A current controlled miniaturized non-radioactive electron emitter for atmospheric pressure chemical ionization based on thermionic emission

Cochems, P.; Runge, Matthias; Zimmermann, Stefan

doi:10.1016/j.sna.2013.11.033

Cited by 16 publications

(18 citation statements)

References 17 publications

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“…While the electron source presented in Ref. 16 already offers the advantage of non-radioactive electron emission with controllable electron energy and electron current, it still lacks the ability to produce a pulsed electron beam. This pulsed operation however is crucial for several of the applications described in the Introduction, such as experiments on gas phase ion chemistry, and can therefore be considered as a key element in the development of a non-radioactive electron source.…”

Section: Methods For Pulsed Operationmentioning

confidence: 99%

“…Thus, the control grid above the filament can not only be used to control the exterior emission current by controlling the extraction of electrons from the filament as in Ref. 16 but also by shaping the electric field inside the electron source as shown by the COMSOL Multiphysics simulation in Figure 3. This simulation is based on a simple rotationally symmetrical model using the electric potentials given in the Introduction and generates electrons without initial kinetic energy at the filament.…”

Section: Methods For Pulsed Operationmentioning

confidence: 99%

“…In order to avoid most of the problems mentioned above and to miniaturize the setup, we developed a highly compact electron source concept employing only a single control grid as published in Ref. 16. This new setup primarily consists of a small, evacuated glass tube with the necessary electrical feedthroughs on the bottom side and a metal electrode on the top side as shown in Figures 1 and 2.…”

Section: Introductionmentioning

confidence: 99%

“…Above the filament, the single control grid is mounted, which was designed in Ref. 16 to control the thermionic emission current by varying the field strength at the surface of the filament. Both the filament and the control grid are referenced to a potential of −10 kV relative to the acceleration electrode.…”

Section: Introductionmentioning

confidence: 99%

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Fast pulsed operation of a small non-radioactive electron source with continuous emission current control

Cochems

Kirk

Bunert

et al. 2015

Review of Scientific Instruments

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Non-radioactive electron sources are of great interest in any application requiring the emission of electrons at atmospheric pressure, as they offer better control over emission parameters than radioactive electron sources and are not subject to legal restrictions. Recently, we published a simple electron source consisting only of a vacuum housing, a filament, and a single control grid. In this paper, we present improved control electronics that utilize this control grid in order to focus and defocus the electron beam, thus pulsing the electron emission at atmospheric pressure. This allows short emission pulses and excellent stability of the emitted electron current due to continuous control, both during pulsed and continuous operations. As an application example, this electron source is coupled to an ion mobility spectrometer. Here, the pulsed electron source allows experiments on gas phase ion chemistry (e.g., ion generation and recombination kinetics) and can even remove the need for a traditional ion shutter.

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Section: Methods For Pulsed Operationmentioning

confidence: 99%

Section: Methods For Pulsed Operationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fast pulsed operation of a small non-radioactive electron source with continuous emission current control

Cochems

Kirk

Bunert

et al. 2015

Review of Scientific Instruments

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“…However, there are non-radioactive alternatives with variable intensity described in literature, e.g., using a UV photo ionization lamp, 9,10 a corona discharge, [11][12][13][14][15] a micro plasma, 16 or nonradioactive electron emitters. 17 Unfortunately, additionally to the reduced sensitivity when using UV ionization, the spectra gained from UV-photoionization and corona discharge differ from the spectra produced with a radioactive ionization sources, so they are not comparable. The main disadvantage of micro plasma and nonradioactive electron sources is that they are not widely commercially available.…”

Section: Introductionmentioning

confidence: 99%

A compact high-resolution X-ray ion mobility spectrometer

Reinecke

Kirk

Heptner

et al. 2016

Review of Scientific Instruments

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For the ionization of gaseous samples, most ion mobility spectrometers employ radioactive ionization sources, e.g., containing (63)Ni or (3)H. Besides legal restrictions, radioactive materials have the disadvantage of a constant radiation with predetermined intensity. In this work, we replaced the (3)H source of our previously described high-resolution ion mobility spectrometer with 75 mm drift tube length with a commercially available X-ray source. It is shown that the current configuration maintains the resolving power of R = 100 which was reported for the original setup containing a (3)H source. The main advantage of an X-ray source is that the intensity of the radiation can be adjusted by varying its operating parameters, i.e., filament current and acceleration voltage. At the expense of reduced resolving power, the sensitivity of the setup can be increased by increasing the activity of the source. Therefore, the performance of the setup can be adjusted to the specific requirements of any application. To investigate the relation between operating parameters of the X-Ray source and the performance of the ion mobility spectrometer, parametric studies of filament current and acceleration voltage are performed and the influence on resolving power, peak height, and noise is analyzed.

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