The problem of creation and the results of experimental investigation of su
perdense subrelativistic electrons microbeams with current density 10(10) A
/cm(2) less than or equal to j less than or equal to 10(14)A/cm(2), duratio
n Deltat = 1-10 ns and energy about 0.01-1 MeV are discussed. The interacti
on of these micro-beams with condensed target and ions beams are investigat
ed. The problems of isomers excitation and active medium for both X-ray las
er and gamma-laser creation by use of super-dense electrons micro-beams are
also studied. (C) 2000 Elsevier Science B.V. All rights reserved.