Dr.X Works G1-ISOK User manual

DC Photogun
G1-ISOK
product manual
version 1.1
Dr.X Works BV
Engelsbergenstraat 18
5616JC Eindhoven
The Netherlands
Phone: [phone]
www.drx.works
[email protected]orks

Contents
1 Introduction 4
2 Installation 5
2.1 Unpacking and inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Installation .................................... 5
2.3 powerrequirements................................ 8
3 Operation 9
3.1 Photogun in a Ultrafast electron diffraction experiment . . . . . . . . . . . 9
3.2 Alignment of laser beam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3 Dailyoperation.................................. 11
4 Technical specification 12
4.1 HighVoltageGun ................................ 12
4.2 Mechanical .................................... 12
5 Environmental 13
6 Maintenance 14
7 Safety 15
8 Warranty 16
9 Mechanical outline 17
A Manual gun training 18
B Matsusada High voltage safety Instructions 19
C Matsusada AU-series Manual 28
DC Photogun version 1.1 3

1. Introduction
In the 100 kV DC electron gun voltages up to 100 kV can be applied across a diode
consisting of a flat copper cathode and a copper anode with a hole, which are separated by
1 cm. The high voltage is applied through a compact coaxial HV feed-through. At 100 kV
this results in a DC electric field of 12 MV/m on the cathode surface. Ultrashort electron
bunches can be generated by photoemission with 266 nm femtosecond laser pulses, the
3rd harmonic of the 800 nm Ti-sapphire wavelength. The electron bunches are typically
created by front illumination of a bulk copper cathode through the hole in the anode, using
the laser incoupler component, but back illumination is also possible on request by using a
glass cathode on which a thin (10-20 nm) layer of copper, silver or gold has been deposited.
Using front illumination of a bulk copper cathode, a 1 µJ 266 nm laser pulse is sufficient
to generate a 1 pC electron bunch. Directly on the exit of the 100 kV DC electron gun
a magnetic solenoid lens is mounted to collimate the electron bunch, which undergoes a
strong Coulomb expansion at typical bunch charges (0.01-1 pC).
DC Photogun version 1.1 4

2. Installation
2.1 Unpacking and inspection
1. Unpack and install the Matsusada 100 kV power supply in a 19” rack. Visually
inspect for damages.
2. Unpack the USB remote control of the Matsusada power supply. Visually inspect for
damages.
3. Unpack the photogun. Visually inspect for damages.
4. Unpack the laser incoupler. Visually inspect for damages.
5. When ordered unpack the focussing and steering coil. Visually inspect for damages.
2.2 Installation
1. Place the photogun on an optical table and fix the breadboard so that it cannot move
anymore. Ground the photogun to the Matsusada power supply using a copper cable
which has a minimal area of 4 mm2.
2. Place the 100 kV power supply no further than 1.5m away from the gun since the HV
cable only has a length of 2m. Make sure the cable is not bend with force. Consult the
Matsusada AU-series manual for installation instructions, you can find the manual
in Appendix C. Please also read the high voltage safety instructions, these can be
found in Appendix B.
DC Photogun version 1.1 5

2.2. Installation
3. Disassemble the Blank CF40 flange from the front of the gun and save the bolts and
washers. Connect the laser incoupler to the CF40 flange on the front of the gun with
the CF40 copper gasket provided by DrX Works. See picture below for installation
instructions.
M6 Bolts
Washers
M6 Thread
Copper Gasket
DC Photogun version 1.1 6

