MEASUREMENTS IN GAS DISCHARGES VII. DISCUSSION OF EXPERIMENTAL RESULTS njo/yi3a-oec=(1)(1.28/1.12)(1.1)=1.24 A serious question arises regarding whether or not temperature determinations have a basis in reality. The We assume that jo /jo, ip/ip, on the basis of the concept of an electron temperature is permissible only charge neutrality of the plasma. eVe=1.1 since if the electrons have a Maxwellian distribution. The V0.01andφ=11.6(see 1). This value of a method here described samples only a small fraction of agrees reasonably well with the other two the electrons present, the electrons collected by the Case 2. As another illustration of the use of Eq. probes being only those which have velocities sufficient (8)and(13), for a case wherein the system is more to overcome the ever present retarding fields at the dissymmetrical than in the previous case, we consider probes. The range of electrons sampled can be extended set of data taken from a simple diode filled with 250u by making tubes with probes of dissimilar of argon. The probes in this tube were equal in area and It is of interest to determine what fraction of the identical in size with those of the preceding case. electrons are sampled in one of the cases studied above The ar current was 200 ma and all data were col- Consider Case 1, whose results are presented in Figs. 11 lected at 100 usec. after cessation of the discharge. The and 12. An approximate expression for floating potential voltage characteristic is plotted in Fig. 13. V,(with respect to space al) is given by The values of the various factors are found from Fig V,=-(kTe/2e)In(Tem/TpM) and ar hen for the case of Figs. 11 and 12, T=950.K.F ∑ip=10.7a,[Eina=0=9.95a, M we use the mass of the argon atom. We assume that R=36.700ohms.G=0.401 is the gas temperature ut350°Kfor Then this case. Then from Eq.(17)V,=0.50 volts. Since ipraipy the probes must be close to V, when id=0 T=11,600(0.240)(995)(0.0367)=1015°K Then from the Boltzmann relation, the ratio of electron The log plot, show Fig. 14 yields a concurrent value of 1055K. It is interesting to note that the values of o again check, their values being(a)1.55 from log plot, (6)1.50 from G, (c)1.51 from Eq. (7) BEH4437-24 (10o4S AFTER DISCHARGE (DDIFFERENTIAL PROBE OLTAGE VOLTS T=目6ooo·1s5然 DIFFERENTIA L, B. Loeb, Fundamental Processes Gases ohn Wiley and Sons, Inc, New York, 1939), first FIG. 13. Double probe current-voltage characteristic p.242