In order to study the high-frequency arc characteristics of gas gap

a test circuit for discharges of a short air gap has been built in this paper.The breakdown voltage across the gap and the current is measured

and the variation of arc and the minimum of arc resistance r

0

is obtained.The arc resistance drops from 10

12

ohms to the minimum r

0

in tens of nanoseconds after breakdown of the short air gap

then recovers after a few microseconds.The minimum r

0

of arc resistance and the arcing duration t corresponding to different loop frequency are also obtained.When the loop frequency changes from 4.8 MHz to 13.5 MHz

r

0

increases f

rom 0.4Ωto 5.0 ft

and t decreases from 4.0μs to 0.9μs.Comparisonsbetween the experimental results and the calculations by various arc resistance models indicate that the calculation by Kushner’s arc model agrees well with the experimental result during early stage of arcing period but with longer arcing time.