Plasma Performance of the Central Cell of a Cat-D Tandem Mirror Reactor
A particle and power balance assessment of the central cell of a conceptual D-D tandem mirror reactor (TMR) is carried out using a two-dimensional (2-D) Fokker-Planck code and a zero-dimensional (0-D) simulation code. The two computational models produce excellent agreement except for the mean triton energy, the difference in which can be attributed to the fact that the 2-D code considers the long slowing-down time of the tritium. It is demonstrated that for an ion confining potential between 200 and 300 keV, a) the central cell of a catalyzed-deuterium (Cat-D) fueled TMR can achieve ignition in the temperature range of 40-60 keV, b) the alpha ash buildup must be strictly controlled to obtain an economical ratio of electrostatic confining potential to central-cell temperature ¿/T, allowing the exhaust tritium to beta decay to helium-3 prior to reinjection results in roughly the same net electrical power output, and c) injecting extra tritium beyond that bred in the plasma allows a drop in the minimum ion confining potential required for ignition. It is shown that the ion confining potential is minimized when Tic, = 50 keV; this results in a plasma Q of 26. A quantitative comparison with a D-T reactor scenario is presented. It is shown that under ideal operating conditions, a conceptual Cat-D TMR has a 35-40 percent higher power conversion efficiency than a D-T device; this must be weighed against the higher temperature and plugging requirements of Cat-D.
Trapping rates in thermal barriers of tandem mirrors
Extensive calculations of trapping rates of passing ions in thermal barriers of tandem mirrors have been performed with the aid of a square-well Fokker-Planck code. Consideration of the form of the kinetic equation and boundary conditions shows that the trapping rate depends on the ratios of barrier potential depth to passing ion temperature, Zeϕ/T, mirror magnetic field to barrier field, R, and total barrier density to passing density, g. A scaling formula is presented which fits the results over a wide range of ϕ̃ = Zeϕ/T, R and g. In the limit of low ϕ̃ the trapping frequency scales as R5/4/(g−l)5/3, and as R2/5ϕ̃/(g−1)2 at large ϕ̃.
Constitutional Identity in the EU— A Shield or a Sword?
This Article consists of five sections. In the first section, it describes why identity questions matter, particularly in Europe. In the second section, the Article tackles the issue of multiple structural ambiguities affecting the concept of constitutional identity in the European constitutional vocabulary. In the third section, the Article explores trends concerning the use of constitutional identity in the European legal discourse and practice, including the development of alternative interpretations and applications of the notion of constitutional identities in the Member States. The fourth section of the Article combines the analytical accounts outlined in the second section with the trends identified in the third section, contending that different conceptions and applications of constitutional identity have varying effects on the European composite constitutional adjudication system and that the institutional and procedural framework should be calibrated accordingly. The final section of this Article draws some conclusions.