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Title: An in-vacuo optical levitation trap for high-intensity laser interaction experiments with isolated microtargets

We report on the design, construction, and characterisation of a new class of in-vacuo optical levitation trap optimised for use in high-intensity, high-energy laser interaction experiments. The system uses a focused, vertically propagating continuous wave laser beam to capture and manipulate micro-targets by photon momentum transfer at much longer working distances than commonly used by optical tweezer systems. A high speed (10 kHz) optical imaging and signal acquisition system was implemented for tracking the levitated droplets position and dynamic behaviour under atmospheric and vacuum conditions, with ±5 μm spatial resolution. Optical trapping of 10 ± 4 μm oil droplets in vacuum was demonstrated, over timescales of >1 h at extended distances of ∼40 mm from the final focusing optic. The stability of the levitated droplet was such that it would stay in alignment with a ∼7 μm irradiating beam focal spot for up to 5 min without the need for re-adjustment. The performance of the trap was assessed in a series of high-intensity (10{sup 17} W cm{sup −2}) laser experiments that measured the X-ray source size and inferred free-electron temperature of a single isolated droplet target, along with a measurement of the emitted radio-frequency pulse. These initial tests demonstrated themore » use of optically levitated microdroplets as a robust target platform for further high-intensity laser interaction and point source studies.« less
Authors:
; ; ; ; ; ;  [1] ;  [2] ; ;  [3]
  1. Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom)
  2. Department of Physics, Harvey Mudd College, Claremont, California 91711 (United States)
  3. Radiation Physics, AWE, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom)
Publication Date:
OSTI Identifier:
22392410
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 86; Journal Issue: 3; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; DISTANCE; DROPLETS; KHZ RANGE 01-100; LASERS; LEVITATION; PHOTONS; POINT SOURCES; RADIOWAVE RADIATION; SPATIAL RESOLUTION; TRAPS; X-RAY SOURCES