You searched for: “thermoammeter
electrothermal ammeter, thermoammeter, thermocouple ammeter
An ammeter (device for measuring an electric current in amperes) that is actuated by the voltage generated in a thermocouple through which it receives the current to be measured.

It is used primarily for measuring radio-frequency currents.

thermoammeter
In engineering, an ammeter that employs a thermocouple to measure radio-frequency current.