These compact small, rugged gaps
were designed for high-reliability
applications where size, switch
speed, and ability to withstand
rugged missile environmental condi-
tions of extreme shock, temperature,
and vibration are required. They are
designed for switching peak currents
up to 10kA at operating voltages
from 2.0 to 4.0 kV with reliable
triggering voltage of 2kV. Prefires
and failure to fire have been fully
evaluated in the basic gap designs.
Switching speeds of 70ns with trigger
pulse energies as low as 500 micro-
joules is typical.
Minia ture Trigge re d
Spa rk Ga ps
Pe rform a nc e
Cha ra c te ris tic s
The triggered spark gap is a three
element, gas-filled, ceramic-to-metal,
hermetically sealed, pressurized
switch that operates in an arc dis-
charge mode, conducting moderately
high peak currents for short dura-
tions. Commutation between two
main electrodes is initiated by a
trigger pulse.
Electrical characteristics are
determined by testing in the circuit
shown in Figure 1. The output circuit
consisting of the switch, a 0.2 µF
capacitor, and a 0.25 ohm current
viewing resistor (CVR) is typical for life
testing. It closely matches the condi-
tions found in many typically used
circuits. For function testing, the 0.25
ohm CVR is replaced with a 0.005
ohm CVR.
Applic a tions
Typical data taken with a 0.005 ohm
CVR are shown in Figure 2. This
curve contains traces of the trigger
voltage and conduction current. First,
the trigger voltage rises to the point
of trigger breakdown. Then there is a
period designated “turn-on” or delay
time during which the arc is forming
followed by main gap conduction.
This delay time varies from 50 to
1500 ns depending on gap operating
voltage, trigger mode, amplitude and
pulse width.
Precision timing and firing for in-flight
functions such as rocket motor igni-
tion, warhead detonation and missile
stage separation. Each of these
Conduction
Current
applications involves the activation
of electro-explosive devices such as:
Trigger
Voltage
Exploding bridgewire (EBW)
•
Exploding foil initiator (EFI)
•
Time
Electronic safe and arm (ESA)
•
Turn-on
Time
Slapper/detonator
•
Figure 2. Trigger Voltage Breakdown and
Main Gap Conduction Current
5 mΩ
2.4-3.5 KV
+
OE
GAP
AE
C
T
NORMAL
OPERATING
REGION
1.0 mΩ
+
+
0.2 µF
T
V
T(IN)
TR
KNEE
2N6798
CVR
—
V
T(min)
SELF-BREAKDOWN
REGION
CUTOFF
REGION
OPERATING
RANGE
V
C
T
T(IN)
Volts DC
20-40
µF
2.2
XFMR
TR-2189/2206
100-200
0.10 TR-2190/2207
E-E(co) E-E(min)
E-E(max)
SBV
E-E = ELECTRODE-TO-ELECTRODE VOLTAGE
Figure 1. Triggered Spark Gap Test Circuit
Figure 3. Transfer Characteristics
p a g e 2
P e r k in E lm e r Op to e le c tro nic s
PERKINELMER [ PERKINELMER OPTOELECTRONICS ]
