Author: Liu, Y.
Paper Title Page
MOPMR055 Radiation-Resistant Fiber Optic Strain Sensors for SNS Target Instrumentation 371
 
  • Y. Liu, W. Blokland, J.D. Bryan, A. Rakhman, B.W. Riemer, R.L. Sangrey, M. Wendel, D.E. Winder
    ORNL, Oak Ridge, Tennessee, USA
  • A. Rakhman
    UTK, Knoxville, Tennessee, USA
  • R. Strum
    San Diego State University, San Diego, USA
 
  Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Measurement of stresses and strains in the mercury target vessel of the Spallation Neutron Source (SNS) is important to understand the structural dynamics of the target. Owing to their compactness, easy system integration, and invulnerability to the electromagnetic interference, fiber optic strain sensors have been installed into the SNS target module starting from the fall of 2015. In this talk, we report on the development of radiation-resistant fiber optic strain sensors for subsequent generations of SNS target instrumentation. The sensors are extrinsic Fabry-Perot interferometers (EFPIs) made from fluorine-doped single-mode fibers. The radiation induced loss of the fiber has been measured in the SNS target 13 at the energy-on-target level exceeding 500 MWhr which results in peak doses on fiber of more than 109 Gy. A superluminescent diode laser at 1300 nm is used as the light source and the strain is measured in real-time using quadrature phase shifted signals generated from a local interferometer. We have demonstrated successful measurements of strains from 1 to 1000 με at a kHz frequency range on a test plate using the developed interrogation optical system.
 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR055  
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WEPOR032 Power Recycling of Burst-mode Laser Pulses for Laser Particle Interactions 2739
 
  • Y. Liu, A. Rakhman
    ORNL, Oak Ridge, Tennessee, USA
  • A. Rakhman
    UTK, Knoxville, Tennessee, USA
 
  Funding: This work has been partially supported by U.S. DOE grant DE-FG02-13ER41967. ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
A number of laser-particle interaction experiments such as the laser assisted hydrogen ion beam stripping or X-/γ-ray generations via inverse-Compton scattering involve light sources operating in a burst mode to match the temporal structure of the particle beam. As the small cross-section in the laser-particle interaction process results in negligible laser power loss, it is desirable to make the interaction inside an optical cavity to recycle the laser power. In many cases, conventional cavity locking techniques will not work since the burst normally has very small duty factor and low repetition rate and it is impossible to generate an effective control signal. In this talk, we report on the development of a doubly-resonant optical cavity scheme and its locking technique that enables a simultaneous resonance of two laser beams with different spectra and/or temporal structures. We demonstrate that such a cavity can be used to recycle burst-mode ultra-violet laser pulses with arbitrary burst lengths and repetition rates. System implementation, technical challenges, experimental results and applications will be described.
* V. Danilov et al., Phys. Rev. ST Accel. Beams 10, 053501 (2007).
** K. Sakaue et al., Rev. Sci. Instrum. 80, 123304 (2009).
*** A. Rakhman, M. Notcutt, and Y. Liu, Opt. Lett. 40, 5562 (2015).
 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR032  
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