BL0M0 screen system
BL0M0 screen system
The BL0M0 beamblock and screen system was NEWLY installed June / July 2018
Essentially the blocking of the FEL beam by the screen and the beam profile viewing have been separated. The beam block is operated as before "the screen" with the same buttons. To look on the beam profile a screen has to be moved in separately with the "move screen to PG / BL" buttons.
Drawings by Svea:
Beam block and Crystal are moved out:
Beam block moved in and crystal in parking position between beam paths:
Beam block
- NOTE the Beam block has the same functionality as the screen before. It is connected ( and can be operated via) the FLASH vacuum interlock as before. Thus if the Beamblock is IN, the FEL beam is blocked in the logic of the Interlock system
- The screen (YAG crystal)) is NOT in the interlock and can not be used to block the beam when in the interlock logic ... it is no block - it is only for looking at the beamprofile !!
- The Beamblock is controlled by the Vacuum SPS and moved via pneumatic
- DOOCS address: TTF2.FEL/HASY.SCREEN/L0/
Screen / Ce:YAG
Crystal
- Crystal and camera are mounted together on a linear motorized stage. Thus the crystal is always in the focus of the camera, however the Camera crystal combination has to be moved to the corresponding position in the beamline . Either to BL , PG or in the parking position ( named "out") between the BL and PG position.
- the red circle in the center has 5 mm diameter
- The camera is equipped with an Iris ( RASPI controlled P iris). for more details see here
- The Ce:YAG crystal is mounted at 45 deg to the beam and the camera, thus if the image is quadratic the beam should be round
The panel indicated if the crystal is in or out and provides always the buttons to move the buttons to the beamline which is set by M0 ( or to be moved out):
retraction
In order to protect the Ce YAG crystal from too much radiation, we implemented a system that retracts the crystal automatically after several minutes .
The idea is, that the crystal can be used for tuning and looking at the beam profile but NOT as beamblock (which is now a separate device). In order to avoid too much moving in and out of the crystal, there is a button (in the red warning box) which resets the timer. If the button is pressed the time window starts again and the crystal stays in ...
It is to note, that before the crystal is retracted automatically it checks if the beam block is in. If this is not the case, the beam block is moved in BEFORE the crystal is retracted ...
Beamprofile
There is also a beamprofile monitor available calculating the beam diameter and divergence (to be started from the upper panel button "Beamprofile") :
ROIs
Since there may be a somewhat different setting needed for the ROIs for BL and PG there is the option (in the expert settings) to set the ROIs different fror PG and BL. The move buttons also set the according ROIs ( moving to BL sets the BL ROIs...). It is also checked that the correct ROI is set when moving the screen . A warning is displayed if the ROI is not the same as in the reference values.
Expert Settings
detailed settings and restarting of the servers can be done by experts on the expert tab:
Reference Values for the camera
Reference image for the camera settings 
:
The jddd panel also checks for these values otherwise an error message will be displayed
Details of the installation
Images of the setup::
Motor
- The motor driving camera and crystal is: mot37 at hasfmirr
- it is connected via patch panel PPBDA M11
- more details in this logbook entry
Crystal
- The Crystal is a 30 x 30 mm Ce:YAG crystal (0.2 mm thick) with a roughened Si scattering (0.6 mm thick) screen behind) mounted at 45 deg to the beam and the camera.
- Camera calibration: For x and for y we have 22 pixel per mm. Thus if the image is quadratic the beam should be round. The crystal is still not quadratic since we see the x dimension shrinked by sqrt(2).
Iris
- the Iris is controled by haskrpiris08 192.168.58.192
- it is connected to the plug "28c-Halle-106 rechts"
- up to now there is no remote power switch installed for the Raspy ... to come
Camera
- The camera is a standard Basler acE 1300 gm
- The camera is mounted upside down thus the "rotation by 180 deg" has to be activated in the camera server
- the camera is connected via internal network to a 4 times PoE Switch on the gallery which is connected to hasvuvblfw1
BL0M0 image:
The GUI and the HELP is still under development ... in case of confusion call Stefan Düsterer 91625