Corroborating VNA and thermal measurements of transmission loss on the DIII-D ECH waveguide system

Ross, M. P.; Thackston, K. A.; Dupuy, A.; Gorelov, Y.; de Boucaud, N.; Nesbet, P.; Torrezan, A.; Bayler, Z.; Watson, N.; Anderson, J.; Squire, J. P.

doi:10.1016/j.fusengdes.2026.115626

Corroborating VNA and thermal measurements of transmission loss on the DIII-D ECH waveguide system

Journal Article · Tue Jan 20 00:00:00 EST 2026 · Fusion Engineering and Design

DOI:https://doi.org/10.1016/j.fusengdes.2026.115626· OSTI ID:3021927

^[1]; ^[1]; Dupuy, A. ^[1]; Gorelov, Y. ^[1]; de Boucaud, N. ^[1]; Nesbet, P. ^[1]; ^[1]; Bayler, Z. ^[2]; Watson, N. ^[3]; ^[1]; ^[1]

General Atomics, San Diego, CA (United States)
University of Denver, CO (United States)
University of Mississippi, MS (United States)

Electron cyclotron heating (ECH) and current drive (ECCD) will play a large role in tokamak-based fusion reactors. At the DIII-D tokamak, 110 GHz microwaves injected into the plasma can provide core heating and current drive as well as impurity control, neoclassical tearing mode mitigation, and breakdown assistance. Understanding the physics of these processes relies on accurate estimates of injected ECH power. DIII-D’s ECH system consists of six MW-class Microwave Power Products (MPP) gyrotron microwave sources. Operating the gyrotrons far from the tokamak removes them from magnetic field interference, so 31.75 mm inner-diameter corrugated waveguides transmit the microwave power the 80 m from the gyrotrons to steerable launchers in the tokamak chamber. Estimates of injected power rely on knowing the generated power at the source and then subtracting transmission loss. Conventional transmission loss measurements based on calorimetric dummy loads are onerous and only possible during extended maintenance periods. This work examines two tools that provide more flexibility for the transmission loss measurements. Furthermore, a resistive temperature detector (RTD) array installed along a waveguide measures heat lost to the transmission line, and low power time domain reflectometry (TDR) measurements with a vector network analyzer (VNA) allows loss measurements without burdensome hardware modifications.

View Accepted Manuscript (DOE)

Research Organization:: General Atomics, San Diego, CA (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)

Grant/Contract Number:: FC02-04ER54698

OSTI ID:: 3021927

Journal Information:: Fusion Engineering and Design, Journal Name: Fusion Engineering and Design Vol. 225; ISSN 0920-3796

Publisher:: Elsevier BVCopyright Statement

Country of Publication:: United States

Language:: English

References (26)

