The Plasmas Division
The Plasmas Division integrates together research on a very wide variety of plasmas. The research is carried out in two research groups, the Atoms,Beams and Plasmas Group (ABP) and the Laser Induced Nuclear and Plasma Accelerator Studies Group (LINPAS).

The Atoms, Beams and Plasmas Research Group
There is an exciting selection of PhD research projects available in the Atoms, Beams and Plasmas research group. The staff who supervise PhD students in this research group include (in alphabetical order) Dr. Nigel Badnell, Prof. Bob Bingham, Prof Geoff Duxbury, Dr Adrian Cross, Dr. Wenlong He, Dr. Brian McNeil, Prof Alan Phelps (group leader), Dr. Kevin Ronald, Dr Robbie Stewart, Prof Hugh Summers and Dr. Colin Whyte. Prof. Paul Thomas is a Visiting Professor and there are numerous international research visitors to the group each year including Professors Bratman, Ginzburg and Denisov. There are more than ten PhD students carrying out their research within the group. The group enjoys excellent links with large research laboratories such as the Rutherford Appleton Laboratory, the Daresbury Laboratory and the Culham Laboratory in the UK and CERN in Geneva and also a wide range of industrial companies. As well as the normal research council funded studentships which students joining the group find attractive, this research group can also provide CASE studentships for students who are interested. The CASE studentships have the advantages of additional bursary funds for the student and the valuable extra experience and interest of carrying out a part of the PhD research while visiting another location. Anyone interested in either one of the standard PhD research studentships, or a CASE studentship, should contact the staff member named within each individual project described below. The projects listed below are only examples of some of the PhD projects that are available in this research group and details of these and further projects can be obtained from Prof. Alan Phelps (

List of current PhD projects

Student: David Bowes
Project title: Investigation of pseudo-spark sourced electron beam applications
Description: The pseudospark is a form of low-pressure discharge originating within a unique hollow cathode structure and, while its rapid current rise time and high current are both desirable features, it may also be used to generate high quality electron beams. Such beams possess high current densities and brightness, as well as self-focusing properties, and the pseudospark cathode has a long lifespan, making it one of the most attractive sources of free electrons currently available. This project aims to investigate the applications of these electron beams, from their role in vacuum devices as generators of high-frequency radiation to their usage in the field of X-ray imaging.

Student: Paul McElhinney
Project title: Gyrotron-travelling wave amplifier with a quasi-optical corrugated horn
Description: Gyrotrons are vacuum electron devices that utilize the cyclotron resonance maser instability to produce high power microwave and mm-wave radiation via the interaction between a relativistic electron beam and a powerful static magnetic field within a waveguide cavity. These devices typically operate as oscillators, where the radiation is generated by means of a convective feedback, but for some applications it is desirable for such devices to operate as amplifiers using an absolute instability. This mode of operation is more difficult to achieve in practice therefore novel design methodologies must be employed to realise such a system. Using bespoke helically corrugated interaction waveguides as well as axially encircling electron beams it is possible to design and construct efficient gyro-amplifiers. The focus of this research was the development of systems that would enable the construction of a gyrotron travelling wave amplifier (gyro-TWA). In particular, emphasis was placed on the design of components that would be capable of separating the electron beam from the radiation. The beam could then be recovered to increase overall efficiency and the radiation can be suitably conditioned for external applications.

Student: Alan Phipps
Project title: Novel surface-field Cherenkov source of coherent radiation based on a 2D Periodic Surface Lattice
Description: I am working on a high power microwave source operating at approximately 94GHz. At this frequency there are various applications, such as communication systems, as there is an atmospheric window at this frequency where the radiation is not easily absorbed. Medical applications for high resolution scanners as microwaves penetrate the body tissue without damaging it. Plasma heating and diagnostics in Magnetically confined Nuclear Fusion. The design of a 2D periodic surface lattice (PSL) or Bragg structure machined into a cylindrical waveguide where we then introduce an azimuthally symmetric EM wave of mode number TM0,6. When the incident wave meets the perturbations it makes the electrons in the wall of the waveguide emit a surface field that penetrate evanescently into the centre of the waveguide (where radius = 0) this surface field travels slower than c and so this device is called a Slow-Wave Structure which is a type of Travelling Wave Tube TWT or Backward Wave Oscillator BWO. A relativistic electron beam is then passed through the strongest part of the surface field and as the magnitude of the z-component of the electron velocity is slightly higher than the phase velocity of the surface field then the electrons will give some of their energy to the field at the operating frequency in the form of Cherenkov radiation. In this way we will hope to produce a MegaWatt source at 94GHz.

