摘要:

The chemical erosion behavior of graphite materials preexposed in the Tokamak Fusion Test Reactor (TFTR) as the bumper limiter has been investigated spectroscopically under deuterium plasma bombardment in the Plasma Interactive Surface Component Experimental Station‐A (PISCES‐A) facility. The deuterium plasma bombardment conditions are ion bombarding energy of 300 eV, ion flux of 1.7×1018ions s−1 cm−2, plasma density of 1.4×1012cm−3, electron temperature of 11 eV, and neutral pressure of 3×10−4Torr. The chemical erosion yield is measured with calibrated CD‐band spectroscopy during the temperaure ramp from 100 to 900 °C at an average rate of ∼5 K/s. The materials used include virgin POCO graphite and graphite tile pieces from the redeposited and eroded areas of the bumper limiter of TFTR. The deuterocarbon formation rate from TFTR redeposits maximizes at ∼500 °C. Essentially the same chemical erosion behavior is observed for TFTR‐eroded and virgin graphites and is characterized by the compound peak, indicative of two erosion yield maxima at around 575 and 700 °C. The maximum erosion yield for TFTR redeposits is found to be ∼15% higher than those of TFTR‐eroded and virgin POCO graphites which is attributed to deuterium incorporated in the redeposited material. In addition, the removal behavior of redeposits by helium plasma bombardment has been studied. The removal rate is evaluated to be similar to the physical sputtering yield of carbon by helium. The surface morphology and surface composition have been analyzed with scanning electron microscopy and electron microprobe analysis along with these erosion yield measurements.

ISSN:0734-2101    

DOI:10.1116/1.576171

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

We describe the results of irradiating sodium trisilicate glass with 248‐nm excimer laser light at fluences from 1 to 5 J/cm2. A threshold for the onset of etching occurs at 3 J/cm2. We investigate the changes in surface topography as a function of laser fluence. We also identify the ionic and neutral species contained in the emission plume. A clear correlation is observed between the etching threshold and (i) onset of emission of fast excited neutrals, as well as (ii) the appearance of atomic Na D resonance radiation. The high velocities (10–15 km/s) of the excited neutrals and ions (H+, Na+, and Si+) are attributed to laser/plume interactions. The character and origin of lower velocity neutral species (atomic O, Si and molecular NaO) are presented. The possible role of surface fracture in the onset of etching is also discussed.

ISSN:0734-2101    

DOI:10.1116/1.576172

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

A new type of plasma reactor for the plasma‐assisted chemical vapor deposition (PACVD) of titanium nitride (TiN) was designed and built. The reactor uses a rf discharge operating at a pressure ∼1 mbar and at a frequency of 13.56 MHz. The dependence of various properties of the coating produced on the deposition parameters is studied in detail. Besides a determination of the thickness of the coating different analytical techniques such as Auger electron spectroscopy (AES), x‐ray diffraction (XRD), and scanning electron microscopy (SEM) have been used to characterize the coating. In order to investigate mechanical properties of the deposit, Vickers hardness and critical load have been determined. TiN coatings of excellent quality have been deposited on all surfaces of objects of complex geometry. The quality of these coatings is equivalent to the quality obtained by classical CVD and physical vapor deposition (PVD) techniques. The deposition temperature of 500 °C permits the coating of hardened steel tools.

ISSN:0734-2101    

DOI:10.1116/1.576173

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

The sputtering of metal in a magnetron glow discharge polymerization reactor system is investigated as a function of magnetic field. A pair of planar electrodes with circular arrangement of permanent magnets is used with a 10‐kHz electric power source. The sputtering of metal from the electrode is investigated for argon (nonpolymer‐forming gas) and methane (polymer‐forming gas) plasmas. In the case of the argon plasma, the sputtering rate is measured by the rate of deposition of metal upon the surface of quartz crystal. In the case of the methane plasma, the sputtering rate is estimated from the polymer deposition rate and the metal content in the deposited polymer determined by electron spectroscopy for chemical analysis (ESCA). In both cases, no appreciable deposition of metal (Cu or Al used as the electrode) is observed if the maximum parallel component of the magnetic field (with respect to the electric field) is<100 G. The sputtering rate by argon plasma is much greater than methane plasma, and the rate increases with the magnetic field strength of a magnetron. The sputtering rate in a methane plasma is related to the deposition of polymer on the electrode surfaces.

