Differential nature of inelastic collisions facilitating runaway electron generation in weakly-ionized plasmas

We report extention of the Dreicer generation theory to situation where the small energy exchange no more predominates. In weakly-ionized plamsas, the Dreicer mechanism can be severely underestimated due to the broken assumption of dominant small energy exchange. This Letter numerically demonstrates that the differential nature of inelastic collisions facilitates the Dreicer generation by developing the new Fokker-Planck-Boltzmann operator of electron-hydrogen atom collisions based on experimental data. This work is envisaged to predict runaway electron generations in future fusion reactors

A COMPARATIVE STUDY OF SPRING TRITICALE VARIETIES IN THE WESTERN SIBERIAN FOREST-STEPPE ZONE UNDER DIFFERENT CONDITIONS OF VEGETATION

Spring triticale (x Triticosecale Wittmack) for Western Siberia is new and poorly studied culture. The objective of this study was to investigate the potential of spring triticale varieties and breeding lines and their adaptation to diferent conditions in Western Siberia. A ield experiment was conducted in Novosibirsk region, Russia in 2014. The experiment included seven spring triticale genotypes: the elite variety Ukro, three mutant forms of the facultative type of development (Sirs 57/2/4, Cecad 90/5, О.312/38) and three hybrids (Sirs 57/2/4 x Ukro, Ukro x K-3881, the complex hybrid winter wheat Filatovka x winter rye Korotko stebelnaya 69304 x Sirs 57/2/4). They were studied at two sowing rates (400 seeds per m2 and 800 seeds per m2) and on two sowing dates (15 May 2014 and 27 May 2014). The following attributes were measured: grain yield, number of ears, plant height, yield components (ear length, number of spikelets per ear, number of grains per ear, grains weight per ear) and yield quality (1 000-grain weight and test weight of one-liter grain volume). The three-factor analysis of variance revealed that sowing rate efect explained the major part of the total experimental variation in almost all of the traits, except 1 000-grain weight and test weight, the variation of which was determined predominantly by genotype efect. The highest grain productivity of varieties was obtained for the 15 May sowing date at the 400 seeds per m2 sowing rate. The three mutant forms used in the experiment showed a lower level of adaptability in comparison with the variety Ukro

Spatiotemporal Evolution of Runaway Electron Momentum Distributions in Tokamaks

Novel spatial, temporal, and energetically resolved measurements of bremsstrahlung hard-x-ray (HXR) emission from runaway electron (RE) populations in tokamaks reveal nonmonotonic RE distribution functions whose properties depend on the interplay of electric field acceleration with collisional and synchrotron damping. Measurements are consistent with theoretical predictions of momentum-space attractors that accumulate runaway electrons. RE distribution functions are measured to shift to a higher energy when the synchrotron force is reduced by decreasing the toroidal magnetic field strength. Increasing the collisional damping by increasing the electron density (at a fixed magnetic and electric field) reduces the energy of the nonmonotonic feature and reduces the HXR growth rate at all energies. Higher-energy HXR growth rates extrapolate to zero at the expected threshold electric field for RE sustainment, while low-energy REs are anomalously lost. The compilation of HXR emission from different sight lines into the plasma yields energy and pitch-angle-resolved RE distributions and demonstrates increasing pitch-angle and radial gradients with energy.United States. Department of Energy (DE-FC02-04ER54698)United States. Department of Energy (DE-FG02-07ER54917)United States. Department of Energy (DE-AC05-00OR22725)United States. Department of Energy (DE-FC02-99ER54512)United States. Department of Energy (DE-SC0016268

A comparison of statistical methods for assessing winter wheat grain yield stability

The multitude of existing methods for assessing the phenotypic stability of plants makes breeders be faced with the problem of choosing an appropriate variant. The purpose of this study was to compare different methods of analyzing the genotype x environment interaction and, on their basis, assess the stability of the yield of 7 varieties of winter wheat. The article compares 17 stability statistics by applying them to data obtained from agrotechnical experiments carried in 2009-2011 for evaluating the grain yield of 7 varieties of winter common wheat of Siberian selection (Novosibirskaya 32, Novosibirskaya 40, Novosibirskaya 51, Novosibirskaya 3, Novosibirskaya 2, Obskaya winter, Omskaya 6). Analysis of variance revealed a significant (p < 0.001) genotype x environment interaction in the experiments, which indicates a different reaction of genotypes to changes in environmental conditions. Genotypes were ranked according to the level of stability. Based on the analysis of the rank correlation matrix, the stability statistics were categorized in five groups. Recommendations were made on which group of methods to use depending on the objectives of the study. In the case when the goal of breeding research is the selection of the most biologically stable varieties with the minimum variance across a range of environments, one should use the methods of the static concept. If it is necessary to choose a genotype with a predictable reaction to changes of environmental conditions, corresponding to the calculated level or forecast, the regression approach is the most appropriate. The stability statistics generally identified Novosibirskaya 32 as the most stable variety from a biological point of view. The regression approach showed that Novosibirskaya 3 was the genotype with the smallest deviation from mean yield in all environments, while methods accessing the contribution of each genotype to the genotype x environment interaction defined Novosibirskaya 51 as the most stable variety

A novel path to runaway electron mitigation via deuterium injection and current-driven MHD instability

Relativistic electron (RE) beams at high current density (low safety factor, q ( a )) yet very low free-electron density accessed with D-2 secondary injection in the DIII-D and JET tokamak are found to exhibit large-scale MHD instabilities that benignly terminate the RE beam. In JET, this technique has enabled termination of MA-level RE currents without measurable first-wall heating. This scenario thus offers an unexpected alternate pathway to achieve RE mitigation without collisional dissipation. Benign termination is explained by two synergistic effects. First, during the MHD-driven RE loss events both experiment and MHD orbit-loss modeling supports a significant increase in the wetted area of the RE loss. Second, as previously identified at JET and DIII-D, the fast kink loss timescale precludes RE beam regeneration and the resulting dangerous conversion of magnetic to RE kinetic energy. During the termination, the RE kinetic energy is lost to the wall, but the current fully transfers to the cold bulk thus enabling benign Ohmic dissipation of the magnetic energy on longer timescales via a conventional current quench. Hydrogenic (D-2) secondary injection is found to be the only injected species that enables access to the benign termination. D-2 injection: (1) facilitates access to low q ( a ) in existing devices (via reduced collisionality & resistivity), (2) minimizes the RE avalanche by 'purging' the high-Z atoms from the RE beam, (3) drives recombination of the background plasma, reducing the density and Alfven time, thus accelerating the MHD growth. This phenomenon is found to be accessible when crossing the low q ( a ) stability boundary with rising current, falling toroidal field, or contracting minor radius-the latter being the expected scenario for vertically unstable RE beams in ITER. While unexpected, this path scales favorably to fusion-grade tokamaks and offers a novel RE mitigation scenario in principle accessible with the day-one disruption mitigation system of ITER