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Vacuum furnace vacuum gauge what

Time:2015-07-16 09:06 Click:
Vacuum Technology vacuum measurement is an important part. Instruments for measuring vacuum gauge called.     
Vacuum furnace and vacuum melting furnace commonly used vacuum gauge are: thermocouple vacuum gauge ionization vacuum gauge and so on.
They work as follows:
(A) thermocouple vacuum gauge    
Thermocouple vacuum gauge by the sensor, thermocouple regulation and measuring instrument components. Thermocouple vacuum system regulated and measured communication, glass shell, the inner tube has a heating wire and thermocouple wire. Wire thermocouple cold junction and hot junction temperature is not the same, since the temperature difference effect, there are thermoelectric power generated in the circuit. The heating filament voltage is kept constant, the potential of the thermocouple wire action depends on the temperature of the heating wire, and the pressure and temperature of the heating wire about the gas to be measured. Low pressure, low heat conductivity, low heat away by the gas, heating wire temperature, thermocouple wire thermoelectric power increases; on the contrary, the thermoelectric power decreases. Loop thermoelectric power meter measurements in millivolts, mV table that is reflected in the number of high and low degree of vacuum. In order to ensure the heating filament voltage stability, and access to the power supply. So measuring instrument is measuring thermoelectric power mV table and regulatory heating wire power supply of two parts.
(B) the ionization vacuum gauge     
This vacuum gauge for measuring high vacuum. In the low pressure gas, the gas molecules are ionized to generate positive ions of the gas pressure is proportional to the number of produced according to the method different from the use of a hot cathode electron emission gas ionization vacuum gauge called hot cathode ionization gauge; wherein the hot cathode Gauge regulated by the hot cathode composition and measuring instruments. Measuring instruments by the regulated power supply, the emission current regulator, the composition of the ion current measurement amplifiers and other components. Hot cathode ionization gauge tube communicates with the vacuum system under test. Hot cathode ionization gauge tube is a transistor, the cathode, and the gate and the collector tube. The collector potential of the negative potential relative to the cathode electrode; a gate electrically positive potential relative to the cathode. When the ionization gauge tube ohmic heating, cathode emit electrons, the electrons reach the gate in the process, collide with gas molecules to produce positive ions and electrons in the ionization phenomenon. When the emission current is constant, the number of days with positive ions is proportional to the measured gas pressure. Positive ions are collector after collection, the measurement circuit amplified by the meter reads the instructions to measure the degree of vacuum (box furnace).
(III) complex vacuum gauge    
Typically, the measurement of low vacuum and high vacuum can not be accomplished in a vacuum gauge, and should be used composite vacuum gauges, ionization and the application of more complex vacuum gauge thermocouple type. Its measurement range is 13.33--666.6 × 10-8Pa. Thermocouple vacuum gauge measurements (10-1--10-3) × 133.32Pa low vacuum; ionization vacuum gauge measuring high of 133.32 × 10-3--666.6 × 10-8Pa. Compound gauge with a thermocouple regulation a gauge tube were connected to the vacuum system by knob, respectively, to two regulated heating, and choose to use.

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