ISSN:0734-2101    

DOI:10.1116/1.576174

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

The relationship between microstructure and properties of dual ion beam sputtered tungsten film is investigated. Film properties, such as electrical resistivity and residual stress, are found to be dependent significantly on the Ar+sputtering energy from the deposition source and also on the flux density and energy of the assisting beam. Resistivity increases with increasing Ar+sputtering energy, and decreases with increasing assisting flux and energy. Residual stress increases with increasing Ar+sputtering energy and decreasing flux of assisting beam. With high Ar+sputtering energy, such as 1200 eV, a flux of energetic particles including sputtered atoms and reflected argon is directed toward film surface resulting in the atomic peening and sputter etching of growing film, which is a characteristic result of directional sputtering using ion beam. Microstructural analysis shows that this process causes the formation of finer grains, denser microdefects, sharp strain contours, and metastable β‐phase tungsten, which correlate consistently with the observed high stress and resistivity. Bombarding the growing film with low‐energy assisting Ar+flux reduces both stress and resistivity by mobilizing the sputtered atoms on film surface. It is shown that the presence of assisting flux reduces the density of microdefect and strain contours within the grain, and stabilizes the bcc α‐phase tungsten without altering the overall microstructure of the tungsten film.

ISSN:0734-2101    

DOI:10.1116/1.576301

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

This paper describes the crystal structure and photochromism of Zn oxide films fabricated by sputtering‐type electron cyclotron resonance microwave plasma.C‐plane preferential orientation and (101) plane preferential orientation are achieved in Zn oxide films deposited on glass substrates below 200 °C. These films have strong crystallite orientation. Films with (101) plane orientation exhibit typical photochromic characteristics induced by x‐ray irradiation. Photochromism is probably caused by a color center, that is, the oxygen vacancy in Zn oxide films. The absorption center exists in an energy range of 1.5 to 4 eV. The activation energy in the fading process is ∼0.03 eV.

ISSN:0734-2101    

DOI:10.1116/1.576302

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Thin CaF2films have been grown at low temperatures (20 °C) using an ion‐beam‐assisted laser evaporation method. Smooth, dense, environmentally stable coatings with bulk refractive indices were produced. This technique was applied to deposit mid‐wave IR dichroic filters using CaF2and Ge layers onto cold substrates.

ISSN:0734-2101    

DOI:10.1116/1.576303

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Imaging thermal detector arrays are currently being developed with large pixel counts at fine pitch. One major cause of image degradation in such arrays is by lateral thermal spread within the pyroelectric ceramic wafer on which the sensing array is defined. This paper discusses the use of ion beam milling to create thermal breaks between adjacent elements, significantly improving the modulation transfer function of the array. Masking techniques, etch rates, and pattern transfer characteristics are described. The effects of the ion milling conditions upon the chemical composition and electric resistivity of pyroelectric ceramic surfaces are described and discussed in the context of thermal detector array applications. The use of broad‐beam ion milling to thin pyroelectric ceramic wafers with minimal surface damage is also briefly described.

ISSN:0734-2101    

DOI:10.1116/1.576304

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

The chemistry of the Al polyimide interface is examined by x‐ray photoelectron spectroscopy sputter profiling. Al deposited on polyimide films without aninsituAr backsputter shows a clearly defined 50‐Å Al2O3layer just prior to the polyimide. This layer is identified by the O/Al atom ratio at 1.5, and the binding energy of the Al 2ptransition. There is a clear separation of the Al/Al2O3/polyimide layers in the sputter profiles. Deposition of Al on polyimide surfaces after Argon backsputtering produces a diffuse Al/polyimide interface with no Al2O3present. There is evidence in the Al 2pspectra for Al–C or Al–O–C type bonds, while the C 1sspectrum clearly has a metal carbide component. Increased adhesion of Al to polyimide surfaces with Ar backsputtering may be due to the differences in chemistry observed in these two instances.

ISSN:0734-2101    

DOI:10.1116/1.576305

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

The carbon vacancies at a V6C5(100) surface and their chemical activity for oxygen have been investigated by low‐energy ion scattering spectroscopy (ISS) and x‐ray photoelectron spectroscopy (XPS). The concentration of carbon vacancies increases with increasing flashing temperature of the sample: 10% and 20% at flashing temperatures of ∼1200 and ∼1600 °C, respectively. The adsorption of oxygen at a V6C5(100) surface is saturated with oxygen exposure of ∼10 L, and the oxidation occurs only at the V6C5(100) surface.

ISSN:0734-2101    

DOI:10.1116/1.576308

出版商:American Vacuum Society    

年代:1989

数据来源: AIP