6.3 UN SAT IS FAC TORY PER FOR MANCE DUR ING DEPOSITION
NO.
SYMP TOM
PROB A BLE CAUSE
COR REC TION
1
High volt age and emis sion cur rent val ues
go up and down in de pend ently of con trols,
and there is vis i ble arc ing or heat ing at the
high-voltage in su la tors.
(a) In su lating ca pa bil ity of one or both HV
feedthroughs is break ing down be cause
they are frac tured or coated, but they are
not yet shorted to ground.
(a) Ex am ine the HV in su la tors. If they are
coated, clean them by glass-bead hon ing.
*
If dam aged, re place them.
(b) In-vacuum HV lead(s) dirty and mak ing
con tact only in ter mit tently.
(b) Clean leads by glass-bead hon ing and
re con nect se curely.
2
High volt age and emis sion cur rent are
nom i nal, but fil a ment cur rent is high. (See
power sup ply in struc tion man ual for nom i -
nal op er at ing val ues.)
(a) Two or more loops of the fil a ment’s
coils are shorted to gether.
(a) Ex am ine fil a ment care fully; re place it if
the coil’s loops are touch ing each other.
3
High volt age, emis sion cur rent, and fil a -
ment cur rent are all nom i nal, but the
melted ma te rial is ei ther al loy ing with or
erod ing the cru ci ble. Cooling wa ter may
also be boil ing.
(a) Sta tion ary beam spot is too close to
the edge of the pocket.
(a) Ap ply beam sweep, if pos si ble, or ad -
just de flec tion cur rent(s) so that the beam
is cen tered in the pocket.
NOTE: Al loying cre ates a di rect ther mal
short, which will de stroy cru ci ble in time. If
wet ting has oc curred, the ma te rial MUST
be de coup led from the cop per be fore op -
er a tion is re sumed. This can only be ac -
com plished by glass-bead hon ing the
cru ci ble.
(b) In ad e quate cool ing of ex posed pocket.
(b) 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.
4
Emis sion cur rent is lim ited at some value
be low its 1.5-A max i mum.
(a) Beam for mer is shorted to gether.
(a) Re align beam formers to cor rect gap
so they are no lon ger short ing (see sec -
tion 4.4).
(b) Emis sion cur rent is lim ited be cause:
(1) Fil a ment is in stalled back wards;
(2) not enough fil a ment is ex posed;
(3) there are shorted loops on the
fil a ment’s coil;
(4) the fil a ment is badly warped; or
(5) an ode is too far from fil a ment.
(b) Check con di tion of fil a ment. If it is in -
stalled in cor rectly, has shorted turns, or is
warped, re place it. If no fil a ment prob lems
are de tected, check po si tion of an ode rel -
a tive to fil a ment. (See sec tion 4.2 when
check ing the po si tions of these parts.)
(c) One of the flanged in su la tors in the
emit ter as sem bly is badly coated.
(c) Dis as sem ble emit ter far enough to
check con di tion of flanged in su la tors. If
coated, re place them.*
Troubleshooting
STIH-270-2PT
0101-9004-0A
6-3
*
Generally, it is possible to clean the insulators on HV feedthroughs by glass bead honing without damaging them.
However, it is best to replace the ceramic insulators in the emitter when they become coated, as they can only be
cleaned abrasively, which usually results in serious damage. If you wish to try to clean these insulators as a stopgap
measure, handle them very carefully and apply the abrasive using as little force as possible.
Содержание Temescal SuperSource2 STIH-270-2PT
Страница 54: ...Operation 3 18 0101 9004 0A STIH 270 2PT...
