Chengkun Huang

Los Alamos National Laboratory, Los Alamos, California, United States

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Publications (51)39.47 Total impact

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    ABSTRACT: We have previously shown initial simulation results from the Quickpic particle in cell (PIC) code that uses the quasi-static approximation indicating that a transformer ratio larger than two can be achieved with a train of one to three electron bunches driving the PWFA interaction into the weakly non-linear regime. Such transformer ratio can be maintained over four betatron wavelengths (or ˜2cm). The parameters for the electron bunches are chosen based on the current experiment running in the Brookhaven National Laboratory Accelerator Test Facility where the effects could be demonstrated. Reaching the weakly nonlinear is crucial to insure that the accelerating structure and the transformer ratio are maintained even in the presence of the transverse evolution of the bunch along the plasma caused by the transverse fields. In this presentation, we will investigate the wakefield evolution over very long plasma length (meter scale) and the parameters of a witness bunch following the drive train.
    11/2011;
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    ABSTRACT: QuickPIC is a 3D parallel quasi-static Particle-In-Cell (PIC) code, which is developed with a PIC framework UPIC. Recently, a new 2D field solver for calculating the plasma response to the drive beam in QuickPIC has been developed. It is based on a new set of Maxwell equations (under the quasi-static approximation) which is using transverse Coulomb gauge. With this new solver, QuickPIC can obtain an accurate solution with only 1 iteration (3 or 4 iterations were needed with the old version). The new 2D field solver is also purely spectral (as compared to the older field solver which uses both finite difference and spectral method), which is not only more accurate. Furthermore, the new solver also reduce the total number of FFT calls, which led to a significant time saving. Comparisons between the results for the old and new solver will be given. In addition, we will show QuickPIC results on modeling two bunch FACET experiments, proton driven PWFA and parameters for a future collider based on PWFA stages.
    11/2011;
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    ABSTRACT: Current Filamentation Instability (CFI) is of central importance for the propagation of relativistic electron beams in plasmas. It could play an important role in the generation of magnetic fields and of radiation in the after‐glow of gamma ray bursts as well as in hot electrons energy transport in the fast‐igniter inertial confinement fusion concept. Using the particle‐in‐cell code QuickPIC, simulations of the electron beam at the Brookhaven National Laboratory—Accelerator Test Facility, BNL‐ATF, propagating in a cm‐long plasma were conducted. Simulation results show that with beam and plasma parameters achievable at the BNL‐ATF, the CFI should be observed within 2 cm of plasma. Simulation results are presented for an experiment currently underway at BNL‐ATF and possible diagnostics for characterizing the instability are discussed.
    AIP Conference Proceedings. 11/2010; 1299(1):516-521.
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    ABSTRACT: Simulation results of possible upcoming Plasma Wakefield Accelerator (PWFA) experiments at FACET are presented. In a two-bunch scenario, the second (accelerated) electron bunch can have multi-GeV energy gain and a small energy spread after less than 1 meter of propagation in a Cs plasma column.
    11/2010;
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    ABSTRACT: In PWFA, accelerating gradient and transformer ratio are two import figures of merit of the wake excitation process.In this talk, simple theories based on a nonlinear wakefield theoretical framework in the blowout regime [1-2] will be presented to predict the optimum density and transformer ratio in the blowout regime. It is found that the peak beam current I/p plays an important role in determining the optimum density and transformer ratio. We show that for narrow beams of low peak current (I/p
    11/2010;
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    ABSTRACT: We study numerically the excitation of plasma wakefields by a train of electron bunches. The purpose is to find a regime in which the wakefield excited by individual electron bunches add and have a large amplitude and a large transformer ratio. This scheme will produce a high energy accelerated bunch with a low energy drive train in a single plasma wakefield accelerator stage. The transverse size of the bunches must be maintained long enough for the driving bunches to efficiently transfer their energy to a trailing witness bunch. It is studied experimentally at the Brookhaven National Laboratory Accelerator Test Facility (ATF). We also investigate the effect of a transverse electron plasma profile on the period of the excited wakefield, an effect that may play a role in the experiments using a capillary discharge as a plasma source. Detailed simulation results will be presented.
