Thesis

Compact gamma-ray sources based on laser-plasma wakefield accelerator

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Awarding institution
  • University of Strathclyde
Date of award
  • 2011
Thesis identifier
  • T13091
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Department, School or Faculty
Abstract
  • Laser-plasma wakefield accelerator (LWFA) is a promising novel technology that is introducing miniaturization to the accelerator world: the unprecedented gradient of acceleration shrinks the accelerator down to table-top size. Moreover, the LWFA comes with an embedded light source: electrons, while accelerating, undergo betatron oscillatory motion that results in synchrotron radiation emitted in a narrow cone along the direction of propagation. In this thesis we study theoretically and we prove experimentally a new regime of betatron oscillation that occurs when electrons experience the electromagnetic field of the laser during acceleration and oscillate resonantly at the laser frequency or its sub-harmonics. The signature of the harmonically resonant betatron (HRB) regime is a large oscillation amplitude and consequently prolific emission of high energy photons up to the MeV range. The HRB source has unique properties: very short pulse length (~10 fs), small source size (few microns), high peak brightness of the order of 1023 photons/s mm2 mrad2 0.1% B.W., which is comparable with a third generation light source. These properties make the source particularly appealing for the life sciences and medical and security applications. As a part of a future applications project, we give the scaling of the photon energy as a function of laser intensity and plasma density, which could extend toward tens of MeV. The thesis also investigates another gamma-ray source that utilises beams from the LWFA: bremsstrahlung radiation from high energy electrons interacting with metal targets. We study the electron beam and target parameters to optimize the emission process and the gamma-ray beam properties to match potential application requirements, such as radioisotope generation via photonuclear process. The results of a proof of concept experiment are presented and compared with simulations. Finally, we investigate numerically the possibility of generating a converging gamma-ray beam based on the bremsstrahlung process. The results are encouraging, and the potential impact of a compact converging gamma-ray beam source is discussed with particular attention to medical applications in cancer treatment.
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Note
  • This thesis was previously held under moratorium from 24th July 2012 until 24th July 2014.
DOI
Date Created
  • 2011
Former identifier
  • 943720

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