A Langmuir probe is a scientific instrument used to measure the electrical properties of plasmas, which are ionized gases consisting of charged particles. It typically consists of a thin metal wire or rod that is inserted into the plasma. By applying a voltage to the probe, researchers can collect data on electron density, temperature, and other important parameters of the plasma. The probe operates by measuring the current that flows through it as a function of the applied voltage. This current-voltage relationship helps scientists understand the characteristics of the plasma, making the Langmuir probe a valuable tool in fields such as fusion research, space physics, and semiconductor manufacturing.