| Issue |
EPJ Web Conf.
Volume 346, 2026
25th Topical Conference on Radio-Frequency Power in Plasmas (RFPPC2025)
|
|
|---|---|---|
| Article Number | 03018 | |
| Number of page(s) | 6 | |
| Section | Radio-Frequency and Microwave Diagnostics and Technology | |
| DOI | https://doi.org/10.1051/epjconf/202634603018 | |
| Published online | 07 January 2026 | |
https://doi.org/10.1051/epjconf/202634603018
Design, Manufacturing, and Installation of DIII-D Lower Hybrid Current Drive Outer Wall Waveguides and Expandable Vacuum Interface
MIT Plasma Science and Fusion Center, Cambridge, MA USA
* Corresponding author: ridzon@psfc.mit.edu
Published online: 7 January 2026
High field side lower hybrid current drive (HFS LHCD) is promising method for efficient, off axis current drive. To operate this system, development of an expandable combination radio frequency (RF) and vacuum interface was necessary to allow the long (~2 m) waveguides to thermally expand with respect to the DIII-D 0 degree R-1 port extension without damage to the waveguide or excessive force on the vacuum seals which was previously observed when baking the waveguides during operations that were installed in 2024. Design of a custom bellows assembly with RF feedthrough that allows >20mm of waveguide thermal expansion is presented. Fabrication of this bellows assembly required simultaneously vacuum brazing multiple 304 stainless steel flanges to an oxygen free high conductivity copper waveguide section which required significant manufacturing development.
© The Authors, published by EDP Sciences, 2026
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