Electron sources with a hot cathode operating in consumption or generation modes are widely used in many vacuum devices as gas ion sources, thermionic energy converters. The main aim of this work is to get information how dynamic properties of the electron source changes within full range of work, therefore the identification of a hot cathode electron source using the step signal and the time domain approach to know dynamic parameters (DC incremental transconductance, time constant, delay time) of the electron source in full range of its operation is made. In the first part, an open-loop system identification using step response method was conducted. For the electron source with a thoriated tungsten cathode (d=0.1 mm, l=45 mm) operating in the range 1 μA to 1 mA, the time constant T varies from 0.71 s to 0.35 s, the delay time T0 from 0.04 s to 0.01 s and the DC incremental transconductance g0 from 0 to 0.0056 S, respectively. In the next step, an approximation of obtained characteristics is made and ultimate gains of thermionic emission current automatic control system for each fixed operating point are estimated. The results of similar investigations for electron sources with an yttrium oxide coated iridium cathode and a tungsten cathode have also been shown. Presented system identification approach can be successfully applied to other types of the hot cathode electron sources.

Thermionic emission sources are key components of electron impact gas ion sources used in measuring instruments, such as mass spectrometers, ionization gauges, and apparatus for ionization cross-section measurements. The repeatability of the measurements taken with such instruments depends on the stability of the ion current, which is a function, among other things, of the electron beam current and electron accelerating voltage. In this paper, a laboratory thermionic electron beam current and accelerating voltage controller is presented, based on digital algorithm implementation. The average value of the percentage standard deviation of the emission current is 0.021%, and the maximum electron accelerating voltage change versus the emission current is smaller than 0.011% in the full operating range of the emission current. Its application as a trap current or emission current-regulated ion source power supply could be useful in many measuring instruments, such as in microelectromechanical system (MEMS) mass spectrometers as universal gas sensors, where a stable emission current and electron energy are needed.

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Fast and complex model-based computations are often needed during the controller design process; therefore, a hot cathode electron source simulator was designed and implemented. The simulator uses the static model of electron source and is based on the LabView environment. It is developed for different materials and dimensions of filaments popular in vacuum instruments. The simulator is able to calculate the maximum temperature of the hot filament, its resistance, voltage drop and temperature and distribution of the electron emission current along the filament length in a steady state. Also, a new method was proposed and implemented for approximate calculations of distributions of the temperature and the electron emission current without measurements of the filament temperature.

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