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Title: Effects of polarization-charge shielding in microwave heating

Abstract

Heating of dielectric objects by radio frequency (RF) and microwaves has long been a method widely employed in scientific research and industrial applications. However, RF and microwave heating are often susceptible to an excessive temperature spread due to uneven energy deposition. The current study elucidates an important physical reason for this difficulty and proposes an effective remedy. Non-spherical samples are placed in an anechoic chamber, where it is irradiated by a traveling microwave wave with 99% intensity uniformity. Polarization charges induced on the samples tend to partially cancel the incident electric field and hence reduce the heating rate. The polarization-charge shielded heating rate is shown to be highly dependent on the sample's shape and its orientation relative to the wave electric field. For samples with a relatively high permittivity, the resultant uneven heating can become a major cause for the excessive temperature spread. It is also demonstrated that a circularly polarized wave, with its rapidly rotating electric field, can effectively even out the heating rate and hence the temperature spread.

Authors:
; ; ;
Publication Date:
OSTI Identifier:
22490085
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 8; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DIELECTRIC MATERIALS; ELECTRIC FIELDS; ENERGY ABSORPTION; HEATING RATE; IRRADIATION; MICROWAVE HEATING; ORIENTATION; PERMITTIVITY; POLARIZATION; RADIOWAVE RADIATION; SHIELDING

Citation Formats

Lin, M. S., Lin, S. M., Chiang, W. Y., Barnett, L. R., and Chu, K. R., E-mail: krchu@yahoo.com.tw. Effects of polarization-charge shielding in microwave heating. United States: N. p., 2015. Web. doi:10.1063/1.4928557.
Lin, M. S., Lin, S. M., Chiang, W. Y., Barnett, L. R., & Chu, K. R., E-mail: krchu@yahoo.com.tw. Effects of polarization-charge shielding in microwave heating. United States. https://doi.org/10.1063/1.4928557
Lin, M. S., Lin, S. M., Chiang, W. Y., Barnett, L. R., and Chu, K. R., E-mail: krchu@yahoo.com.tw. 2015. "Effects of polarization-charge shielding in microwave heating". United States. https://doi.org/10.1063/1.4928557.
@article{osti_22490085,
title = {Effects of polarization-charge shielding in microwave heating},
author = {Lin, M. S. and Lin, S. M. and Chiang, W. Y. and Barnett, L. R. and Chu, K. R., E-mail: krchu@yahoo.com.tw},
abstractNote = {Heating of dielectric objects by radio frequency (RF) and microwaves has long been a method widely employed in scientific research and industrial applications. However, RF and microwave heating are often susceptible to an excessive temperature spread due to uneven energy deposition. The current study elucidates an important physical reason for this difficulty and proposes an effective remedy. Non-spherical samples are placed in an anechoic chamber, where it is irradiated by a traveling microwave wave with 99% intensity uniformity. Polarization charges induced on the samples tend to partially cancel the incident electric field and hence reduce the heating rate. The polarization-charge shielded heating rate is shown to be highly dependent on the sample's shape and its orientation relative to the wave electric field. For samples with a relatively high permittivity, the resultant uneven heating can become a major cause for the excessive temperature spread. It is also demonstrated that a circularly polarized wave, with its rapidly rotating electric field, can effectively even out the heating rate and hence the temperature spread.},
doi = {10.1063/1.4928557},
url = {https://www.osti.gov/biblio/22490085}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 8,
volume = 22,
place = {United States},
year = {Sat Aug 15 00:00:00 EDT 2015},
month = {Sat Aug 15 00:00:00 EDT 2015}
}