A study of some inherent causes for non-uniform microwave heating
Journal
Physics of Plasmas
Journal Volume
24
Journal Issue
10
Date Issued
2017
Author(s)
Abstract
Radio frequency and microwave heating of dielectric objects is often susceptible to an excessive temperature spread due to uneven energy deposition. The exposure to a non-uniform field is a well-studied cause for this difficulty encountered in numerous applications. There are, however, some less-understood causes, which are inherent in nature in that they persist even in a perfectly uniform field. We present an experimental study on three main inherent causes with rice grains as samples. Experiments are conducted in an applicator, in which samples are irradiated by a 24 GHz microwave. High radiation uniformity (∼99%) and polarization control allow a quantitative examination of each cause. Their individual and collective effects are found to be highly significant. In particular, polarization-charge shielding alone can result in a temperature spread of ∼18.2% for the samples examined. Physical interpretations are given and an effective method for its mitigation is demonstrated.
SDGs
Type
journal article