Laser driven tsunami in plasma: an advanced electron accelerator

Discovery of LASER has a profound impact on almost every field of science and technology and related applied research. With advancement of various mode locking techniques it could be possible to generate short duration laser pulses which has eventually brought down in the femtosecond (ultra-short) regime. Using Chirped Pulse Amplification (CPA) technique, proposed by G. Mourou and D. Strickland (Awarded Nobel Prize in Physics, 2018), it has now been possible to develop high-power, several Terawatt (TW) to few Petawatt (PW) level, ultra-short pulse duration laser systems. In CPA technique an ultra-short duration laser pulse from oscillator is first temporally stretched and after desired level of amplification in various amplifier stages is compressed back to the ultra-short duration. Availability of high-power, ultra-short lasers has dramatically changed the physics and applications of high-intensity laser-plasma interaction, a subject of extensive research during laser several decades. In the earlier studies high-power lasers with few nanoseconds to hundreds of picosecond pulse duration were used, primarily due to its relevance to laser-driven inertial confinement fusion. Whereas, using high-power, ultrashort duration laser pulses, focused to a focal spot of several microns diameter, laser intensities in the range of ∼10¹⁸ Wcm^-2 to greater than 10²⁰ Wcm^-2 could be achieved. Laser plasma interaction at such ultra-high intensities could drive giant electron plasma wave (termed here as Tsunami in the plasma) which could be used for accelerating electrons to high-energies (several tens of MeV to few GeV) in a small interaction length of few mm to few cms. Such compact accelerators could also be used to develop laser driven synchrotron (x-rays and γ-rays) sources. In this talk, I shall present a brief overview of this exciting area of advanced laser driven acceleration technique, and recent experimental investigations performed at APAS, LPD, RRCAT, Indore. (author)