  We apply time-dependent R-matrix theory to investigate harmonic generation
from ground state Ar+ with M=0 at a wavelength of 390 nm. Contributions
associated with the different 3s(2)3p(4) ionization thresholds are assessed,
including the interference between these. The dominant contribution originates
from the second ionization threshold, 3s(2)3p(4) (1)D. Changes to the harmonic
yields arising from the higher 3s3p(5) thresholds are also assessed. We further
confirm that Ar+ has a higher harmonic yield than He for the same laser pulse,
despite having a higher ionization threshold.
