This week’s seminar will be given by Rakesh Yembadi, who joined the group last year as a PDRA. His seminar is titled: “kHz electron acceleration exploiting parametric instabilities” – full abstract below. As he is away from Imperial at the moment, he will be presenting remotely on Teams, at the normal day/time, Wednesday the 23rd at 3 PM. We will still set up 741 to stream the seminar as normal.
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kHz electron acceleration exploiting parametric instabilities.
The regime, in which the interaction of TW class, kHz laser pulses with a high rep.rate and mass limited target system is fast evolving and sparsely explored. This scheme provides a way to increase the repetition rate at which compact, short-burst, bright secondary electron/x-ray sources are made with intense lasers and has the potential to increase the average brightness, which is necessary for many imaging/radiography applications.
I will be discussing about pre-plasma evolution and electron/ion acceleration mechanisms in two such target systems: MHz droplets and 10 kHz microparticle dust. Optimized pre-plasma tailoring of these target systems boosts parametric instabilities to generate electron temperatures as large as 200 keV even at a laser intensity of 1016 W/cm2. Measurements, well corroborated by particle- in-cell simulations, reveal that two plasmon decay in the vicinity of the target is the main contributor to hot electron generation. Similarly, micro-particle floating in a low-density plasma is a model system for many basic plasma science studies. Intense femtosecond laser pulse focused on a dust particle will form an intriguing system in which a solid density high temperature micro plasma interacts with the low-density plasma surrounding it. The effect of such interaction on the acceleration mechanism will also be discussed.