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Two experimental apparatuses used to obtain electron transport coefficients in gases are compared based on measurements in CO2 over a wide range of E/N-values. The operation principles of the two experimental systems as well as their data acquisition methods are different. One operates under the time of flight (TOF) principle, where the transport coefficients are obtained by fitting the theoretical form of the electron density of a swarm in an unbounded region, n(x, t), to the measured current at different values of the drift length, I(L, t). The other experimental apparatus operates in the Pulsed Townsend (PT) mode, where the electron transport coefficients are obtained by fitting the spatial integral of n(x, t) over the drift region to the measured, time-dependent current signal, I(t). In both apparatuses, the measured E/N range was extended as much as possible to allow a large overlap for the comparison of the results. The bulk drift velocity, W, obtained by the two systems agrees well (within a few %) over a wide range of E/N values (100 Td ≤ E/N ≤ 1000 Td). The agreement between the data sets for the longitudinal component of the bulk diffusion tensor, D L , is less satisfactory, the TOF data show systematically higher values (by 10–50% depending on E/N) than the PT measurements. Significant differences are also found below 100 Td in case of the effective ionisation frequency, ν e f f , and the (steady state) Townsend ionisation coefficient, α e f f , where the TOF apparatus is unable to give accurate results. Our comparison justifies the correctness of the measured data over the range of agreement and also indicates the interval in E/N where the data obtained by each of the experimental systems can be taken to be reliable. The limits of the operating regimes of the two setups, stemming from the hardware and from the physical limits, are discussed.

In this article we show three quite different examples of low-temperature plasmas, where one can follow the connection of the elementary binary processes (occurring at the nanoscopic scale) to the macroscopic discharge behavior and to its application. The first example is on the nature of the higher-order transport coefficient (second-order diffusion or skewness); how it may be used to improve the modelling of plasmas and also on how it may be used to discern details of the relevant cross sections. A prerequisite for such modeling and use of transport data is that the hydrodynamic approximation is applicable. In the second example, we show the actual development of avalanches in a resistive plate chamber particle detector by conducting kinetic modelling (although it may also be achieved by using swarm data). The current and deposited charge waveforms may be predicted accurately showing temporal resolution, which allows us to optimize detectors by adjusting the gas mixture composition and external fields. Here kinetic modeling is necessary to establish high accuracy and the details of the physics that supports fluid models that allows us to follow the transition to streamers. Finally, we show an example of positron traps filled with gas that, for all practical purposes, are a weakly ionized gas akin to swarms, and may be modelled in that fashion. However, low pressures dictate the need to apply full kinetic modelling and use the energy distribution function to explain the kinetics of the system. In this way, it is possible to confirm a well established phenomenology, but in a manner that allows precise quantitative comparisons and description, and thus open doors to a possible optimization.

This work presents swarm parameters of electrons (the bulk drift velocity, the bulk longitudinal component of the diffusion tensor, and the effective ionization frequency) in C 2 H n , with n=2, 4, and 6, measured in a scanning drift tube apparatus under time-of-flight conditions over a wide range of the reduced electric field, 1 TdE/N1790 Td (1 Td = 10 −21 V m 2 ). The effective steadystate Townsend ionization coefficient is also derived from the experimental data. A kinetic simulation of the experimental drift cell allows estimating the uncertainties introduced in the data acquisition procedure and provides a correction factor to each of the measured swarm parameters. These parameters are compared to results of previous experimental studies, as well as to results of various kinetic swarm calculations: solutions of the electron Boltzmann equation under different approximations (multiterm and density gradient expansions) and Monte Carlo simulations. The experimental data are consistent with most of the swarm parameters obtained in earlier studies. In the case of C 2 H 2 , the swarm calculations show that the thermally excited vibrational population should not be neglected, in particular, in the fitting of cross sections to swarm results.

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