Focusing of Drive and Test Bunches in a Dielectric Waveguide Filled with Inhomogeneous Plasma

Abstract

The paper presents the results of numerical PIC-simulation of accelerated (test) and drive bunches dynamics in a dielectric waveguide of the THz frequency range filled with radially inhomogeneous plasma. The wakefield was excited by the azimuthally-symmetric on-axis drive electron bunch in a quartz dielectric tube embedded in metal waveguide. A radial displacement of test bunch is absent too. At simulations of plasma, we used different transverse density profiles, viz., the density profile formed in the capillary discharge, and the radially nonuniform density profile with the vacuum channel along the waveguide axis. For all the cases under study the plasma density was low, so that the plasma frequency was lower than the fundamental dielectric mode frequency. The obtained PIC-simulation data have shown that the vacuum channel in the inhomogeneous plasma cylinder improves the accelerated bunch focusing. There is the optimum vacuum-channel size value, at which the focusing turns out to be the strongest. The improvement in the accelerated bunch focusing is accompanied by the decrease in the accelerating gradient as compared with the full plasma filling of the drift channel. The best acceleration takes place in the absence of plasma; however, in that case the accelerated bunch focusing does not occur. K: Accelerator modelling and simulations (multi-particle dynamics; single-particle dynamics); Wake-field acceleration (laser-driven, electron-driven); Beam dynamics; Plasma generation (laser-produced, RF, x ray-produced) 1Corresponding author.

Acceleration and focusing of positron bunch in a dielectric wakefield accelerator with plasma in transport channel

“…We have analyzed this possibility analytically and numerically for the case of filling the bunch transport channel of DWA with plasma homogeneous in the cross section [26]. If the plasma is created by means of a capillary discharge [27,28], then the transport of witness electron bunches can even be improved [29,30]. To obtain strong focusing fields, a superdense plasma is not required [30].…”

Focusing of Positron Bunch When Moving in Electron Bunch Wakefield in the Dielectric Waveguide Filled With Plasma

“…For improvement of transportation of the drive and accelerated bunches the vacuum channel in plasma that reduces bunches scattering and deviation (PWFA research) can be used. In the work [14] by means of PICsimulation the effect of influence of the vacuum channel in radially heterogeneous plasma for the drive and accelerated electron bunches focusing in PDWA has been studied.…”

Acceleration and focusing of positron bunch in a dielectric waveguide accelerator with homogeneous plasma in transport channel

“…We have analyzed this possibility analytically and numerically for the case of filling the bunch transport channel of DWA with a plasma homogeneous in the cross section [23]. If the plasma is created as a result of a capillary discharge [24,25], then the transport of witness electron bunches can even be improved [26,27]. To obtain strong focusing fields, a superdense plasma is not required [27].…”

“…If the plasma is created as a result of a capillary discharge [24,25], then the transport of witness electron bunches can even be improved [26,27]. To obtain strong focusing fields, a superdense plasma is not required [27]. Experimental studies of the transport of electron bunches in plasma-filled wake dielectric structures (PDWA) have already started [28,29], and the * sotnikov@kipt.kharkov.ua; Gennadiy.Sotnikov@gmail.com first experimental confirmation of the focusing of electron bunches in 2.8 GHz DWA has been obtained [28,30].…”

“…Experimental studies of the transport of electron bunches in plasma-filled wake dielectric structures (PDWA) have already started [28,29], and the * sotnikov@kipt.kharkov.ua; Gennadiy.Sotnikov@gmail.com first experimental confirmation of the focusing of electron bunches in 2.8 GHz DWA has been obtained [28,30]. It should be noted that the focusing of accelerated witness bunch electrons is observed for certain conditions on the plasma density [23,27].…”