A High-Efficiency Second-Harmonic Gyrotron with a Depressed Collector

The gyrotron with an electrically insulated collector has been manufactured and tested. The 60% output efficiency is obtained for the Collector Potential Depression (CPD) operation regime. The results of the numerical simulation of the electron energy spectrum in the collector region of the second-harmonic technological 24 GHz gyrotron are presented. It is shown, that the minimal electron beam energy is about 20% of the initial value and that the gyrotron cavity should be expanded to achieve the highest output efficiency of the gyrotron with energy recovery. The highest experimental decelerating voltage is in good agreement with the calculation of the electron energy spectrum.     

Magnetic structure of the Sm5Ge4-type Tb2Ti3Ge4

The orthorhombic Sm₅Ge₄-type Tb₂Ti₃Ge₄ shows square modulated non-collinear magnetic ordering with wave vector K=[±1/3, 1/2, 1/2] at 2 K. The terbium magnetic moments lie in the bc plane and magnetic moment value of 7.5(2) μ_B/Tb is obtained at 2 K.     

Force action of a shock wave on a solid body

Approximate engineering methods for determining the forces acting on solid bodies upon interaction with shock waves are proposed. These methods are verified experimentally with the use of a shock tube. The forces acting on bodies are measured by fast–response acceleration transducers. Good correspondence between measurement data and calculation results obtained by exact and approximate methods is observed.     

Quaternary structure of glucosooxidase from penicillium vitale

Conclusions The molecular weights of the products of denaturation of glucosooxidase from penicillium vitale were investigated by the method of sedimentation equilibrium in an ultracentrifuge. The N- and C-terminal amino acids of this protein were determined. It is shown that glucosooxidase consists of four identical, paired peptide chains with molecular weights close to 40,000.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1437–1439, June, 1972.     

Control of the process of cooling of ceramic products with allowance for the constraints on thermal stresses

A three-dimensional problem on the control of furnace temperature during cooling of ceramic products of arbitrary shape with allowance for the constraints on thermal stresses is analyzed. An algorithm for calculating a temperature regime making it possible to avoid the occurrence of fracture and irreversible deformation in the products being cooled is proposed. With the example of cooling of a ceramic holder for a spiral wire, a computational experiment is performed. A temperature regime in which the cooling of the product accomplishes in a certain time without exceeding the admissible values of thermal stresses is identified.     

Electrical transport and magnetic ordering in R 2Ti3Ge4 (R=Dy, Ho and Er) compounds

New R ₂Ti₃Ge₄ (R=Dy, Ho and Er) intermetallic compounds have been synthesized and characterized by X-ray diffraction and low temperature ac magnetic susceptibility, electrical resistivity and thermoelectric power measurements were carried out. The compounds crystallize in the parent, Sm₅Ge₄-type orthorhombic structure (space group Pnma) and lanthanide contraction is observed as one moves along the rare-earth series. The changeover from paramagnetic to antiferromagnetic phase happens at low temperatures and the ordering temperature scales with the de Gennes factor. The electrical resistivity is metallic with a negative curvature above 100 K. Thermopower displays a weak maximum at temperatures less than 50 K signifying the possible phonon and magnon drag effects.