2.2. Installation
4. Connect one turbo pump to the back of the photogun and another turbo pump to
the top port of the 6-way cross that houses the laser incoupler. See below for where
to connect the pumps. Make sure to add at least one (preferably non-magnetic)
pressure gauge to either the front / back turbo to monitor the pressure of the gun.
Place the gauge as close as possible to get a reliable pressure measurement.
Turbo Back
Electron Beamline
Turbo front
5. (optional) Position the focussing and steering coil behind the laser incoupler. Both
coils can be mounted using a standard optical post assembly e.g. from Thorlabs.
Connect the coils to a DC power supply. Please refer the Specsheets on the DrX
Works website (https://www.drx.works) for maximum operating currents.
6. Connect the the collimator coil to a chiller and to a DC power supply which can
minimally deliver 12A at 10V. For safety reasons please implement an interlock such
that the coil can only be operated when water is flowing through the heat-sink. This
can be done by monitoring the flow rate in the water return line.
7. Connect the CF16 bellows to the experiment (The generated electron pulse will exit
here). It is good practice to place a valve in-between the gun and the experiment so
DC Photogun version 1.1 7

2.3. power requirements
that the can be vented separately. Note that every time when the gun is vented it
needs to be trained again.
8. All vacuum flanges should now be sealed. Start pumping down the system.
9. Connect the high voltage cable coming from the photogun to the Matsusada high
voltage power supply.
10. For safety reasons please configure a pressure interlock between the controller of the
vacuum gauge and the high voltage power supply (see section 4-7 Door switch (LD)
which can be found in the Matsusada AU-series manual - Appendix C). The high
voltage may only be enabled when the pressure is below 5 ·10−6mbar.
11. In order to setup the usb control of the HV power supply please connect the USB
optical module to a computer via the supplied USB cable. Next, connect the optical
cable between the latter module and the CO-HV module. Finally, Connect the DB25
connector between the CO-HV module and the AU-series high voltage power supply.
12. Install the photogun trainer software and the USB drivers which can be downloaded
for the DrX Works website (https://www.drx.works).
13. When the pressure is sufficiently low (<5·10−6mbar) start training the photogun to
a voltage of 105 kV using the DrX Works photogun trainer software. When no usb
control of the power supply is present (we strongly advise to use automatic training)
please refer to Appendix A for manual training of the photogun. Training can easily
take a week and needs to be repeated every time the gun is vented. For safety reasons
monitor the radiation level during training and daily operation.
14. Once the gun has been trained operate the gun at a voltage no larger than 100 kV.
For safe operation please inform Chapter 3
2.3 power requirements
The Matsusada AU-series power supply operates on single phase AC mains power between
200-240 VAC (110V available on request) with a frequency between 50 and 60 Hz.
DC Photogun version 1.1 8

3. Operation
3.1 Photogun in a Ultrafast electron diffraction experiment
Example of a ultrafast electron diffraction system including compression and deflection
cavity for electron bunch compression and temporal characterization.
60.00
60.00
80.00
850.82
471.20
281.63
42.25
18.39
379.62
343.73
155.78
60.00
DC Photogun version 1.1 9

3.2. Alignment of laser beam
3.2 Alignment of laser beam
Align the laser beam on the cathode and make sure that the reflected beam exits via the
laser in-coupler. Focus the electron beam on the cathode. Monitor the size of the laser
spot on the cathode via a virtual focus on a UV camera. Monitor the reflected beam on a
UV camera (can be the same camera) to check if the beam is aligned to the center of the
cathode. The machining groves of the cathode are imprinted on the reflected beam. The
center of these rings should overlap with the center of the laser beam.
Cathode information
Material : High purity oxygen-free copper (>99.99%)
Work function : 4.31 −4.91 eV
Central wavelength : 267 nm (4.65 eV)
Damage Threshold : 100 J/m2for 100 fs pulse
Reflectivity : 43% (Theoretical)
Emission area : flat circular area in center (1 mm in diameter)
Damage emission : 103−104electrons per µm2
Efficiency : 10−5electrons / photon
Angle of incidence : ∼4.5◦
Polarization effects : Negligible due to head-on irradiation
183.88
14.60
169.36
15.73
60.77
91.10
45°
45°
9°
DC Photogun version 1.1 10

