ATTOTECH GR020 Manual - Page 10

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Operation

The valve must be cooled for steady operation and be powered by a high voltage amplifier

delivering negative voltages. Maximum negative voltage is -350 V. The backing pressure in the

valve body should be set up to maximum 5 bars.

Turning on-off procedure

The following is a general presentation of the turning on/off procedure. If you ordered the Attotech

driver, you may skip to section "Turning on-off with the Attotech Driver".

The trigger frequency must not exceed 1 kHz and the opening gate must be in the range 120μs to

500μs. Once the cooling is on and the backing pressure (1-5 Bar) is steady, progressively

increase the negative voltage driving the valve until you see the pressure in your experimental

chamber rising. It should be noted that the opening is not linear: the valve stays closed up to a

certain threshold (called hereafter the opening voltage) after which the amount of gas sent in the

target increases rapidly with the voltage. Be careful when approaching the typical opening

voltages given in the table in the "specifications" section.

Once the right amount of gas is set, you should let it run for approximately 15 minutes to reach

a thermal steady state. During this time, it might be necessary to slightly readjust the high

voltage.

Note that the opening voltage depends on the gas used (see table in the specifications section)

Scan the delay controlling when the valve starts to open to find temporal overlap of the released

gas and your laser.

To turn off the valve, first, turn down the negative driving voltage, then, turn off the electrical

power, the cooling and close the backing gas bottle.

Turning on-off procedure with the Attotech Driver (Option)

Preliminary checks



Make sure the Main power switch (#1) is off.



Check that the low voltage signal is not connected to the high voltage amplifier, (#5) is

off.



Fully turn counter clockwise the Peak voltage adjustment knob (#4)



Make sure that the TTL signal feeding the Gate input connector (#8) is positive. The

trigger frequency must not exceed 1 kHz and the opening gate must be in the range

120μs to 500μs.



Make sure you are using the right power voltage (120/240V) and that the amplifier's

socket is plugged.



Turn on the cooling of the valve

Turning on



Apply a steady backing pressure (1-5 Bar) to the gas inlet of the valve.



Turn on the Main power switch (#1)



(Optional). Progressively turn clockwise the Peak voltage adjustment knob (#4) and use

an (high Z) oscilloscope to monitor the signal available on the Low Voltage Monitor

connector (#6). It should show an image of the input gate with the amplitude displayed in

the Peak Voltage indicator (#2) divided by 100. Make sure it is positive. Turn the Peak

voltage adjustment knob (#4) back to zero.