    11/2010;
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    ABSTRACT: In a plasma wakefield accelerator (PWFA) with a drive bunch density higher than the plasma, a pure ion column is formed behind the drive bunch (blow-out regime). Due to the ion restoring force, which is linearly increasing with radius, beam electrons perform betatron oscillations. We consider the case of a witness bunch entering the plasma with a radial offset or a transverse momentum component. In this case, the whole witness bunch oscillates about the beam axis defined by the drive bunch. We use the particle in cell code QUICKPIC [1] to simulate the plasma wakefields and we study the radiation characteristics as a function of the electron bunches and plasma parameters. We place the witness bunch at the position where the synchrotorn- radiated power is compensated for by the energy gain from the wakefields. Detailed results will be presented.[4pt] [1] C.H. Huang, et al., J. Comp.Phys., 217(2), 658, (2006).
    11/2010;
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    ABSTRACT: Fourth generation of light sources (e.g.,LCLS and the XFEL) require high energy electron drivers (16-20GeV) of very high quality. We are exploring the possibility of using a high transformer ratio PWFA to meet these challenging requirements. This may have the potential to reduce the size of the electron drivers by a factor of 5 or more, therefore making these light source much smaller and more affordable. In our design, a high charge (5-10nC) low energy driver (1-3GeV) with an elongated current profile is used to drive a plasma wake in the blowout regime with a high transformer ratio (5 or more). A second ultra-short beam that has high quality and low charge beam (1nC) can be loaded into the wake at a proper phase and be accelerated to high energy (5-15GeV) in very short distances (10s of cms). The parameters can be optimized, such that high quality (0.1% energy spread and 1mm mrad normalized emittance) and high efficiency (60-80%) can be simultaneously achieved. The major obstacle for achieving the above goals is the electron hosing instabilities in the blowout regime. In this poster, we will use both theoretical analysis and PIC simulations to study this concept.
    11/2009;
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    ABSTRACT: Plasma Wakefield Acceleration (PWFA) has been proposed as a possible way to reduce the size and cost of the next linear collider. The needs to faithfully simulate the drive beam evolution and the main beam dynamics in the future plasma-based linear collider using Particle-In-Cell codes are extremely challenging. However, the recent progress on the development of quasi-static model and the usage of massive parallel computing resources have enabled simulation studies of the near term PWFA experiments and for the conceptual designs of the next generation facilities in full details with realistic linear collider parameters and including necessary effects such as ion motion. The simulation needs for modelling the plasma-based advanced accelerator at the energy frontier is discussed and a path towards this goal is outlined. Results from full scale simulations that include all particles in real plasma will be reported.
    01/2009;
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    ABSTRACT: The acceleration of highly polarized particle beams is critical not only to test and validate current physical models, but it is also critical in the search for new physics in high-energy physics (HEP) experiments. Plasma-based accelerators can play an important role in next generations of accelerators, as they can reduce the size of standard acceleration structures by two-three orders of magnitude. However, for high-energy physics applications, and in addition to beam quality requirements such as the emmittance, luminosity, energy, or energy spread, the evolution of the electron beam polarization is also crucial for the use of future linear plasma based colliders in HEP experiments. In this work, the spin-precession in plasma-based acceleration scenarios is examined using the Thomas-- Bargmann-Michel-Telegdi equations. Analytical expressions which show that lower depolarizations can be achieved by using narrower beams, with lower initial energies, are derived. In addition, it is found that mildly relativistic regimes lead to lower depolarizations in comparison to strongly relativistic regimes. Our findings are confirmed with 3D particle-in-cell simulations using QuickPIC.
    01/2009;
