Broyer P, Cathignol D, Theillère Y, Mestas J L
INSERM U281, Lyon, France.
Med Biol Eng Comput. 1996 Sep;34(5):321-8. doi: 10.1007/BF02519998.
In extracorporeal lithotripsy, the electro-acoustic efficiency of electrohydraulic generators is limited by the inductance of the electrical discharge circuit. A new shock-wave generator is described that uses a coaxial discharge line enabling electro-acoustic efficiency to be greatly increased. The line is built using a para-electric ceramic with a relative dielectric constant of 1700, manufactured for use in high-voltage impulse mode. A coaxial spark gap, with minimal inductance, has been developed to obtain the triggered breakdown of the discharge line. Shock waves are created with a coaxial electrode plugged directly into the spark gap and immersed in an electrolyte of degassed saline. Electrode gap and electrolyte resistivity are adjusted to match the resistivity of the electrolyte volume between the underwater electrodes to the characteristic impedance of the line. The discharge line generates in the medium a rectangular current pulse with an amplitude of about 6000 A and a rise time of 50 ns. Compared with conventional generators, measurements of the expansive peak pressure pulse show an increase of 105% at 10 kV, 86.5% at 12 kV and 34.5% at 14 kV charging voltage. Electro-acoustic efficiency is found to be 11% instead of 5.5% for a conventional discharge circuit.
在体外冲击波碎石术中，液电式发生器的电声效率受放电电路电感的限制。本文描述了一种新型冲击波发生器，它采用同轴放电线路，可大幅提高电声效率。该线路采用相对介电常数为1700的顺电陶瓷制成，用于高压脉冲模式。已开发出一种电感极小的同轴火花隙，以实现放电线路的触发击穿。冲击波由直接插入火花隙并浸入脱气盐水电解液中的同轴电极产生。调整电极间隙和电解液电阻率，使水下电极之间电解液体积的电阻率与线路的特性阻抗相匹配。放电线路在介质中产生一个矩形电流脉冲，幅度约为6000 A，上升时间为50 ns。与传统发生器相比，膨胀峰值压力脉冲的测量结果表明，在充电电压为10 kV时增加了105%，12 kV时增加了86.5%，14 kV时增加了34.5%。发现电声效率为11%，而传统放电电路为5.5%。
