In the spectral range of the extreme ultraviolet at a wavelength of 13.3 nm, we have studied the photoionization of xenon at ultrahigh intensities. For our ion mass-to-charge spectroscopy ...experiments, irradiance levels from 10(12) to 10(16) W cm(-2) were achieved at the new free-electron laser in Hamburg FLASH by strong beam focusing with the aid of a spherical multilayer mirror. Ion charges up to Xe21+ were observed and investigated as a function of irradiance. Our surprising results are discussed in terms of a perturbative and nonperturbative description.
Abstract
The interaction of gamma quantum from distant sources with thermal bremsstrahlung photons of hot intracluster gas with producing electron-positron pair in case of 10 galaxy clusters is ...considered. It is supposed that intracluster gas in considered clusters is isothermal and electron number density may be described by β distribution with β = 2/3. It is presented that the optical depth due to considered interaction is about 10
−8
— 10
−
.
The plasma parameters in a glow discharge plasma near the front of shock wave moving perpendicularly to the discharge axis has been investigated using a double electrical probe. It has been ...discovered that the shock wave propagation is accompanied by an increase in the potential of discharge plasma. A relatively small change in the potential is observed before the shock wave arrival and a significant one behind shock wave front. The varying potential in the glow discharge plasma distorts the current of the double probe. A method of its correction is proposed, which consists in the joint processing of two signals obtained in separate experiments with different surface areas of the negative probe electrode. The method allows us determine the ionic current and the change in the potential of space. The magnitude of ion current corresponding to the charged particles concentration remains unperturbed before the shock wave arrival to the measurement point. A gradual increase in the ionic current is observed behind the shock wave front in contrast with the abrupt change in gas-dynamic parameters on the shock wave front.
Investigation results of the effect of electron cooling are considered. The current state-of-the-art is analyzed. The possibilities are discussed for the experimental study of the electron cooling ...phenomenon using a large shock tube and plasma-gas-dynamic stand at the Ioffe Institute.
We propose a method for correcting the double probe signal during measurements in plasma of an electrode discharge varying with time. The technique has been verified in experiments on the interaction ...of a shock wave with transverse glow discharge in the regime of steady discharge operation and a decaying plasma.
Exceptional behavior of light-matter interaction in the extreme ultraviolet is demonstrated. The photoionization of different rare gases was compared at the free-electron laser in Hamburg, FLASH, by ...applying ion spectroscopy at the wavelength of 13.7 nm and irradiance levels of thousands of terawatts per square centimeter. In the case of xenon, the degree of nonlinear photoionization was found to be significantly higher than for neon, argon, and krypton. This target specific behavior cannot be explained by the standard theories developed for optical strong-field phenomena. We suspect that the collective giant 4d resonance of xenon is the driving force behind the effect that arises in this spectral range.
Non-equilibrium air plasma generated in free glow discharge is characterized by optical emission spectroscopy techniques in the wavelength range of 340-440 nm. The rotational and vibrational ...temperature are studied as a function of distance from the electrode, to find out differences in the distribution of plasma parameters along with the discharge axis. In this work, the rotational and the vibrational temperature is determined from rovibrational spectra of second positive N2 system. It is observed that N2+/N2 intensity ratio increases from anode to cathode along the discharge axis.
We present an analysis of the current state of electron transpiration cooling (ETC) effect studies as applied to high-temperature aerodynamics of hypersonic vehicles. The possibility of experimental ...study of the ETC effect using the plasma-dynamic device at the Ioffe Institute is considered. The distribution of vertical component of the electric field and gas temperature distribution across the glow discharge is measured. The region of homogeneity of plasma parameters is determined.
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