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Latest News
College students help develop waste measuring device at Hanford
A partnership between Washington River Protection Solutions (WRPS) and Washington State University has resulted in the development of a device to measure radioactive tank waste at the Hanford Site. WRPS is the contractor at Hanford for the Department of Energy’s Office of Environmental Management.
Kazuyoshi Hada, Kazunobu Nagasaki, Kai Masuda, Shinji Kobayashi, Shunsuke Ide, Akihiko Isayama, Ken Kajiwara
Fusion Science and Technology | Volume 67 | Number 4 | May 2015 | Pages 693-704
Technical Paper | doi.org/10.13182/FST14-811
Articles are hosted by Taylor and Francis Online.
By using a one-dimensional model, we analyze plasma start-up assisted by second-harmonic extraordinary-mode electron cyclotron (EC) resonance heating (ECRH). The model leads to energy transport equations for electrons and ions, particle transport equations for electrons and hydrogen atoms, and a toroidal current equation. These equations are solved for a cylindrically symmetrical plasma; that is, a torus straightened to a cylinder with a circular cross section and on-axis ECRH power absorption. The calculation indicates that ECRH has a threshold power for plasma start-up in JT-60SA. For example, approximately 1 MW of ECRH power is required for plasma start-up for an initial hydrogen atom density nH(t=0) = 3.0 × 1018 m-3, an error field Berr = 1 mT, carbon and oxygen impurity fractions nc/ne = no/ne = 0.1%, and an EC beam radius of approximately 5 cm. This estimated ECRH power is less than the planned power and increases sublinearly with the initial hydrogen atom density. The threshold power depends weakly on the error field and carbon impurity concentration. This is especially prominent for plasma start-up with a low initial hydrogen atom density. This result implies that suppressing the error field and carbon impurity density is helpful for reliable plasma start-up.