DE2807995A1 - Electron spectrometer with two helical electrodes - tuned to same transmission speed and used in tandem - Google Patents

Abstract

The spectrometer has two helical electrodes tuned to the same transmission speed and used in tandem. The deflected beam leaves the tandem at a voltage node after the first helix and is focussed by the external electric field produced by the second helix- of the same phase as the first. Alternatively, the beam may remain inside the tandem, being diverged by the first and converged by the second helix. The electron trap or detector is located at the voltage node between the helices and on their axis. The helices may have the same constant dia. or their diameters may vary in steps.

Description

Additional registration

Title of the invention: Electron spectrometer patent description The invention relates to an electron spectrometer using deflection electrodes in a helix shape according to the main invention.

In the high-frequency electric field of such electrodes takes place a conical spreading of the electron beam in synchronicity with the change of polarity adjacent turns of the helix. For taking the measurement signal by means of an electron detector It is advisable to focus the divergent beam.

In the main invention, the focusing is, among other things, by means of an electrostatic Cylindrical mirror obtained, which is arranged behind the helix and on the same Transmission energy is set. The present additional invention is the Task based on a focusing of the divergent electron beam by the Use of multiple helix electrodes to achieve.

This object is achieved in that two, on the same transmission speed, coordinated helix electrodes in a tandem arrangement be used.

In one embodiment of the invention, the conically deflected leaves Beam the tandem arrangement in the tension node behind the first helix and become in the electric field in the outer space oscillating in phase with the first helix second helix focused. This beam guidance is known as external focusing.

In another embodiment of the invention, the electron beam remains within the tandem arrangement with a conical expansion in the first Helix and a focusing by the electric field in the interior of the antiphase to the first helix vibrating second helix. This beam guidance is called internal focusing designated.

It is further noted that by means of the tandem arrangement according to the invention According to the principle of the main invention, a divergent beam can also be generated. The beam is then not deflected inside or outside, but further spread apart when the two helix electrodes are in reverse of that described above Operating mode oscillate in phase or out of phase. Of course, diverges the resonant electron beam, however, also after focusing as described above. The conically diverging Electron beams are focused as described in the main invention.

In all the cases described, the resonance is achieved by light-touching of the current of a centric, near the focus arranged electron detector is displayed.

In a further embodiment of the invention, an electron collector is used or detector, preferably behind a pinhole, in the area of the voltage node arranged between the helix electrodes of the tandem arrangement at the level of the axis. This enables the non-resonant electron beam to be checked and masked out achieved.

Have in one embodiment of the tandem arrangement according to the invention the two helix electrodes have the same diameter. This results in a special simple construction.

For the purpose of favorable beam guidance, the Invention of a tandem arrangement with a stepped diameter of the two helix electrodes used.

In a further embodiment of the invention, the two helix electrodes are the tandem arrangement made in one piece, preferably with a closed ring End parts and a ring-shaped closed middle part between the e.g. two helix electrodes. The rings define the by their short-circuit properties respective voltage nodes of the high-frequency field.

In a further embodiment of the invention, the annular central part takes the tandem arrangement, the bracket and, if applicable, the electrical feedthroughs for the electron detector or collector mentioned above.

For the above-described, inventive deflection of the resonant The ring-shaped central part is the electron beam in the outer space of the tandem arrangement provided with an annular gap.

For optimal focusing, the two helix electrodes are placed in the tandem arrangement according to the invention with independently controllable high-frequency voltages, but in phase with regard to the transmission of resonant electrons, fed.

In particular for the internal focusing described, the two In another embodiment of the invention, however, helix electrodes are also in phase opposition swing freely, so that only one voltage supply, optionally on the front or posterior helix, is necessary.

The tandem arrangement of the helix electrodes is particularly useful when using the described external focusing in a further embodiment of the invention Coaxially enclosed by a cylinder electrode with adjustable DC voltage. This provides a further setting option for the focusing.

Two embodiments of the invention, each with a tandem arrangement for outside or. Inner focusing are shown in the drawings. As in the lower one Part of the drawings shown, the helix electrodes oscillate in phase in the first case, in the second case out of phase. The resonant electrons succumb to one another two pulsating constant fields, the strength of which is determined by the voltage difference (distance between full and dotted curve part) is given.

In both cases the electron beam passes axially through the front, field-free ring part 1 in the front helix 2 of the tandem arrangement, where it is in the case of resonance is spread conically. In Figure 1, the jet passes through an annular gap in the middle, field-free ring part 3 in the outer space of the rear helix 4, which passes through the cylinder 8 is limited, and leaves the tandem arrangement in the field-free Outer space of the rear ring part 5 with a focus on the detector 6. In In contrast, in FIG. 2 the beam enters the interior of the rear helix 4 and leaves the tandem arrangement in the field-free interior of the rear ring part 5 also with a focus on the detector 6. In both cases the non-resonant Beam through the electron collector arranged centrally within the middle ring part 3 or detector 7 hidden.

The invention is not restricted to these exemplary embodiments. For example, more than two helix electrodes with alternating beam guidance, as described above, can be arranged one behind the other. In particular, is on this Way also a beam exit in the axial direction and a favorable operation as an electron monochromator possible, if necessary using additional, known El ektronenl i nsen.

Claims (12)

Claims 1. Electron spectrometer with deflection electrodes according to the main invention, characterized in that two, on the same transmission speed Matched helix electrodes can be used in a tandem arrangement. 2. Electron spectrometer according to claim 1.), characterized in that that the conically deflected beam behind the tandem arrangement in the tension node the first helix leaves and is in phase in the external electric field with the first helix vibrating second helix is focused. 3. Electron spectrometer according to claim 1.), characterized in that that the beam remains within the tandem arrangement, with a conical one Spreading in the first helix and focusing by the electric field in the interior of the second helix oscillating in phase opposition to the first helix. 4. Electron spectrometer according to claim 1.) 2.) 3.), characterized by placing an electron collector or detector, preferably behind a perforated diaphragm, in the area of the voltage node between the helix electrodes the tandem arrangement at the height of the axis. 5. Electron spectrometer according to claim 1.) 2.) 3.) 4.), characterized by means of helix electrodes with the same diameter. 6. Electron spectrometer according to claim 1.) 2.) 3.) 4.), characterized by a tandem arrangement with a stepped diameter of the two helix electrodes. 7. Electron spectrometer according to claim 1.) 2.) 3.) 4.) 5.) 6.), thereby characterized in that the two helix electrodes of the tandem arrangement are made from one piece are made, preferably with ring-shaped closed end parts and one ring-shaped closed middle part. 8. Electron spectrometer according to claim 1.) 2.) 3.) 4.) 5.) 6.) 7.), characterized in that the central annular part holds the support and electrical feedthroughs an electron detector or collector. 9. Electron spectrometer according to claim 1.) 2.) 4.) 5.) 6.) 7.) 8.), characterized in that the annular central part is provided with an annular gap is. 10. Electron spectrometer according to claim 1.) 2.) 3.) 4.) 5.) 6.) 7.) 8.) 9.), characterized in that the two helix electrodes with independently controllable high-frequency voltages are fed. 11. Electron spectrometer according to claim 1.) 3.) 4.) 5.) 6.) 7.) 8.), characterized in that the helix electrodes vibrate freely. 12. Electron spectrometer according to claim 1.) 2.) 4.) 5.) 7.) 8.) 9.) 10.), characterized in that the tandem arrangement of the helix electrodes from one Cylinder electrode is enclosed with adjustable DC voltage.