  A new solar burst emission spectral component has been found showing sub-THz
fluxes increasing with frequency, spectrally separated from the well known
microwave component. Rapid pulsations are found present in all events observed
at the two frequencies of the solar submillimeter-wave telescope (SST): 212 and
405 GHz. They were studied in greater detail for three solar bursts exhibiting
the new THz spectral component. The pulse amplitudes are of about 5-8% of the
mean flux throughout the bursts durations, being comparable for both
frequencies. Pulsations range from one pulse every few seconds to 8-10 per
second. The pulse repetition rates (R) are linearly proportional to the mean
burst fluxes (S), following the simple relationship S = k R, suggesting that
the pulsations might be the response to discrete flare particle accelerator
injections quantized in energy. Although this result is consistent with
qualitative trends previously found in the GHz range, the pulse amplitude
relative to the mean fluxes at the sub-THz frequencies appear to be nearly ten
times smaller than expected from the extrapolation of the trends found in the
GHz range. However there are difficulties to reconcile the nearly simultaneous
GHz and THz burst emission spectrally separated components, exhibiting rapid
pulsations with considerably larger relative intensities in the GHz range.

Astrophysics