Practical formula for Mach number probe diagnostics in weakly magnetized plasmas

A practical formula for Mach number probe diagnostics in unmagnetized and weakly magnetized plasmas is proposed. The unmagnetized theoretical models are modified so as to make them applicable to the different shapes of Mach number probes by including the broadening of the collection angle and are extended to the weakly magnetized case. The calculated Mach numbers based on the modified expression show good agreement with each other regardless of the probe shape geometry, and are revealed to be consistent with the spectroscopic results. Applicability of the modified expression to the supersonic flow when using the Hutchinson’s model and in the existence of the multidirectional flows is numerically examined.