SU397833A1 - In P T B - Google Patents

Description

The invention relates to an electrovacuum technique, in particular, to a technique for measuring the electron work function.

A known installation for measuring the electron work function by the method of contact potential difference (CPD), comprising a sensor, a 800 Hz power source, a vibrating sample drive system, a signal amplifier from the sensor, an oscilloscope, a 50 Hz power source and a compensation system.

The known installation does not allow measuring the FCC directly on the surface of parts of any shape and size; In addition, when measuring the work function of the electrode, the data obtained is not quite accurate.

The aim of the invention is to extend the functionality of the installation and improve the accuracy of measurement of the electron work function.

The goal is achieved due to the fact that the vibrating plate of the sensor-capacitor is not a test sample, but a reference electrode. This makes it possible to measure the electron work function directly from the surfaces of the investigated parts.

In addition, the reference electrode actuator is made on the basis of a tuning fork, one of the legs of which is connected to an inductance coil. The tuning fork allows you to simultaneously stabilize the amplitude and frequency of oscillation of the vibrating electrode, and also to accurately match the phase signal arriving at the oscilloscope from the feedback wheel with the signal arriving at the oscilloscope from the sensor-capacitor. This improves the measurement accuracy of the electron work function.

FIG. 1 shows a block diagram of a predlo enna installation for measuring the work function.

electron; in fig. 2 shows the electrical installation diagram.

The installation contains a sensor-capacitor /, electrometric cascade 2, amplifier 3, oscilloscope 4, the correction system unit 5,

the compensation system unit 6, the power source 7, the vibrating electrode drive system unit 5.

The installation works as follows. When power switches are turned on

The vibrating electrode drive system unit 8 (Fig. 1) causes the vibrating plate 10 (Fig. 2) of the sensor-capacitor to vibrate with respect to the fixedly mounted sample 9. Moreover, as a result of

between the vibrating electrode and the sample of potential difference, equal to the contact potential difference, between the plates of the sensor-capacitor creates an alternating electrostatic field, the potentials of which

fed through amplifier 3 (fig. 1) to oscilloscope plates 4. The second pair of oscilloscope plates from the inductance coil of the vibrating electrode actuator unit receives a phase matching signal from the amplifier 3, resulting from the addition of these two signals on the oscilloscope an ellipse signal appears. To measure the magnitude of the contact potential difference to one nz of electrodes, a compensation voltage of opposite sign is applied using the compensation system unit 6. The moment of full compensation is recorded by the appearance of a zero signal on the oscilloscope screen (in the form of a straight line). The voltage equal to the contact potential difference is determined by a voltmeter (Fig. 2) of the compensation system.

To improve the accuracy of measurements, a tuning fork // (Fig. 1) was used as a drive of a vibrating electrode, which, using a generator and a low-power electromagnetic system, was 1PLAYED and maintained at a resonant frequency. The block of the correction system 5 (Fig. 1), which serves for the permanent control "Zero count scales, consists of an additional removable reference electrode and a correctional chain 12 (Fig. 2). In the control," zero count scales instead of the test sample 9 (Fig. 2 ) an additional reference electrode is established. A properly tuned setup should issue a bullet signal on the oscilloscope screen (in

as a straight line). If a signal other than zero appears on the oscilloscope screen, it must be corrected by moving the potentiometer slider of the correction chain 12 (Fig. 2).

The invention can be used both in laboratory and in industrial conditions.

Nredmet of the invention

An installation for measuring the electron output work by the method of contact potential difference containing a sensor-capacitor with

two electrodes, an electrometric cascade, an amplifier, an oscilloscope, a correction unit, a block of a compensating system, a source of filament, a block of a tuning fork drive system of a vibrating electrode,

that, in order to improve the measurement accuracy, one of the electrodes of the sensor-capacitor is made in the form of a plate fixed on the leg of the tuning fork.

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