[en] Calculations of microwave radiation power dependence upon magnetron parameters with a real voltage pulse shape being considered showed fairly good agreement with similar dependencies obtained experimentally. This allowed to choose magnetron optimal parameters in agreement with a high current accelerator as a power source. Next way to increase radiated power is to sum up powers of some pulse relativistic magnetrons. A scheme is based on the principle of nonsymmetry allowing a rather strong mismatch of magnetrons eigenfrequencies and being not so critical to a choice of connection line length. The strong coupling provides fast phase locking and high efficiency of the pulse powers addition

[en] The discovery of the Principle of Phase Stability by Vladimir Veksler and Edwin McMillian and the end of the war released a surge of accelerator activity at the Lawrence Berkeley Laboratory (then The University of California Radiation Laboratory). Six accelerators incorporating the Principle of Phase Stability were built in the period 1945--1954

[en] Using the evolutionary methodology for crystal structure prediction, we have predicted the orthorhombic Cmcm and Pnma phases for ScB₄. The earlier proposed CrB₄-, FeB₄-, MnB₄-, and ReP₄-type structures for ScB₄ are excluded. It is first discovered that the Cmcm phase transforms to the Pnma phase at about 18 GPa. Moreover, both phases are dynamically and mechanically stable. The large bulk modulus, shear modulus, and Young’s modulus of the two phases make it an optimistic low compressible material. Moreover, the strong covalent bonding nature of ScB₄ is confirmed by the ELF analysis. The strong covalent bonding contributes greatly to its stability. (paper)

[en] The crystalline phases ratio cubic/monoclinic or cubic/tetragonal in the PSZ/Mg zirconia account for its high thermal shock resistence. The optimization of the phases ratio is obtained through thermal annealing after sinterization. This work presents the effect of iron and silicon on the thermal annealing of ZrO2 + 4% MgO ceramic. (author)

[en] We study the entanglement dynamics of two atoms with initial tripartite entangled W-like state in the Tavis–Cummings model. We find that the entanglement evolvement is sensitive not only to the entanglement degree of the initial state but also to the concrete form of the initial state. The so-called sudden death effect occurs only for some initial states

[en] By using a system of internal phase-defining slits, beams with energy resolution δE/E approximately equal to 1:1000 have been attained at TRIUMF. The eventual aim of an energy spread of <100 keV implies separated turn extraction over the entire energy range of 200-520 MeV. To achieve this, work has proceeded toward the following three requirements: i) beam phase stability of +-2₀, ii) rf voltage stability of δV/V = 5x10^-₅ and iii) flat-topping of the rf fundamental with the addition of a third harmonic. Phase stability of +-1.5₀ has been demonstrated for several hours, using 3 software feedback loops: i) slow magnet drifts measured with an NMR probe to control the magnet power supply; ii) fast fluctuations in the field detected with an outer trim coil provide a correction to the rf frequency; and iii) phase fluctuations measured with the beam itself provide a final rf frequency correction. These loops have been implemented with dedicated CAMAC-based microprocessors

No abstract available

[en] The problem of phase and amplitude stabilization of the fields in superconducting resonators is described. The problem arises from the fast (approx. 50 Hz) resonator eigenfrequency modulation of magnitude (approx. 100 Hz) which is much larger than the resonator bandwidth (approx. 10 Hz). The problem is compounded by the fact that the coupling between the electrical and mechanical modes of the resonator can lead to instabilities (ponderomotive instabilities). The solution suggested involves operating the resonators in self-excited loops, and electronically modifying the loop parameters in order to lock the loop oscillations to an external phase and amplitude reference without attempt to modify the instantaneous resonator eigenfrequency. It is found that this method of phase stabilization is well suited to resonators with small energy contents and small eigenfrequency deviations since the power required is equal to their product; this occurs when the loaded bandwidth of the resonator is twice the maximum eigenfrequency deviation to be compensated for. It is also found that when the loop is free-running, the field amplitude is stable and no ponderomotive instabilities are present as long as the non-ideal effects are limited. When the loop is locked to an external phase and amplitude reference, ponderomotive instabilities can occur; however, the loop can be made stable by adjustment of the loop phase shift, and the stable range can be increased by using high amplitude and phase feedback gains. It is also found that under certain feedback conditions, the error on the particle energy gain can be made to vanish, although residual phase and amplitude errors are still present. A microprocessor-controlled feedback system based on this analysis is then described and results of experiments performed in conjunction with a 150 MHz lead (Pb) plated superconducting split-ring resonator are presented. The experiments show excellent agreement with the analysis

No abstract available

[en] Published in summary form only