Influence of the erosion of the discharge channel wall on the efficiency of a stationary plasma thruster

The integral characteristics of stationary plasma thrusters are studied experimentally during their long-term operation. It is shown that the monotonic fall of the thrust efficiency and specific impulse within the initial 500?C1000 h of operation is explained, in particular, by a decrease in the propellant utilization efficiency. A physical mechanism underlying this phenomenon is suggested, and expressions predicting the variation of the output characteristics of the thrusters during the operating life are derived. Satisfactory agreement is observed between experimental and predicted results on the anode specific impulse variation in the course of testing several thrusters with different powers for endurance. An experimentally found correlation between the magnetic field configuration and the position of the erosion zone boundary on the discharge chamber wall is accounted for.     

Research program for the radioactive beams of the ACCULINNA-2 separator

The ACCULINNA-2 separator is intended to provide beams of exotic nuclei with Z = 1?30, energies of 10?C50 MeV/amu, and intensities that allow one to study excitation spectra and decay dynamics of neutron- and proton-drip nuclei. Examples from studies of the ¹⁰He and ⁶Be nuclei are presented.     

Deuterium accumulation in an assembly of nickel foils irradiated by high-temperature deuterium plasma

The accumulation of deuterium in an assembly of nickel foils by the pulsed irradiation of a deuterium plasma is studied. It is established that implanted deuterium is transferred to a much greater depth than that corresponding to the projective range of deuterium plasma ions with a maximum velocity of 10⁸ cm/s. The maximum concentration (up to 4 at % deuterium) is observed in the second Ni foil. The observed phenomenon can be explained by the action of shock waves and concomitant stresses on the transport and redistribution of deuterium to greater depths.     

Polymeric waveguides based on photopolymerizing methacrylate compositions

Contact photolithography was used to fabricate three-layer polymeric waveguide structures with transverse dimensions of 50 × 90 μm on the basis of two photopolymerizing methacrylate compositions with different refractive indices. The optical loss on the wavelength of 632.8 nm was 0.37 ± 0.14 dB cm^?1. This loss is mostly due to the light scattering by the material of the waveguide layer produced by bulk polymerization.     

Investigation of skin secretory peptidome of <Emphasis Type="Italic">Rana lessonae</Emphasis> frog by mass spectrometry

Amphibian skin secretion represents a cerain scientific interest as a source of biologically active natural peptides. In the present research skin peptidome of wide-spread European frog Rana lessonae (Camerano, 1882) was studied for the first time ever. Peptide sequencing was accomplished with Fourier transform ion cyclotron resonance mass spectrometer in collision-induced and electron capture dissociation modes. A portion of amphibian peptides contains intramolecular C-terminal disulfide cycle which obstructs mass spectrometric sequencing. Two methods were utilized to overcome this difficulty: reduction with dithiotreithol followed by thiol group alkylation and oxidation into sulfonic acid groups with performic acid. Integrated approach employed in the present study allowed the identification of 49 peptides (of 6 to 37 amino acid residues), including 19 novel species.     

Probing many-body interactions in an optical lattice clock

We present a unifying theoretical framework that describes recently observed many-body effects during the interrogation of an optical lattice clock operated with thousands of fermionic alkaline earth atoms. The framework is based on a many-body master equation that accounts for the interplay between elastic and inelastic p$p$-wave and s$s$-wave interactions, finite temperature effects and excitation inhomogeneity during the quantum dynamics of the interrogated atoms. Solutions of the master equation in different parameter regimes are presented and compared. It is shown that a general solution can be obtained by using the so called Truncated Wigner Approximation which is applied in our case in the context of an open quantum system. We use the developed framework to model the density shift and decay of the fringes observed during Ramsey spectroscopy in the JILA ⁸⁷${}^{87}$Sr and NIST ¹⁷¹${}^{171}$Yb optical lattice clocks. The developed framework opens a suitable path for dealing with a variety of strongly-correlated and driven open-quantum spin systems.     

The pyroelectric effect in magnetoelectric 0.8 PZT-0.2 MZF and 0.8 PZT-0.2 NZF composites

The pyroelectric response is measured using the dynamic method in preliminarily polarized magnetoelectric 0.8PbZr_0.53Ti_0.47O₃-0.2Mn_0.4Zn_0.6Fe₂O₄(0.8 PZT-0.2 MZF) and 0.8PbZr_0.53Ti_0.47O₃-Ni_0.4Zn_0.6Fe₂O₄ (0.8 PZT-0.2 NZF) composites, where PZT is a ferroelectric, and MZF and NZF are manganese-zinc and nickel-zinc ferrites, respectively. Values of the pyroelectric coefficient Γ for the materials under study vary over the range of 1.5–4 × 10⁻⁸ C cm⁻² K⁻¹. It is shown that the polarized samples of the composites have a heterogeneous distribution of polarization across the sample thickness. The heterogeneity is more pronounced in the near-surface layers of the investigated materials.     

Robust quantum state transfer in random unpolarized spin chains

We propose and analyze a new approach for quantum state transfer between remote spin qubits. Specifically, we demonstrate that coherent quantum coupling between remote qubits can be achieved via certain classes of random, unpolarized (infinite temperature) spin chains. Our method is robust to coupling-strength disorder and does not require manipulation or control over individual spins. In principle, it can be used to attain perfect state transfer over an arbitrarily long range via purely Hamiltonian evolution and may be particularly applicable in a solid-state quantum information processor. As an example, we demonstrate that it can be used to attain strong coherent coupling between nitrogen-vacancy centers separated by micrometer distances at room temperature. Realistic imperfections and decoherence effects are analyzed.