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Emission active salt for barium-tungsten cathode and preparation of emission active salt

A barium tungsten cathode and active salt technology, which is applied in the field of barium tungsten cathode emission active salt and its preparation, can solve the problem of affecting the distribution of electron clouds in space, the unstable operation of magnetrons, and the difficulty of high-power magnetrons starting to vibrate and work normally etc. to achieve the effect of high primary electron emission capability and large secondary emission coefficient

Active Publication Date: 2019-04-16
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the secondary electron emission accounts for about 90% of the anode current during normal operation, if the secondary emission coefficient of the cathode is large enough, it does not need too high thermal emission or the ionization of residual gas molecules is enough to start the device, and the thermal emission of the cathode is too large On the contrary, it will affect the distribution of electron clouds in space, which will cause the magnetron to work unstable.
At present, barium tungsten cathodes and other types of secondary emission materials such as oxide cathodes, rare earth molybdenum metal ceramic cathodes and alloy cathodes used in magnetrons, due to their emission performance, radioactivity, stability and cost, make high-power It is difficult for the magnetron to vibrate and maintain its normal operation

Method used

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  • Emission active salt for barium-tungsten cathode and preparation of emission active salt
  • Emission active salt for barium-tungsten cathode and preparation of emission active salt
  • Emission active salt for barium-tungsten cathode and preparation of emission active salt

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Experimental program
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Effect test

Embodiment 1

[0034] Weigh 88.6g of Ba(NO 3 ) 2 , 20g of Ca(NO 3 ) 2 4H 2 0 and 63.56g of Al(NO 3 ) 3 9H 2 O and other raw materials, the molar ratio of the three is 4:1:2, then weigh 13.27g, the mass fraction is 6% of Y (NO 3 ) 3 ·6H 2 0 was dissolved in 3L of deionized water to form a nitrate solution, and 120g of excess (NH 4 ) 2 CO 3 Dissolve in deionized water as a precipitant. After the precipitation is complete, wash the precipitate with deionized water and ethanol solution, and then place it in an oven at 120°C for drying to form a precursor powder. The morphology of the obtained precursor powder is as follows: figure 1 As shown, put it in a muffle furnace for decomposition at a temperature of 750°C and keep it warm for 3 hours. After being ground, pass through a 200-mesh standard sieve, put it into a high-temperature hydrogen furnace for sintering in a hydrogen environment, set a sintering temperature of 1530°C, keep it for 3 hours, and take it out to obtain aluminate. ...

Embodiment 2

[0036] Weigh 88.6g of Ba(NO 3 ) 2 , 20g of Ca(NO 3 ) 2 4H 2 0 and 63.56g of Al(NO 3 ) 3 9H 2 O and other raw materials, the molar ratio of the three is 4:1:2, then weigh 17.69g, the mass fraction is 8% Y (NO 3 ) 3 ·6H 2 0 was dissolved in 3L of deionized water to form a nitrate solution, and 140g of excess (NH 4 ) 2 CO 3 Dissolve in deionized water as a precipitant. After the precipitation is complete, wash the precipitate with deionized water and ethanol solution, then place it in a 120°C oven for drying to form a precursor powder, and then put it in a muffle furnace for decomposition. The decomposition temperature is 750°C, and the temperature is kept for 3.5 hours. After being ground, pass through a 200-mesh standard sieve, put it into a high-temperature hydrogen furnace for sintering in a hydrogen environment, set the sintering temperature at 1545°C, keep it warm for 4 hours, and take it out to obtain aluminate. Its phase composition is as follows: image 3 show...

Embodiment 3

[0038] Weigh 88.6g of Ba(NO 3 ) 2 , 20g of Ca(NO 3 ) 2 4H 2 0 and 63.56g of Al(NO 3 ) 3 9H 2 O and other raw materials, the molar ratio of the three is 4:1:2, then weigh 22.12g, the mass fraction is 10% of Y (NO 3 ) 3 ·6H 2 0 was dissolved in 3L of deionized water to form a nitrate solution, and 152g of excess (NH 4 ) 2 CO 3 Dissolve in deionized water as a precipitant. After the precipitation is complete, wash the precipitate with deionized water and ethanol solution, then place it in a 120°C oven for drying to form a precursor powder, and then put it in a muffle furnace for decomposition. The decomposition temperature is 750°C and the temperature is kept for 4 hours. After being ground, pass through a 200-mesh standard sieve, put it into a high-temperature hydrogen furnace for sintering in a hydrogen environment, set a sintering temperature of 1555°C, keep it warm for 3.5 hours and take it out to obtain aluminate, whose phase composition is as follows Figure 4 ...

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Abstract

The invention relates to an emission active salt for a barium-tungsten cathode and a preparation of the emission active salt, and belongs to the technical field of the preparation of a hot cathode electron emission material. Precursor powder of the salt is prepared by a liquid phase coprecipitation method by using Ba(NO3)2, Ca(NO3)2.4H20, Al(NO3)3.9H2O and Y(NO3)3.4H2O as raw materials and (NH4)2CO3as a precipitant, and a final emission active substance salt is obtained by roasting the precursor powder. After the barium-tungsten cathode is fully activated, the pulse emission current density reaches above 12A / cm<2> at 1100 DEG C b; and under 1100 DEG C b, the secondary emission coefficient reaches up to 4. The active salt prepared by the method is impregnated into the barium-tungsten cathode to have a high primary electron emission capacity and a high secondary emission coefficient, and is expected to be used in the fields such as magnetron.

Description

technical field [0001] The invention relates to a novel emission active salt for barium tungsten cathode and a preparation method thereof, in particular to aluminate such as 411 aluminate (n(BaO):n(CaO):n(Al) for barium tungsten cathode 2 o 3 )=4:1:1) to add Y with a mass fraction of 4%-10% 2 o 3 The invention relates to the preparation of a new type of emission active salt, the barium tungsten cathode prepared by the salt has high thermal emission capability and secondary electron emission coefficient, and belongs to the technical field of preparation of electron emission thermal cathode materials. Background technique [0002] Vacuum electronic devices refer to active devices that generate signal amplification and conversion effects through the transmission of electrons or ions between electrodes in a vacuum or gas medium, and are widely used in contemporary national defense equipment, national economy, information systems and people's daily life and play an important r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01J1/142H01J9/04
CPCH01J1/142H01J9/042H01J9/045
Inventor 王金淑潘兆柳周帆杨韵斐李俊辉吴浩
Owner BEIJING UNIV OF TECH