A SWEPT MAGNETIC FIELD TWO-LEVEL MASER AMPLIFIER
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.