Progress in ITER ECE Diagnostic Design and Integration

Udintsev, V. S.; Danani, S.; Taylor, G.; Giacomin, T.; Guirao, J.; Pak, S.; Hughes, S.; Worth, L.; Vayakis, G.; Walsh, Michael J.; Schneider, M.; Pandya, Hitesh Kumar B.; Kumar, Ravinder; Kumar, Vinay; Jha, S.; Thomas, Stephen R.; Padasalagi, Shrishail; Kumar, Siddharth; Phillips, P. E.; Rowan, W. L.; Austin, M. E.; Khodak, Andrei; Feder, R.; Neilson, H.; Basile, Allan; Hubbard, A.; Saxena, Ashish Kumar; Nazare, C.; Maquet, P.; Gimbert, Nathalie

doi:10.1051/epjconf/201920303003

Cited by 7 publications

(9 citation statements)

References 3 publications

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“…The design, research and development of the ITER ECE diagnostic system have progressed very well since the last progress updates presented [2]. The preliminary design review on the transmission line, the Fourier transform spectrometer, and the low-frequency radiometer has been completed and is near closure.…”

Section: Discussionmentioning

confidence: 99%

“…The ITER electron cyclotron emission (ECE) diagnostic system [1,2] has primary roles in providing measurements of the core electron temperature profile and the electron temperature fluctuation associated with neoclassical tearing mode (NTM) instabilities. Together with the Thomson scattering systems [3], they are adequate to provide the core electron temperature profile with specifications that meet the requirements from the perspective of plasma control and physics studies.…”

Section: Introductionmentioning

confidence: 99%

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Progress in ITER ECE diagnostic design and integration

Liu¹,

Udintsev²,

Danani³

et al. 2022

J. Inst.

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The ITER electron cyclotron emission (ECE) diagnostic system has primary roles in providing measurements of the core electron temperature profile and the electron temperature fluctuation associated with the neoclassical tearing modes. The ITER ECE system includes a radial and oblique line-of-sight. Four 43-meter long low-loss transmission lines (TLs) are designed to transmit millimeter wave power in the frequency range of 70–1000 GHz in both X- and O-mode polarization from the port plug to the ECE instrumentation room in the diagnostic building. The measurement instrumentation includes two Fourier transform spectrometer (FTS) systems and two radiometer systems. The Indian Domestic Agency (IN-DA) and United States Domestic Agency share the responsibility. The IN-DA scope excluding instrumentation and control has passed its preliminary design review and is progressing towards the final design review (FDR). In parallel, the diagnostic integration in different areas is ongoing. Several captive components for the TLs have passed FDR and will be manufactured for installation in the tokamak building soon. A peer review meeting has been held on the prototype hot calibration source, and its integration and new thermal analysis in the diagnostic shield module are continuing. A prototype TL is being tested. A prototype polarizing Martin-Puplett type FTS, operating in the frequency range 70–1000 GHz, features an in-vacuo fast scanning mechanism and a cryo-cooled dual-channel THz detector system. Its performance has been assessed in detail against ITER requirements.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Progress in ITER ECE diagnostic design and integration

Liu¹,

Udintsev²,

Danani³

et al. 2022

J. Inst.

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“…Trapped UH wave PDIs in the ITER full-field scenarios may create strong microwave signals with frequency shifts ∼ 10 GHz from f 0 = 170 GHz [1]. This makes them a potential risk to the ITER electron cyclotron emission (ECE) and low-field side reflectometer systems, operating in the frequency ranges 70−1000 GHz [67,68] and 30−165 GHz [69], respectively. PDIs involving a significant amount of X-mode ECRH power reflected from the high-field side wall reaching the UHR are unlikely to occur in the fullfield ITER scenario, as the fundamental ECR is located close to the plasma center and therefore expected to be optically thick for the O-mode ECRH waves [61].…”

Section: Potential O-mode Ecrh Pdi Scenarios At Itermentioning

confidence: 99%

“…This means that 110 GHz and 104 GHz ECRH waves are also likely to drive PDIs involving decay of the O-mode ECRH waves into trapped UH waves and low-frequency lower hybrid waves in regions allowing UH wave trapping on the highfield side in ITER half-field scenarios. Such trapped UH wave PDIs would again pose a risk to the ECE [67,68] and low-field side reflectometer [69] systems at ITER. Operation with pellet fueling above n G e would allow the trapped UH wave PDIs to occur near the plasma center and on the low-field side in addition to the high-field side; once again, the requirement of n e < n G e at the plasma edge means that there will always be some point with R < R 0 + a at which f 0 = f UH in stable plasmas.…”

Section: Potential O-mode Ecrh Pdi Scenarios At Itermentioning

confidence: 99%

Parametric Decay Instabilities during Electron Cyclotron Resonance Heating of Fusion Plasmas, Problems and Possibilities

Hansen

Nielsen²,

Stober³

et al. 2023

EPJ Web Conf.

