Abstruct-Arcing in electrical contacts of telephone switching relays and the subsequent erosion have been the subject of a great deal of work. Nevertheless the problem depends on many parameters (the electrical circuit, environment, relay type, etc.) and knowledge is incomplete. The AgCu 90/10 contact used in the French CP 400 telephone switching system and, more particularly, the consequence of arcing in the current range l-500 mA are the subject of this paper. Two methods are used to study arcing: measurement of the arc duration and analysis of the emission spectrum from the arc. The first results show that these two arc characterizations are related to erosion and that the variations with current are similar. SOUARE PULSE MERCURY RESISTIVE LOAD GENERATOR REED RELAY Fig. 1. The resistive circuit and the driving circuit of the contact.
This paper is a theoretical and experimental study of the propagation of longitudinal electron waves in a collisionless, homogeneuos, isotropic plasma, composed of Maxwellian and supra-thermal electrons. Assuming the supra-thermal electrons are mono-energetic, the velocity distribution function is chosen as a Maxwellian plus water-bag distribution; then, using the method of residues (inverse Fourier–Laplace transform), the behaviour of the electric field is found to be in good agreement with experimental results obtained for a plasma of Maxwellian and quasi-mono-energetic electrons. The plasma parameters can be deduced from the theoretical dispersion curves matching the experimental points; they are found to agree well with those measured by electrostatic probes. Experimental values of damping and excitation coefficients are also compared with the theoretical. The results suggest that a longitudinal electron wave propagation experiment may be used as a powerful diagnostic tool to examine non-Maxwellian plasmas.
This paper is a theoretical and experimental study of the propagation of longitudinal electron waves in a collisionless, homogeneous, isotropic plasma, whose velocity distribution function is a truncated Maxwellian. Using the method of residues and numerical calculation, the behaviour of the electric field is found to be in good agreement with experimental results. The plasma parameters can be deduced from the theoretical dispersion curves matching the experimental points; they are found to agree well with those measured by electrostatic probes. In conclusion, a pragmatic approach to the resolution of the plasma inverse problem is discussed.
Reçu le 16 avril 1971, révisé le 15 juillet 1971)Résumé. -Nous décrivons un montage expérimental simple permettant la détection des ondes électrostatiques longitudinales dans un plasma chaud, sans collision et en l'absence de champ magnétique. Ces ondes sont excitées à des fréquences 03C9p 03C9 1,6 03C9p par un condensateur grillagé et détectées par un brin.Les enregistrements obtenus permettent d'une part de déterminer la courbe de dispersion et d'autre part, de connaître la variation de l'atténuation en fonction de la fréquence. Les valeurs de fréquence plasma (à 4 %), de longueur de Debye (à 6 %) et de température électronique (à 20 %) sont calculées à partir des données expérimentales et de la courbe théorique de dispersion D (03C9, k) = 0. La validité des résultats obtenus est discutée. Ils sont ensuite comparés à ceux déduits des mesures par sondes de Langmuir. L'accord entre ces résultats est satisfaisant. Enfin une étude de diagnostic de plasma a également été faite par mesure directe de l'impédance du condensateur.Abstract. -We report here an experimental apparatus used to detect electrostatic longitudinal waves in an isotropic and collisionless hot electron plasma with no magnetic field applied. These waves are excited, at frequencies 03C9p 03C9 1,6 03C9p, using a plane grid capacitor, and detected by a wire probe. The experimental output records of spatial variation of the electric field allow us to determine Landau's dispersion curve and to measure damping as a function of rf frequency. Plasma frequency 03C9p (at 4 %), Debye lenth 03BBD (at 6 %) and electronic temperature Te (at 20 %) are calculated by fitting experimental points with the fondamental curve of Landau's dispersion relation. The validity of the results obtained is discussed. They are hence compared with those obtained by Langmuir probe. Good agreement is found between these experimental results. Plasma diagnostic has also been performed by measurement of grid capacitor impedance. REVUE DE PHYSIQUE APPLIQUÉE TOME 6, DÉCEMBRE 1971, PAGE
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