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2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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Fusion Science and Technology
Latest News
The journey of the U.S. fuel cycle
Craig Piercycpiercy@ans.org
While most big journeys begin with a clear objective, they rarely start with an exact knowledge of the route. When commissioning the Lewis and Clark expedition in 1803, President Thomas Jefferson didn’t provide specific “turn right at the big mountain” directions to the Corps of Discovery. He gave goal-oriented instructions: explore the Missouri River, find its source, search for a transcontinental water route to the Pacific, and build scientific and cultural knowledge along the way.
Jefferson left it up to Lewis and Clark to turn his broad, geopolitically motivated guidance into gritty reality.
Similarly, U.S. nuclear policy has begun a journey toward closing the U.S. nuclear fuel cycle. There is a clear signal of support for recycling from the Trump administration, along with growing bipartisan excitement in Congress. Yet the precise path remains unclear.
K. Ohkubo, S. Kubo, T. Shimozuma, Y. Yoshimura, H. Igami, S. Kobayashi
Fusion Science and Technology | Volume 62 | Number 3 | November 2012 | Pages 389-402
Technical Paper | doi.org/10.13182/FST12-A15338
Articles are hosted by Taylor and Francis Online.
In the system of electron cyclotron heating, highly overmoded, corrugated circular waveguides are used. To analyze propagating mode content in the waveguide, burn patterns of the thermal paper placed on the waveguide aperture are observed at several positions. Theoretical burn patterns are obtained by taking into account a nonlinear grayscale response of the thermal paper to the calculated power profiles. We have developed a new method of mode analysis by nonlinear optimization, which is based on an iterative error reduction of differences between observed and theoretical patterns. To examine the status of polarization, the transformation between hybrid modes and linearly polarized (LP) modes is derived. The method is applied to the 82.7-GHz transmission line connected with the gyrotron. The propagating wave is linear polarized and consists of [approximately]4% of the LP11 odd mode, [approximately]95% of the LP01 mode, and [approximately]1% of other modes. The calculated burn pattern is similar to the observed one, like a plateau. By using both center of power and weighted averages of the perpendicular wavenumber in these profiles, offset and tilting angles of an injecting electromagnetic beam to the waveguide entrance are inferred. These are verified to be consistent with the results by the coupling code of a Gaussian beam with hybrid modes.
