NOTE
If the longitudinal deflection current is controlled by either the
e-beam power supply or a standard (i.e., non-bipolar) beam sweep
controller, the beam spot should move toward the emitter assembly
as you increase the longitudinal deflection current. If increasing the
current moves the beam in the opposite direction, the leads to the
longitudinal coil are reversed. In that event, switch off the electron
beam power supply, disconnect the coil-current cable at the sweep
controller, vent the vacuum system to atmosphere, and reverse the
wires for the longitudinal current. The easiest place to reverse these
wires is at the terminal strip where they connect to the vacuum
cubicle’s wiring. DO NOT operate gun with the longitudinal coil
leads improperly connected. Doing so will distort the beam and
seriously shorten the lifetime of the permanent magnet. Note that this
problem will not arise if you are using a bipolar sweep controller.
15.
Once the flu o res cence is cen tered in the pocket, use the po si tion con trol(s) on ei ther the e-beam
power sup ply or the beam sweep con trol ler to check the po si tion in ter lock lim its. If the source is not
con trolled by a beam sweep con trol ler, use the power sup ply’s lon gi tu di nal po si tion con trol to
slowly run the beam spot from one end of the pocket to the other. At both the front and rear ends, the
beam should be ex tin guished just be fore it gets to the edge of the cop per. If the source is con trolled
by a sweeper, then check the po si tion in ter lock lim its in both axes. If the lim its are not set prop erly,
switch off the high volt age and the fil a ment cur rent and fol low the ap pro pri ate pro ce dure to set them
cor rectly. Then be gin this pro ce dure again from step 1.
CAU TION
If the beam impinges on the edge of the crucible, copper will be
evaporated and the run will be contaminated. Serious damage to the
crucible will also result if the source is allowed to continue operating
with the beam spot in this position.
16.
Once you have ver i fied that the po si tion in ter lock lim its have been set cor rectly, slowly in crease the
emis sion cur rent un til the beam spot ap pears in the same area as the flu o res cence.
17.
If you are us ing a sweep con trol ler, switch on its sweep func tion and es tab lish an ap pro pri ate pat -
tern. If not, re ad just the beam spot’s po si tion as de sired to op ti mize the heat ing and evap o ra tion of
the tar get ma te rial. For many ma te ri als, evap o ra tion rates can be im proved if the beam spot is
slightly be hind pocket cen ter.
18.
Slowly in crease the emis sion cur rent un til the de sired evap o ra tion level is reached.
Op er a tion from this point on will vary from ap pli ca tion to ap pli ca tion. If you en coun ter any prob lems in op er -
at ing the source, re fer to the trou ble shoot ing pro ce dures in Sec tion 6.
CAU TION
Whenever you prepare to vent the system, allow two to three
minutes for the filament and the rest of the emitter assembly to cool
first. Exposing a hot filament to atmosphere will cause rapid
oxidation and shorten filament life.
Operation
3-8
0101-9004-0A
STIH-270-2PT
