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Title: Different precursor populations revealed by microscopic studies of bulk damage in KDP and DKDP crystals

Abstract

We present experimental results aiming to reveal the relationship between damage initiating defect populations in KDP and DKDP crystals under irradiation at different wavelengths. Our results indicate that there is more than one type of defects leading to damage initiation, each defect acting as damage initiators over a different wavelength range. Results showing disparities in the morphology of damage sites from exposure at different wavelengths provides additional evidence for the presence of multiple types of defects responsible for damage initiation.

Authors:
; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
886666
Report Number(s):
UCRL-CONF-216862
TRN: US200616%%1091
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: Boulder Damage Symposium, Boulder, CO, United States, Sep 19 - Sep 21, 2005
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING; DEFECTS; IRRADIATION; MORPHOLOGY; PRECURSOR; WAVELENGTHS

Citation Formats

DeMange, P, Negres, R A, Radousky, H B, and Demos, S G. Different precursor populations revealed by microscopic studies of bulk damage in KDP and DKDP crystals. United States: N. p., 2005. Web.
DeMange, P, Negres, R A, Radousky, H B, & Demos, S G. Different precursor populations revealed by microscopic studies of bulk damage in KDP and DKDP crystals. United States.
DeMange, P, Negres, R A, Radousky, H B, and Demos, S G. Mon . "Different precursor populations revealed by microscopic studies of bulk damage in KDP and DKDP crystals". United States. doi:. https://www.osti.gov/servlets/purl/886666.
@article{osti_886666,
title = {Different precursor populations revealed by microscopic studies of bulk damage in KDP and DKDP crystals},
author = {DeMange, P and Negres, R A and Radousky, H B and Demos, S G},
abstractNote = {We present experimental results aiming to reveal the relationship between damage initiating defect populations in KDP and DKDP crystals under irradiation at different wavelengths. Our results indicate that there is more than one type of defects leading to damage initiation, each defect acting as damage initiators over a different wavelength range. Results showing disparities in the morphology of damage sites from exposure at different wavelengths provides additional evidence for the presence of multiple types of defects responsible for damage initiation.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Oct 31 00:00:00 EST 2005},
month = {Mon Oct 31 00:00:00 EST 2005}
}

Conference:
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  • We describe a new damage testing approach and instrumentation that provides quantitative measurements of bulk damage performance versus fluence for several frequencies. A major advantage of this method is that it can simultaneously provide direct information on pinpoint density and size, and beam obscuration. This allows for more accurate evaluation of material performance under operational conditions. Protocols for laser conditioning to improve damage performance can also be easily and rapidly evaluated.This damage testing approach has enabled us to perform complex experiments toward probing the fundamental mechanisms of damage initiation and conditioning.
  • Over the course of testing a substantial number of KDP and DKDP crystals from rapid and conventional growth processes, we have discovered that there is a consistent difference in the value of the damage resistance between z-cut and tripler, x-cut and y-cut crystals for a given test fluence. This increase in damage probability for tripler, x and y-cut crystals is consistent for both conventional and rapid growth KDP as well as DKDP. It also holds for unconditioned (S/1) and conditioned (R/l) tests and has values of 2.1 {+-} 0.6 and 1.5 {+-} 0.3 respectively. Testing has also revealed that theremore » is no sensitivity to incident laser polarization. This is in direct contradiction to models based on simple, non-spherical absorbers. This result plus new information on the size and evolution of bulk damage density (see Runkel et al., this proceedings) has led to a reinterpretation of the growth parameter data for rapid growth NIF boules. It now appears that variations in impurity concentration throughout the boule do not affect the damage probability curve as dramatically as previously thought; although, this is still a topic of intensive investigation.« less
  • In this work, we investigate the laser-induced damage resistance at 355 nm in DKDP crystals grown with varying growth parameters, including temperature, speed of growth and impurity concentration. In order to perform this work, a DKDP crystal was grown over 34 days by the rapid-growth technique with varied growth conditions. By using the same crystal, we are able to isolate growth-related parameters affecting LID from raw material or other variations that are encountered when testing in different crystals. The objective is to find correlations of damage performance to growth conditions and reveal the key parameters for achieving DKDP material inmore » which the number of damage initiating defects is reduced. This approach can lead to reliable and expedite information regarding the importance of different crystal growth parameters on the laser damage characteristics of these crystals.« less
  • The interaction of damage initiating defect precursors in KDP and DKDP crystals with laser pulses is investigated as a function of laser parameters to obtain experimental results that contain information about the type and nature of the defects. Specifically, the focus is to understand (a) the interaction of the precursors with sub-damage laser pulses leading to improvement to the damage performance (laser conditioning) and (b) the synergetic effects during multi-wavelength irradiation. Our results expose complex behaviors of the defect precursors associated with damage initiation and conditioning at different wavelengths that provide a major step towards revealing the underlying physics.