Dome Fuji, Antarctica Core DF2 Dielectric Anisotropy Measurements

Dielectric anisotropy data of DF2 ice core were acquired as an indicator of the crystal orientation fabric. We measured dielectric anisotropy at 5 m intervals between the depths of 100 and 2400 m. At each sampling depth, a 1 m long ice core (two 0.5 m sections) was assessed with a 0.02 m step. Each ice core sample was formed into a slab shape with a thickness of 68-79 mm and width of 53-62 mm. We used an open microwave resonator, employing frequencies between 14 and 20 GHz. The open resonator was a semi-confocal type with a flat mirror and a concave mirror having a 250 mm radius of curvature, set 225 mm apart. The Gaussian beam at the sample insertion position between the two mirrors had a half-power diameter of 38 mm. The dielectric anisotropy values were volume-weighted averages within the volume covered by the Gaussian distribution of the beam. Dielectric anisotropy and its standard deviation were determined at intervals of approximately 0.5 m along the core sample, using 23 data points for each interval. The measurements were conducted at temperatures in the range of -30+-1.5 dgreeC in a cold room at the National Institute of Polar Researech, Japan.DF2冰芯的介电各向异性（dielectric anisotropy）数据采集得到，用作晶体定向组构（crystal orientation fabric）的指示指标。我们在100 m至2400 m的深度区间内，以5 m为间隔开展介电各向异性测量。在每个采样深度处，以0.02 m为步长，对一段长1 m的冰芯（分为两段0.5 m的子段）进行测试分析。每块冰芯样品被加工为板状，厚度介于68 mm至79 mm，宽度介于53 mm至62 mm。本研究采用工作频率介于14吉赫兹（GHz）至20吉赫兹（GHz）的开放式微波谐振腔。该开放式谐振腔为半共焦型（semi-confocal），配备一块平面镜与一块曲率半径为250 mm的凹面镜，两者间距设置为225 mm。在两块镜片之间的样品放置位置处，高斯波束（Gaussian beam）的半功率直径为38 mm。介电各向异性数值为波束高斯分布覆盖体积内的体积加权平均值。我们沿冰芯样品以约0.5 m为间隔测定介电各向异性及其标准偏差，每个间隔采用23个数据点进行计算。本次测量在日本国立极地研究所（National Institute of Polar Research）的低温室内开展，环境温度控制在-30±1.5 ℃范围内。