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Title: Investigation on the similarity law of low-pressure glow discharges based on the light intensity distributions in geometrically similar gaps

Authors:
ORCiD logo; ORCiD logo; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1373989
Grant/Contract Number:
SC0001939
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 8; Related Information: CHORUS Timestamp: 2018-02-14 14:40:48; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English

Citation Formats

Fu, Yangyang, Wang, Xinxin, Zou, Xiaobing, Yang, Shuo, Verboncoeur, John P., and Christlieb, Andrew J. Investigation on the similarity law of low-pressure glow discharges based on the light intensity distributions in geometrically similar gaps. United States: N. p., 2017. Web. doi:10.1063/1.4997425.
Fu, Yangyang, Wang, Xinxin, Zou, Xiaobing, Yang, Shuo, Verboncoeur, John P., & Christlieb, Andrew J. Investigation on the similarity law of low-pressure glow discharges based on the light intensity distributions in geometrically similar gaps. United States. doi:10.1063/1.4997425.
Fu, Yangyang, Wang, Xinxin, Zou, Xiaobing, Yang, Shuo, Verboncoeur, John P., and Christlieb, Andrew J. 2017. "Investigation on the similarity law of low-pressure glow discharges based on the light intensity distributions in geometrically similar gaps". United States. doi:10.1063/1.4997425.
@article{osti_1373989,
title = {Investigation on the similarity law of low-pressure glow discharges based on the light intensity distributions in geometrically similar gaps},
author = {Fu, Yangyang and Wang, Xinxin and Zou, Xiaobing and Yang, Shuo and Verboncoeur, John P. and Christlieb, Andrew J.},
abstractNote = {},
doi = {10.1063/1.4997425},
journal = {Physics of Plasmas},
number = 8,
volume = 24,
place = {United States},
year = 2017,
month = 8
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on August 4, 2018
Publisher's Accepted Manuscript

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  • The cathode sheath formation in a transient spatially small X-ray preionized high-pressure glow discharge with parameters typical for neon buffered XeCl lasers is investigated experimentally. Pictures of the light emission are taken with high temporal ({approx}1 ns) and spatial ({approx}25{mu}m) resolution using a gated CCD-camera as well as a streak camera. Quantitative data on the spatial and temporal development of the sheath structure are given. The most prominent feature is an extremely fast formation of a thin and very bright cathode sheath at a time which could be time correlated with an accuracy of {+-}0.2 ns with the discharge current.more » The results can be used to check numerical model calculations of the sheath formation.« less
  • The presentation of images with lesions of known pathology that are similar to an unknown lesion may be helpful to radiologists in the diagnosis of challenging cases for improving the diagnostic accuracy and also for reducing variation among different radiologists. The authors have been developing a computerized scheme for automatically selecting similar images with clustered microcalcifications on mammograms from a large database. For similar images to be useful, they must be similar from the point of view of the diagnosing radiologists. In order to select such images, subjective similarity ratings were obtained for a number of pairs of clustered microcalcificationsmore » by breast radiologists for establishment of a ''gold standard'' of image similarity, and the gold standard was employed for determination and evaluation of the selection of similar images. The images used in this study were obtained from the Digital Database for Screening Mammography developed by the University of South Florida. The subjective similarity ratings for 300 pairs of images with clustered microcalcifications were determined by ten breast radiologists. The authors determined a number of image features which represent the characteristics of clustered microcalcifications that radiologists would use in their diagnosis. For determination of objective similarity measures, an artificial neural network (ANN) was employed. The ANN was trained with the average subjective similarity ratings as teacher and selected image features as input data. The ANN was trained to learn the relationship between the image features and the radiologists' similarity ratings; therefore, once the training was completed, the ANN was able to determine the similarity, called a psychophysical similarity measure, which was expected to be close to radiologists' impressions, for an unknown pair of clustered microcalcifications. By use of a leave-one-out test method, the best combination of features was selected. The correlation coefficient between the gold standard and the psychophysical similarity measure through the use of seven features was relatively high (r=0.71) and was comparable to the correlation coefficients between the ratings by one radiologist and the average ratings by nine radiologists (r=0.69{+-}0.07). The correlation coefficient was improved compared to that of a distance-based method (r=0.58). The result indicated that similar images selected by the psychophysical similarity measure may be useful to radiologists in the diagnosis of clustered microcalcifications on mammograms.« less
  • A kinetic study of low-pressure microwave discharges in Ar, He, and O{sub 2} is carried out using electron-transport parameters and rate coefficients derived from solutions to the Boltzmann equation, together with the continuity and transport equations for the charged particles, taking into account stepwise-ionization processes. The Boltzmann equation is solved over a wide range of the applied frequency, {omega}/2{pi}, but assuming that {omega} {gt} {tau}{sup {minus}1}{sub e}, {tau}{sub e}, denoting the characteristic time for electron-energy relaxation by collisions. The formulation provides discharge characteristics for the maintenance field and for mean absorbed power per electron in the three gases, which aremore » shown to agree satisfactorily with experimental data obtained from surface-wave discharges. In this paper it is shown that such an agreement would not always be obtained without consideration of the role played by stepwise-ionization processes in sustaining the discharge.« less