support posts 46 the support posts or pins 46 and 48 are preferably crimped over the filament 50 generally as shown with an extending tail 44 directly in contact with the wall of the extractor cup 40 the filament pigtail 44 may be connected to the wall by a braze alloy with the connection made in the embodiment of fig1 or the filament pigtail may simply act as springy wire which maintains contact with the extractor including during the high temperature operation of the tube fig6 shows another variation for direct connection with the extractor cup 40 a the filament 52 in this arrangement is secured to only a single filament support post or pin 54 and extends to the extractor cup 40 a where it is permanently secured and where the filament is supported the extractor cup may have a side slot or hole 40 b for receiving the end or leg of the filament 52 the side hole or slot 40 b can be filled with a conductive material that cures upon firing alternatively the end of the filament 52 could be brazed to the extractor wall without a slot or it could be coated with a braze alloy and permanently secured to the wall upon heating as in the embodiment of fig1 in this form of connection the extractor cup serves as one lead of the filament power source and it is connected to a lead 56 extending up from the base of the cathode assembly and from the catheter not shown then connected by a conductor 58 to the wall of the extractor cup 40 a if the lead 56 reaches the surface of the base 60 which may in some embodiments comprise a seal material then the electrical connection 58 can comprise.