High efficiency radio frequency pulse generation in a nonlinear corrugated coaxial transmission line with ferrite saturated by permanent magnets

The work on the development of a generator of high-power, high-frequency pulses based on a nonlinear transmission line with saturated ferrite is presented. A feature of the generator is that the ferrite rings are saturated in the field of permanent magnets, unlike traditional generators with a solenoid wrapped around the transmission line. Due to the changed structure of the inner conductor, which is a corrugated conductor, the line has spatial dispersion. The paper demonstrates the generation of high-frequency pulses with a duration of up to 6 ns and a center frequency of 2.7 GHz. This pulse duration with a frequency above 2 GHz was not previously observed in traditional nonlinear transmission line geometry. The maximal peak power achieved was 70 MW for an incident voltage pulse of 90 kV. The energy efficiency of video pulse energy conversion into radio pulse was 6% [G. Kataev, Electromagnetic Shock Waves (Sov. Radio, Moscow, 1963)]. The paper discusses the performance of RF and microwave NiZn ferrites for the purposes of radio pulse generation.

Quantum translator-rotator: inelastic neutron scattering of dihydrogen molecules trapped inside anisotropic fullerene cages

We report an inelastic neutron scattering investigation of the quantum dynamics of hydrogen molecules trapped inside anisotropic fullerene cages. Transitions among the manifold of quantized rotational and translational states are directly observed. The spectra recorded as a function of energy and momentum transfer are interpreted in terms of the rotational potential and the cage dimensions. The thermodynamics of orthohydrogen and parahydrogen are investigated through temperature dependence measurements.

Solid-state NMR spectroscopy using the lost I spin magnetization in polarization transfer experiments

A variation of the cross polarization (CP) experiment is discussed. The method requires two scans where the difference signal is equivalent to the I spin magnetization that is transferred to the S spins. The acquired signal is equivalent to F1 sum projection of a two-dimensional (2D) heteronuclear correlation experiment and is obtained by just two scans without the need to increment the indirect time domain t(1). Any polarization transfer method and any kind of spin manipulations during the t(1) incrementation period of a 2D NMR experiment can be applied. The method allows fast measurements of the CP transfer, particularly if various S spins signal overlap and is good for spectral editing of I spin signals with contact to S spins. Various examples for biomaterials are presented. Most importantly, this novel approach is ideal for detailed investigations of organic-mineral interfaces in bone, here demonstrated for O-phospho-l-serine as simple model compound.