Drawing Number: 21096
Revision: NR
SERIES 134A20 TOURMALINE PRESSURE BAR GENERAL OPERATION MANUAL
1
1.0
INTRODUCTION
Series 134A20 Tourmaline Pressure Bar with In-
Line Amplifier consists of a Series 134A
Tourmaline Pressure Bar connected to a three-inch,
low-noise cable that connects into Series 402 In-
Line Source Follower Voltage Amplifier. See
Figure 1.
The Tourmaline Pressure Bars is a high-pressure,
fast rise time, suppressed-resonance blast sensor
ideal for single-shot, high-frequency measurements
of incident or reflected shock wave pressures found
in studies of plasma physics and hyper-sonics.
Ranges up to 20,000 psi are available.
The Series 134A20 is typically powered by a PCB
Series 480 ICP
®
Power Conditioner (constant
current) or equivalent. Power and signal is
conducted over a single-conductor coaxial cable
with the shield serving as a signal return. Output
from the power conditioner is usually fed into a
high-speed readout instrument, such as a digital
oscilloscope.
2.0
DESCRIPTION
The Series 134A20 Tourmaline Pressure Bar with
In-Line Amplifier consists of three components
attached together and calibrated as a system. The
Series 134A Tourmaline Pressure Bar senses and
transduces a pressure/shock wave into a high-
impedance, electrostatic charge. This charge is sent
through the three-inch, low-noise cable into the
Series 402A In-Line Amplifier, where it is
converted into a low-impedance voltage with less
than 100 ohms output impedance. See Figure 2.
The circuit in the in-line amplifier consists of a
MOSFET input IC with a very high trans-
conductance, resulting in a voltage gain that is very
close to unity. The source terminal "follows" the
gate voltage instantaneously, without a shift in
phase (i.e., the amplifier is non-inverting).
2.1
SYSTEM OUTPUT
The system output of Series 134A20 is a low-
impedance output governed by the following
equation:
3
C
2
C
1
C
Q
V
where:
V = voltage sensitivity of system (V/psi)
Q = charge output of Tourmaline Bar (pC/psi),
Model 134A
C1 = capacitance of Tourmaline Bar (pF),
Series 134A
C2 = capacitance of three-inch cable (pF),
Model 003A000-03
C3 = capacitance of input of in-line amplifier
(pF), Series 402A
A system calibration is supplied with Series
134A20 that shows the system output in mV/psi.
3.0
INSTALLATION
See the Installation Drawing included in the back
of this manual for a description of the Tourmaline
Bar and its installation.
Install in a gas medium
where the measurement is to be taken. The sensor
can not be normally used in a liquid medium.
