[en] The dose dependence of the exchange bias field modification by He-ion bombardment in an applied magnetic field was investigated for an oxidic antiferromagnet/ferromagnet bilayer system consisting of NiO/NiFe in continuation of previous investigations for metallic antiferromagnet/ferromagnet systems (FeMn/NiFe, PtMn/NiFe, CrMn/NiFe). For low ion doses (<1.5x10¹⁵ ions/cm²), in a magnetic field applied parallel to the as-grown exchange bias field direction, the exchange bias field H_eb is enhanced compared to the as-grown field H_eb,0, i.e. H_eb/H_eb,0>1. For higher doses, the relative exchange bias field H_eb/H_eb,0 is found to decrease gradually with increasing dose to roughly zero. Bombardment with low doses in a magnetic field applied antiparallel to the direction of H_eb,0 results in magnitudes of |H_eb/H_eb,0|>1 and reverses the sign of H_eb. For higher ion doses H_eb again approaches zero. These findings are similar to the findings for the bilayer system FeMn/NiFe, but differ to those for the systems PtMn/NiFe and CrMn/NiFe. The experimental results are compared with a simulation using the SRIM code