SPATIAL OBSERVATIONS BY THE CUTLASS COHERENT SCATTER RADAR OF IONOSPHERIC MODIFICATION BY HIGH-POWER RADIO-WAVES

Results are presented from an experimental campaign in April 1996, in which the new CUTLASS (Co-operative UK twin-located Auroral Sounding S ystem) coherent scatter radar was employed to observe artificial field aligned irregularities (FAI) generated by the EISCAT (European Incohe rent SCATter) heating facility at Tromso, Norway. The distribution of backscatter intensity from within the heated region has been investiga ted both in azimuth and range with the Finland component of CUTLASS, a nd the first observations of artificial irregularities by the Iceland radar are also presented. The heated region has been measured to exten d over a horizontal distance of 170 +/- 50 km, which by comparison wit h a model of the healer beam pattern corresponds to a threshold electr ic field for FAT of between 0.1 and 0.01 V/m. Differences between fiel d-aligned and vertical propagation heating are also presented.