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Application of electrostatic Langmuir probe to atmospheric arc plasmas producing nanostructures
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10.1063/1.3614538
/content/aip/journal/pop/18/7/10.1063/1.3614538
http://aip.metastore.ingenta.com/content/aip/journal/pop/18/7/10.1063/1.3614538
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Schematic view of experimental setup and coordinate system used in this work.

Image of FIG. 2.
FIG. 2.

(Color online) Schematic view of electrostatic probes used in this work.

Image of FIG. 3.
FIG. 3.

(Color online) V-I characteristics of single probe at 0.1 Torr (h = 7 mm, I arc  = 60 A, t = 100 ms after arc ignition, circular probe: r = 25 mm, z = 25 mm, probe diameter = 2.6 mm). The ratio |I p /I n | is close to that predicted by conventional collisionless probe theory. (a) entire V-I curve, (b) magnified in vicinity of floating potential.

Image of FIG. 4.
FIG. 4.

(Color online) Saturation currents and their ratio as function of background He pressure (h = 7 mm, I arc  = 55 A, t = 50 ms after arc ignition, surrounding probe: r = 25 mm). Value at p = 0.1 Torr on Fig. 4(b) was obtained using 2.6 mm diameter circular probe at conditions presented in Fig. 3.

Image of FIG. 5.
FIG. 5.

(Color online) Temporal evolutions of U arc and I arc and typical images of 500 Torr He arc in initial CS and later AA modes (h = 7 mm, I arc  = 55 A).

Image of FIG. 6.
FIG. 6.

(Color online) Characterization of the arc in CS mode. (a), (b) Typical arc image and corresponding V-I characteristic of probe taken at 200 ms after ignition (p = 500 Torr, h = 5 mm, I arc  = 40 A, t = 200 ms after arc ignition, surrounding probe: r = 14 mm). (c) Probe V-I characteristic and arc image with unstable electron saturation part (p = 500 Torr, h = 7 mm, I arc  = 50 A, t = 50 ms after arc ignition, surrounding probe: r = 25 mm). (d), (e) Temporal evolutions of I arc and U arc and current pulse detected by the probe (biased about −50 V with respect to the grounded cathode) at the moment of shutter opening (p = 500 Torr, h = 3 mm, I arc  = 60 A, t = 1.2 s after arc ignition, shielded probe: z = 2 mm, r = 8 mm, bias −50 V), and (f) corresponding image of the collector surface after exposure to plasma flow (total charge to the probe—about +8 mC) under the SEM.

Image of FIG. 7.
FIG. 7.

(Color online) Characterization of the arc in AA mode. (a), (b) Typical arc image and corresponding V-I characteristic of probe taken at 500 ms after ignition (p = 500 Torr, h = 3 mm, I arc  = 55 A, t = 500 ms after arc ignition, surrounding probe: r = 28 mm). (c), (d) Temporal evolutions of I arc and U arc and current pulse detected by the probe (biased about +50 V with respect to the grounded cathode) at the moment of shutter opening (p = 500 Torr, h = 3 mm, I arc  = 70 A, t = 0.9 s after arc ignition, shielded probe: z = 2 mm, r = 8 mm, bias +50 V]. (e)-(g) SEM images of the probe collector surface after its exposure to plasma flow for positive (e), (f), and negative (g) bias (p = 500 Torr, h = 3 mm, I arc  ∼ 70 A). The total charge transfers to the probes were −2.1 mC and +7.8 mC for +50 V and −50 V probe bias, respectively. The images (e), (h) were taken on the periphery of deposited area to present rarified deposit structure, while the image (f) at the center of deposited area (+50 V probe bias).

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/content/aip/journal/pop/18/7/10.1063/1.3614538
2011-07-27
2014-04-24
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Application of electrostatic Langmuir probe to atmospheric arc plasmas producing nanostructures
http://aip.metastore.ingenta.com/content/aip/journal/pop/18/7/10.1063/1.3614538
10.1063/1.3614538
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