Development of a Feasible High-Power mm Microwave Pulse Source Utilizing Superconducting Cavity

利用超导腔开发可行的高功率毫米微波脉冲源

基本信息

批准号：
60850014
负责人：
MINAMI Kazuo
金额：
$ 7.55万
依托单位：
Niigata University (1986)Tokyo Institute of Technology (1985)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

项目摘要

It is the purpose of the present project to develop a feasible mm microwave pulse sourse, utilizing the storage and quick extraction of energy from a superconducting cavity, in which the time constants can be of the order of <10^(-2)> sec. In the first year, we designed and constructed a niobium cavity, a mm microwave AFC circuit and a FRP cryostat etc. Moreover, small semi-circular discharge tubes with 20-50 Torr helium gas at room temperature were designed to use for the output discharge antenna. Niobium cavity was designed to be <TE_(0,1,17)> cylindrical mode with resonant frequency 24.5 GHz, and the inner diameter 44 mm, the length 111 mm. In the next year, i.e., the final year of the project, we first measured precisely the frequency characteristic of the niobium cavity at room temperature. Various parameters of the cavity were obtained. The resonant frequency and the loaded Q value were, respectively, 23.77 GHz and 2x <10^3> . To increase the loaded Q value of niobium cavity, we electro-polished The inner surface of the niobium cavity, in which the roughness of the surface was estimated to be less than 0.1 <micro> m. In the electro-polishing solution, the DC current with 60 mA/ <cm^2> was given between a niobium anode and the part of the niobium cavity, i.e., the two disks and the cylinder, respectively. Electro-polishing took 4 hours. Then, the parts were fabricated quickly in a clean room. After evacuating and baking, vacuum inside the cavity was attained to be 3x <10^(-8)> Torr. The electro-polished cavity was considered to have loaded Q value of the <10^8> at helium temperature 4.2 K. At this moment, we are carrying out the final experiment to give the voltage 20 kV, current 2000 A, time width 1 <micro> sec to the discharge antenna. We are expecting to have the final purpose of the present project, i.e., pulse power gain of <10^4> .

本项目的目的是开发一种可行的毫米微波脉冲源，利用超导腔的能量存储和快速提取，其中时间常数可以为 <10^(-2)> 秒量级。第一年，我们设计并建造了铌腔、毫米微波AFC电路和FRP低温恒温器等。此外，还设计了小型半圆形放电管，在室温下装有20-50 Torr氦气，用于输出放电天线。铌腔设计为<TE_(0,1,17)>圆柱模，谐振频率24.5 GHz，内径44 mm，长度111 mm。第二年，即项目的最后一年，我们首先精确测量了室温下铌腔的频率特性。获得了腔体的各种参数。谐振频率和负载Q值分别为23.77GHz和2x<10^3>。为了提高铌腔的负载Q值，我们对铌腔的内表面进行了电解抛光，表面粗糙度估计小于0.1μm。在电抛光溶液中，在铌阳极和铌空腔部分（即两个圆盘和圆柱体）之间分别施加60mA/<cm^2>的直流电流。电解抛光耗时4小时。然后，在洁净室中快速制造零件。抽真空和烘烤后，腔体内的真空度达到3x<10^(-8)>Torr。认为电抛光腔在氦气温度4.2 K下已加载<10^8>的Q值。此时，我们正在进行最后的实验，电压20 kV，电流2000 A，时间宽度1 <微>秒到放电天线。我们期望本项目的最终目的，即脉冲功率增益 <10^4> 。