
The FELIX diagnostic station is the first station in the FELIX optical transport system. The FEL pulse is sampled online for spectrum and pulse period/amplitude-characteristics and then sent on to the various user stations. Several attenuators and filters are available. Pulse slicing can be performed here. FELIX is horizontally polarized in the diagnostic station.
Optical Hardware
[edit | edit source]Attenuators
[edit | edit source]There are two sets of IR attenuators:
Short wavelength
[edit | edit source]Lasnix model 102, serial #192 (4–36 µm) Attenuator Colloquial name Transmission (%) Attenuation (dB) 1 sw3dB 47 3.28 2 sw5dB 28 5.53 3 sw10dB(1) 11 9.59 4 sw10dB(2) 9.5 10.18 5 sw10dB(3) 9 10.46
Long wavelength
[edit | edit source]Lasnix model 224, serial #109 (30–320 µm) Attenuator Colloquial name Transmission (%) Attenuation (dB) 1 lw3dB 50 3.01 2 lw5dB 31.5 5.02 3 lw10dB(1) 10.1 9.96 4 lw10dB(2) 9.9 10.04 5 lw10dB(3) 10.1 9.96
spectrometer tank
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spectrometer
[edit | edit source]Please check for correctness, is it still up to date?, information found in Thesis of Guido Knippels (1996), "The Short-Pulse Free-Electron LAser: Manipulation of the Gain Medium" , page 26:
The spectrometer, (SpectraPRo VM-504, Acton Research, Acton MA, USA) contains 3 gratings, mounted on a remotely controlled turret. It accommodates the wavelentghrange from 5 - 110 um. The spectrum is recorded for every individual macropulse with a 48-channel pyroelectric detector array, with 600 um pitch (LIM 221, Infratec, Dresden, Germany.) Each channel is sampled with 12 bits resolution, and the bandwidth of the detector and amplifiers is 1 MHz (MKHSAD2, Microkey, Noordhoorn, The Netherlands), resulting in a 0,5 us time resolution.
All shots measured with the spectromere are saved here: \\hfmlfelixdisk\hfmlfelixdisk\data\fft\spectrometer.
Software
[edit | edit source]The FELIX diagnostic station is remotely controllable via the Stepper driver rack, which can control 5 devices which are located inside the diagnostic station vacuum chamber.
The motors are in openloop mode and are fitted with either one or 2 limit/home switches.
MQTT Topic tree
[edit | edit source]Read
[edit | edit source]| topic | description |
|---|---|
| FELIX/diagnostics/axisx/position | the actual step position of the stepper motor. |
| FELIX/diagnostics/axisx/state | status text of the axis. |
| FELIX/diagnostics/axisx/enabled | status boolean if the driver has the stepper coils energized. |
| FELIX/diagnostics/axisx/moving_forward | status boolean if the stepper motor is moving forward. |
| FELIX/diagnostics/axisx/moving_reverse | status boolean if the stepper motor is moving reverse. |
| FELIX/diagnostics/axisx/forward_limit_active | status boolean if the stepper motor is hitting the forward limit switch. |
| FELIX/diagnostics/axisx/reverse_limit_active | status boolean if the stepper motor is hitting the reverse limit switch. |
| FELIX/diagnostics/axisx/overheating | counter which increments when a motion is being performed, and decreases if stationary it disables motion if it gets to high. |
| FELIX/diagnostics/axisx/error out | JSON wrapped error out cluster from VISA errors. |
| FELIX/diagnostics/axisx/VISA resource name | COM port which it communicates to. |
| FELIX/diagnostics/servers | List of servers for this device. |
| FELIX/diagnostics/clients | List of clients for this device. |
| FELIX/diagnostics/MOTD | Message of the day |
Write
[edit | edit source]| topic | message | action |
|---|---|---|
| FELIX/diagnostics/axisx/commands/decellarate_stop | True | slowly stop the motion, by decreasing the speed. |
| FELIX/diagnostics/axisx/commands/setpoint_position | 1500 | set the number of motor steps, where the axis should move to. |
| FELIX/diagnostics/axisx/commands/move_to_position | True | move to the motor position which is set in the setpoint topic. |
| FELIX/diagnostics/axisx/commands/abrupt_stop | True | Stops the motion immediatly, without slowly slowing down the speed. |
| FELIX/diagnostics/axisx/commands/setpoint_speed | 2000 | speed setting of steps per second. |
| FELIX/diagnostics/axisx/commands/setpoint_accelerate | 1000 | accelerate/braking speed setting of steps per second per seoond |
| FELIX/diagnostics/axisx/commands/move_home | True | accelerate/braking speed setting of steps per second per second |
Settings
[edit | edit source]These settings are read from a config file stored locally on the machine which runs the CM. These settings get published to the felixbroker after reading them from the config file.
