Laser Plasma Accelerators (JAI)

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:               Professor Zulfikar Najmudin

Type:                           Experimental + numerical

Funding:                     JAI studentship       

Supervisor: Prof Zulfikar Najmudin

This PhD project will examine the potential of Laser Wakefield Acceleration (LWFA) as a novel and efficient method for generating high-quality electron beams for Free Electron Laser (FEL) applications.

Wakefield accelerators driven by intense lasers are now used to routinely generate multi-GeV electron beams in our experiments [1]. The generated beams already have many applications including the generation of intense sources of x-rays [2]. The electron beams that are currently produced tend to have high charge they are usually in a large energy spread. Though these are then useful for generating incoherent sources of radiation, they cannot yet be used to drive a free-electron laser. A free electron laser is the latest generation of x-ray source which uses the coherent interaction between a radiation field and the electrons generating it to produce coherent radiation – a beam driven laser [3]. At high enough electron energy, the output of these new laser sources can be in the x-ray regime. But FEL’s need really high-quality drivers, such as those typically found only in high-energy physics labs. A breakthrough in the use of FEL’s could arise if they could be driven by much smaller and potentially more widespread accelerators such as LWFA’s. However, for this to be possible, the quality of output of LWFAs has to improve.

In this project, we will study ways of making the beams produced from LWFA suitable to drive FELs. In particular, the beams should have low energy spread and have a brightness such that the FEL enters the exponential growth phase of the FEL instability. The study will involve theoretical analysis, advanced numerical simulations, and experimental validations, both on our local laser system amd also at national facilities, to verify that the production of such beams is possible.

[1] Põder, K., Wood, J. C., Lopes, N. C., Cole, J. M., Alatabi, S., Backhouse, M. P., Foster, P. S., Hughes, A. J., Kamperidis, C., Kononenko, O., Mangles, S. P. D., Palmer, C. A. J., Rusby, D., Sahai, A., Sarri, G., Symes, D. R., Warwick, J. R., & Najmudin, Z. (2024). Multi-GeV Electron Acceleration in Wakefields Strongly Driven by Oversized Laser Spots. Physical Review Letters, 132(19), 195001.  https://doi.org/10.1103/PhysRevLett.132.195001
[2] Kneip, S., McGuffey, C., Martins, J. L., Martins, S. F., Bellei, C., Chvykov, V., Dollar, F., Fonseca, R., Huntington, C., Kalintchenko, G., Maksimchuk, a., Mangles, S. P. D., Matsuoka, T., Nagel, S. R., Palmer, C. a. J., Schreiber, J., Phuoc, K. T., Thomas, A. G. R., Yanovsky, V., … Najmudin, Z. (2010). Bright spatially coherent synchrotron X-rays from a table-top source. Nature Physics, 6(12), 980–983. https://doi.org/10.1038/NPHYS1789
[3] McNeil, B. (2009). Free electron lasers: First light from hard X-ray laser. Nature Photonics. http://www.nature.com/nphoton/journal/v3/n7/full/nphoton.2009.110.html

Funding: Potential JAI quota studentship