We currently have two postdoctoral research positons available

Research Associate in Laser-Plasma Acceleration

Research Associate in Plasma Source Development for AWAKE

The following provide examples of the range of PhD projects available at the John Adams Institute at Imperial College. Please contact us for more information about specific projects:

Novel particle acceleration based on laser wakefield accelerators 

Supervisor: Prof. Zulfikar Najmudin

Laser wakefield accelerators are being investigated for the next generation of particle accelerators. A high intensity laser pulse generates a large amplitude plasma wave, which can accelerate particles at a rate more than thousands of times faster than conventional accelerators. Acceleration of electrons sourced directly from the plasma is now well established with wakefield accelerators. However, the beams produced are not yet of the quality required for the high energy physics applications.  This project will investigate novel techniques to improve the beam quality from laser wakefield accelerators including structuring of targets and staged acceleration. The work will be performed using the high-power lasers at the Rutherford-Appleton Laboratory as well as with the laser being developed in the basement of the Blackett Laboratory.

Funding: JAI studentship

Radiation pressure effects at the focus of intense lasers

Supervisor: Prof. Zulfikar Najmudin

State-of-the-art lasers can now reach intensities well in excess of 10²⁰ Wcm^-2 at focus. When directed onto a target that is sufficiently dense that it can stop the laser beam, the intense radiation pressure can directly drive the critical density surface of the target. This can manifest itself in a number of ways. It can drive a collisionless shocks which can be diagnosed by the ions it accelerates in its path. Alternatively, for sufficiently thin targets, the whole plasma can be propelled forward gaining momentum as it propagates. The result in both cases is the production of dense beams of energetic ions. These ions could have numerous applications, not least in next-generation particle accelerators. The project proposed here will investigate radiation pressure driven acceleration schemes through optimisation of targets and of the characteristics of the laser beam that drives them. The experiments will take place on the high intensity lasers at the Rutherford-Appleton Laboratory and the IR laser at the ATF Brookhaven National Laboratory. A near term goal is to produce protons with energies exceeding 100 MeV, which would be of interest for applications such as radiation treatment of tumours or for fast heating of fusion capsules.

Funding: JAI studentship

Femtosecond x-ray probing of high-energy-density physics experiments using plasma wiggler radiation

The bright x-rays produced due to transverse (or “betatron”) oscillations of the electron beam in a self-injecting laser wakefield accelerator [Mangles, Nature 2004; Kneip, Nature Phys 2010] have a unique combination of properties namely small source size, ultra-short duration and broad spectral coverage.  These properties make them ideal for studying high-energy-density matter.

Project 1: Femtosecond x-ray probing of plasma opacity

Supervisor: Stuart Mangles

In this project you will develop experiments to make ultra-fast time resolved measurements that use the unique capabilities of this “plasma wiggler radiation”.  The broad spectrum of the plasma wiggler radiation, combined with its ultra-short (femtosecond) duration will be used to provide an ideal white-light source for unprecedented time resolved measurements of the opacity of rapidly-heated plasmas. Such measurements will help to develop models of the opacity of high-energy-density matter, which are vital for our understanding of, for example the structure and evolution of the Sun.  These models could be tested robustly over a broad parameter space by examining the heating of matter using “conventional” laser heating using facilities such as the Cerberus laser here at Imperial college and the Astra Gemini Laser at the Rutherford Appleton Laboratory, and by heating matter so that it is far from equilibrium using international x-ray free electron lasers such as the LCLS.

Project 2: Ultra-fast Imaging of Shocks “on-the-fly”

The small, micrometre scale source size of plasma wiggler [Kneip Nature Phys 2010] means it can perform high-resolution x-ray phase contrast imaging [Kneip Applied Phys Lett 2011].  Combining this impressive imaging capability with the ultra-short duration of the x-rays will make it possible to perform time resolved imaging of laser-induced shocks in solid material, this will allow you to image shocks “on the fly”. 

Third generation synchrotron light sources have recently been used to provide single-shot x-ray phase contrast imaging of dynamic shocks on the fly, however they are limited to temporal resolution of ~ 100 ps.  In this project you will develop experiments to perform similar measurements but with unprecedented < 100 fs resolution – an improvement of a factor of more than 1 million.  Such ultra-fast resolution will permit the observation of rapid phase transitions in shocked materials and allow detailed studies of the equation of state.