NO.
SYMP TOM
PROB A BLE CAUSE
COR REC TION
4
cont.
(d) Bad con nec tions to HV leads, which
may in volve the con nec tions to the fil a -
ment bus bars, the con nec tions to both
sides of the HV feedthroughs, or the con -
nec tions to the fil a ment trans former.
(d) Check for loose con nec tions or ox i -
dized sur faces at all HV ter mi nals. If sur -
faces ap pear ox i dized, sand or file them
un til bright. Clean in-vacuum fil a ment
leads by glass-bead hon ing and re at tach
them, be ing sure to make tight, se cure
con nec tions.
(e) Volt age of fil a ment cur rent is low. (This
volt age should be 12 V ac.)
(e) Check the con nec tions at the fil a ment
trans former and the out put of the e-beam
power sup ply’s gun con trol cir cuit.
5
Short fil a ment life.
(a) Vac uum cham ber does not evac u ate
prop erly be low 5 x10
-4
torr.
(a) Leak-check the vac uum cham ber.
Clean sys tem. If hivac pump is a dif fu sion
pump, change its oil. If it is a cryopump,
change its trap.
6
Pro nounced drop in de po si tion rate.
(a) Beam den sity may be too high, caus -
ing cav i ta tion of mol ten pool.
(a) Re duce beam den sity by ex pos ing
more of the fil a ment or by chang ing the
po si tion of the pole piece ex ten sions.
(b) The per ma nent mag net is so weak that
the beam can not be cen tered lon gi tu di -
nally.
(b) With gun op er at ing at low power,
check beam-spot po si tion with zero lon gi -
tu di nal coil cur rent ap plied. If spot is too
far to ward rear of source (see Fig ure 6-1),
re place per ma nent mag net or have it
regaussed.
(c) Mag netic in ter fer ence from an other
e-beam source mounted in the same
cham ber.
(c) Make sure that mag netic shield ing is
cor rectly in stalled be tween the sources
(see sec tion 2.4 for in struc tions).
(d) Other mag netic fields are af fect ing
beam po si tion.
(d) Make sure gun is iso lated as
com pletely as pos si ble from any other
pos si ble source of mag netic in ter fer ence.
(e) In ad e quate cool ing.
(e) Check to see that the gun’s cool ing
wa ter is chilled to max. 20° C and that its
flow rate is at or above the min i mum value
spec i fied in sec tion 1.4.
7
Beam power will not go above 5 kW.
(a) Fil a ment is in stalled back ward.
(a) In stall new fil a ment, mak ing sure that it
is in stalled the right way around. (See sec -
tion 4.2 for in struc tions on re plac ing fil a -
ments.)
8
Emis sion cur rent drifts af ter a long pe riod
of op er a tion.
(a) One or more of the emit ter’s flanged
in su la tors is cracked.
(a) Dis as sem ble emit ter far enough to
check con di tion of the flanged in su la tors.
Re place any cracked in su la tors found.
9
Evap o ra tion rate drops and, con cur rently
there is a sig nif i cant broad en ing of the
beam spot. In ad di tion, the cool ing wa ter
may boil if the lat eral `tails’ of the beam
spot touch the edges of the pocket.
(a) Fil a ment has be come warped.
(a) Re place the fil a ment, mak ing sure that
1/4 to 1/3 of the fil a ment’s coil is vis i ble
be low the beam for mer.
Troubleshooting
6-4
0101-9004-0A
STIH-270-2PT
Содержание Temescal SuperSource2 STIH-270-2PT
Страница 54: ...Operation 3 18 0101 9004 0A STIH 270 2PT...
