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Odstrcil T, Laggner FM, Rosenthal AM, Bortolon A, Hughes JW, Spendlove JC, Wilks TM. Robust identification of multiple-input single-output system response for efficient pickup noise removal from tokamak diagnostics. Rev Sci Instrum 2022; 93:103503. [PMID: 36319373 DOI: 10.1063/5.0100988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/04/2022] [Indexed: 06/16/2023]
Abstract
Electromagnetic pickup noise in the tokamak environment imposes an imminent challenge for measuring weak diagnostic photocurrents in the nA range. The diagnostic signal can be contaminated by an unknown mixture of crosstalk signals from coils powered by currents in the kA range. To address this issue, an algorithm for robust identification of linear multi-input single-output (MISO) systems has been developed. The MISO model describes the dynamic relationship between measured signals from power sources and observed signals in the diagnostic and allows for a precise subtraction of the noise component. The proposed method was tested on experimental diagnostic data from the DIII-D tokamak, and it has reduced noise by up to 20 dB in the 1-20 kHz range.
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Affiliation(s)
- T Odstrcil
- General Atomics, San Diego, California 92186-5608, USA
| | - F M Laggner
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - A M Rosenthal
- MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA
| | - A Bortolon
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - J W Hughes
- MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA
| | | | - T M Wilks
- MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA
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Rosenthal AM, Hughes JW, Bortolon A, Laggner FM, Wilks TM, Vieira R, Leccacorvi R, Marmar E, Nagy A, Freeman C, Mauzey D. A 1D Lyman-alpha profile camera for plasma edge neutral studies on the DIII-D tokamak. Rev Sci Instrum 2021; 92:033523. [PMID: 33820041 DOI: 10.1063/5.0024115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 02/11/2021] [Indexed: 06/12/2023]
Abstract
A one dimensional, absolutely calibrated pinhole camera system was installed on the DIII-D tokamak to measure edge Lyman-alpha (Ly-α) emission from hydrogen isotopes, which can be used to infer neutral density and ionization rate profiles. The system is composed of two cameras, each providing a toroidal fan of 20 lines of sight, viewing the plasma edge on the inboard and outboard side of DIII-D. The cameras' views lie in a horizontal plane 77 cm below the midplane. At its tangency radius, each channel provides a radial resolution of ∼2 cm full width at half maximum (FWHM) with a total coverage of 22 cm. Each camera consists of a rectangular pinhole, Ly-α reflective mirror, narrow-band Ly-α transmission filter, and a 20 channel AXUV photodetector. The combined mirror and transmission filter have a FWHM of 5 nm, centered near the Ly-α wavelength of 121.6 nm and is capable of rejecting significant, parasitic carbon-III (C-III) emission from intrinsic plasma impurities. To provide a high spatial resolution measurement in a compact footprint, the camera utilizes advanced engineering and manufacturing techniques including 3D printing, high stability mirror mounts, and a novel alignment procedure. Absolutely calibrated, spatially resolved Ly-α brightness measurements utilize a bright, isolated line with low parasitic surface reflections and enable quantitative comparison to modeling to study divertor neutral leakage, main chamber fueling, and radial particle transport.
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Affiliation(s)
- A M Rosenthal
- MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA
| | - J W Hughes
- MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA
| | - A Bortolon
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - F M Laggner
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - T M Wilks
- MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA
| | - R Vieira
- MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA
| | - R Leccacorvi
- MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA
| | - E Marmar
- MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139, USA
| | - A Nagy
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - C Freeman
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - D Mauzey
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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