Gas-Jet Source of Vacuum Ultraviolet and Ultrasoft X-Ray Radiation

Gas-Jet Source of Vacuum Ultraviolet
and Ultrasoft X-Ray Radiation

A unique method of generating electromagnetic radiation in a wide spectral region is developed at the B.I. Verkin Institute for Low Temperature Physics and Engineering of NAS Ukraine. The method is based on the excitation by electrons of a spatially confined supersonic gas jet, which is formed in a vacuum chamber and pumped with a cryogenic pump. Under the temperature and gas pressure at the nozzle inlet is changed, the jet can be contained not only atoms but also clusters of different sizes ranging up to microcrystals. The area of jet-electron beam intersection is a source of electromagnetic radiation in a wide wavelength range which include ultrasoft X-ray (USX), vacuum ultraviolet (VUV), near ultraviolet, visible and infrared spectral regions. On the basis of this method was made a small-sized gas-jet source of vacuum ultraviolet and ultrasoft X-ray radiation, GJS. It possesses unique potentialities and makes it possible:

to change spectral distribution of radiation intensity in separate sections of spectral range on varying of type gas or gaseous mixture, its temperature and pressure at the nozzle inlet;
to vary absolute intensity and spectrum composition of radiation under changes of electron beam current and energy;
to introduce radiation into the super-high vacuum chamber without any optical window;
to produce atom, molecule and cluster beams of inert and other atmospheric gases. The cluster size varies in the range from 10 to 10⁵ atoms per cluster.

In a short-wave spectral region the source is not inferior in its energy and spectral characteristics to the source of synchrotron radiation.

APPLICATION FIELDS

Fundamental studies

Applied studies

The source can be used to solve a variety of problems in atom and molecular physics, cluster physics, physics of electron and atom collisions, spectroscopy, plasma physics, in field of photo-chemistry, biophysics end ecology. The source was employed in unique experiments on:

study of X-ray radiation spectra of atoms, molecules and clusters on successive probing of valence and inner electron shells by electron beam. Determined are the peculiarities and regularities of bremsstrahlung, including a new type of electromagnetic radiation (first revealed at ILTPh &E of NASU) polarization bremsstrahlung generating at scattering of electrons of different energy by rare gas atoms and clusters;
investigation of VUV radiation spectra, energy structure and relaxation processes under quasi-continuous transition from an atom to solid;
problem of formation of excitons under transition from clusters to microcrystals.

The source is employed to solve a number of problems in field of photolithography, material resistance to radiation, laser physics, space material science, metrology measurements in VUV and USX spectral range. For example, it may be used:

to simulate the VUV and USX radiation of the Sun, including solar flares, in the conditions of the Earth;
to study the effect of space factors on mechanical, optical and other properties of organic and inorganic materials in high vacuum. The source may be modernized to simulate a simultaneous influence of electromagnetic radiation and intense electron beams on materials.
elaboration and investigation of the nuclear radiation scintillational detectors on the base of inert gases.

Technical characteristics of GJS

Spectral wavelength range — 1 to 200 nm
Radiation spectrum — continuous spectrum with overlapping emission lines
Integral irradiance of an object at a distance of 0.7 m — 0.2 W/m²
Working substance — Ar, Kr, Xe, their mixtures and also atmospheric molecular gases
Source chamber pressure — 10^-4÷10^-5 mm Hg
Electron energy diapason — 0÷2 keV
Supersonic jet temperature — 20÷60 K
Overall dimensions, m — 0.5x0.5x2
Mass — 60 kg

B.I. Verkin Institute for Low Temperature Physics and Engineering of NAS Ukraine
47 Nauky Ave., Kharkiv 61103 , UKRAINE Tel: +(380)-57-340-22-23 Fax: +(380)-57-340-33-70
E-mail: ilt@ilt.kharkov.ua
WWW: http://www.ilt.kharkov.ua