The ablation systems, ablation probes, and corresponding methods according to the present disclosure reduce or eliminate energy radiating from an ablation probe into the environment. Some ablation probes include a retractable sheath that shields at least the radiating portion of the ablation probe. The retractable sheath and/or the ablation probe may include conduits through which a fluid may flow to shield the radiating portion and to drive the retractable sheath to an extended state. Other ablation probes include apertures defined in the probe walls through which the fluid can flow to expand a balloon surrounding the radiating portion. Yet other ablation probes include a thermal indicator to indicate the temperature of the ablation probe to a user. The ablation systems include fluid circuits and associated mechanical controls for varying the contents and/or flow rate of the fluid provided to the radiating portion of the ablation probe.