In order to obtain the Deflagration to Detonation Transition (DDT) distance in the detonative tube

an ion probe system based on comparative electric circuit was made.This system was used to measure the flame propagation velocities along the tube

and furthermore to determine the DDT distance.As compared with high frequency pressure transducers

this system was simpler and cheaper

especially it could be used in the high temperature condition for a longer time.In this paper

the DDT distances of acetylene and oxygen mixture were measured with this system

and the results were consistent with that of high frequency pressure transducers.