What is the temperature reached by cathode in order to produce plasma

1.	What is the temperature reached by cathode in order to produce plasma beam?
A.	12000 ¬¨¬®‚Äö√†¬¥C
B.	18000 ¬¨¬®‚Äö√†¬¥C
C.	28000 ¬¨¬®‚Äö√†¬¥C
D.	40000 ¬¨¬®‚Äö√†¬¥C
Answer» D. 40000 ¬¨¬®‚Äö√†¬¥C

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