3.3. Daily operation
3.3 Daily operation
Operate the gun at a voltage not higher than 100 kV. The 100 keV electron gun and
electron beam can produce radiation so for your own safety monitor the radiation level
during operation.
DC Photogun version 1.1 11

4. Technical specification
4.1 High Voltage Gun
Normal operation Training
Maximal Voltage (kV) 100 105
Maximum Current (µA) 10 100
4.2 Mechanical
Power Supply Photogun
Dimensions (LHW) 19” x 2U x 500mm 390 ×420 ×520 mm
Weight approx. 20kg approx. 50 kg
DC Photogun version 1.1 12

5. Environmental
Operating temperature range 0 to 40◦C ambient, however temperature fluctuations should
be kept as small as possible to prevent drifting. The DC Photogun should be operated in
a clean environment. On no account must the DC Photogun be exposed to water ingress.
DC Photogun version 1.1 13

6. Maintenance
No maintenance is required in normal operation and there are no user-serviceable parts
within the DC Photogun. Each product is factory tested and supplied with a set of test
results. If degradation in performance to below the specified levels occurs, or a failure is
suspected, then the complete unit should be returned to the manufacturer together with
details of the fault.
DC Photogun version 1.1 14

7. Safety
Hazardous voltages are present within this line-operated unit. Do not remove any panels.
The DC Photogun must be grounded. Line supply is filtered within the amplifier. A
replaceable fuse is fitted to the line input connector which should be changed only when the
AC power is disconnected from the connector. Monitor radiation levels during operation.
Please review the high voltage safety document which can be found in Appendix B and C.
DC Photogun version 1.1 15

8. Warranty
Dr.X Works B.V. warrants for 2 years from date of shipment that the goods supplied will be
in full compliance with the agreed specifications and will be free from defects in material and
workmanship. Any and all other warranties (except of title) express or implied, relating to
fitness for particular purpose, merchantable quality or otherwise are expressly disclaimed.
Seller will not be responsible for special or consequential loss or damages. Liability shall
be limited to the repair or replacement of defective products subject to the return of the
product intact, and un-tampered with by the buyer.
DC Photogun version 1.1 16

9. Mechanical outline
DC Photogun version 1.1 17

A. Manual gun training
We strongly advise to training the gun using the DrX photogun training software.
When the pressure is below 5 ·10−6mbar you can start ramping the voltage. While doing
this it is advisable to monitor radiation level and vacuum pressure level. An interlock
should be installed on the Matsusada high voltage power supply to prevent operation of
the high voltage when the vacuum is above 5 ·10−6mbar.
1. Set the maximum current to 100 µA
2. Slowly increase the voltage to 40 kV at ramp speed of 2 kV/s
Small corona discharges may appear. When a breakdown occurs (the red led on
the Power supply is off) decrease the voltage setting with approximately 1 kV and
push the red button twice to enable the power supply. Hereafter slowly increase the
voltage again.
3. When reaching 40 kV - reduce ramp speed to 1 kV/s
4. When reaching 70 kV - reduce ramp speed to 0.25 kV/s
5. In manual mode it is possible to increase the voltage just above the nominal voltage
(for a 100kV power supply this is approximately 102.5kV) . Don’t increase the voltage
over 110 kV. Train the photogun at a slightly higher voltage (102.5 kV) than the
nominal operating voltage.
6. Decrease the voltage to the nominal voltage (100 kV) before using the gun.
7. Set the maximum current to 10 µA
DC Photogun version 1.1 18

B. Matsusada High voltage safety Instruc-
tions
DC Photogun version 1.1 19

www.matsusada.com
Safety and Usage of
High Voltage
Power supply
Highvoltage power supplies must be handled with care.
"We use ours carefully, so we'll be fine."
"We never had any problems, so we're probably ok."
... But, are you sure there is nothing you've neglected or overlooked?
Let Matsusada Precision, which specializes in the manufacture of
high voltage power supplies, show you the correct way to
use a high voltage power supply.