1993 Fiscal Year Final Research Report Summary

Basic Research of Water Triggered Lightning and Development of Fountain

Research Project

Project/Area Number	04805026
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	電力工学
Research Institution	Kumamoto University
Principal Investigator	MAEDA Sadao Kumamoto University Engineering, Professor, 工学部, 教授 (10040370)
Co-Investigator(Kenkyū-buntansha)	TAKAKI Kouichi Oita National College of Technology, Lecturer, 講師 (00216615) KATSUKI Sunao Kumamoto University Engineering, Research Associate, 工学部, 助手 (80233758) AKIYAMA Hidenori Kumamoto University Engineering, Associate Professor, 工学部, 助教授 (50126827)
Project Period (FY)	1992 – 1993
Keywords	LIGHTNIG / TRIGGERED LIGHTNING / WATER TRIGGERED LIGHTNING / WATER JET / ROCKET TRIGERED LIGHTNING / LASER TRIGGERED LIGHTNING
Research Abstract	A new method to trigger lightning by a water jet is proposed and investigated experimentally by using an impulse generator. Lightning has been triggered successfully by using a thin wire that is pulled up by a rocket. However, the use of rockets has made it impossible to perform the experiment in urban areas. Here it is proposed to use a water column instead of the thin wire. A spherical electrode of 20mm in diameter and a plane electrode, or plane electrodes with an area of 1mx1m are used for the basic experiment of triggering the lightning by a water jet. The obtained results are summarized as follows ; (1)The discharge of an upward leader begins between the tip of water jet and the electrode with a high voltage. (2)The current flows through the water column after the discharge in the air. (3)The discharge at the surface of the water column occurs by increasing the voltage. (4)The 50% flashover voltage decreases considerably as the height of the water jet increases. The decrease of the 50% flashover voltage by the water jet is equal to the decrease in the case of using a metal conductor instead of the water jet. (5)A system to produce the water jet, which was composed of a water chamber and a high pressure chamber of air, was constructed. The experimental results and the analyzes of data show that a water column with 100m height is able to be made under a thunder cloud.