A novel fast simulation technique for axisymmetric PWFA configurations in the blowout regime

In the blowout regime of plasma wakefield acceleration (PWFA), which is the most relevant configuration for current and future applications and experiments, the plasma flow that is excited by the ultra-relativistic drive beam is highly nonlinear. Thus, fast and accurate simulations codes are indispensable tools in the study of this extremely important problem. We have developed a novel algorithm that deals with the propagation of axisymmetric bunches of otherwise arbitrary profile through a cold plasma of uniform density. In contrast to the existing PWFA simulation tools, our code PLEBS (PLasma-Electron Beam Simulations) uses a new computational scheme which ensures that the transverse and longitudinal directions are completely decoupled---a feature which significantly enhances the speed and robustness of the new method. Our numerical results are benchmarked against the QuickPic code and excellent agreement is established between the two approaches. Moreover, our new technique provides a very convenient framework for studying issues such as beam loading and short-range wakefields within the plasma cavity

Microbunched Electron Cooling with Amplification Cascades

The Microbunched Electron Cooling (MBEC) is a promising cooling technique that can find applications in future hadron and electron-ion colliders to counteract intrabeam scattering that limits the maximum achievable luminosity of the collider. To minimize the cooling time, one would use amplification cascades consisting of a drift section followed by a magnetic chicane. In this paper, we first derive and optimize the gain factor in an amplification section for a simplified one-dimensional model of the beam. We then deduce the cooling rate of a system with one and two amplification cascades. We also analyze the noise effects that counteract the cooling process through the energy diffusion in the hadron beam. Our analytical formulas are confirmed by numerical simulations for a set of model parameters.Comment: arXiv admin note: text overlap with arXiv:1806.0278

State of the mineral component of rat bone tissue during hypokinesia and the recovery period

Experiments were conducted on young growing rats. Hypokinesia lasting from 20 to 200 days caused retarded gain in weight and volume of the femur and delayed development of the cortical layer of the diaphysis. In contrast, the density of the cortical layer of the femoral diaphysis increased due to elevation of the mineral saturation of the bone tissue microstructures. Incorporation of Ca into the bone tissue in hypokinesia had a tendency to reduce. Partial normalization of the bone tissue mineral component occurred during a 20 day recovery period following hypokinesia

Effect of six-month hypokinesia in dogs on mineral component, reconstruction and mechanical properties of bone tissue

Ca45 incorporation into the bones of the limbs, particularly in the area of the muscle attachment increased in dogs as a result of 6 month hypokinesia. There were no phenomena of osteoporosis in the cortical layer of the diaphyses; however, changes in the form of osteons, an increase in the number of anastomoses between the channels and the thinning of the subperiosteal layer pointed to disturbances of the bone tissue reconstruction. Mineral saturation of the bone microstructures of the experimental dogs had a tendency to rise. No changes in the mechanical properties of the long bones occurred as a result of hypokinesia in dogs

Uncorrelated Energy Spread and Longitudinal Emittance of a Photo injector Beam

Longitudinal phase space properties of a photoinjector beam are important in many areas of high-brightness beam applications such as bunch compression, transverse-to-longitudinal emittance exchange, and high-gain free-electron lasers. In this paper, we discuss both the rf and the space charge contributions to the uncorrelated energy spread of the beam generated from a laser-driven rf gun. We compare analytical expressions for the uncorrelated energy spread and the longitudinal emittance with numerical simulations and recent experimental results

Measurements of Compression and Emittance Growth after the First LCLS Bunch Compressor Chicane

The Linac Coherent Light Source (LCLS) is a SASE xray free-electron laser project presently under construction at SLAC. The injector section from RF photocathode gun through first bunch compressor chicane was installed during the fall of 2006. The first bunch compressor is located at 250 MeV and nominally compresses a 1-nC electron bunch from an rms length of about 1 mm to 0.2 mm. Transverse phase space and bunch length diagnostics are located immediately after the chicane. We present preliminary measurements and simulations of the longitudinal and transverse phase space after the chicane in various beam conditions, including extreme compression with micron-scale current spikes

Measurements of Coherent Synchrotron Radiation and its Impact on the LCLS Electron Beam

In order to reach the high peak current required for an x-ray FEL, two separate magnetic dipole chicanes are used in the LCLS accelerator to compress the electron bunch length in stages. In these bunch compressors, coherent synchrotron radiation (CSR) can be emitted-induced either by a short electron bunch, or by any longitudinal density modulation that may be on the bunch. We present measurements, simulations, and analysis of (1) the CSR-induced energy loss, (2) the related transverse emittance growth, and (3) the microbunching-induced CSR directly observed at optical wavelengths