arXiv subjects

P. A. Naik

Publications and source records attributed to P. A. Naik.

3 recordsLinked to original sources

arXiv2017

Betatron resonance electron acceleration and generation of quasi-monoenergetic electron beams using 200fs Ti:Sapphire laser pulses

Generation of collimated, quasi-monoenergetic electron beams (peak energy ~17-22MeV, divergence ~10mrad, energy spread ~20%) by interaction of Ti:sapphire laser pulse of 200fs duration, focussed to an intensity of ~ 2.1x10^18 W/cm^2,with an under-dense (density~3.6x10^19 to ~1.1x10^20 cm-3) He gas-jet plasma was observed. Two stages of self-focusing of the laser pulse in the plasma were observed. Two groups of accelerated electrons were also observed associated with these stages of the channeling and is attributed to the betatron resonance acceleration mechanism. This is supported by 2D PIC simulations performed using code EPOCH and a detailed theoretical analysis which shows that present experimental conditions are more favorable for betatron resonance acceleration and generation of collimated, quasi-thermal/quasi-monoenergetic electron beams.

physics.plasm-ph↗

arXiv2016

Quasi-monoenergetic electron beams from laser plasma acceleration using nitrogen gas jet

An experimental investigation on laser plasma acceleration of electrons has been carried out using 3 TW, 45 fs duration titanium sapphire laser pulse interaction with nitrogen gas jet at intensity of 2x10^18 W/cm^2. We have observed stable generation of well collimated electron beam with divergence and pointing variation ~ 10 mrad from the nitrogen gas jet plasma at an optimum plasma density around 3x10^19 cm^-3. The energy spectrum of the electron beam was quasi-monoenergetic with average peak energy and charge around 25 MeV and 30 pC respectively. The results will be useful for better understanding and control of ionization injection and laser wakefield acceleration of electrons in high-Z gases and also to develop practical laser wakefield accelerators for various applications including injectors for high energy accelerators.

physics.plasm-ph↗

arXiv2016

A simple and straightforward technique for single shot measurement of terahertz profile

A new detection scheme capable of acquiring the entire spatiotemporal profile of terahertz radiation in a single laser shot is being demonstrated. The design allows temporal resolution of the order of transform-limited pulse duration of the probe, which is an absolute benefit over the compromised resolution of otherwise prevalent single-shot detection schemes based on spectral encoding of terahertz waveform on a temporally chirped readout pulse. This makes the technique perfectly suitable for sensitive spectroscopy studies. The single shot detection technique presented here relies on space-to-time mapping of terahertz temporal profile by use of a converging probe intensity front. The present approach does not require any specialized optics and is implemented using very straightforward alignment procedure. It has shown to reproduce the temporal waveform of terahertz radiation faithfully.

physics.plasm-ph↗