An innovative device capable of generating a cold atmospheric pressure plasma inside a 5 m long flexible tube with 2 mm inner diameter is presented. In order to analyze the inner‐tube plasma, optical ...emission spectroscopy in the (vacuum) ultraviolet spectral range and Fourier transformed infrared spectroscopy were performed. By admixing small concentrations of nitrogen and oxygen to the standard argon gas flow rate of 1.5 slm, a drastically change in the plasma composition was observed. Additionally, it is possible to form a jet‐like plasma at the end of the tube. The microbicidal efficacy of the inner‐tube plasma and the jet‐like plasma was shown for Bacillus atrophaeus spores.
In this paper a setup is presented, to generate a DBD inside a long, flexible and thermo labile tube with the purpose to decontaminate the inner tube walls. The main application for these modified tubes is the implementation as biopsy channels in endoscopes, which are highly contaminated and difficult to sterilize. Besides decontamination of the inner tube it is also possible to ignite a jet‐like discharge at the tube end.
► We measure the evolution of the thermal radiative properties of carbon materials at high temperature and also with adding VUV radiation. ► VUV radiation modifies the microstructure and acts on the ...thermal radiative properties. ► A mean value of the α/ɛ ratio of 1.14 can be retained for C/C composites for the Solar Probe Plus mission.
The Solar Probe Plus (SP+) mission will approach the Sun as close as 9.5 solar radii in order to understand the origin of the solar corona heating and the acceleration of the solar wind. Submitted to such extreme environmental conditions, a thermal protection system is considered to protect the payload of the SP+ spacecraft. Carbon-based materials are good candidate to fulfill this role and critical point remains the equilibrium temperature reached at perihelion by the heat shield. In this paper, experimental results obtained for the solar absorptivity α, the total hemispherical emissivity ɛ and its ratio α/ɛ, conditioning the equilibrium temperature of the thermal protection system, are presented for different kinds of carbon materials heated at high temperatures with or without vacuum-UV (100<λ<200nm) radiation. The synergistic effect of ion bombardment is also presented for one kind of material.
Results of investigations of UV and VUV radiation sources (excilamps) based on inert gases and mixtures of inert gases with halides are presented. Conditions are described in which maximum radiation ...parameters are attained. Photoreactors and irradiators promising for application in medicine, agriculture, and gas industry have been developed based on the excilamps.
The vacuum ultraviolet (VUV) emissions from 115 to 200 nm from the effluent of an RF (1.2 MHz) capillary jet fed with pure argon and binary mixtures of argon and xenon or krypton (up to 20%) are ...analyzed. The feed gas mixture is emanating into air at normal pressure. The Ar 2 excimer second continuum, observed in the region of 120-135 nm, prevails in the pure Ar discharge. It decreases when small amounts (as low as 0.5%) of Xe or Kr are added. In that case, the resonant emission of Xe at 147 nm (or 124 nm for Kr, respectively) becomes dominant. The Xe 2 second continuum at 172 nm appears for higher admixtures of Xe (10%). Furthermore, several N I emission lines, the O I resonance line, and H I line appear due to ambient air. Two absorption bands (120.6 and 124.6 nm) are present in the spectra. Their origin could be unequivocally associated to O 2 and O 3 . The radiance is determined end-on at varying axial distance in absolute units for various mixtures of Ar/Xe and Ar/Kr and compared to pure Ar. Integration over the entire VUV wavelength region provides the integrated spectral distribution. Maximum values of 2.2 mW middotmm -2 middotsr -1 are attained in pure Ar and at a distance of 4 mm from the outlet nozzle of the discharge. By adding diminutive admixtures of Kr or Xe, the intensity and spectral distribution is effectively changed.
Effects of β, X and VUV irradiation on the optical properties have been studied in various simple and complex fluoride crystals by using optical absorption, X- and UV-excited luminescence (XL and ...PL), thermoluminescence (TL) and photo-transferred TL (PTTL) techniques. In most tested crystals, the main TL peaks with the same thermal activation energies appear after VUV as well as after X or β irradiation, thus indicating that the same traps are induced by the different types of radiation. The TL excitation spectra generally show absorption maxima on the long wavelengths tail of the fundamental absorption. Within this study, various dosimetric properties, as well as the possible application of the crystals as sensitive radiation detectors and dosimeters for the VUV have also been investigated. The TL sensitivities of the various studied materials have been compared to that of the classic dosimeter TLD-100 (LiF:Mg,Ti). For example, the sensitivity of SrF
2:Pr
3+ has been found to be the highest among the examined crystals and at a dose of 90
Gy its response is higher by a factor of ∼3 than that of TLD-100. The sensitivity of CsGd
2F
7:Pr
3+ and KYF
4:Pr
3+ are slightly higher than that of TLD-100, whereas that of nanostructured CaF
2:ZnO crystals is about twice that of TLD-100, but the sensitivity of LiF:Eu is much lower. The SrF
2:Pr
3+ crystals also showed some important dosimetric properties.
