Filter-Units

Version 23.1 by sndueste on 2021/08/17 16:55
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Filter control

General infos

The filter control panel can be used to move in filters AND to calculate the transmission of the fundamental wavelength of the FEL and its 3rd harmonic.

The moving procedure is supervised by a protection system. First of all the fast shutter is closed before moving the filter wheel (to protect the filters during moving) and blocked till the movement is over. Then the fast shutter has to be opened again with the Fast shutter control button. It does not open automatically! 

In addition the pulse energy and the number of bunches in the FEL is monitored. IF the radiation dose exceeds a certain limit the filters can not be moved into the beam. Then the beam has to be attenuated using the gas attenuator to a range where the filters can be used again. More info: JdddFilterProtection

Current limits are:    doselimits.jpg:


Calculation of the transmission

The shown transmission values for the filters are based on the CXRO webpage AND on measurements performed at the PTB (data see below).

The measured transmissions may differ from calculated ones in certain wavelength ranges significantly. Since we do not have measured values for all filters / thicknesses there may be situations where the shown transmission may be e.g. smaller for a thinner filter of the same material (since it was measured) in comparison to a thicker (not measured) one ...


The transmission is given for the fundamental Wavelength and in addition for the third harmonic of the FEL ( which is typically 1% of the fundamental). The bars below the shown transmission are just a guide to the eye to distinguish between large and weak transmission easier. The values are calculated for the current wavelength set in the FEL. 

filter overview.jpg


Since for certain combinations of filters the transmission of the third harmonic can be significantly higher than for the fundamental it may happen that more third harmonic as fundamental passes ... thus there is a warning indicating that this may be a problem ...

3rd harmwarning.jpg

By pressing on the transmission values of a certain filter one can open the window showing the transmission as function of the photon energy / Wavelength:


transmissioncurves.jpg


To help finding the right filter setting one can also have an overview of all filters available and look on the transmission for a certain wavelength / photon energy independent of the actual FEL wavelength. Using the tab "transmission" one can type in a photon energy or wavelength → press "calculate transmission" and then see transmission of the fundamental and the 3rd harmonic for this wavelength ... (this is a separate transmission calculator and playing with it does not alter anything on the filter wheels or in the FEL / undulator settings!)


transmissino calculation.jpg

More (special) info

Mounted filters, replacement in N2 box

Filter transmission - expert info

  • The transmission data for the transmission calculation in jddd uses combined data from CXRO and the measures transmission from BESSY. This is also the reason that for some values there is a deviation from expected scaling (e.g. same material but different thickness) or tabulated values. The calculated data for extrapolating the experimental values  was scaled to fit the experimental values at the crossover
  • 2020-09-16 14_51_08-combined filter transmission for server.opju _ - __win.desy.de_home_sndueste_My .png 
  • However comparing the transmission data for Al 100 nm and 200 nm for the measured (PTB) and calculated (CXRO) data shows a rather good agreement for 17 nm and shorter WL while at longer WL a systematic difference can be seen. future measurements with the FEL have to be done ... 

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    The transmission data can be found at e.g. (depending on the filter wheel) /export/doocs/server/blfilters2_server/data/ as files generated from CXRO. We use the WL range 0.5 nm to 60 nm 
  • Transmission of filters calculated from CXRO  as pdf for FLASH1 and FLASH2 filter wheels
  • AllFiltersPTB.pdf: Transmission of filters as measured by PTB as pdf (and here are the actual data of the measurements)
  • Transmission_PTB_CXRO.pdf: Transmission of Nb, Zr, Al, Si Luxel filters measured between 2.5nm and 25nm by the PTB in comparison with CXRO data
  • Experimental measurements for the transmission: Laurents transmissiont measurements for "Rohringer" Beamtime - shows deviations for Si !


Documentation of the filter protection in jddd


Data collection of FEL parameters and Filter damage


Filter material

Thickness[nm]

Wavelength [nm]

pulse energy [µJ]

# of Bunches

Apertures?

Integral dose (mJ)

Filter unit

survived?

date

Comments












Al

100

13

300

1

3mm

~3

BL wheel 2

hours

Sept 2014

Adrians beamtime

Al

198

13

1.8

401

3mm

~0.7

BL wheel 2

~10 minutes

August 2014

only in combination with Nb 385nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime

Nb

385

13

1.8

401

3mm

~0.7

BL wheel 1

~10 minutes

August 2014

only in combination with Al 198nm on wheel 2, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime

Nb

197

13

2.5

401

3mm

~1

BL wheel 2

~10 minutes

August 2014

only in combination with Al 423 nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime

Al

423

13

2.5

401

3mm

~1

BL wheel 2

~15 minutes

August 2014

only in combination with Al 423nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime

Al

101

13

2.5

401

3mm

~1

BL wheel 2

~15 minutes

August 2014

only in combination with Al 423nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime

Al

298

13

2.5

401

3mm

~1

BL wheel 2

~15 minutes

August 2014

only in combination with Al 423nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime

C Al C

500

13

2.5

401

3mm

~1

BL wheel 2

~15 minutes

August 2014

only in combination with Al 423nm on wheel 1, Attenuator with Xe at 5% transmission (0.15mbar), Industry beamtime

Al

423

13

2.5

401

3mm

~1

BL wheel 1

~1 h

August 2014

Industry beamtime, Attenuator with Xe at 5% transmission (0.15mbar)

Al

423

13

70

1

3mm

0.07

BL wheel 1

~1 h

August 2014

Industry beamtime

Al

193

13

52

1

3mm

0.05

BL wheel 1

~1 h

August 2014

Industry beamtime

Al

193

13

50-80

1

3mm, 5mm, 10mm

~0.1

BL wheel 1

~30min

August 2014

Industry beamtime

Si

419

19

15-20

87

3mm

1.3

BL wheel 1

36h

June 2014

Al

400

19

15-20

87

3mm

1.3

BL wheel 1

many h

June 2014

Zr

200

19

2-3

77

1mm

0.2

BL wheel 1

few h

June 2014

Al

100

13

6-8

15

1mm !

~ 0.1

BL

short ? - then BROKEN

Jan 2014

Al

200

4

180

1

none, but 2-3 mm beam in the hall

~ 0.2

BL

yes, minutes

Dec 2013

Al

400

4

180

1

none, but 2-3 mm beam in the hall

~ 0.2

BL

yes, minutes

Dec 2013

Si3N4

350

4.3

180

1

none, but 2-3 mm beam in the hall

~ 0.2

BL

yes, minutes

Dec 2013

Al

100

4.3

180

1

none, but 2-3 mm beam in the hall

~ 0.2

BL

BROKEN

Dec 2013

Si

220

4.3

180

1

none, but 2-3 mm beam in the hall

~ 0.2

BL

BROKEN

Dec 2013

Zr

220

4.3

180

1

none, but 2-3 mm beam in the hall

~ 0.2

BL

BROKEN

Dec 2013

Al

100

6.8

80

30

3mm

2.4

BL

BROKEN

Mar 2011


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