Publications
Showing 127 results for Author: Theodore M. Biewer
Jul, 2026
Journal
Overview of Wendelstein 7-X high-performance operation
The Wendelstein 7-X (W7-X) stellarator has completed two consecutive experimental campaigns OP 2.2 (Sep.-Dec. 2024) and OP 2.3 (Feb.-May 2025) under a new operational strategy enabling more than one year of uninterrupted device availability. This approach, supported by exceptionally high subsystem reliability, allowed sustained high-efficiency plasma operations with up to…
Mar, 2026
Conference Paper
Eliminating Signal Bias Caused by Vacuum System Backstreaming in the Diagnostic Residual Gas Analyzer of ITER
In fusion neutral gas analysis, such as with the Diagnostic Residual Gas Analyzer (DRGA) for ITER, the primary measurement range of interest comprises the low-amu species (1 to 6), especially deuterium and helium. The challenge in successfully obtaining accurate measurements is two-fold. First, the sensitivity of the method must be sufficient to resolve trace amounts accur…
Mar, 2026
Conference Paper
Conceptual design of a Doppler spectrometer for 102 m/s cross-field flows in tokamak divertors
The cross-field transport in the scrape-off-layers (SOLs) and divertors in tokamaks is of a similar size to the poloidal component of the parallel flow, thereby significantly impacting the plasma transport there. However, its direct observation has been challenging because the drift velocity (102–103 m/s) is significantly below the detection limit of conventional diagnosti…
Mar, 2026
Conference Paper
Preface to the Proceedings of the 25th Topical Conference on High-Temperature Plasma Diagnostics
The 25th Topical Conference on High-Temperature Plasma Diagnostics (HTPD 2024) was held in Asheville, NC, USA, at the Renaissance Asheville Downtown Hotel from 21 to 25 April 2024. This biennial conference brings together scientists and engineers from a variety of fields, including magnetic confinement fusion, inertial confinement fusion, space plasmas, astrophysics, and i…
Feb, 2026
Journal
Final Design of the Material Plasma Exposure eXperiment
The Material Plasma Exposure eXperiment (MPEX) has completed its design phase. MPEX will be a unique facility to investigate plasma material interactions (PMIs) under fusion prototypic divertor conditions in steady state. This includes plasma exposure conditions expected in a fusion reactor divertor. Materials to be investigated will include solids, liquids, and neutron pr…
Nov, 2025
Journal
Application of the portable diagnostic package to the Wisconsin high-temperature-superconducting axisymmetric mirror (WHAM)
We present an application of the Portable Diagnostic Package (PDP) on the Wisconsin High-temperature-superconducting Axisymmetric Mirror (WHAM), which integrates an optical emission spectroscopy (OES) system and an active Thomson scattering (TS) system. The OES system facilitates a comprehensive impurity line survey and enables flow measurements through the Doppler effect…
Aug, 2025
ORNL Report
ORNL PORTABLE DIAGNOSTIC PACKAGE FOR EVALUATING MIRROR PERFORMANCE
Oak Ridge National Laboratory (ORNL) and Realta Fusion successfully executed a one-year collaborative effort to deploy the Portable Diagnostic Package (PDP) on the Wisconsin HTS Axisymmetric Mirror (WHAM) and to assess future diagnostic needs. The PDP consists of an optical emission spectroscopy (OES) subsystem and a Thomson scattering (TS) subsystem. Within the first two…
Jul, 2025
Journal
Feasibility of fusion plasma burn control via real-time, sub-divertor neutral gas isotopic and compositional analysis
The ability to provide fusion burn control without requiring physical access through the first wall and fuel breeding blankets, would be vital for any future, magnetically confined fusion power reactor. A multi-sensor, fusion fuel cycle exhaust, neutral gas analysis system on JET, capable of delivering real time data, and accessing only the sub-divertor region, provides an…
Oct, 2024
Journal
Experimental validation of a collision-radiation dataset for molecular hydrogen in plasmas
Quantitative spectroscopy of molecular hydrogen has generated substantial demand, leading to the accumulation of diverse elementary-process data encompassing radiative transitions, electron-impact transitions, predissociations, and quenching. However, their rates currently available are still sparse and there are inconsistencies among those proposed by different authors. I…