Analysys of the concept of a superconducing bolometer with rf readout

The concept of a superconducting transition-edge bolometer with rf readout, which was proposed in a number of earlier publications, is analyzed. It is shown that such a device cannot in fact operate at the edge of the superconducting transition, and nonequilibrium effects in the superconductor play the major role in its response to the electromagnetic action. A mathematical model is developed, which explains qualitatively the experimental results reported earlier and indicating an unstable response to the action of a readout (pump) signal. The possibility of obtaining a stable response with an optimal choice of parameters of the device is also demonstrated.