# Laser-Plasma Accelerator Workshop 2019

5-10 May 2019
MedILS
Europe/Berlin timezone

## Simulations of long-term wakefield evolution in a radially bounded plasma

6 May 2019, 17:55
20m
Meeting Room (MedILS)

### Meeting Room

#### MedILS

Oral Contribution

### Speaker

Konstantin Lotov (Budker INP)

### Description

In plasma wakefield accelerators, intense laser or particle beams drive strong Langmuir waves with the energy density as high as the rest energy of plasma electrons. A large fraction of this energy remains in the plasma after passage of the accelerated beam and causes rapid expansion of the plasma column boundary. The energy initially stored in coherent electron oscillations first transforms into incoherent motion of plasma electrons with multi-keV velocities and, later, into radial motion of plasma ions. The resulting stream of fast ions escapes the initial plasma channel, penetrates the surrounding neutral gas and creates some seed'' plasma there through impact ionization. Once new ions appear at a given location, more electrons come there and further ionize the gas causing near-exponential growth of the plasma density. The energy needed for gas ionization is small compared to the initial wave energy, so the plasma boundary expands with nearly constant velocity corresponding to the velocity of the fast ion front, with the plasma amount growing proportionally. Numerical simulations that include the described effects show quantitative agreement with results of ps-time-resolved optical shadowgraphy that measured evolving plasma density profile at FACET.

Working group Theory and computation

### Primary authors

Konstantin Lotov (Budker INP) Prof. Michael Downer (University of Texas at Austin) Dr Mark Hogan (SLAC) Mr Vadim Khudyakov (Budker INP) Thales Silva (Instituto Superior Técnico) Alexander Sosedkin (Budker INP) Jorge Vieira (Instituto Superior Técnico) Dr Vitaly Yakimenko (SLAC) Rafal Zgadzaj (University of Texas at Austin)