Magneto-acoustic ceramics for parametric sound wave phase conjugators

The paper reflects the recent experimental results on the elaboration and s tudy of active materials for magneto-acoustic phase conjugators (MAPCs). Th e results of complex measurements of MAPC parameters are demonstrated on ty pical samples of NiFe2O4 magnetostrictive ceramics. The mechanism of strong dispersion of gain increments and output power of MAPCs is studied and exp lained by dispersion of critical values of the parametric modulation depth of sound velocity. A maximum output power 240 W at frequency 5 MHz is obtai ned for active element MAPC with critical current I-c = 9 A and electrical Q-factor equal to 80. (C) 2000 Elsevier Science B.V. All rights reserved.