Pulse Height Analysis System (PHA) designed for W7-X Presented by Monika KUBKOWSKA

Transcription

1 Pulse Height Analysis System (PHA) designed for W7-X Presented by Monika KUBKOWSKA This scientific work has been partly supported by Polish Ministry of Science and Higher Education within the framework of the scientific financial resources in the year 2014 and 2015 allocated for the realization of the international co-financed project.

2 Purpose and Description of the PHA System The PHA is intended to provide the spectral energy distribution with an energy resolution of about 200 ev along a central line of sight. The measurements yield impurity survey spectra in the X- ray region above 0.35 kev up to 20 kev typically allowing: - to identify the line radiation from all relevant impurities; - to determine their concentration in the plasma core; - slope of the hydrogen and low-z continuum radiation is used to determine the central electron temperature; - the intensity of the continuum radiation together with additional spectroscopic data allows to assess Zeff in the plasma center.

3 Purpose and Description of the PHA System Proposed System: 3 detectors in vacuum, horizontal port sightlines through plasma center Si drift diode detectors (SDD) additional exchangeable filters (3) adaptive aperture control in situ energy calibration (X-ray tube) Port Allocation AEK50 M. Kubkowska 14th CWGM Warsaw, Poland Page 3

4 RayX code applied for development of the PHA diagnostic 4

5 RayX code Main assumptions 5

6 RayX code A computer code has been developed for W7-X for checking the performance of a spectroscopy system and optimizing individual parts, like detectors and pinholes. 6

7 RayX code The software tool makes it possible to investigate the influence of a geometrical configuration of the diagnostic systems on the intensity and shape of the spectra. 7 7

8 RayX code For analyzing of the impurities, code simulates the real composition of the ions charge, according to the temperature and concentration profile of the plasma. For this purpose coronal model of ions equilibrium was used. It was assumed that ionization is realized mainly by interaction between atoms or ions and electrons while recombination is realized by interaction of ions and electrons. 8

9 Input parameters - Temperature and electron density Electron density and temperature profiles for 8 MW of ECRH scenario foreseen for W7-X Y. Turkin, Fusion Sci. Technol. 50 (2006) 387 Y. Turkin et al, Phys. Plasmas 18 (2011)

10 Sample of RayX results Content of impurities: C 3%, O 0.5%, Fe 0.002%, ff+fb+bb transitions mm of Be filter for 8MWECRH profile 4 Plasma-pinhole = 7 m Pinhole- detector = 1 m pinhole size = 200 um Etendue = Volume of plasma = 1.47 cm D Pix L PD D pin D pin L PP Spectrum [photons/[s ev]] Total spectrum ff+fb+bb without filter after 8 m Be filter C 5%, O 0.3%, Fe 0.002% Energy [kev] Pixel Energy[keV] Photons Charge[C] Current[A] Volume[cm 3 ] PhotEmis[ph/m 3 /s] E E E+19 10

11 PNDetector Considered detectors AMPTEK 11

12 Design of the PHA diagnostics gate valve Electric isulation Filters and slits box Calibration source mechanical isulation membrane bellow turbomolecular pump detectors 12 12

13 Design of the PHA diagnostics L PP = 7 m L PD = 1 m 13

14 Design of the PHA diagnostics filter box To plasma To detectors Sets of piezo-slits Changeable Be filters 14

15 Design of the PHA diagnostics Filter box Vacuum chamber A prototype of the filter control mechanism by a wobble stick using a small (fast) and large pneumatic cylinder as actuator has been tested in the laboratory. Mechanism for changing filters Gas container 15

16 Design of the PHA diagnostics Filter box in vacuum in air Gas container Application of wobble-stick allows rotation in vacuum 16 16

17 Design of the PHA diagnostics Channel Detector Energy range SD3 low energy Polymer window + Al light protection SDD 8µm Be window SDD 8µm Be window 250 ev - 20 kev Be foil thickness Pos.1 Pos. 2 Pos. 3 open Detector flange 10 µm 25 µm 1 20 kev open 50 µm 100 µm 5 20 kev 25 µm 100 µm 500 µm 17

18 Transmission of the window of the 1st channel 18 18

19 Energy response of the 1st &2nd channel Response of Absorber m Be 25 m Be 50 m Be 100 m Be 500 m Be Energy (kev) 1/e 19

20 Detectors details PNDetector Type SDD & SD pnW Both SDD - Silicon Drift Detector on high ohmic and ultra-pure FZ-Silicon Thickness 450 um. Chip area 36 mm 2 Active area 10 mm 2 "internal collimator" housing TO8 16 pin 20

21 Resolution of the PHA system Application of piezo-slits required ~ photons 135 ev 21

22 Design of the PHA diagnostics slit PZS3V: piezo slit drive, vacuum compatible version SG strain gauge measurement system Slit Edges, stainless steel, overlapped Oscillation free closed loop operation Small signal rise/fall time: 30 ms EMC (Electromagnetic compatibility) 12V40SG piezo amplifier System complies with the requirements: EN 55011, class B EN group 1, part 2 22

23 Data acquisition system PHA in OP1.1 stand-alone system h SDD detector preamp board 4-channel USB2 Digital X-ray Processors DXP Mercury, XIA, USA USB 2.0 Converter USBoptical fiber Gefen USB 400 FO - Optical 4 Port USB 2.0 Hub Optical fiber PC computer USB Converter optical fiber USB Gefen USB 400 FO - Optical 4 Port USB 2.0 Hub 23

24 Data acquisition system Module contains 4 channels of pulse processing electronics with full MCA per channel. Peaking time range: 0.1 to 160μs. Digitization: 14 bit at 50 MHz. External gate allows data acquisition on all channels to be synchronized. Preamplifier, input offset and pileup inspection criteria are computer controlled. 24

25 Laboratory tests

26 Laboratory tests 26

27 PHA energy calibration Stainlesss steel (Fe, Cr, Ni) hole Ti Cu Fluorescence material 27

28 Mini X-ray tube for calibration! 28

29 Energy calibration of the PHA 1mm Al window Mini X-ray tube Fluorescence materials inside (Ni, Fe, Cr, Cu, Al) To the detector 29

30 Calibration spectra 30

31 Energy resolution vs energy FWHM ev 31

32 PHA system is expected in OP 1.1 May/June 2015 transfer to IPP Laboratory test 32

33 12,June 2015 instalation on W7-X 33

34 TEAM A.Czarnecka, W.Figacz, S.Jablonski, N.Krawczyk, J.Kaczmarczyk, L.Ryc, J.Pokorska, P.Gasior A. Weller, Ch. Biedermann, H. Thomsen, R. Koenig, R.Burhenn and W7-X team 34

35 Thank you for your attention! 35