When the electrical process is performed in the second atmosphere, such as in a gas of a carbon compound, in order to suppress the change of the partial pressure of the gas in {TAIL ~ the vacuum container} over time and in order to suppress {HEAD ~ the range} of partial pressure distribution in the vicinity of the electron emitting element, the following measures are taken 
When the electrical process is performed in the second atmosphere , such as in a gas of a carbon compound , in order to suppress the change of the partial pressure of the gas in { TAIL ~ the vacuum container } over time and in order to suppress { HEAD ~ the range } of partial pressure distribution in the vicinity of the electron emitting element , the following measures are taken
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