A theoretical analysis of transient ionization processes occurring in a low-barrier GaAs Mott diode under the influence of space radiation high energy charged particles and simulating pulsed laser radiation is carried out. The diode response to the As+ ion action with an energy of 200 MeV, corresponding to a linear energy transfer of 26 MeV cm2/mg, is compared with the response to the femtosecond pulses optical radiation action of various durations (10-1000 fs) and photon energies exceeding the GaAs band gap.