# 17th Advanced Accelerator Concepts Workshop

31 July 2016 to 5 August 2016
Gaylord Hotel and Conference Center
US/Eastern timezone

## Laser-accelerated comb-like electron beams as a source of pulsed polychromatic gamma-rays.

2 Aug 2016, 11:00
15m
Woodrow Wilson B (Gaylord Hotel)

### Woodrow Wilson B

#### Gaylord Hotel

Oral Working Group 7

### Speaker

Dr. Serge Kalmykov (University of Nebraska-Lincoln)

### Abstract

Laser wakefield acceleration using an optimally designed multi-color stack of 10-TW-scale laser pulses generates a train of polychromatic fs-scale electron bunches with the brightness up to $10^{17}$ A/m$^2$. Inverse Thomson scattering from these comb-like e-beams produces synchronized sequences of multi-color 10-MeV-scale gamma-ray flashes. These may be used for pump-probe experiments in HEDP or in nuclear forensics.

### Summary

Synchronized sequences of quasi-monochromatic, fs-length gamma-ray flashes may be an asset to pump-probe experiments in dense plasmas. The design of such polychromatic radiation source relies on inverse Thomson scattering (ITS) from background-free, comb-like electron beams.

Our simulations show that the sequences of synchronized, fs-length electron bunches with a low phase-space volume, brightness up to 10^17 A/m^2, and controlled energy spacing may be produced in both plasma channels and uniform plasmas. A cavity of electron density, driven by an optimally designed multi-color stack of 10-TW-scale laser pulses, experiences expansions and contractions, periodically injecting electrons from the ambient plasma, accelerating them to the GeV range in a millimeter-scale plasma, without compromising their quality [S. Y. Kalmykov et al., Phys. Plasmas 22, 056701 (2015)]. This periodic injection is naturally achieved in a plasma channel [S. Y. Kalmykov et al., Plasma Phys. Control. Fusion 58, 034006 (2016)]. The channel, however, is not a prerequisite for this effect. The number of comb components, as well as their charge and energy spacing, can be controlled in a uniform plasma by independently varying focal spots of the laser stack components. This coherent control of the electron beam phase space on a femtosecond time scale enables great freedom in manipulating the parameters of multi-color ITS gamma-rays.

This work was supported in part by the NSF grant PHY-1535678.

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### Primary author

Dr. Serge Kalmykov (University of Nebraska-Lincoln)

### Co-authors

Prof. Bradley Shadwick (University of Nebraska-Lincoln) Dr. Isaac Ghebregziabher (The Pennsylvania State University) Dr. Xavier Davoine (CEA, DAM, DIF, Arpajon, France)

### Presentation Materials

 Slides summary
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