Experiment: Thermionic Diode (115 V, 50/60 Hz)

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Description
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Thematic focus:_..

• Record the characteristic for a thermionic diode at different cathode heater voltage
• Identify the space charge and saturation regions
• Confirm the Schottky-Langmuir law

Experiment description:_..

In a thermionic diode, free electrons carry a flow of current between the heated cathode and the anode when a positive voltage is applied between the cathode and anode. The current increases along with the voltage until a saturation point is reached. However, if the voltage is negative, the current is zero.
The relationship between the anode current I_A and the anode voltage U_A is investigated as the characteristic of the diode. The reverse-bias region, the region where current begins to flow, the space charge region, and the saturation region are identified.
The Schottky-Langmuir law is verified by the I_A-U_A-relation within the space charge region.