major conferences of plasma accelerators, including AAC, LPAW and EAAC.
12:10-12:35
Experimental demonstration of electron bunch generation from a plasma photocathode
Dr Aihua Deng, UCLA, USA
Abstract
Dr Deng will talk about the experiments performed at the Facility for Advanced Accelerator Experimental Tests (FACET) at the SLAC National Accelerator Laboratory, which is termed 'E210: Trojan Horse Plasma Wakefield Acceleration'. A new technique will be introduced, called the 'plasma photocathode'. It generates high quality electron beams directly within the large fields of a particle beam driven plasma wave by means of an ionizing laser pulse. The talk will demostrate controlled electron bunch generation in a plasma wakefield accelerator with an ionizing laser pulse to liberate electrons from helium gas in a preformed hydrogen plasma. Two injection modes will be introduced in the experiments: all-optical density down ramp injection and the real plasma photocathode injection. Optically-triggered density ramp injection is shown to provide a stepping stone for experimental parameter adjustments that yield beam generation from a plasma photocathode. The 'plasma photocathode' technique opens a path to beam phase space characteristics exceeding those of conventional photocathodes, and thus to combine the ultra-high energy gain of plasma accelerators with ultra-high beam quality. It will open the door to production of 'designer electron beams' with unprecedentedly low emittance, short duration and high brightness based on precision control of injection in extremely high field waves.
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Dr Aihua Deng, UCLA, USA
Dr Aihua Deng, UCLA, USA
Dr Aihua Deng is now a postdoc scholar in department of Physics & Astronomy at UCLA. She received a PhD in Physics from the Shanghai Institute of Optics and fine Mechanics (SIOM), Chinese Academy of Sciences. Her research background is electron beam generation based on laser wakefield accelerator (LWFA) using relativistic high power laser. In 2012, she joined the Particle Beam Physics Laboratory (PBPL) group in UCLA as a postdoc researcher. Dr Deng is an experimentalist developing research on the high brightness beam generation based on plasma wakefield acceleration (PWFA) and relative applications.