Hasil untuk "physics.acc-ph"

G. Gutierrez, F. Pálizas, G. Doglio et al.

J. Campbell, G. Fahey, B. W. Wolf

F. Hammes, W. Verstraete

S. Khanal, Wen‐Hsing Chen, Ling Li et al.

E. Svastova, A. Hulikova, Monika Rafajová et al.

J. Wootton, C. Pfister, James D. Forester et al.

I. Mainie, R. Tutuian, S. Shay et al.

Jorge Feuchtwanger, Víctor Etxebarria, Joaquín Portilla et al.

Hydrogen electron cyclotron resonance ion sources plasma measurements based on simple optical emission spectroscopy on a new compact low current ion source designed and built by the authors is presented. By observing the plasma luminescence both directly and through a low-cost transmission diffraction grating, basic characterization of the Hydrogen plasma obtainable in the ion source is carried out. Through simple processing of CCD captures of these images, optimal values for the ion source relevant operation parameters, including RF power and frequency, and Hydrogen mass flow are easily obtained. Despite the simplicity of the method and its limited accuracy as compared to the use of a full standard optical spectrometric set-up, it is shown that the presented approach can cope with basic plasma diagnostic tasks as far as the successful operation of the ion source is concerned.

D. Simeoni, G. Parise, A. R. Rossi et al.

We investigate the impact of a non-negligible background temperature on relativistic plasma wake-fields generated when a beam of charged particles passes through a neutral plasma at rest. We focus on the blowout regime, wherein the plasma response is highly non-linear: plasma electrons are radially blown out and expelled away from the propagation axis of the beam particles, creating a region (bubble) of ions without electrons. Our study builds upon earlier investigations for non-linear models of plasma wakefields developed in the limit of zero background temperature (Lu et al., Phys. Rev. Lett. 96, 165002 (2006)). In the presence of a non-zero background temperature, we characterize the model and focus on its predictions for the bubble size and the electromagnetic fields inside the bubble. Model predictions are studied in combination with PIC simulations.

B. Morgan, O. Lahav

Jiang Jiang, Jie Chen, Y. Xiong

S. Berthrong, E. Jobbágy, R. B. Jackson

Jürgen Struckmeier, Jürgen Klabunde, Martin Reiser

The behavior of K-V, waterbag, parabolic, conical and Gaussian distributions in periodic quadrupole channels is studied by particle simulations. It is found that all these different distributions exhibit the known K-V instabilities. But the action of the K-V type modes becomes more and more damped in the order of the types of distributions quoted above. This damping is so strong for the Gaussian distribution that the emittance growth factor after a large number of periods is considerably lower than in the case of an equivalent K-V distribution. In addition, the non K-V distributions experience in only one period of the channel a rapid initial emittance growth, which becomes very significant at high beam intensities. This growth is attributed to the homogenization of the space-charge density, resulting in a conversion of electric-field energy into transverse kinetic and potential energy. Two simple analytical formulae are derived to estimate the upper and lower boundary values for this effect and are compared with the results obtained from particle simulations.

I. Tsymbalov, D. Gorlova, K. Ivanov et al.

We propose a novel method for changing the length of laser wakefield electron acceleration in a gas jet by a cylindrical blast wave created by a perpendicularly focused nanosecond laser pulse. The shock front destroys the wake thus stopping interaction between the laser pulse and accelerated electron bunch allowing one to directly control the interaction length and avoid dephasing. It also improves the electron beam quality through the plasma lensing effect between the two shock fronts. We demonstrated both experimentally and numerically how this approach can be used to form quasi-monoenergetic electron bunch with controlled energy and improved divergence as well as to track changes in the bunch parameters during acceleration.

Xing-Long Zhu, Min Chen, Zheng-Ming Sheng

The continuous development of bright x/gamma-ray sources has opened up new frontiers of science and advanced applications. Currently, there is still a lack of efficient approaches to produce gamma-rays with photon energies up to GeV and with high peak brilliance comparable to modern free-electron lasers. Here we report a novel mechanism called beam fast pinching radiation burst to generate such gamma-ray sources. It is achieved by injecting a GeV electron beam into a submillimeter plasma with an upramp density profile, enabling violent beam pinching to occur rapidly. During this process, a burst of collimated gamma-rays is efficiently produced with photon energy up to GeV, energy conversion efficiency exceeding $30\%$, and peak brilliance exceeding $10^{28}$ photons s$^{-1}$ mm$^{-2}$ mrad$^{-2}$ per $0.1\%$ bandwidth. All of these are several orders of magnitude higher than existing gamma-ray sources. This opens a novel avenue for the development of extremely bright gamma-ray sources for both fundamental research and cutting-edge applications.

J. Slonczewski, M. Fujisawa, Mark Dopson et al.

Igor L. Medintz, M. Stewart, S. Trammell et al.

D A Gorlova, I N Tsymbalov, I P Tsygvintsev et al.

Direct laser electron acceleration in near-critical density plasma produces collimated electron beams with high charge $Q$ (up to $μ$C). This regime could be of interest for high energy THz radiation generation, as many of the mechanisms have a scaling $\propto Q^2$. In this work we focused specifically on challenges that arise during numerical investigation of transition radiation in such interaction. Detailed analytical calculations that include both diffraction and decoherence effects of characteristics of transition radiation in the THz range were conducted with the input parameters obtained from 3D PIC and hydrodynamic simulations. The calculated characteristics of THz radiation are in good agreement with the experimentally measured ones. Therefore, this approach can be used both to optimize properties of THz radiation and distinguish the transition radiation contribution if several mechanisms of THz radiation generation are considered.

W. L. Zhang, T. Grismayer, L. O. Silva

Signatures of strong-field quantum electrodynamics are determined for collisions between round ultrarelativistic leptonic beams in the quantum limit of beamstrahlung. In the low disruption regime, we derive the integrated beamstrahlung photon spectrum that features a characteristic peak close to the beam energy. The conditions to precisely observe this peak experimentally are given regarding the beam parameters. Moreover, the effects of electron-positron pair creation and beam disruption on the photon spectrum are discussed and explored with 3-dimensional particle-in-cell QED simulations. The photon spectrum is associated with the emission of ultrashort and highly collimated gamma-ray beams with a peak spectral brightness exceeding $10^{30}\ \mathrm{photons}/(\mathrm{s}\ \mathrm{mm}^2\ \mathrm{mrad}^2\ 0.1\% \mathrm{BW})$ at $100\ \mathrm{GeV}$-level photon energies (close to the beam energy).

Michael G. Anderson, James K. Walters, Enrique M. Anaya et al.

The WARP Reactor Concept promises orders of magnitude increase of intense ion beam energies and respective radiation yields at a fraction of the size and cost over existing z-pinch class accelerators allowing the economically viable study of new Relativistic High Energy Density Physics regimes for probing the intersection between General Relativity and Quantum Field Theory along with game-changing direct applications from rep-rated Magnetized Liner Inertial Fusion devices for energy production and advanced propulsion to multi-pulse compact flash x-ray/neutron radiography sources for assessing nuclear weapons stockpile. An overview of the WARP Reactor Concept is presented.