Rapid Fine Structure in a Burst of Hard Solar X-Rays Observed by OSO-5

A number of bursts of hard solar X-rays have been observed in nine channels simultaneously covering the energy range from 14 to 250 keV. The spectra of these bursts were sampled for 0.2 sec every 1.8 sec. One such burst, of 9-mm duration, with an intensity-time profile having a complex, quasi-periodic structure, is presented. A mechanism based on the repetitive production of monoenergetic electrons is qualitatively shown to explain the time structure of the X-ray burst