6 – 10
Transpector SPS Operating Manual
filament would stay on and react with the oxygen, producing relatively volatile
tungsten oxides, until the filament diameter had been reduced to the point where
the tension on the wire was sufficient to cause the wire to pull apart.
depicts an Transpector SPS over-pressure trip calculation. The total
pressure current curve after 5E-1 is due to the pure collisional scattering. Without
collisional scattering, it would be linear. The point where the CIS total pressure
current and DAC line meet is called the over-pressure trip point. When the total
pressure current exceeds the DAC line (Region II) the filament is turned off.
NOTE:
In Region II, there is a six second delay in turning emission on and off.
At 5 Torr in Region III, there is no overpressure and no emission error, but the
filament would last only hours. At 100 Torr, the filament would be destroyed
instantly.
Figure 6-2 Transpector SPS over-pressure trip calculations
6.6 Pneumatic Digital Pressure Switch and Pressure Gauge
The Pneumatic Digital Pressure Switch and Pressure Gauge:
provide a visual display of the air (or nitrogen) pressure provided to the
pneumatic block
ensure proper pressure for the Transpector SPS to function. If the pressure has
decreased below 58 psi (3.999 bar) [399.9 kPa] or exceeds 100 psi (6.895 bar)
[689.5 kPa], the Transpector SPS system will shut itself down
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
1.E+08
1.E+09
1.E-11
1.E-10
1.E-09
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02
F
ila
m
e
n
t L
ife
tim
e
in
O
2
/H
2
O
(s
)
Io
n
C
u
rr
e
n
t
(A
m
p
s
)
Ion Source Total Pressure (Torr)
SPS Overpressure Trip Calculations
Collected
DAC = 150
Lifetime (s)
CIS total pressure current
filament will stay
on in this region
Region I
filament will turn
off in this region
Region II
filament
will stay
on and be
destroyed
Region III
Filament
