Inertial Confinement Fusion

A PhD project for October 2025
Direct Drive ICF modelling including CBET and LPI frameworks
Supervised by Prof. J. Chittenden (Imperial College)
Funding - confirmed Home Fee Status
Mostly computational with some elements of theory and experiment

Direct Drive (DD) inertial fusion energy (IFE) schemes directly illuminate a fusion fuel pellet with laser light. They present a compelling approach to energy generation given their relative simplicity and increased efficiency compared to the indirect drive approach typically used on the National Ignition Facility (NIF).
An approach to further increasing the implosion efficiency in DD approaches is to separate the compression of the fusion fuel from the heating phase. Shock ignition is one such concept and uses a strong converging shock driven by a laser as the fuel is being compressed, to provide the fusion spark.
In large-scale DD laser experiments, laser plasma instability (LPI) mechanisms can influence the coupling of laser energy to the imploding capsule. One effect arising from LPIs is cross beam energy transfer (CBET). In NIF experiments the CBET mechanism can be controlled and used to improve the symmetry of energy coupling to the capsule.
In general LPI mechanisms are highly non-linear and difficult to model but if their behaviour can be predicted this provides a route to controlling their effects and therefore improving the efficiency of DD implosions.
This PhD will study the shock ignition and other novel direct drive Inertial Confinement Fusion designs using the CHIMERA radiation hydrodynamics code, utilising the framework developed to simulate CBET to enable to more general LPI modelling. The project will be based within the Centre for Inertial Fusion Studies at Imperial College.

Supervisor:    Prof Jeremy Chittenden

Type:                Mostly computational with elements of theoretical and experimental

Funding:          Funding confirmed - requires Home Fee Status

The demonstration of ignition in indirect drive inertial confinement fusion experiments has provided the first laboratory platform to study the physics of thermonuclear burning plasma. This PhD project will use numerical simulations of experiments on the National Ignition Facility to provide in depth understanding of the physical processes at work which lead to ignition of the fuel, the subsequent burn process and how this leads to high energy yields. This will include an assessment of different diagnostic signatures of ignition and burn, options for improved target designs leading to higher energy yields on NIF and scaling considerations to understand the opportunities for higher yields at larger laser driver energies and powers. The project will be based in the Centre for Inertial Fusion Studies and will make use of the CHIMERA radiation-hydrodynamics code developed at Imperial College, to undertake 3D modelling of burning plasmas in Inertial Confinement Fusion as well as extensive models for synthetic neutron and gamma ray diagnostics.

Supervisor:         Professor Zulfikar Najmudin
Type:                     Experimental + numerical
Funding:               JAI studentship
 

Recent results on NIF at the Lawrence Livermore Lab have demonstrated the potential of inertial confinement fusion as a method of power generation, with significantly more energy being produced in output of the fusion process than put into the interaction by the laser system [1].

Whilst these experiments have been revolutionary, the sheer scale and complexity of the facility required to produce these results is a barrier to the production of a power plant based on these techniques. However, there are routes to more efficient production of the conditions required for inertial confinement fusion, which would mean that they could be produced on facilities of a much smaller and potentially more widespread scale. Direct drive inertial confinement fusion would use laser beams directly impacting the fuel capsule, as opposed to the indirect drive scheme used until now which first converts laser energy into x-rays. It would enhance the efficiency of the compression, though this is likely to come at the expense of stability and corresponding final compression ratio [2]. However, there are schemes that can still produce gain from less compressed targets. Amongst these, “fast ignition” schemes separate the ignition of the capsule from the compression phase [3]. In fact, a short fast pulse source of energy either in a laser or particle beam could then provide the spark needed to ignite the fusion pellet at considerably lower energy requirement than igniting through further compression. In this project, we will consider the use of energetic deuteron beams as a source to initiate ignition of a DT fuel capsule. As well as heating the plasma to sufficient temperature, the deuterons can also react with the DT fuel themselves, thus potentially requiring less energy than, for example, ignition with proton beams.

This project will have two main components. The first will be the development of high-charge but relatively low-energy deuteron beams that could be used for neutron generation applications. Amongst the schemes we will consider will be the collisionless shock acceleration scheme in a gas target developed by our group [4]. Secondly, we will determine the deuteron beam characteristics required to ignite a precompressed DT fusion pellet. We will then calculate the compression / deuteron beam requirements to make the most economical laser driver for such an interaction.

