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Latest News
First astatine-labeled compound shipped in the U.S.
The Department of Energy’s National Isotope Development Center (NIDC) on March 31 announced the successful long-distance shipment in the United States of a biologically active compound labeled with the medical radioisotope astatine-211 (At-211). Because previous shipments have included only the “bare” isotope, the NIDC has described the development as “unleashing medical innovation.”
Osamu Mitarai, Akio Sagara, Nobuyoshi Ohyabu, Ryuichi Sakamoto, Akio Komori, Osamu Motojima
Fusion Science and Technology | Volume 56 | Number 4 | November 2009 | Pages 1495-1511
Technical Paper | doi.org/10.13182/FST09-A9253
Articles are hosted by Taylor and Francis Online.
A new control method for the unstable operating point in the force-free helical reactor (FFHR) is proposed for low-temperature and high-density ignited operation. While in the stable ignition regime, the error of the fusion power of e'DT(Pf) = +(Pf0 - Pf) is used to obtain the desired fusion power with proportional-integral-derivative control of the fueling, we have discovered that in the unstable ignition regime, the error of the fusion power with an opposite sign of e'DT(Pf) = -(Pf0 - Pf) can stabilize the unstable operating point. Here, Pf0 is the fusion power set value, and Pf is the measured fusion power. Around the unstable operating point, excess fusion power (Pf0 < Pf) supplies fueling, increases the density, and then decreases the temperature. Less fusion power (Pf0 > Pf) in the subignited regime reduces the fueling, decreases the density, and then increases the temperature. While the operating point rotates to the clockwise direction in the stable ignition boundary, it rotates to the counterclockwise direction in the unstable ignition regime. Using this control algorithm, it is demonstrated that the operating point can reach the steady-state condition from an initial very low-temperature and low-density regime. The fusion power can also be shut down from the steady-state condition without any problems. Furthermore, characteristics of the stable and unstable ignition regimes are compared for the same fusion power, and control robustness to changes with various parameters has been studied.