Time response of a type IIa natural diamond photoconductor to long-pulse low-intensity soft x rays

For the study of soft x rays from plasmas and laser-plasma interactions, type IIa diamond photoconductor detector (PCD) is an important diagnostic for emissions from z pinches, [R. B. Spielman, Rev. Sci. Instrum. 63, 5056 (1992)], synchrotons, and laser-produced plasmas [D. R. Kania et al., Rev. Sci. Instrum. 61, 2765 (1990)]. Among diamond’s advantages are its time response (in the picosecond-to-nanosecond range for high-intensity fast pulses of soft x rays [D. R. Kania et al., J. Appl. Phys. 68, 124 (1990)]), and its band gap of 5.45 eV (which reduces its visible and near-uv sensitivity to near zero). We have investigated type IIa PCD using low-intensity slow pulses generated by a pulsed e beam hitting a copper target, with repetitions up to 50 kHz. The time response in this case is presented, leading to a proposal for a new type of diamond PCD for tokamaks, where the single detector has an array capability for position sensing and energy analysis.