A  SWEPT MAGNETIC  FIELD TWO-LEVEL MASER AMPLIFIER

 

swept mag.field 2-level maser.jpg (49653 bytes)A magnetic field was swept through the value required to invert electron spins by adiabatic fast passage in a crystal sample situated in a microwave cavity dual resonant at X Band and K Band frequencies. The magnetic field was further increased to obtain magnetic resonance conditions at the K Band frequency producing amplification of a weak pulse at this frequency by stimulating emission from the electron spin population previously inverted at the X Band frequency.

The maximum frequency at which the amplification was obtained depended on the the maximum value attainable for the magnetic field and the electron spin lattice relaxation time which is an energy exchange parameter in the crystal and determines the time for which the spin population remains inverted.