September 10, 2025
Realta Fusion is sponsoring ongoing research at the University of Wisconsin-Madison’s Wisconsin HTS Axisymmetric Mirror (WHAM) experiment to evaluate a path toward a magnetic mirror fusion energy system. In July 2024, WHAM achieved first plasma via ECH breakdown and within its first week implemented its Neutral Beam Injection (NBI) heating system and the endring biasing system for stabilization. NBI-sustained discharges on WHAM have exhibited relatively short fast-ion confinement times due to charge-exchange neutral losses. Measurements of the neutral population are important for quantifying progress. To assist in this challenge, Realta is working on computational models describing neutral recycling and the effecton fast-ion confinement. These models are being incorporated into the RealTwin ™ digital twin model for predictive analysis of WHAM and a next-step mirror device called Anvil. Validating these models with empirical data is a crucial step toward ensuring accurate performance forecasts. As part of this proposal, Realta and WHAM seek specialized expertise from Oak Ridge National Laboratory (ORNL)scientists to measure neutral and fast-ion density profiles across the plasma-data critical both for verifying the computational models and for informing strategies to mitigate CX losses. The proposed work consists of two primary thrusts: Fast Ion Measurement: First detection of the fast ions in the WHAM device by high-dynamic-range spectroscopy (HDRS). Adaption of the CXSFIT code to fitting this spectrum will enable localized measurements of the fast-ion population. Neutral Profile Measurement: Executing direct neutral profile measurements in the plasma core to establish scaling relationships under varying input power, mirror ratio, and other experimentally controlled parameters. Realta believes that reducing risk in its numerical modes is necessary before increased investment in future devices. Leveraging UW-Madison’s state-of-the-art experimental facilities along with ORNL’s diagnostic expertise will provide the necessary validation of the simulated neutral recycling. Achieving these objectives lays the groundwork for enhanced confinement schemes in mirror devices and spurs further development of Realta’s
RealTwin platform – ultimately strengthening confidence in the path to high performance, commercially viable fusion energy in mirror confinement devices.