Student: Karen Gillespie
Project title: Beam wave interactions in magnetised plasmas
Description: AKR is radio frequency emission, at around 300 kHz, caused by electrons, sourced from the solar winds, accelerating towards the Earth's ionosphere into the auroral zone. The emission occurs at high altitudes around 1.5 - 3 Earth radii in a region called the Auroral density cavity. This project aims to investigate the emission mechanisms of Aurora kilometric radiation through laboratory experiments and numerical simulations.

Student: David Constable
Project title: Numerical Investigation of Novel Gyro-Multiplier Arrangements
Description: When attempting to generate high frequency radiation in a gyro-device, it is advantageous to operate at a high harmonic of the electron cyclotron frequency. However, the starting current of the electromagnetic mode corresponding to the high harmonic resonance may simultaneously satisfy the starting criteria of a mode of a lower harmonic. Therefore, operation of a gyro-device at a high harmonic can prove problematic. An attractive alternative to high harmonic operation can be realised through the use of a gyro-multiplier. Such schemes allow the generation of high frequency, high harmonic radiation through the non-linear interaction between an electron beam and a low frequency, low harmonic mode. As a result, the beam current necessary need only be as high as is required to start the low harmonic oscillation. While in comparison to high harmonic devices, gyro-multipliers suffer from lower efficiency of the upper resonance, their output powers are still sufficient for many applications, whilst the systems themselves are typically much more compact. This project examines the dynamics of such gyro-multiplier arrangements through numerical simulation.

Student: Kathleen Matheson
Project title: Efficiency enhancement for fast-wave amplifiers
Description: This research investigates the potential for efficiency enhancement of a gyro-travelling wave amplifier (gyro-TWA) with a helically corrugated interaction waveguide and a cyclotron autoresonance maser (CARM) amplifier. CARM amplifiers typically realise relatively low efficiencies owing to sensitivity to velocity spread in the beam electrons whilst helically corrugated Gyro-TWAs have, to date, demonstrated relatively high efficiencies. Through implementation of phase trapping regimes of operation for each amplifier it is anticipated these efficiencies can be further improved. To achieve this key parameters along the axes of propagation of each amplifier are tapered, altering the associated characteristic dispersion curves to hold the interaction resonance at a given frequency for the entire length of the amplifier, which in theory should result in increased efficiency. This project studies the effect of these phase trapping regimes on amplifier performance using numerical simulations.

Student: Kathryn Humphrey
Project title: Energy Transfer between Laser Beams by Stimulated Brillouin Scattering in Plasmas
Description: The exchange of energy between crossing laser beams in plasma is of particular interest for indirect and direct drive inertial confinement fusion. In order to ensure uniform compression of the fuel capsule it is essential that the laser beams incident on the hohlraum deliver symmetrical irradiation and heating to the pellet to mitigate the possibility of the capsule prematurely breaking apart before the fusion process takes place. One mechanism which can be exploited to ensure uniform spherical compression of the target is stimulated Brillouin scattering whereby the laser energy from adjacent beams can be transferred from one to the other to deliver a tuneable mechanism by which laser energy can be redistributed to specific areas of the target. This project aims to investigate the Brillouin scattering mechanism and optimise the energy transfer process so it can be used in large scale experimental facilities, such as the National Ignition Facility, for the demonstration of nuclear fusion ignition.

Student: Martin King
Project title: Numerical and experimental investigation into beam-plasma instabilities
Description: The instabilities excited by the transit of an electron beam through a plasma is of practical interest in both astrophysical and applied plasma physics. Examples include the cyclotron maser instability that occurs in the auroral electron flux through the polar magnetosphere and the two-stream instability that can occur in fast-ignition inertial confinement fusion. This project investigates these instabilities through the use of numerical modelling and scaled laboratory experiments.

Student: Ross Bryson
Project title: Investigation of the anomalous Doppler resonance
Description: The anomalous Doppler resonance occurs when the negative harmonic of an electron beam interacts with an electromagnetic wave. This resonance can only be achieved in a slow wave regime such as a dielectric loaded waveguide or plasma, this project is particularly concerned with using plasma as the wave medium. One area of particular interest is the study of energetic electrons in magnetic confinement fusion devices such as tokamaks as the energetic electrons have the potential to disrupt the plasma and damage the machine. The project will model the characteristics of the anomalous Doppler resonance using powerful Particle-in-Cell computational code, these predictions will be used to inform a laboratory experiment where the accuracy of the computer code and the validity of the analytical theory can be assessed.

Student: Jason Garner
Project title: High power, high frequency coherent radiation source based on the cyclotron resonance maser instability
Description: Gyro-devices employ fast wave interaction structures for which the phase velocity of the incident electromagnetic wave exceeds the speed of light. Coherent electromagnetic radiation can be generated or amplified as a result of Bremsstrahlung emission from electron bunches in an annular beam of gyrating relativistic electrons. An investigation into utilising the cyclotron resonance maser (CRM) emission mechanism in a high power (~kW), high frequency (10's - 100'sGHz) coherent radiation source will be performed.