[1] Abu-Shawareb, H., Acree, R., Adams, P., Adams, J., Addis, B., Aden, R., Adrian, P., Afeyan, B. B., Aggleton, M., Aghaian, L., Aguirre, A., Aikens, D., Akre, J., Albert, F., Albrecht, M., Albright, B. J., Albritton, J., Alcala, J., Alday, C., … Zylstra, A. B. (2022). Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment. Physical Review Letters, 129(7). https://doi.org/10.1103/PhysRevLett.129.075001

[2] Craxton, R. S., Anderson, K. S., Boehly, T. R., Goncharov, V. N., Harding, D. R., Knauer, J. P., McCrory, R. L., McKenty, P. W., Meyerhofer, D. D., Myatt, J. F., Schmitt, A. J., Sethian, J. D., Short, R. W., Skupsky, S., Theobald, W., Kruer, W. L., Tanaka, K., Betti, R., Collins, T. J. B., … Zuegel, J. D. (2015). Direct-drive inertial confinement fusion: A review. In Physics of Plasmas (Vol. 22, Issue 11). https://doi.org/10.1063/1.4934714

[3] Tabak, M., Hammer, J., Glinsky, M. E., Kruer, W. L., Wilks, S. C., Woodworth, J., Campbell, E. M., Perry, M. D., & Mason, R. J. (1994). Ignition and high gain with ultrapowerful lasers. Physics of Plasmas, 1(5), 1626. https://doi.org/10.1063/1.870664

[4] Palmer, C., Dover, N., Pogorelsky, I., Babzien, M., Dudnikova, G., Ispiriyan, M., Polyanskiy, M., Schreiber, J., Shkolnikov, P., Yakimenko, V., & Najmudin, Z. (2011). Monoenergetic Proton Beams Accelerated by a Radiation Pressure Driven Shock. Physical Review Letters, 106(1), 014801. https://doi.org/10.1103/PhysRevLett.106.014801

Supervisor:        Dr Grigory Kagan

Type:                    Theoretical/computational

Funding:              Pending

Magnetic field constrain charged particle orbits, thus affecting their collisional transport. On the other hand, magnetic field penetration into a plasma is governed by the electric conductivity; i.e., a charged particle transport process. This interplay results in a very intriguing physics of plasma mixing at magnetized interfaces.

Interplay between kinetic effects and magnetic fields at plasma interfaces

Supervisor:      Dr Grigory Kagan

Type:                  Theoretical/Computational

Funding:             [TBC]

When the mean-free-path is comparable to the plasma size, the particle distribution is no longer Maxwellian. In turn, for a charged particle, the mean-free-path scales as the square of this particle energy, so the tail of their distribution can be order-unity different from thermodynamic equilibrium even if the bulk particles are Maxwellian. It is the tail ions and electrons that are mostly responsible for fusion reactions and hard X-ray emission from HED plasmas. This project will elucidate the non-trivial connection between the kinetic and nuclear/radiation physics.

Non-equilibrium tails of particle distribution

Supervisor:    Dr Grigory Kagan

Type:                 Theoretical/Computational

Funding:           To be confirmed

When the plasma becomes dense one can no longer distinguish the binary acts of collisions; a new approach need to be developed for understanding the micro-physics. This is the case in the warm-dense-matter regimes relevant to many astrophysical and laboratory plasmas. Of particular interest is the diffusion and thermal conduction. This project will aim at the very basic plasma physics; new many-body kinetic methods will be utilized to gain an insight into how the non-ideal plasma transport is different from the conventional, ideal case.

Transport in non-ideal, dense plasmas

PhD project for October 2025

Supervisor:            Prof. Simon Bland

Type:                        Experimental

Funding:                  Fully funded for UK students

Warm dense plasmas are extremely difficult to model, combining the properties of plasmas with coupling between particles (atoms, electrons, ions) more commonly associated with solids and liquids. One method to produce these plasmas is through the ablation of targets by intense bursts of X-ray radiation.
This PhD builds on previous efforts on the MAGPIE facility to explore the effects of X-ray bursts on solar panels; studying how X-ray energies and intensities will affect the heating and ablation of targets on the nanosecond scale. We will use an array of diagnostics including interferometry, Thomson scattering, X-ray radiography and spectrometry to produce quantitative measurements of the ablating plasmas from different target materials and compare them to cutting edge simulations. This will enable us to better understand the ablation process and optimize it for different purposes such as creating flows of dense plasmas for laboratory astrophysics experiments..