Inflection-point method of interpreting emissive probe characteristics

Smith, J. R.; Hershkowitz, N.; Coakley, Peter

doi:10.1063/1.1135789

Cited by 274 publications

(153 citation statements)

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“…[26][27][28][29][30][31][32][33][34][35] As the name suggests, an emissive probe is sufficiently hot to emit electrons via the thermionic emission mechanism, where the current density is approximately described by the Richardson-Dushman equation (cf. e.g.…”

Section: Emissive Probe Techniquesmentioning

confidence: 99%

Plasma potential mapping of high power impulse magnetron sputtering discharges

Rauch

Mendelsberg

Sanders

et al. 2012

Journal of Applied Physics

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Pulsed emissive probe techniques have been used to determine the plasma potential distribution of high power impulse magnetron sputtering (HiPIMS) discharges. An unbalanced magnetron with a niobium target in argon was investigated for pulse length of 100 µs at a pulse repetition rate of 100 Hz, giving a peak current of 170 A. The probe data were taken with a time resolution of 20 ns and a spatial resolution of 1 mm. It is shown that the local plasma potential varies greatly in space and time. The lowest potential was found over the target's racetrack, gradually reaching anode potential (ground) several centimeters away from the target. The magnetic pre-sheath exhibits a funnel-shaped plasma potential resulting in an electric field which accelerates ions toward the racetrack. In certain regions and times, the potential exhibits weak local maxima which allow for ion acceleration to the substrate. Knowledge of the local E and static B fields lets us derive the electrons' E × B drift velocity, which is about 10 5 m/s and shows structures in space and time.

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Section: Emissive Probe Techniquesmentioning

confidence: 99%

Plasma potential mapping of high power impulse magnetron sputtering discharges

Rauch

Mendelsberg

Sanders

et al. 2012

Journal of Applied Physics

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“…Operation of emissive probes in the limit of zero emission 10 is a diagnostic technique we developed to investigate weak electric fields and to distinguish between bulk and beam species. They provide a sensitive and relatively nonperturbing diagnostic of plasma potential with a resolution approaching 0.1 V and a spatial resolution of 0.1 cm.…”

Section: A Emissive Probesmentioning

confidence: 99%

Sheaths: More complicated than you think

Hershkowitz¹

2005

Physics of Plasmas

184

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Sheaths in low temperature collisionless and weakly collisional plasmas are often viewed as simple examples of nonlinear physics. How well do we understand them? Closer examination indicates that they are far from simple. Moreover, many predicted sheath properties have not been experimentally verified and even the appropriate "Bohm velocity" for often encountered two-ion species plasma is unknown. In addition, a variety of sheathlike structures, e.g., double layers, can exist, and many two-and three-dimensional sheath effects have not been considered. Experimental studies of sheaths and presheaths in weakly collisional plasmas are described. A key diagnostic is emissive probes operated in the "limit of zero emission." Emissive probes provide a sensitive diagnostic of plasma potential with a resolution approaching 0.1 V and a spatial resolution of 0.1 cm. Combined with planar Langmuir probes and laser-induced fluorescence, they have been used to investigate a wide variety of sheath, presheath, and sheathlike structures. Our experiments have provided some answers but have also raised more questions.

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“…As part of these experiments we made an effort to more directly determine the plasma potential using an emissive probe technique [30][31][32][33]. Thoriated tungsten filaments were located on 2 sides of a poloidal limiter on field lines that directly connect to two of the antennas labeled 'D' and 'J4' in Figure 1.…”

Section: Introductionmentioning

confidence: 99%