resistance vacuum gauge composition and working principle
resistance vacuum gauge composition:
Resistance vacuum gauge consists of resistance gauge, ionization gauge and electronic circuit.
The resistance unit circuit completes the constant temperature and power regulation of resistance gauge hot wire, as well as the sampling and amplification of bridge voltage signal with the change of vacuum degree, and then converted into digital signal through analog-to-digital (A / D).
One part of the ionization unit circuit provides the working voltage and stability of the emission current required by the ionization gauge; the other part completes the detection and amplification of the ion current, and converts it into digital signal through analog-to-digital (A / D).
The digital circuit with microprocessor as the core, on the one hand, completes the non-linear processing and calculation of vacuum digital signal of resistance unit, and finally sends it to the display; on the other hand, it completes the sampling and calculation of digital signal of ionization unit and sends it to the display for display; at the same time, it completes the automatic switching of ion current amplification range and emission current conversion. On the other hand, it receives the key commands of the front panel or the external control signal of the rear panel and sends out the corresponding execution instructions; at the same time, it outputs the vacuum control signal, vacuum degree analog signal and computer communication signal.
resistance unit working principle:
The resistance unit adopts heat conduction resistance vacuum gauge (also known as Pirani gauge). Based on this gauge, the temperature of hot wire passing current varies with vacuum (pressure). The change of resistance of hot wire is caused by the change of temperature. Therefore, the vacuum is measured by measuring the change of resistance.
ionization meter working principle:
The ionization unit adopts hot cathode ionization gauge. Based on this kind of gauge, under low pressure (vacuum), the filament of the ionization tube passing through the current is “heated” to emit electrons, so it is called hot cathode ionization gauge; at the same time, DC high voltage is applied to the accelerating pole of the ionization gauge, so that the electron is accelerated in the electric field generated between the electrode of the gauge tube, so as to ionize the gas molecule by bombarding, and the positive ionization generated by ionization is received by the collector.
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