太赫兹波段煤的湿度与介电特性关系

Relationship between moisture and dielectric properties of coal at terahertz band electromagnetic radiation

基于自由空间法测试材料介电常数的原理,在室温条件下,测量了太赫兹波段100～110 GHz频率范围电磁波辐射条件下不同地区不同类型的煤样在不同湿度时的介电常数,研究湿度对煤的介电特性的影响,为研发旨在防治煤矿水害的基于太赫兹透射成像的煤矿孔中径向裂隙探测技术提供理论和数据基础。实验分别测出了煤样在100,105和110 GHz电磁波辐射时不同湿度条件下对应的介电常数实部和虚部,计算了不同湿度条件下的损耗正切。通过实验数据分析得出以下结论,室温条件下太赫兹波段的电磁波辐射时,煤的介电常数实部和虚部均随湿度的增加而单调增大,损耗正切随湿度的增加也呈现增大趋势。

Based on the principle of dielectric constant of materials measurement by free space method,the authorsmeasured,under room temperature,the complex dielectric constant of coals which are different types and from differentareas,and studied the dependence of moisture and the dielectric constant of coals at terahertz（THz） band electromag-netic radiation from 100 GHz to 110 GHz. The study provides a theoretical and data foundation for the research and de-velopment of the borehole radial crack detection technology which is based on the THz transmission imaging in order toprevent and control coal mine water disasters. This experiment measured the complex dielectric constant and calculatedthe loss tangent of coals under different moisture conditions at 100,105 and 110 GHz. Through the analysis of experi-ment data,under room temperature,it concludes that both the real part and imaginary part of dielectric constant of coalincrease with moisture increase,and the loss tangent also presents an increasing trend with moisture increase at tera-hertz band electromagnetic radiation.