Spectral observations of high-frequency radio emission on electron beam injection in the ionosphere in the ''Zarnitsa-2'' experiment

Results of observations of high-frequency radio emission in the range from 27 to 51MHZ arising during electron beam injection in ionosphere (Zarnitza-2 experiment) are given. The experiment was carried out by means of a specially developed radiospectrograph. Principal regularities of radioemission dynamics may be attributed to ignition of plasma-beam discharge in near rocked area. Injection cycle of electron beam consisted of two pulses of different duration (0.8 and 0.08 s) separated with 0.8 s spacing. In 130 seconds of flight (altitude h approximately 136 km) transition to the second injection regime was performed where injection current I2 approximately 0.45 A and beam electron energy E2 approximately 7 keV (I1 approximately 0.28 A, E1 approximately 9.2 keV). Beginning from 236th second till 267th second of flight the injection of quasineutral plasma with 10 A ion current was simultaneously carried out with beam injection. A new property of radioemission spectrum established in the given experiment is the presence of equidistant maxima of radiation intensity during the existence of a drift component. Radiation on gyrofrequency harmonics clearly stands out only in some range of altitudes depending on the mode of electron accelerator