Imperial College London

Dr Aakash A. Sahai

Faculty of Natural SciencesDepartment of Physics

Research Associate



+44 (0)20 7594 3791a.sahai Website CV




735Blackett LaboratorySouth Kensington Campus





My research seeks to develop novel compact particle accelerators based on plasmas and unravel their applications such as in material science & medicine, which are not yet conceivable due to the inaccessibility of conventional accelerators. I carry out this work by computationally modeling and experimentally validating a variety of non-linear and relativistic energy-density propagating structures with large charge-separation fields that are excited by different energy sources interacting with various types of plasmas.

This work is carried out as part of the Plasma Physics group and the John Adams Institute for Accelerator Science. My quest lies at the confluence of distinctly identified research areas such as advanced accelerator physics, non-linear plasma physics, computational electromagnetics & electrodynamics, high-energy density physics and astrophysics etc.

Recent talks on YouTube -
Strongly mismatched LWFA regime - [arXiv manuscript]
Positron acceleration in plasma-based accelerators - [arXiv manuscript]CRUNCH IN

These unusual plasma density structures that are excited by increasingly high-intensity energy-sources sustain spatial charge-separation between the plasma particles with differing inertia. As the intensity (energy density) of the driving energy-sources increases, density structures and interaction processes tend towards unfamiliar and exotic regimes. Matter under such extreme conditions are usually found in astrophysical objects.


Plasma-based acceleration methods that use the extraordinary electromagnetic fields of such structures, hold the promise for developing low-cost, compact and tunable sources of high-energy particle beams and pulses of light. This has the potential to transform several fields of scientific research that rely on light & particle sources for visualizing or manipulating physical, biological & chemical processes.  

In my work, I analytically model the interaction of energy sources of high energy density (intense beams of photons or particles) with a variety of plasmas. This leads to estimates of properties of the mechanisms & processes excited by these interactions.

As these interactions invariably excite non-linear phenomena in the plasma, computational modeling is often a more accurate way to investigate the dynamics of interaction and evolution. The interaction space typically contains around a trillion particles whose dynamics evolves in time, requiring cutting-edge numerical methods & approximations for accurate modeling. Such theoretical explorations eventually lead to predictions of measurable signatures or scaling laws that could be obtained in a well-designed experiment.

Relativistic transparency effect allowing a laser pulse to punch through an opaque plasma without causing the motion of the whole plasma

My research interests span topics in applied electromagnetics, computational physics, plasma physics, accelerator physics, intense laser-plasma and beam-plasma interactions, nonlinear dynamics and laser diodes. 

Imperial 2nd Yr. B.Sc. Physics Academic Tutorials - 2017-18
Imperial 2nd Yr. B.Sc. Physics Academic Tutorials - 2016-17 
Unifying Laser, Plasma & Accelerator Physics
, USPAS, June 2016 with Prof. Seryi
Imperial 3rd Yr. B.Sc. Physics Academic Tutorials (Comp. Exam) - 2015-16 
Electronics Design Lab, Duke University, Fall 2014
Laser Plasma Accelerators (with E.Esarey & C.Schroeder), USPAS, Jan 2013
Electromagnetics, Duke University, Fall 2011

PhD, Duke University, NC, USA [thesis]
MS, Stanford University, CA, USA [thesis]
MS, Indiana University Bloomington, IN, USA [thesis]

Google Scholar

Selected Publications

Journal Articles

Sahai AA, Strongly-Mismatched Regime of Self-Guided Laser-Plasma Acceleration

Sahai AA, Quasi-monoenergetic Laser-Plasma Positron Accelerator using Particle-Shower Plasma-Wave interactions

Sahai AA, 2017, Excitation of a nonlinear plasma ion wake by intense energy sources with applications to the crunch-in regime, Physical Review Accelerators and Beams, Vol:20

Tzoufras M, Tsung FS, Mori WB, et al., 2014, Improving the Self-Guiding of an Ultraintense Laser by Tailoring Its Longitudinal Profile, Physical Review Letters, Vol:113, ISSN:0031-9007

Sahai AA, Tsung FS, Tableman AR, et al., 2013, Relativistically induced transparency acceleration of light ions by an ultrashort laser pulse interacting with a heavy-ion-plasma density gradient, Physical Review E, Vol:88, ISSN:1539-3755

Sahai AA, 2014, Motion of the plasma critical layer during relativistic-electron laser interaction with immobile and comoving ion plasma for ion acceleration, Physics of Plasmas, Vol:21, ISSN:1070-664X


Sahai AA, Katsouleas TC, Optimal positron-beam excited plasma wakefields in Hollow and Ion-Wake channels

Sahai AA, Katsouleas TC, Bingham RA, et al., Proton acceleration by a relativistic laser frequency-chirp driven plasma snowplow

Sahai AA, Katsouleas TC, Muggli P, 2014, Self-injection by trapping of plasma electrons oscillating in rising density gradient at the vacuum-plasma interface, IPAC 2014, JACoW, Pages:1479-1482

Sahai AA, Katsouleas TC, Longitudinal instabilities affecting the moving critical layer laser-plasma ion accelerators, Advanced Accelerator Workshop 2014

More Publications