Langmuir probe diagnostic on magnetic plasma devices often encounters more challenges in data processing than in non-magnetized plasmas, the latest itself being far from simple. In this paper, a theory of particle collection by a probe at the plasma potential in collisionless weakly ionized plasmas is constructed, accounting for velocities distributed according to the Maxwell equation and different mechanisms of particle collection depending on their speed. Experimental validation of the presented theory has been done with 2 cylindrical probes (rpr = 75 μm and Lpr = 1 cm and rpr = 0.5 mm and Lpr = 1 cm) parallel to B→ on a linear plasma device Aline, with magnetic fields of 0.0024–0.1 T and plasma densities of 1015–1017 m−3 in helium. Cylindrical probe measurements are compared to data from a planar probe perpendicular to the magnetic field, and the results for electron density, temperature, and plasma potential are presented. The introduced theory is initially constructed for a cylindrical probe but is applicable to various probe sizes, shapes, and orientations. Alongside the main subject, a number of associated issues are addressed with different details: a probe design issue relative to the magnetized environment, the “intersection” method of plasma potential evaluation, and the robustness of the conventional “1st derivative” method, a current bump near the plasma potential, lower limit for electron temperature estimation, and self-consistent calculation of electron temperature and density.

10We report in this work the investigation of the transport behavior of Ti neutral atoms 11 sputtered in reactive high power impulse magnetron sputtering (R-HiPIMS) device 12 used for TiN coating deposition. The time resolved tunable diode laser induced 13 fluorescence (TR-TDLIF), previously developed to study the transport of tungsten 14 atoms, was improved to measure Ti neutral atoms velocity distribution functions. We 15 find that the TR-TDLIF signal has to be fitted using three Gaussian distributions, 16 corresponding to the energetic (EN), thermalized (TH) and quasi-thermalized (QTH: 17 TH atoms with non-zero mean velocity) atoms populations. Then, the ability to 18 distinguish populations of atoms and to determine their corresponding deposited flux 19 and energy may be of great interest to control film properties as desired for targeted 20 applications. From the fitting, the vapor transport parameters (flux and energy) are 21 calculated and studied as function of distance from the target, pressure and percentage 22 of nitrogen in Ar/N2 gas mixture. The study focuses on the effect of added nitrogen on 23 the transport of sputtered atoms. 24 Keywords: time resolved tunable diode laser induced fluorescence, reactive 25 magnetron sputtering, high power impulse magnetron sputtering (HiPIMS), atoms 26 velocity distribution function, transport of sputtered atoms, titanium, nitrogen 27 I. Introduction 28 Since the 1970s, magnetron sputtering (MS) process has been developed for the growth of 29 thin films by physical vapor deposition (PVD) [1]. The developments of conventional reactive 30 direct current (R-dcMS) and radiofrequency (R-rfMS) magnetron sputtering methods allow 31 the deposition of a wide range of thin films of materials such as metals, oxides, nitrides, 32 ceramics, etc. [2]. Consequently, MS is a widely used deposition technology in many 33 industrial applications.34 2 In conventional magnetron sputtering discharges, sputtered species are mainly emitted by 35 the cathode as neutral particles and ions of the sputtered material do not contribute 36 significantly to the deposition process. Ionized Physical Vapor Deposition (IPVD) reactors 37have then been developed since the 1990s to improve the quality of deposited films in terms 38 of mechanical properties (higher density, reduced porosity, better resistance to corrosion) and 39 of conformity for deposition on complex substrate geometry [3][4][5][6][7][8]. The main goal of IPVD is 40 to ionize a fraction of neutral species sputtered from the magnetron target in order to transfer 41 potential energy to ions, and to collimate and control the obtained ion particle fluxes by 42 applying a negative bias voltage to the substrate. IPVD reactors consist of a magnetron 43 discharge assisted by an additional plasma source, located in the area between the substrate 44 and the magnetron cathode, which ionizes the sputtered vapor flowing from the magnetron. 45Reactors using helicon [9], electron cyclotron resonance (ECR) coupled discharge [10] or 46 microw...

A quasi-static theoretical 1D model is developed to describe the sheath structure of a strongly emissive plasma-facing material and is subsequently applied to emissive probes' experimental data—which are usually supposed to be an efficient tool to directly measure plasma potential fluctuations. The model is derived following the space-charge limited emission current model developed in Takamura et al., [Contrib. Plasma Phys. 44(1–3), 126–137 (2004)], adding the contribution of secondary emission due to back-diffusion of plasma electrons at the emitting surface. From this theory, current-voltage characteristics of emissive probes are derived. A theoretical relation between the floating potential of an emissive probe and plasma parameters is obtained and a criterion is derived to determine the threshold between the thermoemission limited current regime and space-charge limited current regime. In the space-charge limited regime, a first order expansion is then applied to the quasi-static relation to study the effect of plasma fluctuations on emissive probe measurements. Both the mean values and the fluctuations of the floating potential of an emissive probe predicted by the model, as well as the potential value at which the transition between emission current regimes occurs, are compared to three sets of experimental data obtained in two different plasma devices.