Optogalvanic study of a negative ion plasma in a hollow cathode discharge in oxygen

Amemiya, Hiroshi; Ogawa, Kazuhiko; Suzuki, Takanori; Endou, M.

doi:10.1088/0022-3727/26/12/014

Cited by 15 publications

(6 citation statements)

References 32 publications

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“…The current-voltage (I -V a ) characteristics of the discharge in O 2 showed that, except at low values of I , V a fell gradually with I (negative resistance). Such a negative resistance in the I -V a characteristics in O 2 had been seen previously (Amemiya et al 1993) in a tube with a larger radius.…”

Section: Results On the Tube Of 4 MM Diametersupporting

confidence: 75%

“…b is set to be about 0.2 mm by the lens, such that the waist of the beam is calculated from the formula given by the wave theory of optics (Kogelnik 1965). The probe voltage was set near the space potential by taking the probe characteristics shown in figure 6(a) later to have the maximum sensitivity (Amemiya et al 1993).…”

Section: Results On Optical Data In the 8 MM Diameter Tubementioning

confidence: 99%

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Characteristics of a hollow-cathode discharge containing negative ions

Amemiya¹,

Ogawa²

1997

J. Phys. D: Appl. Phys.

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Characteristics of the hollow-cathode discharge containing negative ions have been investigated focusing on a discharge in oxygen. Discharges with other gases which do not generate negative ions were measured for comparison. The electron energy distribution f(E) was measured by using the probe technique and the negative ion density by the laser photodetachment technique. Radial variations in the negative ion density, the discharge pattern and optical emissions were measured. The form of f(E) has a depletion in the low-energy part, suggesting that the effect of dissociative attachment occurs to generate negative ions.

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Section: Results On the Tube Of 4 MM Diametersupporting

confidence: 75%

Section: Results On Optical Data In the 8 MM Diameter Tubementioning

confidence: 99%

Characteristics of a hollow-cathode discharge containing negative ions

Amemiya¹,

Ogawa²

1997

J. Phys. D: Appl. Phys.

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“…In a hollow cathode plasma, electrons are confined by reflection in the cathode sheath region and ionization is promoted, resulting in the generation of a high-density, constant-current plasma. 85,86 In our design of the hollow cathode arrangement, the sample to be oxidized is biased to the same voltage as the cathode and placed inside the hollow cathode ( Fig. 1).…”

Section: Discussionmentioning

confidence: 99%

Glow discharge plasma treatment for surface cleaning and modification of metallic biomaterials

Aronsson

Lausmaa

Kasemo

1997

J. Biomed. Mater. Res.

107

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Glow discharge plasma treatment is a frequently used method for cleaning, preparation, and modification of biomaterial and implant surfaces. The merits of such treatments are, however, strongly dependent on the process parameters. In the present work the possibilities, limitations, and risks of plasma treatment for surface preparation of metallic materials are investigated experimentally using titanium as a model system, and also discussed in more general terms. Samples were treated by different low-pressure direct current plasmas and analyzed using Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS), atomic force microscopy, scanning electron microscopy, and light microscopy. The plasma system is a home-built, ultra-high vacuum-compatible system that allows sample introduction via a load-lock, and precise control of pressure, gas composition and flow rate, etc. This system allows uniform treatment of cylindrical and screw-shaped samples. With appropriate plasma parameters, argon plasma remove all chemical traces from former treatments (adsorbed contaminants and other impurities, and native oxide layers), in effect producing cleaner and more well-controlled surfaces than with conventional preparation methods. Removal (sputtering) rates up to 30 nm/min are possible. However, when inappropriate plasma parameters are used, the result may be increased contamination and formation of unintentional or undesired surface layers (e.g., carbides and nitrides). Plasma-cleaned surfaces provide a clean and reproducible starting condition for further plasma treatments to form well-controlled surface layers. Oxidation in pure O 2 (thermally or in oxygen plasmas) results in uniform and stoichiometric TiO 2 surface oxide layers of reproducible composition and thicknesses in the range 0.5-150 nm, as revealed by AES and XPS analyses. Titanium nitride layers were prepared by using N 2 plasmas. While mild plasma treatments leave the surface microstructure unaffected, heavy plasma treatment can give rise to dramatic morphologic changes.Comparison of these results with corresponding analyses of commercial implants and electropolished and/or anodically oxidized samples shows that the plasma treatment offers superior control of the surface status. However, it is also shown that improper control of the plasma process can produce unwanted and irreproducible results.

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“…Since lasers can make control of the material in the submicron range possible by the property of high collimation, they are also used for the processing of electrical devices [1,2] and measurements of plasma. One established measurement technique for discharges in electronegative gases is photodetachment optogalvanic spectroscopy [3,4] which utilizes the reaction of electron detachment from a negative ion by a photon with a certain energy. A theoretical approach using a simulation of the relaxation process after photodetachment has also been performed [5].…”

Section: Introductionmentioning

confidence: 99%

The effect of laser-induced photodetachment in rf discharges

Shibata

Nakano

Makabe

1997

J. Phys. D: Appl. Phys.

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Using the relaxation continuum (RCT) model, numerical analysis of oxygen rf glow discharges between parallel plates with laser irradiation parallel to the electrode was performed. The oxygen discharge sustained by a sinusoidal wave voltage at a frequency of 13.56 MHz, amplitude of 200-230 V and pressure of 0.5-1.0 Torr is irradiated by the laser with a power of 300 W, width of 2 mm and wavelength of 0.53 µm. Under these conditions, laser-induced photodetachment occurs with a large enough rate to affect the discharge structure significantly. When the plasma is irradiated continuously, the number density of ions in the incident region decreases by about 30%. The electron number density and the flux in the discharge when the pulsed laser is turned on and off every ten rf cycles, show prominent temporal variation with the variation of the electric field. Electron cooling is enhanced during the laser irradiation.

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Optogalvanic study of a negative ion plasma in a hollow cathode discharge in oxygen

Cited by 15 publications

References 32 publications

Characteristics of a hollow-cathode discharge containing negative ions

Characteristics of a hollow-cathode discharge containing negative ions

Glow discharge plasma treatment for surface cleaning and modification of metallic biomaterials

The effect of laser-induced photodetachment in rf discharges

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