Development of high-frequency current probe utilizing high T_c Josephson junction

利用高T_c约瑟夫森结的高频电流探头的开发

• 批准号: 12650430
• 负责人: ENPUKU Keiji
• 金额: $ 2.3万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650430/
• 关键词: superconducting magnetometer; high T_c superconductor; Josephson junction; bicrystal junction; flux focusing effect; junction array; Josephson penetration death; high-frequency current probe; 高周波磁界; 電流プローブ; ジョセフソン侵入長; 臨界電流; 冷凍機冷却

In this research, we developed high T_c superconducting magnetic sensor for high-frequency current probe. Our results are summarized as follows.1. We developed the magnetic sensor utilizing bicrystal junctions. Using the change of the current-voltage characteristics of the junction with the magnetic field, we can convert the magnetic field to the voltage with the conversion efficiency of dV/dB. Compared to the SQUID, the present sensor can measure the absolute value of the magnetic field.2. The magnetic sensor is made using the 30-degree bicrystal junction. The I-V curve of the junction is studied both theoretically and experimentally in order to optimize the conversion efficiency dV/dB. Key factors which determine the conversion efficiency, such as the ration of the junction width to the Josephson penetration depth λ_j, flux focusing effect, and temperature dependence, are clarified.3. Performance of the series array of the junction is compared with that of the conventional induction coil. When the sensor area is 100 μm x 50 μm, the sensitivity of the junction array is more sensitive up to 7 GHz than the induction coil. Moreover, the sensitivity is independent of the frequency, unlike the case of the induction coil. Therefore, wide-band measurement is possible with the present sensor.4. Current probe is made with the magnetic sensor, and the magnetic field produced by the high frequency current is measured. The current with frequency of 130 MHz is successfully measured. With the improvement of the measurement system, we will demonstrate the measurement of GHz signal.

在本研究中，我们研制了用于高频电流探头的高温超导磁传感器。我们的研究结果总结如下。我们开发了利用双晶结的磁传感器。利用结的电流-电压特性随磁场的变化，可以将磁场转换为转换效率为dV/dB的电压。与SQUID相比，该传感器可以测量磁场的绝对值。该磁传感器采用30度双晶结制作。为了优化转换效率dV/dB，从理论和实验两方面研究了结的I-V曲线。阐明了影响转换效率的关键因素，如结宽度与约瑟夫森穿透深度λ_j的比值、通量聚焦效应和温度依赖关系。并与传统感应线圈串联阵列的性能进行了比较。当传感器面积为100μm×50μm时，结阵列的灵敏度比感应线圈的灵敏度高达7 GHz。此外，与感应线圈的情况不同，灵敏度与频率无关。因此，用目前的传感器进行宽带测量是可能的。利用磁传感器制作电流探头，测量高频电流产生的磁场。成功地测量了频率为130 MHz的电流。随着测量系统的完善，我们将演示GHz信号的测量。

项目成果

K.Enpuku et al.: "Properties of a flux dam inserted in the pick up coil of a high Tc superconducting quantum interference device magnetometer"Jpn. J. Appl. Phys.. Vol.40no.6A. 4013-4018 (2001)

K.Enpuku 等人：“插入高 Tc 超导量子干涉装置磁力计拾波线圈中的磁通坝的特性”Jpn。

K.Enpuku et al.: "Properties of flux dam inserted in the pickup coil of high Tc superconducting quantum Interference device (SQUID) magnetometer"Japanese Journal of applied Physics. (to be published). (2001)

K.Enpuku 等人：“插入高温超导量子干涉装置 (SQUID) 磁力计拾波线圈中的磁通坝的特性”日本应用物理学杂志。

K.Enpuku et al: "Biological immunoassay with high Tc superconducting quantum interference device (SQUID) magnetometer"IEICE Trans.Electron.. Vol.E84-C,No.1. 43-48 (2001)

K.Enpuku 等人：“使用高 Tc 超导量子干涉装置 (SQUID) 磁力计进行生物免疫测定”IEICE Trans.Electron.. Vol.E84-C,No.1。

K.Enpuku et al.: "A four-junction switch for controlling the opening and closing of a pickup coil in high Tc SQUID magnetometer"Jpn. J. Appl. Phys.. Vol.40no.8B. L869-L871 (2001)

K.Enpuku 等人：“用于控制高 Tc SQUID 磁力计中拾波线圈的打开和关闭的四结开关”Jpn。

K.Enpuku et al.: "A four-junction switch for controlling the opening and closing of a pickup coil in high T_c superconducting quantum interference device magnetometer"Japanese Journal of Applied Physic. 40(8B). L869-L871 (2001)

K.Enpuku等：“一种用于控制高T_c超导量子干涉装置磁力计中拾波线圈打开和关闭的四结开关”日本应用物理学杂志。