Characteristics of a hollow-cathode discharge containing negative ions

Amemiya, Hiroshi; Ogawa, Kazuhiko

doi:10.1088/0022-3727/30/5/021

Cited by 15 publications

(6 citation statements)

References 25 publications

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“…The Onumber density show a gradual increase as the discharge power is increased even above 12 W of power for all discharge pressures 150, 225, 300 and 375 mTorr. Similar dependence on power was also reported by [26][27][28][29].…”

Section: Negative Ion Number Density and Electronegativitysupporting

confidence: 88%

Laser induced photo-detachment of O₂ in DC discharge

Legorreta¹,

Patiño²,

Yousif³

2018

Plasma Sci. Technol.

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Determination of the negative ion number density of O 2 and Oin a DC discharge of oxygen plasma was made employing Langmuir probe in conjunction with eclipse laser photodetachment technique. The temporal evolution of the extra electrons resulting from the photodetachment of O 2 and Owere used to evaluate the negative ion number density. The ratio of O 2 number density to Ovaried from 0.03 to 0.22. Number density of both O 2 and Oincreased with increasing power and decreased as the pressure was increased. Electron number density was evaluated from the electron energy distribution function (EEDF) using the I-V recorded characteristic curves. Electron temperature between 2 and 2.7 eV were obtained. Influence of the a O 2 1 g D ( ) metastable state is discussed.

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Section: Negative Ion Number Density and Electronegativitysupporting

confidence: 88%

Laser induced photo-detachment of O₂ in DC discharge

Legorreta¹,

Patiño²,

Yousif³

2018

Plasma Sci. Technol.

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“…In a hollow cathode gas discharge [22] the density of O − 2 is comparable with the density of O − at low gas pressure (∼40 Pa) and low discharge current (∼10 mA). With the increase of the discharge current and pressure, the density of O − becomes higher than that of O − 2 .…”

Section: Langmuir Probe Experimental Results and Discussionmentioning

confidence: 99%

“…Below we will discuss the question of the type of negative ions present in the oxygen discharge [22]. The main generation mechanism for oxygen negative ions is dissociative attachment [23] O…”

Section: Langmuir Probe Experimental Results and Discussionmentioning

confidence: 99%

Second derivative Langmuir probe measurements of negative oxygen ion concentration taking into account the plasma depletion caused by negative ion sink on the probe surface

Popov

Gateva

2001

Plasma Sources Sci. Technol.

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Taking into account the effect of plasma depletion caused by negative ion sink on the probe surface, a refinement of the second derivative Langmuir probe method for the determination of negative ion concentration is proposed. The concentration of the negative ions is obtained by comparing the experimental data with the calculated second derivative probe current signals at a finite ratio of probe radius and negative ion free path.In a specially constructed dc discharge tube with coaxial electrodes, second derivative Langmuir probe measurements are performed in pure oxygen (gas pressure 30-110 Pa, discharge current 40-80 mA). The negative ion concentrations at different discharge current and gas pressure values are obtained. The factors affecting the uncertainties of the results are discussed.The values of the negative oxygen ion concentration obtained by laser photodetachment measurement are in good agreement with those obtained by the second derivative Langmuir probe measurements.The proposed processing of the experimental data extends the applicability of the second derivative Langmuir probe method for accurate measurements of the negative ion concentration at higher gas pressures and finite probe radii.

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“…Moreover, the reduction of oxide phases and organic compound vaporization caused by both the ion bombardment and the presence of hydrogen reactive species tends to increase the amount of oxygen atoms of the plasma at the beginning of the heating process. Oxygen being a strong former of negative ions (Amemiya and Ogawa 1997), and hence an electron receptor, it tends to decrease the electron current density and the plasma ionization, causing an effect of temperature decrease (Maliska et al 1997). This partially explains why the sample heating efficiency dropped when the lowest flow was used.…”

Section: Evolution Of the Electrical Discharge Parameters In The Sint...mentioning

confidence: 99%

Influence of the gas mixture flow on the processing parameters of hollow cathode discharge iron sintering

Brunatto¹,

Muzart²

2007

J. Phys. D: Appl. Phys.

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A study was made to verify the influence of the gas mixture flow on the iron sintering process with simultaneous surface enrichment of alloying elements by hollow cathode discharge. In this process, two independent cathodes formed an annular discharge: (1) a pressed cylindrical sample of iron powder, acting as the central cathode, was placed concentrically inside an external (hollow) cathode; (2) the external cathode, machined from a AISI 310 steel bar, acted both to confine the geometry of the plasma and as a source of alloying elements (Cr and Ni). The sintering was carried out at 1423 K, for a period of 7.2 × 103 s, under a gas mixture of 80% Ar + 20% H2 and a pressure of 399 Pa, at flow rates of 2 × 10−6, 5 × 10−6, and 8 × 10−6 m3 s−1, with an inter-cathode radial space of 5.8 mm. The discharge was generated using a pulsed voltage power source with a 200 µs period. The gas mixture flow plays an important role both in the cleanliness of the sintering atmosphere (reflected in the electric power utilized to maintain the sample's temperature) and in the amount of metallic atoms deposited on the sample's surface (as a result of the sputtering and the oxidation/reduction process on the cathode surfaces).

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Characteristics of a hollow-cathode discharge containing negative ions

Cited by 15 publications

References 25 publications

Laser induced photo-detachment of O₂ in DC discharge

Laser induced photo-detachment of O₂ in DC discharge

Second derivative Langmuir probe measurements of negative oxygen ion concentration taking into account the plasma depletion caused by negative ion sink on the probe surface

Influence of the gas mixture flow on the processing parameters of hollow cathode discharge iron sintering

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Characteristics of a hollow-cathode discharge containing negative ions

Cited by 15 publications

References 25 publications

Laser induced photo-detachment of O2 in DC discharge

Laser induced photo-detachment of O2 in DC discharge

Second derivative Langmuir probe measurements of negative oxygen ion concentration taking into account the plasma depletion caused by negative ion sink on the probe surface

Influence of the gas mixture flow on the processing parameters of hollow cathode discharge iron sintering

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Laser induced photo-detachment of O₂ in DC discharge

Laser induced photo-detachment of O₂ in DC discharge