OEM-TECH QBU-BT-10 kV Pockels Cell Drivers User Manual

OEM-TECH QBU-BT-10 kV Pockels Cell Drivers

Warning
This equipment produces high voltages that can be very dangerous. Please read user manual before starting operations.

Important note
please measure the output with symmetrical (differential) high voltage probe only. Measurement made with inappropriate equipment is a common cause of driver’s failure.

Overview

QBY-BT is a laboratory Pockels cell driver with following unique features:

• Wide range of output voltages – 0-4kV in one device
• Fast rise and fall times – 3-4ns
• Extra low delay/jitter in external synchronization mode
• Fully functional internal synchronization mode – pulse width is smoothly adjustable in 10-1000ns range with sub-nanosecond step, pulse repetition rate is also smoothly adjustable

The driver is perfectly suitable for control of regenerative amplifiers.

Contents of delivery
By default we supply a stand-alone version of the driver including:

• QBY-BT Pockels cell driver – 1pc
• AC/DC power supply – 1pc
• HV Output cable (15cm long) – 1pc
• Additional cables, e.g. Interface or BNC-SMA as well as demo software utility for Windows OS is available on request.

Description – top view

CONTROL

DESCRIPTION Knob

1. Edit parameters:
   • Clockwise rotation – increase the parameter
   • Counterclockwise rotation – decrease the parameter
   • Press (push) – apply changes
2. Menu navigation:
   • Rotation – menu navigation
   • Press (push) – sub-menu selection, check-box state change, parameter edit
3. Screen saver – exit screen saver screen
4. Error/warning messages – skip message

Display

**Main screen

**

Status pictograms

Description – Side view (HV Output side)

HV OUTPUT
(Harting 09 69 210 0033 housing, 09 69 281 2550 contacts):

Description – Side view (inputs and interfaces)

OWER (Switchcraft L712RALP): +24VDC, 1A power connector.

INTERFACE (Connfly electronic DS1110-01-5)

RS485 interface

3| RS485 A
4| +5VDC| +5VDC, 150mA auxiliary output
5| GND| Interface ground

SYNCRO INPUTS – 2PCS (Molex 732512201)
In external synchronization mode a trigger signal applied to Synchro Input 1 starts HV pulse at driver’s output, another trigger signal applied to Synchro Input #2 ends HV pulse at driver’s output. Signal characteristics are 5V TTL, 50 Ω both for Synchro Input #1 and #2.

SYNCRO OUTPUT (Molex 732512771)
When enabled in driver’s Settings menu, a synchro output pulse is applied to this connector. It can be used for synchronization of other equipment with the driver, e.g. when the driver is run in Internal synchronization mode. Signal characteristics are 5V TTL, 50 Ω

Safety

Warning! This equipment produces high voltages that can be very dangerous.

• Don’t be careless around this equipment
• Do not open the coverage case of the Pockels cell driver
• Do not self-repair the driver
• Do not operate without a connected load
• Avoid casual contacts of personnel with output cables and with a load
• Do not connect / disconnect cables while driver is turned on
• Do not turn the driver on if it was already damaged with water, chemicals, mechanical or electrical shock

Operations

1. Connect a Pockels cell to the driver, connect the driver to the AC/DC power supply
2. Plug in the AC/DC power supply into the mains grid
3. After the main screen is loaded, select the desired VOLTAGE,  REP. RATE, PULSE WIDTH, and the desired OPERATING MODE using corresponding buttons
4. Press START button. Since that moment the driver starts operations. It must be indicated with corresponding pictogram
5. Press STOP button to stop operations
6. Disconnect the AC/DC power supply from the mains grid

Technical notes

• Performance of the module greatly depends on load capacitance. Full performance (see also Performance section) is only achievable at 5pF load or about.
• Note: higher load capacitance reduces the maximum achievable repetition rate
• Module’s output is bipolar. It means that 4kV pulse is physically formed by applying +2kV to positive output wire and –2kV to negative (see figure below)
• Nevertheless, all descriptions of HV output are given in terms of voltage differences. Please keep it in mind!
• Both Synchro inputs have active trailing edges

Specifications

Input
Voltage| 24VDC
Current| 1A max
HV Output
Description| High voltage pulses applied to the output
Type| Bipolar
Pulse amplitude| 0-4kV adjustable
Pulse width| 10-1000ns adjustable (*)
Pulse repetition rate| Adjustable:

–          up to 5kHz at 4kV

–         up to 65kHz at low voltages See also Performance section

Rise / fall times| 3-4ns ()
Load capacitance| 5pF recommended 10pF maximum
Synchronizations
Modes of operation| External synchronization Internal synchronization
Input-to-output delay (in External synchronization mode)| <10ns
Jitter (in External synchronization mode)| <0.2ns
Cooling| Forced air cooling with embedded fan
Protections| From overheating
---|---
Environmental
Operating temperature| 0…+40°C
Storage temperature| -20…+40°C
Humidity| 10-90%, non-condensing
Mechanical**
Dimensions| 182x111x67mm
Weight| <1kg

• even shorter on request (see also How to order? section)
• even faster on request (see also How to order? section)

Dimensions

How to order?

By default we supply QBY-BT driver based on QBY-4001 board. On request we can build QBY-BT driver based on QBU-nano board of any available modification. Advantages are even faster rise and fall times, a shorter pulse width and higher output voltages. The main disadvantage is a pulse repetition rate limited with 0.5-2kHz max. Please contact us for this option.

RS485 interface description
RS485 interface description, Modbus protocol description, demo software utility for Windows OS are available on request

Performance
For continuous operation in internal synchronization modes we guarantee the performance table as follows: External synchronization mode demonstrates usually a little better performance. In the burst-mode (= short time operations) performance is increasing approximately twice and may achieve 100 kHz value at low operating voltage and load capacitance. Higher load capacitance decreases the performance.

5 pF load capacitance, 25°C ambient temperature

Voltage, kV| 0.7| 1.0| 1.5| 2.0| 3.0| 4.0
Max. rep. rate, kHz| 65| 60| 40| 25| 10| 5

Output voltage measurements

Important note: please measure the output with symmetrical (differential) high voltage probe only. Measurement made with inappropriate equipment is a common cause of driver’s failure.

Typical output

References

• QBY-BT Pockels cell driver on GaN in a case - OEM Tech

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