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We review parametric decay instabilities (PDIs) expected in connection with electron cyclotron resonance heating (ECRH) of magnetically confined fusion plasmas, with a specific focus on conditions relevant for the ITER tokamak. PDIs involving upper hybrid (UH) waves are likely to occur in O-mode ECRH scenarios at ITER if electron density profiles allowing trapping of UH waves near the ECRH frequency are present. Such PDIs may occur near the plasma center in ITER full-field scenarios heated by 170 GHz O-mode ECRH and on the high-field side of half-field ITER plasmas heated by 110 GHz or 104 GHz O-mode ECRH. Additionally, 110 GHz O-mode ECRH of half-field ITER scenarios may have low ECRH absorption, due to the electron cyclotron resonance being located on the high-field side of the main plasma. This potentially allows PDIs driven by a significant amount of ECRH radiation reaching the UH resonance in X-mode to occur, as X-mode radiation can be generated by reflection of unabsorbed O-mode radiation from the high-field side wall. The occurrence of PDIs during ECRH may damage microwave diagnostics, such as the electron cyclotron emission and low-field side reflectometer systems at ITER, as well as complicate the calculation of heating and current drive characteristics. However, if PDIs are induced in a controlled manner, they may provide novel diagnostic tools and allow the generation of a moderate fast ion population in plasmas heated only by ECRH.

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“…In ITER, the electron cyclotron emission (ECE) diagnostic [1] will be used to determine the plasma electron temperature, plasma energy, ECE radiated power and runaway electrons in the frequency range 70 GHz -1 THz by measuring the cyclotron radiation. The typical ECE system consists of front end optics including in-situ calibration sources, a set of transmission lines (TLs), and ECE radiation measurement instruments like radiometers and Michelson interferometers.…”

Section: Introductionmentioning

confidence: 99%

Comparative studies of various types of transmission lines in the frequency range 70 GHz 1 THz for ITER ECE diagnostic

et al. 2019

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In ITER, an Electron Cyclotron Emission (ECE) diagnostic is planned to measure the electron temperature by measuring the cyclotron radiation in the frequency range of 70-1000 GHz. The cyclotron radiation is usually of low power and needs to be transported with low attenuation over a long distance of ~ 43 m, through a suitable transmission system. Pertaining to long distance, the transmission system will consist of straight waveguide sections, miter bends and waveguide joints. Low power, low loss transmission in a broadband frequency range over long distance makes the design of the transmission system challenging. To arrive at a suitable transmission system, attenuation measurements of three types of transmission lines (TLs) have been performed i.e. circular smooth walled, corrugated and dielectric coated waveguide. A polarizing Michelson interferometer based on Martin-Puplett design has been used to measure the spectrum from waveguide set ups and liquid nitrogen has been used as the black body radiation source. The measured spectrum shows atmospheric water vapour absorption lines in all types of TLs. The preliminary measurement shows that the attenuation of smooth walled waveguide is found to be comparable to corrugated waveguide up to ~ 600GHz and better than corrugated waveguide above 600 GHz for the chosen set of experimental conditions. Further, to avoid water absorption lines, a smooth walled TL is evacuated up to rough vacuum (~10-2mbar) and it was observed that the attenuation is decreased and overall transmission is improved.

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Progress in ITER ECE Diagnostic Design and Integration

Cited by 7 publications

References 3 publications

Progress in ITER ECE diagnostic design and integration

Progress in ITER ECE diagnostic design and integration

Parametric Decay Instabilities during Electron Cyclotron Resonance Heating of Fusion Plasmas, Problems and Possibilities

Comparative studies of various types of transmission lines in the frequency range 70 GHz 1 THz for ITER ECE diagnostic

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