Coupling of tilting Gaussian beam with hybrid mode in the corrugated waveguide Ohkubo, K.; Kubo, S.; Idei, H. International Journal of Infrared and Millimeter Waves, Vol. 18, Issue 1 https://doi.org/10.1007/BF02677895	journal	January 1997
Status, Operation, and Extension of the ECRH System at ASDEX Upgrade Wagner, D.; Stober, J.; Leuterer, F. Journal of Infrared, Millimeter, and Terahertz Waves, Vol. 37, Issue 1 https://doi.org/10.1007/s10762-015-0187-z	journal	July 2015
Heating Effects in Overmoded Corrugated Waveguide for ITER Anderson, J. P.; Doane, J. L.; Grunloh, H. L. Journal of Infrared, Millimeter, and Terahertz Waves, Vol. 37, Issue 1 https://doi.org/10.1007/s10762-015-0203-3	journal	September 2015
3D wavebeam field reconstruction from intensity measurements in a few cross sections Chirkov, A. V.; Denisov, G. G.; Aleksandrov, N. L. Optics Communications, Vol. 115, Issue 5-6 https://doi.org/10.1016/0030-4018(94)00630-D	journal	April 1995
Polarizer miter bends for high-power microwave transmission: Ohmic loss and cooling Doane, John; Grunloh, Howard; Martin, Ward Fusion Engineering and Design, Vol. 102 https://doi.org/10.1016/j.fusengdes.2015.11.017	journal	January 2016
High power experiment and heat load evaluation of transmission line for the ECH/CD system in JT-60SA Kobayashi, T.; Yamazaki, H.; Hiranai, S. Fusion Engineering and Design, Vol. 175 https://doi.org/10.1016/j.fusengdes.2022.113009	journal	February 2022
Design status of the ECRH system for CFETR Tang, Yunying; Wang, Xiaojie; Zhang, Liyuan Fusion Engineering and Design, Vol. 182 https://doi.org/10.1016/j.fusengdes.2022.113225	journal	September 2022
Evaluation of transmission efficiency of the ECH/CD transmission lines in integrated commissioning phase on JT-60SA Yamazaki, H.; Kobayashi, T.; Takahashi, K. Fusion Engineering and Design, Vol. 196 https://doi.org/10.1016/j.fusengdes.2023.114015	journal	November 2023
High power mm-wave loss measurements of ITER ex-vessel waveguide components at the FALCON test facility at the Swiss Plasma Center Goodman, Timothy P.; Torreblanca, Humberto; Marraco Borderas, Cinta EPJ Web of Conferences, Vol. 277 https://doi.org/10.1051/epjconf/202327704010	journal	January 2023
Heating and current drive by electron cyclotron waves Prater, R. Physics of Plasmas, Vol. 11, Issue 5 https://doi.org/10.1063/1.1690762	journal	May 2004
The targeted heating and current drive applications for the ITER electron cyclotron system Henderson, M.; Saibene, G.; Darbos, C. Physics of Plasmas, Vol. 22, Issue 2 https://doi.org/10.1063/1.4908598	journal	February 2015
HE ₁₁ mitre bends and gaps in a circular corrugated waveguide Doane, J. L.; Moeller, C. P. International Journal of Electronics, Vol. 77, Issue 4 https://doi.org/10.1080/00207219408926081	journal	October 1994
High power testing of water-cooled waveguide for ITER-like ECH transmission lines Anderson, J. P.; Doane, J. L.; Grunloh, H. J. Nuclear Fusion, Vol. 57, Issue 5 https://doi.org/10.1088/1741-4326/aa6414	journal	March 2017
High-performance ECRH at W7-X: experience and perspectives Laqua, H. P.; Baldzuhn, J.; Braune, H. Nuclear Fusion, Vol. 61, Issue 10 https://doi.org/10.1088/1741-4326/ac1a1b	journal	August 2021
Progress on performance tests of ITER gyrotrons and design of dual-frequency gyrotrons for ITER staged operation plan Ikeda, Ryosuke; Kajiwara, Ken; Nakai, Taku Nuclear Fusion, Vol. 61, Issue 10 https://doi.org/10.1088/1741-4326/ac21f7	journal	September 2021
Conceptual design of a modular EC heating system for EU-DEMO Bruschi, Alessandro; Hogge, Jean-Philippe; Jelonnek, John Nuclear Fusion, Vol. 64, Issue 10 https://doi.org/10.1088/1741-4326/ad66e3	journal	August 2024
The optimisation of the STEP electron cyclotron current drive concept Freethy, Simon; Figini, Lorenzo; Craig, Steven Nuclear Fusion, Vol. 64, Issue 12 https://doi.org/10.1088/1741-4326/ad7a8a	journal	October 2024
A two-terminal IC temperature transducer Timko, M. P. IEEE Journal of Solid-State Circuits, Vol. 11, Issue 6 https://doi.org/10.1109/JSSC.1976.1050818	journal	December 1976
The chirp z-transform algorithm Rabiner, L.; Schafer, R.; Rader, C. IEEE Transactions on Audio and Electroacoustics, Vol. 17, Issue 2 https://doi.org/10.1109/TAU.1969.1162034	journal	June 1969
Experimental Verification of Phase Retrieval of Quasi-Optical Millimeter-Wave Beams Idei, H.; Shimozuma, T.; Shapiro, M. A. IEEE Transactions on Microwave Theory and Techniques, Vol. 54, Issue 11 https://doi.org/10.1109/TMTT.2006.884632	journal	November 2006
Linearly Polarized Modes of a Corrugated Metallic Waveguide Kowalski, Elizabeth J.; Tax, David S.; Shapiro, Michael A. IEEE Transactions on Microwave Theory and Techniques, Vol. 58, Issue 11 https://doi.org/10.1109/TMTT.2010.2078972	journal	November 2010
2.2-MW Record Power of the 170-GHz European Preprototype Coaxial-Cavity Gyrotron for ITER Rzesnicki, Tomasz; Piosczyk, Bernhard; Kern, Stefan IEEE Transactions on Plasma Science, Vol. 38, Issue 6 https://doi.org/10.1109/TPS.2010.2040842	journal	June 2010
Mode Content Determination of Terahertz Corrugated Waveguides Using Experimentally Measured Radiated Field Patterns Jawla, Sudheer K.; Nanni, Emilio A.; Shapiro, Michael A. IEEE Transactions on Plasma Science, Vol. 40, Issue 6 https://doi.org/10.1109/TPS.2012.2190105	journal	June 2012
Design of Circular Corrugated Waveguides to Transmit Millimeter Waves at ITER Doane, J. L. Fusion Science and Technology, Vol. 53, Issue 1 https://doi.org/10.13182/FST08-A1662	journal	January 2008
Calorimetric Measurements of the Radio-Frequency Power and of the Transmission Line Losses on the DIII-D ECH System Cengher, M.; Lohr, J.; Gorelov, I. A. Fusion Science and Technology, Vol. 55, Issue 2 https://doi.org/10.13182/FST09-A4073	journal	February 2009
Quasi-Optical High Purity HE₁₁-Mode Exciter for Oversized Corrugated Waveguide Transmission Sakaguchi, Masatsugu; Idei, Hiroshi; Kubo, Shin Plasma and Fusion Research, Vol. 7, Issue 0 https://doi.org/10.1585/pfr.7.2405037	journal	January 2012

Similar Records

110 GHz ECH system for DIII-D

Conference · Wed May 01 00:00:00 EDT 1991 · OSTI ID:5837501

3 MW, 110 GHz ECH system for the DIII-D tokamak

Conference · Wed Jul 01 00:00:00 EDT 1998 · OSTI ID:656754

DIII-D Electron Cyclotron Heating and Current Drive System Status and Plans

Journal Article · Tue May 03 20:00:00 EDT 2022 · IEEE Transactions on Plasma Science · OSTI ID:1963716

Related Subjects

ECH
Gyrotrons
Transmission
VNA
Waveguide

Corroborating VNA and thermal measurements of transmission loss on the DIII-D ECH waveguide system

Citation Formats

References (26)

Similar Records

Related Subjects