A Low-Cost, Time-Resolved Faraday Cup Array for Characterizing Long-Pulse Electron Beams

A compact, low-cost Faraday cup array was developed to support ongoing efforts at Xcimer Energy to characterize the long-pulse electron beam in the LPK diode system. Traditional diagnostics such as radiochromic film provide spatial fluence profiles but lack time resolution and require complex calibration. In contrast, this new diagnostic offers time-resolved measurements of beam current with simplified hardware and reduced cost.

The array’s design emphasizes impedance matching between the inner and outer conductors to minimize parasitic capacitance and preserve signal fidelity. Its miniaturized geometry, informed by GEANT4 Monte Carlo simulations, ensures effective stopping of electrons in the target energy range while maintaining low material thickness. Additional modeling using CST magnetostatic solvers guided the electrical layout to support high-fidelity signal acquisition.

The diagnostic was successfully integrated into the LPK system and is intended to complement existing tools for validating simulations and improving beam uniformity. The simplicity and cost-effectiveness of the design make it a promising candidate for broader deployment in long-pulse electron beam diagnostics.