MAKE YOUR OWN LANGMUIR PROBE I-V CHARACTERISTIC

• A Maple 10 routine is provided at the link below that will enable you to create your own Langmuir Probe I-V characteristic. You will first need to calculate the electron and ion saturation currents to the probe.

• Ieo is the electron saturation current and Ipo is the positive ion saturation current.
  
  

where n_e = n_i is the plasma density in m^-3, e = 1.6x10^-19 C, A_probe is the collecting area of the probe in m² , kTe is the electron temperature in J = Te [ev] x 1.6x10^-19, m_e is the electron mass = 9.1x10^-31 kg, and m_i is the ion mass
= A m_proton, where m_proton = 1.67x10^-27 kg, and A is the atomic weight of the positive ion.

• The other parameter that must be specified to produce a Langmuir characteristic is the the plasma space potential Vs in volts.
• The MAPLE program will plot the characteristic (black curve)  as well as the individual electron (blue curve) and ion currents (red curve)
• MAPLE Worksheet  (you will need CLASSIC Maple 10 to run this)