The rate constants for reactions involved in the radiolysis of water under relevant thermodynamic conditions in supercritical water-cooled reactors are estimated for inputs in simulations of the radiation chemistry in Generation IV nuclear reactors. We have discussed the mechanism of each chemical reaction with a focus on non-equilibrium reactions. We found most of the reactions are activation controlled above the critical point and that the rate constants are not significantly pressure dependent below 300 °C. This work will aid industry with developing chemical control strategies to suppress the concentration of eroding species.

Several designs of plasma flow meters have been used on satellites to measure ionospheric winds, including retarding potential analyzers, ion drift meters, "top hat" analyzers, ion imagers, and segmented Langmuir probes. The first satellites equipped with ion drift meters were deployed in the 1960s and 1970s (Galperin Abstract A relatively simple design of a segmented flow meter is presented for measuring in situ plasma flow velocities and other space plasma parameters. The response of the flow meter to space environment is simulated for plasma conditions representative of the ionosphere at mid and low latitudes using a Particle in cell code. A synthetic data set consisting of ion currents collected by several segments of the flow meter, and the physical parameters for which they were calculated, is then used to construct a solution library from which inference models can be constructed, using radial basis function and neural network regressions. Simulation results show that with such a flow meter, it should be possible to infer plasma flow velocities in the direction perpendicular to the ram direction, with uncertainties of ±45 m/s or less. Models can also be constructed to infer plasma densities, with a maximum relative error of 23%. This work is presented as a first assessment and proof of concept for an original design of a simple and robust flow meter. Plain Language SummaryWe present a new plasma flow meter geometry intended to measure plasma flow velocities in Earth ionosphere. Kinetic simulations are used to construct a synthetic data set from which inference models are constructed and validated. This new concept of flow meter is simple and robust, and the analysis shows that transverse velocities can be estimated with a root mean square error of 20 m/s, in the range of plasma environment conditions considered. It is also shown that the same instrument can be used to infer the electron densities with a root mean square relative error of order 10%.

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Langmuir probes are widely used to characterize space plasma and laboratory plasma. A variety of Langmuir probe geometries are being used, such as spherical (

Langmuir probes are widely used to characterize space plasma and laboratory plasma. A variety of Langmuir probe geometries are being used, such as spherical (