GHz-rate full-field holographic observation of Ultra-Short Pulsed Laser (USPL) plasma dynamics generated from acrylic polymer, aluminium and steel targets and their correlation to RF emissions.
Abstract
Laser-matter interactions take place via several key mechanisms with the range of time scales spanning some fifteen orders of magnitude. Early times are characterised by energy absorption into the material with characteristic timescales of 10-15 s. Plasma initiation occurs on the picosecond 10-12s timescale while vaporisation and melting are inherently thermal processes and are delayed in their response by the characteristic energy-lattice transfer time. Shockwave emission are long-lived with typical time scales ranging from 10-12 s to more than 10-3 s. Additional complexity occurs when multiple pulses are introduced to the material – a subsequent pulse not interacting with “virgin” material but the product of previous. This project aims to further develop existing diagnostic instrumentation that to be employed in USPL processes to understand the dynamic at play when lasers interact with materials, and the resultant RF emission and optimization. This will be accomplished through direct observation using an ultra-high speed Pulsed Digital Holographic system (developed at Cambridge University), and its optimization for the specific application. This would include developing the system to be able to measure 3D spatial information such as plasma and shockwave induced refractive index gradients, and particulate ejecta with the ability to resolve temporal events down to 500 ps and frame rates in the GHz time domain. The camera made will be able to take a maximum of 4 frames over the selected time frame, higher temporal resolution will be achieved by taking images of multiple events on different triggering times.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 09, 2018
- Source ID
- FA95501710337
Entities
People
- William O Neill
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Cambridge