Plasma-Wakefield Acceleration of an Intense Positron Beam

Abstract

Plasma wakefields are both excited and probed by propagating an intense 28.5 GeV positron beam through a 1.4 m long lithium plasma. The main body of the beam loses energy in exciting this wakefield while positrons in the back of the same beam can be accelerated by the same wakefield as it changes sign. The scaling of energy loss with plasma density as well as the energy gain seen at the highest plasma density is in excellent agreement with simulations.

Transverse self-modulation of ultra-relativistic lepton beams in the plasma wakefield accelerator

“…Numerical simulations support this evaluation, showing cm-scale evolution distances with leptons (see below) rather than meter-scale distances with protons [17]. A S-M experiment could therefore be performed using the long lepton bunches of early single bunch PWFA experiments [18] (∝ 500 µm) and high-density plasmas currently available for two ultra-short bunches PWFA experiments [9] (∝ 10 17 cm −3 ). With these parameters many of the S-M physics could be tested very soon over centimeter to meter-scale plasma lengths and with most of the diagnostics also available (see below).…”

Plasma Channels and Accelerator Applications — A Tutorial

“…For example, a linear collider requires positron beams as well as electron beams. For positron drive beams, the electrons must come in radially from the outside, so a hollow plasma channel has obvious advantages [16,49]. This type of radial profile will be difficult to accomplish with beam field ionization, but is routinely produced in capillary discharges.…”

“…This type of radial profile will be difficult to accomplish with beam field ionization, but is routinely produced in capillary discharges. Also, the accelerating gradients for positron beam drivers are significantly lower than for electron beam drivers [16,49], so the plasma is likely to be several meters long even for a SLAC afterburner, and tens of meters for an afterburner for the proposed International Linear Collider (ILC).…”

Nonlinear propagation of broadband intense electromagnetic waves in an electron-positron plasma

“…Various collective phenomena in electron-positron plasmas have been demonstrated in the laboratory, such as the creation of wake fields by ultra-relativistic positron beams [8] and two-stream instabilities in streaming electron-positron plasmas [9]. The natural saturation mechanism for a two-stream instability is particle trapping in which electrons and positrons are trapped in the electrostatic potential of the large-amplitude wave.…”