Incoherent scattering by free electrons as a technique for studying the ionosphere and exosphere: some observations and theoretical considerations

In co herent scattering b y t h e fr ee electrons of t he ionosph ere has been suggested a~ a techniqu e for meas urin g t he electron d ensity p~'ofil e both below ~nd above t ht:; F r e~l on maxitnum. This p a per r eports observattons whlCh co nfirm t he eXIstence of t h e In co her ent scatter a nd sho w t hat its in tensity is essent iall y t he predictcd value. The obser ved Doppler broadenin rr is co ns iderably s ma ller t han origin all y predicted. In t he second part Of . t he paper, a n ~xp l a n at i o n fo r t he r educed Doppler broadenin g is offered .. The scatter .IS explall1ed as a ri sin g fr om statistical flu ctuations of electron den Stty, t h e dlstl'lbu ttOll of which IS can tJOlled by t he p osi t ive ions.