Temporal measurement of plasma density variations above a semiconductor bridge (SCB)

The plasma density variations above a semiconductor bridge (SCB) device employing a capacitor discharge firing set have been measured in vacuum (⩽10^-5 torr). A novel diagnostic technique using a microwave resonator probe was used to measure the resultant plasma density variations as a function of time. This method is superior to Langmuir probes in this application because Langmuir probe measurements are affected by sheath effects, small bridge area, and unknown fraction of multiple ions. Our experimental results indicate that the plasma density is observed to increase to a peak value of 5.5× 10¹¹ cm^-3 and decay exponentially with time, which is consistent with diffusion dominating the plasma transport. The time needed for reaching the peak plasma density is about 1.6 μs, which is the duration of the late time discharge of an SCB device