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    ABSTRACT: Plasma Wakefield Accelerator has been proven to be a promising technique to lower the cost of the future high energy colliders by offering orders of magnitude higher gradients than the conventional accelerators. However, it has been shown that ion motion is an important issue to account for in the extreme regime of ultra high intensity and ultra low emittance beams, characteristics of future high energy colliders. In this regime, the transverse electric field of the beam is so high that the plasma ions cannot be considered immobile at the time scale of electron plasma oscillations, thereby leading to a nonlinear focusing force. Therefore, the transverse emittance of a beam matched to the initial linear focusing will not be preserved under these circumstances. However, Vlasov's equation predicts a matched profile even in the nonlinear focusing force case. Furthermore, we extend the idea and introduce a plasma section that can match the entire beam to the mobile-ion regime of plasma by adiabatically reducing the plasma ion mass. We also find the analytic solution for the optimal matching section. Simulation results are presented.
    01/2009;
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    ABSTRACT: Simulating the electron cloud effect on a beam that circulates thousands of turns in circular machines is highly computationally demanding. A novel algorithm, the pipelining algorithm is applied to the fully parallelized quasi-static particle-in-cell code QuickPIC to overcome the limit of the maximum number of processors can be used for each time step. The pipelining algorithm divides the processors into subgroups and each subgroup focuses on different partition of the beam and performs the calculation in series. With this novel algorithm, the accuracy of the simulation is preserved; the speed of the simulation is improved by one order of magnitude with more than 10^2 processors are used. The long term simulation results of the CERN-LHC and the Main Injector at FNAL from the QuickPIC with pipelining algorithm are presented. This work is supported by SiDAC and US Department of Energy
    11/2008;
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    ABSTRACT: Plasma density is one factor that contributes to the onset of ionization induced electron trapping in a plasma wakefield accelerator. Here, experimental measurements and theory exhibit the dependence of trapping on plasma density.
    11/2008;
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    ABSTRACT: A positron beam accelerated by a beam-driven plasma wakefield is investigated by numerical simulation. Both of the electron driving beam and positron driving beam are used. A preliminary parameters design is obtained for such acceleration scheme.
    10/2008; -1:6091P.
  • Chengkun Huang, F.S. Tsung, W.B. Mori
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    ABSTRACT: High-energy physics frontier is approaching the teraelectron-volt energy range for the study of the Higgs particle. To reach teraelectron-volt energy for charged particles, a high-gradient acceleration structure is desirable. Recent plasma wakefleld acceleration (PWFA) experiment has shown sustained acceleration gradient of 50 GeV/m in a meter-long plasma [1]. To study the relevant physics in an "afterburner" concept [2], i.e., an energy booster based on PWFA for the ILC-type parameters, we conduct 3-D particle-in-cell (PIC) simulation of the nonlinear beam-plasma interactions. A multiscale PIC model is developed using the quasi-static description of the interaction. We present images from the simulation, which illustrate the physical picture of an afterburner and the evolution of the accelerated beam.
    IEEE Transactions on Plasma Science 09/2008; · 0.87 Impact Factor
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    ABSTRACT: In plasma based acceleration for electrons, the blowout regime turns out to be of very importance due to its ability to provide an ideal accelerating and focusing structure and its ability to support large amount of charge (e.g., nC). A theoretical model has been successfully developed to describe this highly nonlinear regime [1]. Based on this model, many important aspects of the blowout regime can be accurately addressed. Here the solutions for four different problems in the blowout regime will be presented, including the optimum plasma density for maximum wakefield amplitude for given beam parameters, beam loading, the transformer ratio for a linearly ramped electron beam driver (optimizing the transformer ratio), and the electron hosing instability. Full and reduced particle-in-cell simulations will be also presented to justify these theoretical analyses. [1] W. Lu et al, Phys. Rev. Lett. 96, 165002 (2006)
    01/2008;