Irradiation effects and dosimetric properties have been studied for
CaF
2
,
KYF
4
and
CsY
2
F
7
crystals doped with
Pr
3
+
. In particular, thermoluminescence (TL) excitation spectra have been ...measured in the 120–200
nm region and the
CaF
2
:
Pr
3
+
and
KYF
4
:
Pr
3
+
crystals show excitation maxima at 135 and 140
nm, respectively. Some of the main TL peaks appear after vacuum ultraviolet (VUV) irradiation at the same temperatures as after
β
irradiation, indicating that they are due to the same radiation-induced trapping levels. Optically stimulated luminescence (OSL) and phototransferred TL (PTTL) have also been recorded in pre-irradiated samples and stimulation spectra have been measured. The OSL emission spectra show some of the same bands as in the case of the XL and TL, indicating that they are due to the same luminescence centers. The TL sensitivity of
CaF
2
:
Pr
3
+
is
∼
5 times higher than that of TLD-100, and the TL sensitivity of
KYF
4
:
Pr
3
+
is slightly higher than that of TLD-100, whereas the sensitivity of
CsY
2
F
7
:
Pr
3
+
is much lower. The main TL peaks of
KYF
4
:
Pr
3
+
and
CaF
2
:
Pr
3
+
appear above 480 K and, accordingly, only low TL fading is expected during storage at RT. The dose dependence of the main TL peaks is nearly linear in a dose range up to about 2000
Gy.
We present the realization of high-resolution holographic microscopy using the original Gabor geometry and imaging with radiation in the vacuum-ultraviolet (VUV) spectral region. Synchrotron VUV ...radiation with a wavelength of 13.8
nm was focused on a small pinhole generating a highly divergent light cone suitable for digital in-line holography. Objects of different thickness and materials have been used to test the imaging properties of holographic microscopy in the VUV wavelength range. The effective numerical aperture was limited by the illuminated area of the detector, yielding a theoretical resolution below 1
μm and an experimental one of approximately 1
μm.
Narrowband VUV radiation (near a wavelength of 147 nm), corresponding to the optical transition of a heteronuclear dimer ArXe*, was recorded from plasma formed during the excitation of an Ar–Xe ...mixture at a pressure of 400 mbar by a high-voltage nanosecond discharge initiated by runaway electrons. Amplifying properties of the discharge plasma related to this radiation were found.
Vacuum ultraviolet photochemistry of polymers Skurat, Vladimir
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
08/2003, Letnik:
208, Številka:
Complete
Journal Article
Recenzirano
The interaction of vacuum UV radiation (wavelength range from 1 to 200 nm) with polymers is interesting for fundamental and applied sciences. This interest is stimulated by various reasons:
•
Wide ...applications of polymeric materials in semiconductor technology, where they are used as photoresist materials in combination with VUV light sources (lasers, excimer lamps, synchrotron radiation and others).
•
Polymers are widely used as spacecraft materials in the last 20 years. On near-Earth orbits, the polymeric materials of spacecraft surfaces are destroyed by solar radiation.
•
VUV radiation is one of the components of gas discharge plasmas, which are used for treatment of polymer, with the aim of modifying their surface properties.
The main features of interaction of VUV radiation with polymers are discussed.
The spectra of intrinsic absorption of saturated polymers (polyethylene, polypropylene, polytetrafluoroethylene and others) are situated mainly in the VUV region. The photochemistry of polymers in the VUV region is very different from their photochemistry at wavelengths longer than 200 nm, where the absorption spectra belong to impurities and polymer defects.
The polymer photochemistry in the VUV region is wavelength-dependent. At wavelengths longer than about 140 nm, the main role is played by transformations of primary-formed singlet excited molecules. At shorter wavelengths the role of photoionization increases progressively and the main features of VUV photolysis become similar to the picture of radiolysis, with significant contributions of charge pairs and triplet excited molecules.
Very important features of VUV light absorption in polymers are high absorption coefficients. Because of this, the surface layers absorb large doses of energy. This leads to very profound transformation of material on the polymer surface. In particular for polymers which are considered destroyed by radiation (for example, perfluoropolymers), this leads to VUV-induced erosion under vacuum conditions. The energetic yield of erosion is intensity-dependent because of the limited rate of sublimation of polymer fragments.
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