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Barbui T, Chellai O, Delgado-Aparicio L, Ellis R, Hill K, Stratton B, Wallace J, Wisniewski J, Cantone B, Dumont R, Fedorczak N, Hatchressian J, Lotte P, Malard P. Design and engineering challenges of a multi-energy hard x-ray camera for long-pulse profile measurements at WEST tokamak. Fusion Engineering and Design 2021. [DOI: 10.1016/j.fusengdes.2021.112957] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Delgado-Aparicio LF, VanMeter P, Barbui T, Chellai O, Wallace J, Yamazaki H, Kojima S, Almagari AF, Hurst NC, Chapman BE, McCollam KJ, Den Hartog DJ, Sarff JS, Reusch LM, Pablant N, Hill K, Bitter M, Ono M, Stratton B, Takase Y, Luethi B, Rissi M, Donath T, Hofer P, Pilet N. Multi-energy reconstructions, central electron temperature measurements, and early detection of the birth and growth of runaway electrons using a versatile soft x-ray pinhole camera at MST. Rev Sci Instrum 2021; 92:073502. [PMID: 34340413 DOI: 10.1063/5.0043672] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 04/26/2021] [Indexed: 06/13/2023]
Abstract
A multi-energy soft x-ray pinhole camera has been designed, built, and deployed at the Madison Symmetric Torus to aid the study of particle and thermal transport, as well as MHD stability physics. This novel imaging diagnostic technique employs a pixelated x-ray detector in which the lower energy threshold for photon detection can be adjusted independently on each pixel. The detector of choice is a PILATUS3 100 K with a 450 μm thick silicon sensor and nearly 100 000 pixels sensitive to photon energies between 1.6 and 30 keV. An ensemble of cubic spline smoothing functions has been applied to the line-integrated data for each time-frame and energy-range, obtaining a reduced standard-deviation when compared to that dominated by photon-noise. The multi-energy local emissivity profiles are obtained from a 1D matrix-based Abel-inversion procedure. Central values of Te can be obtained by modeling the slope of the continuum radiation from ratios of the inverted radial emissivity profiles over multiple energy ranges with no a priori assumptions of plasma profiles, magnetic field reconstruction constraints, high-density limitations, or need of shot-to-shot reproducibility. In tokamak plasmas, a novel application has recently been tested for early detection, 1D imaging, and study of the birth, exponential growth, and saturation of runaway electrons at energies comparable to 100 × Te,0; thus, early results are also presented.
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Affiliation(s)
| | - P VanMeter
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - T Barbui
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - O Chellai
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - J Wallace
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - H Yamazaki
- National Institutes for Quantum and Radiological Science and Technology, Naka, Ibaraki 311-0193, Japan
| | - S Kojima
- Kyushu University, Kasuga-kouen 6-1, Kasuga, Japan
| | - A F Almagari
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - N C Hurst
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - B E Chapman
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - K J McCollam
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - D J Den Hartog
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - J S Sarff
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - L M Reusch
- Edgewood College, Madison, Wisconsin 53711, USA
| | - N Pablant
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - K Hill
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - M Bitter
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - M Ono
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - B Stratton
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - Y Takase
- The University of Tokyo, Kashiwa 277-8561, Japan
| | - B Luethi
- DECTRIS Ltd., 5405 Baden-Dättwil, Switzerland
| | - M Rissi
- DECTRIS Ltd., 5405 Baden-Dättwil, Switzerland
| | - T Donath
- DECTRIS Ltd., 5405 Baden-Dättwil, Switzerland
| | - P Hofer
- DECTRIS Ltd., 5405 Baden-Dättwil, Switzerland
| | - N Pilet
- DECTRIS Ltd., 5405 Baden-Dättwil, Switzerland
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Chellai O, Delgado-Aparicio LF, VanMeter P, Barbui T, Wallace J, Hill KW, Pablant N, Stratton B, Disch C, Luethi B, Pilet N. Calibration of a versatile multi-energy soft x-ray diagnostic for WEST long pulse plasmas. Rev Sci Instrum 2021; 92:043509. [PMID: 34243460 DOI: 10.1063/5.0043456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/12/2021] [Indexed: 06/13/2023]
Abstract
