Problem 1.4 The pictures show the results of electron temperature and electron density measurements made with a double Langmuir probe in a self-field, gas-fed MPD thruster. Measurements with Langmuir probes can be considered reliable when the working fluid is a plasma. Verify this condition at the measurement points, considering that the electrodes represent perturbation for a plasma: a boundary layer around each electrode is formed, with a thickness of few Debye lengths (say ten as a conservative assumption). In the layer (called also sheath) quasi-neutrality condition is not longer satisfied and hence the fluid cannot rigorously be considered a plasma. 2.9 1.8 10 3.3 0.7 3.1 33 0.2 0.2 3.4 3.4 +0 02.6 032 3.2 5 3.50 3.5 74. 111 1000 o 162 n (100/m) . Te (V) 10 3.4 38 C .C Problem 1.4 The pictures show the results of electron temperature and electron density measurements made with a double Langmuir probe in a self-field, gas-fed MPD thruster. Measurements with Langmuir probes can be considered reliable when the working fluid is a plasma. Verify this condition at the measurement points, considering that the electrodes represent perturbation for a plasma: a boundary layer around each electrode is formed, with a thickness of few Debye lengths (say ten as a conservative assumption). In the layer (called also sheath) quasi-neutrality condition is not longer satisfied and hence the fluid cannot rigorously be considered a plasma. 2.9 1.8 10 3.3 0.7 3.1 33 0.2 0.2 3.4 3.4 +0 02.6 032 3.2 5 3.50 3.5 74. 111 1000 o 162 n (100/m) . Te (V) 10 3.4 38 C .C