The config file also contains the option to force the COM ports and whether the axis should be enabled or not.
| topic | message | action |
|---|---|---|
| FELIX/diagnostics/axisx/settings/active | True | Enable communication with this axis com port. |
| FELIX/diagnostics/axisx/settings/description | Beamsplitter Wheel | Text field which contains a axis description of which it drives. |
| FELIX/diagnostics/axisx/settings/position0 | 118000 | preset motor step position. |
| FELIX/diagnostics/axisx/settings/position1 | 170000 | preset motor step position. |
| FELIX/diagnostics/axisx/settings/position2 | 180000 | preset motor step position. |
| FELIX/diagnostics/axisx/settings/position3 | 190000 | preset motor step position. |
| FELIX/diagnostics/axisx/settings/position4 | 200000 | preset motor step position. |
| FELIX/diagnostics/axisx/settings/position5 | 250000 | preset motor step position. |
CM - Stepper Driver Rack.exe
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This program is used to communicate with the driver rack. It runs on the machine felsax which is located near the diagnostic station.
It connects with MQTT and can be controlled remotely by the user interface.
This devices communicates with 5 COM ports which are connected to a USB hub inside the 19"rack.
UIM - Stepper Driver Rack.exe
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This program can be run from any computer which is connected to the machine-(green) or usernetwork(yellow).
In order to control a device the user has to become Master Operator.
Devices to control
[edit | edit source]Beamsplitter Wheel
[edit | edit source]The Beamsplitter Wheel is a rotary stage with 6 defined positions with 1 home switch at position 0
| Position | Steps (approx.) |
|---|---|
| None | 0 |
| None | 46k |
| Mirror | 92k |
| 45-150um (PP) | 138k |
| 45-150um (PP) | 188k |
| 0-45um (CsI) | 236k |
Beamsplitter Diamond
[edit | edit source]Not implemented (yet)
Translation stage (Focussing of FELIX)
[edit | edit source]Not implemented (yet)
Spectrometer Slit
[edit | edit source]Not implemented (yet)
Needs mechanical mount for motor to fit the slitknife adjuster
Pulse slicer
[edit | edit source]This motor is able to put the Pulse slicing silicon slab inside the FELIX beam.
The inside position is protected by the forward limit switch.
The outward position is blocked mechanically by a screw.
| Position | Steps (approx.) |
|---|---|
| In | 105k |
| Out | 0 |
Vacuum routines
[edit | edit source]Purging the diagnostic station
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Evacuating the diagnostic station
[edit | edit source]| Step | Action | Detail | ||
|---|---|---|---|---|
| 1 | Close the lid. | |||
| 2 | Close the purging valve. |
| ||
| 3 | Put on the top cover clamps. |
| ||
| 4 | Turn on the pump controller by pushing the ON button. |
| ||
| 5 | Wait until the pressure reaches UR*E-4 after this wait for another half an hour | |||
| 6 | Open the incoming Beamline valve. |
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| 7 | Open the outgoing Beamline valve. |
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| 8 | Put the pump station valve in protected by turning the key. |
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Notes and remarks
[edit | edit source]- The FELIX beam is horizontally polarized at the entrance of the diagnostic station.





