The tungsten filament cathode is heated to what temperatures in EBM?

1.	The tungsten filament cathode is heated to what temperatures in EBM?
A.	1000 to 1500 ¬¨‚àë¬¨¬µ‚àö‚â†C
B.	1500 to 2000 ¬¨‚àë¬¨¬µ‚àö‚â†C
C.	2500 to 3000 ¬¨‚àë¬¨¬µ‚àö‚â†C
D.	3500 to 5000 ¬¨‚àë¬¨¬µ‚àö‚â†C
Answer» D. 3500 to 5000 ¬¨‚àë¬¨¬µ‚àö‚â†C

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