Picosecond Resolution Collector Sensor for Diagnostics of Subrelativistic Electron Bunches

A collector sensor with the fastest to-date response has been developed to perform time-domain diagnostics of subrelativistic electron bunches generated in gas and vacuum. This article considers the formation of the sensor response signal in measuring the current of electron bunches with energy of hundreds of kiloelectronvolts, duration of $\approx 10$ ps, and charge of up to $\approx 50$ pC. A simulation of the signal transformation with respect to the actual bunch current envelope has been performed. The simulation data have shown that the signal transformation is due to a mismatch between the collector unit (CU) and the transmitting duct of the sensor. The influence of the transverse structure, current rise rate, and current pulse duration of the bunch on the signal waveform is analyzed. With an appropriate bandwidth of the oscilloscope used, the bunch charge can be determined from the signal of the sensor and the duration and amplitude of the bunch current pulse can be restored. The features of the diagnostics of bunch sequences using the proposed sensor are discussed.