On the Measurement of Electron Temperature of a Pulsed Washer Gun Argon Plasma by Triple Langmuir Probe Diagnostic Technique

Pulsed argon plasma of the order of 140 μs duration is produced by a washer gun under low pressure conditions. The low pressure plasmas have many industrial applications such as etching, coating for corrosion, diamond and diamond like carbon coating, super hard nano composite coating, synthesis of novel nanostructure etc. Measurement of fundamental parameters like electron temperature of such pulsed plasmas is always challenging and should be determined properly. Triple probe diagnostic is the most advanced, convenient and inexpensive method for measurement of plasma temperature which does not require any voltage, frequency sweeps, or switching like single or double probe diagnostic methods. In this work we have introduced a triple Langmuir probe to measure the electron temperature of pulsed washer gun argon plasma. A triple probe of pure tungsten material with appropriate circuit is designed and fabricated in our laboratory. The triple probe signal is recorded by a digital storage oscilloscope at the distance of 0.05 m from the gun mouth. It is observed that the electron temperature remains constant at ⁓ 1.2 eV within the small variation of base pressure ranging from 0.2 to 1.0 mbar. This method is applicable to both stationary and transient plasma which can be used for various industrial as well as research purpose.