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    ABSTRACT: Recent plasma wakefield acceleration (PWFA) experiment using short (˜100fs), high peak current (>10KA) electron beam as wakefield driver has demonstrated sustained acceleration gradient of ˜50GeV/m over 85 cm. The rapid progress of PWFA experiments has attracted interests regarding the possibility of making an ``afterburner'' for a linear collider. In the ``afterburner'' concept, electron acceleration is achieved by placing a trailing electron beam into the wakefield (either by beam splitting or external injection) to extract energy deposited in the plasma wave wake. Several important aspects of the ``afterburner'' design in the blow-out regime, such as wakefield generation, efficient beam loading and hosing instability have been investigated theoretically. These relevant physics will have great impact on the beam quality of a possible ``afterburner'' design. A multi-stage ``afterburner'' design with 25GeV energy gain in each stage is explored numerically with a 3D quasi-static code QuickPIC. Parameters are suggested for a 0.5 TeV PWFA afterburner with this design and simulation result will be presented.
    01/2008;
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    ABSTRACT: In LWFA schemes the laser pulse must propagate several centimeters and maintain its coherence over this distance, which corresponds to many Rayleigh lengths. These Wakefields and their effect on the laser can be simulated in quasistatic approximation [1, 2]. In this approximation the assumption is that the driver (laser) does not change shape during the time it takes for it to pass by a plasma particle. As a result the particles that are trapped and moving with near-luminal velocity can not be treated with this approximation. Here we have modified the 2D code WAKE with an alternate algorithm so that when a plasma particle gains sufficient energy from wakefields it is promoted to beam particle status which later on may become trapped in the wakefields of laser. Similar implementations have been made in the 3D code QUICKPIC [2]. We also have done comparison between WAKE and results from 200 TW laser simulations using OSIRIS [3]. These changes in WAKE will give users a tool that can be used on a desk top machine to simulate GeV acceleration.[0pt] [1] P. Mora and T. M. Antonsen Jr., Phys Plasma 4, 217 (1997)[0pt] [2] C. Huang et al. Comp Phys. 217 (2006)[0pt] [3] W. Lu et al. PRST, Accelerators and Beams 10, 061301 (2007)
    01/2008;
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    ABSTRACT: In LWFA schemes the laser pulse must propagate several centimeters and maintain its coherence over this distance, which corresponds to many Rayleigh lengths. These Wakefields and their effect on the laser can be simulated in quasistatic approximation [1, 2]. In this approximation the assumption is that the driver (laser) does not change shape during the time it takes for it to pass by a plasma particle. As a result the particles that are trapped and moving with near-luminal velocity can not be treated with this approximation. Here we have modified the 2D code WAKE with an alternate algorithm so that when a plasma particle gains sufficient energy from wakefields it becomes trapped to satisfy the trapping conditions. Similar implementations have been made in the 3D cod QUICKPIC [2]. We also have done simulation and comparison of results for centimeter scale GeV electron accelerator experiments from LBL [3] with WAKE. These changes in WAKE will give users a tool that can be used on a desk top machine to simulate GeV acceleration. [1] P. Mora and T. M. Antonsen Jr., Phys Plasma 4, 217 (1997) [2] C. Huang et al. Comp Phys. 217 (2006) [3] W. P. Leemans et al. Nature Phys 2, 696 (2006) Letters
    11/2007;
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    ABSTRACT: The amount of charge, the final energy, and the quality of the charged particle beam that is generated from a plasma-based accelerator depends on how the charge is loaded into the wake. In recent experiments the wakes are created by either the radiation pressure of the laser or the space-charge force of the electron beam expelling the plasma electrons outward. We present a theory for beam loading valid for such nonlinear multi-dimensional wakes. We start from the equation for the blowout radius derived by Lu et al. [1]. Analytical solutions are found for this equation when the wake is loaded by flat-top or trapezoidal electron beams. As a result expressions for the accelerating field, the shape of the bubble and the amount of charge are obtained. These are compared to those predicted by the linear theory of Katsouleas et al. [2]. We also discuss the optimum current profile to minimize the final energy spread while maximizing the mean energy and the number of particles. [1] W. Lu et al, Phys. Rev. Lett. 96, 165002 (2006). [2] T. Katsouleas et al, Particle Accelerators, 1987, Vol. 22, pp. 81-99.
    11/2007;

Publication Stats

175 Citations
39.47 Total Impact Points

Institutions

  • 2010
    • Los Alamos National Laboratory
      Los Alamos, California, United States
  • 2001–2008
    • University of California, Los Angeles
      • • Department of Physics and Astronomy
      • • Department of Electrical Engineering
      Los Angeles, CA, United States