A compact multi-energy soft x-ray diagnostic is being installed on the W Environment in Steady-state Tokamak (WEST), which was designed and built to test ITER-like tungsten plasma facing components in a long pulse (∼1000 s) scenario. The diagnostic consists of a pinhole camera fielded with the PILATUS3 photon-counting Si-based detector (≲100 kpixel). The detector has sensitivity in the range 1.6-30 keV and enables energy discrimination, providing a higher energy resolution than conventional systems with metal foils and diodes with adequate space and time resolution (≲1 cm and 2 ms). The lower-absorption cut-off energy is set independently on each one of the ∼100 kpixels, providing a unique opportunity to measure simultaneously the plasma emissivity in multiple energy ranges and deduce a variety of plasma parameters (e.g., Te, nZ, and ΔZeff). The energy dependence of each pixel is calibrated here over the range 3-22 keV. The detector is exposed to a variety of monochromatic sources-fluorescence emission from metallic targets-and for each pixel, the lower energy threshold is scanned to calibrate the energy dependence. The data are fit to a responsivity curve ("S-curve") that determines the mapping between the possible detector settings and the energy response for each pixel. Here, the calibration is performed for three energy ranges: low (2.3-6 keV), medium (4.5-13.5 keV), and high (5.4-21 keV). We determine the achievable energy resolutions for the low, medium, and high energy ranges as 330 eV, 640 eV, and 950 eV, respectively. The main limitation for the energy resolution is found to be the finite width of the S-curve.
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Affiliation(s)
- O Chellai
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | | | - P VanMeter
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - T Barbui
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - J Wallace
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - K W Hill
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - N Pablant
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - B Stratton
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - C Disch
- DECTRIS Ltd., Baden-Daettwil 5405, Switzerland
| | - B Luethi
- DECTRIS Ltd., Baden-Daettwil 5405, Switzerland
| | - N Pilet
- DECTRIS Ltd., Baden-Daettwil 5405, Switzerland
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Baquero-Ruiz M, Avino F, Chellai O, Fasoli A, Furno I, Jacquier R, Manke F, Patrick S. Dual Langmuir-probe array for 3D plasma studies in TORPEX. Rev Sci Instrum 2016; 87:113504. [PMID: 27910384 DOI: 10.1063/1.4968024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 11/06/2016] [Indexed: 06/06/2023]
Abstract
We have designed and installed a new Langmuir-probe (LP) array diagnostic to determine basic three-dimensional (3D) features of plasmas in TORPEX. The diagnostic consists of two identical LP arrays, placed on opposite sides of the apparatus, which provide comprehensive coverage of the poloidal cross section at the two different toroidal locations. Cross correlation studies of signals from the arrays provide a basic way to extract 3D information from the plasmas, as experiments show. Moreover, the remarkable signal-to-noise performance of the front-end electronics allows us to follow a different approach in which we combine information from all probes in both arrays to reconstruct elementary 3D plasma structures at each acquisition time step. Then, through data analysis, we track the structures as they evolve in time. The LP arrays include a linear-motion mechanism that can displace radially the probes located on the low field side for experiments that require fine-tuning of the probe locations, and for operational compatibility with the recently installed in-vessel toroidal conductor.
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Affiliation(s)
- M Baquero-Ruiz
- Swiss Plasma Center (SPC), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - F Avino
- Swiss Plasma Center (SPC), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - O Chellai
- Swiss Plasma Center (SPC), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - A Fasoli
- Swiss Plasma Center (SPC), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - I Furno
- Swiss Plasma Center (SPC), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - R Jacquier
- Swiss Plasma Center (SPC), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - F Manke
- Swiss Plasma Center (SPC), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - S Patrick
- Swiss Plasma Center (SPC), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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