8
Gas
The gas connection on the valve body-back is a 6 mm Swagelok positionable elbow. Instructions
on how to mount the tube in the connector can be downloaded from,
“An Installer’s Pocket Guide for Swagelok Tube Fittings (MS-13-151, R3)” page 10
http://www.swagelok.com/downloads/webcatalogs/EN/MS-13-151.PDF
The elbow can be oriented to face any direction, instructions on page 14 in the Swagelok pocket
guide.
For stable operation the backing pressure inside the body must be well regulated. A good quality
passive regulator is usually sufficient.
Electrical connections
The high voltage amplifier driving the pulsed valve is connected to the Lemo connector on the
valve body-back. Make sure that the cables and connectors are specified for 500 V rms. At 5
Bars backing pressure, the negative operating voltage must not exceed -350 V. Keep in mind that
in high pressure atmosphere discharges occur at lower electric fields, hence the voltage limit.
A delay box with microsecond resolution triggered by the laser directly or a photo diode can be
used to feed the high voltage amplifier.
If you ordered the Attotech amplifier, go directly to section “connection of Attotech amplifier”.
Otherwise, we recommend the E470-00 amplifier from PI, though other types might work as well.
Be aware that the piezo disc requires a power up to 50 W from the amplifier for kHz operation.
The shape of the electrical signal should be checked on an oscilloscope with a high voltage probe
prior to operation. Input and output impedances of the equipment must be set correctly to
preserve the signal shape.
Recommended values for the opening gate are 120-500
μ
s.
Delay box
Pulse valve
HV amplifier
0 to -350 V
120-500
s
opening
Trigger
0
1V - 3.5 V
T
0
T
1
T
2
time
0
-100 V to
- 350 V
T
0
T
1
T
2
time
G = -100