One of the versions of this EOS is shown

One of the versions of this EOS is shown in Fig. 1. The cathode has bracket-shaped cross-section. Nanocarbon emitting coating is deposited onto its inner surface. The anode in the form of two thin tungsten wires is placed inside the cathode box. Full axial length of the system may substantially exceed its cross-sectional dimensions (6 × 6 mm). This enables us to extend emitter area to a desired value, not increasing the field gap distance between the cathode and the anode. The anode wires have large geometric aspect ratio (length/thickness), but their straight shape helps to avoid deformation and maintain their transverse positions by application of a sufficient longitudinal strain force. Electron trajectories in the presented electron–optical system have been simulated with the help of Simion3D 6.0 software. Simulation results for the optimized EOS geometry are shown in Fig. 2. It may be seen that in this geometry electrons emitted from a substantial part (about 20–25%) of cathode area are injected onto infinite (closed) trajectories. This makes the probability of their eventual collision with atoms present in the gauge volume very high, which means high ionization efficiency for a given value of Bisindolylmaleimide V current. Fig. 3 presents the second version of the developed EOS. In this case, the emitting nanocarbon coating is deposited onto the inner side of the mesh cylinder (grid) separating the ionization volume from the collector of ions. This layout helps to increase relative number collected ions approximately twice, because the grid intercepts only a minor part of ionic current produced in the gauge. Another advantage of this layout consists in additional geometric field enhancement at mesh wires (that can be estimated by the factor close to 2), reducing the gauge operational voltage for the same value of electric field at the emitting surface. According to simulation results illustrated by Fig. 4, the trap quality also improved. Relative part of the emitting surface injecting electrons onto infinite trajectories grew to approximately 50%. The trap volume where the electron space charge is confined also increased and its shape simplified, hence we can believe that electron losses caused by their scattering at gas molecules and ions became smaller, and each confined electron can ionize larger number of molecules.
Experimental test of prototypes Exponential shapes of current characteristics (Fig. 5) witness to the field-induced nature of the observed emission from the nanocarbon coating. A comparison of current plots for the two prototypes confirms the theoretical conclusion about higher emission efficiency achieved in the second EOS version. Operational characteristics of the two prototypes, representing dependencies of the collected ionic current against the residual gas pressure for a fixed value of current of electron emission, are shown in Figs. 6 and 7. In both cases, the dependencies are monotonous; hence the prototyped gauges can be used for unambiguous definition of gas pressure. The ionic current is sufficient for reliable registration, at least in the interval of pressure values 10–6–10–5 Torr.
Introduction In our Case, the objective of further improvement of material processing techniques at GESA-series material-treatment electron beam facilities [1] required accurate measurement of electron energy distributions at the target, with resolution in position over the beam cross-section and in time within the facility current pulse. Typical GESA electron beam parameters are the following: an electron acceleration voltage U0 = 60–400 kV, a beam current at the target is of 50–500 A corresponding to a current density up to 10 A/cm2, a guiding magnetic field at the target B0 = 0.02–0.10 T, an operation in single pulses with a duration of 10–100 µs. The new “Soffron60” electron beam analyzer was specially designed for operation at these conditions, near the lower limit of U0. It was intended to supplement the “wells” measurement technique [2], installed earlier and providing very operative though rather generalized data on electron energy distribution parameters – in most cases, only the mean pitch angle of electron trajectories.