X-radiation Emission Research Articles

Investigation on X-Radiation for 126 kV Vacuum Interrupters**supported by National Key Basic Research Program of China (973 Program) (No. 2015CB251002)

When subjected to high voltages between opened contacts, vacuum interrupters may emit X-rays. In order to ensure that these are of an acceptable level, vacuum interrupters should comply with the limits for X-ray emission and the test procedures to be carried out to verify this based on relevant standards and specifications. In this paper, a comprehensive experimental study has been performed for 126 kV vacuum interrupters used in a transmission system to understand the X-radiation level and its influence by three main parameters, namely applied power-frequency voltage, contact gap and power-frequency voltage conditioning. The radiation instrument is an FJ347 radiometer and the X-radiation dose was measured at the power-frequency test voltage. These tests demonstrated that the X-radiation emission level for a 126 kV vacuum interrupter did not exceed the following: 5 μSv per hour at a rated voltage of 126 kV and 150 μSv per hour at a power-frequency voltage of 230 kV at 1 m distance. The X-radiation dose increased with the applied power-frequency voltage increasing and decreased with the contact gap increasing. The X-radiation dose for 126 kV vacuum interrupters decreased by 57% after the conditioning procedure with a certain power-frequency voltage. During the conditioning procedure, the average value of the X-radiation dose was 4.49 mSv, which means if a professional conditions 180 interrupters per year, it will be safe at the 6.4 m distance.

Note: Enhanced production of He⁺ from the Versatile Ion Source (VIS) in off-resonance configuration.

The Versatile Ion Source (VIS) is a microwave discharge ion source installed at INFN-LNS and here used as test-bench for the production of high intensity low emittance proton beams and for studies on plasma physics. A series of measurements have been carried out with VIS in order to test the source with light ions. In particular a He(+) beam has been characterized in terms of plasma discharge parameters. The experiment has been triggered by the observation of X-radiation emission from the plasma for some configuration of the magnetic field profile. The plasma electron energy distribution function is in fact modified when in some regions of the plasma chamber under-resonance discharge takes place, fulfilling the condition that allows the electromagnetic wave to electrostatic wave conversion. These tests allowed obtaining more than 50 mA of He(+) beams.

Scope of plasma focus with argon as a soft X-ray source

The X-radiation emission from a low energy plasma focus with argon as a filling gas is investigated. Specifically, the attention is paid to determine the system efficiency for argon K-lines and Cu-K/sub /spl alpha// line emission at different filling pressures, and identify the radiation emission region. The highest argon line emission found at 1.5 mbar is about 30 mJ and the corresponding efficiency is 0.0015%. The same pressure is suitable for high Cu-K/sub /spl alpha// emission, which is about 70 mJ in 4/spl pi/ geometry and the system efficiency is 0.003%. The bulk of X-radiation is emitted from the region close to the anode tip, whereas some radiation emission takes place from the formed hot spots along the focus axis. These radiations are found suitable for backlighting in Al (1-1.56 keV) and Ti (2.9-4.96 keV) energy transmission bands.

Efficiency of plasma focus for argon K-series line radiationemission

X-radiation emission from a low-energy Mather-type plasma focusoperated with argon is investigated. Attention is paid to finding thepressure range for the highest argon K-series line emission. The argon lineradiation yield is highest at 1.5 mbar and the emitted energy in 4πgeometry is estimated to be about 30 mJ, with a system efficiency of0.0015%. The emission at an energy exceeding 3 keV is found to be highestat a 0.5 mbar filling pressure, giving a total yield of 0.7 J in 4πgeometry, which corresponds to a device efficiency of about 0.028%. Thisemission is mainly due to the interaction of energetic electrons with theanode.

Monochromatic x-ray emission of a fully ionized hydrogen plasma

Subnanosecond emission phenomena have been studied at a modified 1 kJ Mather type plasma focus device. High energy particle beams, nonthermal infrared and microwave emission as well as anisotropic soft X-rays are observed. In the plasma a hydrodynamic instability leads to a final radius of r ⋍ 50 μ m and a length of l = 500 μm through which a current of l = 200 kA is driven. Induced by the high power density, microinstabilities modulate the plasma density periodically. Due to particle-wave interaction, electrons and ions are accelerated to energies beyond 1 MeV. The electron beam is emitted in pulses with a pulse period of about 10–30 ps and a pulse width in the range of 1–3 ps. Simultaneously, anisotropic emission of soft X-rays at a wavelength of about λ = 1 nm into a cone with a half angle θ = 0.2 rad is observed. The relative line width Δλ λ = 2×10 −3 , indicates a temporal coherent emission of X-radiation by the fully ionized hydrogen plasma. Assuming an FEL-like process as generation mechanism of the soft X-rays, the periods length of the density structure and the relativistic factor γ of the electron beam are determined as λ ⋍ 17 nm and γ ⋍ 3 . The observed phenomena in the plasma can be theoretically described as a self-organization process in terms of a three-wave-coupling model of a beam-plasma system.

A technique for detecting critical loads in the scratch test for thin film adhesion

A new technique has been developed for detecting critical loads when using the scratch test to determine the adhesion of deposited thin films. In this technique, a 2μ diam 15 keV electron beam impinges upon the sample and the intensity of the induced x-radiation emission from the film and the substrate are monitored simultaneously and used to determine the applied normal load necessary to cause a diamond probe to cleanly strip off the film. Preliminary results are discussed using this technique to study the adhesion of rf sputtered TiC films on high speed steel substrates. Preheating of the substrate prior to deposition was shown to significantly increase the film adhesion.

Auger Peaks in the Energy Spectra of Secondary Electrons from Various Materials

The energy spectra of secondary electrons from carbon, beryllium, aluminum, nickel, copper, barium, platinum, and the oxides of beryllium, aluminum, nickel, copper, and barium have been measured with equipment of high stability and sensitivity. Characteristic peaks due to Auger electrons emitted as a result of absorption of a valence electron by an excited x-ray level were observed for all these materials.The peaks exhibit structure which is of some theoretical interest. The structure can be related to the distribution in energy of electrons in the valence band, and it complements that observed in soft x-ray emission work. Since the emission of the Auger electron is not subject to the selection rules governing the emission of x-radiation, additional information can be obtained from the Auger electron energy distribution.Excitation of Auger peaks by a beam of low velocity electrons provides an interesting technique for surface analysis.Plasma peaks of the type reported by Ruthemann, and interpreted by Pines and Bohm, were also observed.