Study on suppression of gyro-BWO by distributed wall losses

In this paper, the effect of distributed wall losses on the starting length and starting frequency of a TE₂₁ mode gyro-BWO is investigated for different operating magnetic fields by using a linear theory. Numerical results show that the gyro-BWO can be suppressed efficiently when the cold attenuation resulted from the wall losses is approximately equal to the linear growth rate of the corresponding gyro-BWO without wall losses. The gyro-BWO is also easier to be suppressed by wall losses if its operating point is closer to the cutoff frequency of the operating mode.