[en] Experimental tests of the existence of a critical gradient are suggested, with the ITG-mode as a theoretical example. Implications for ITER designs are discussed

[en] Verification of the basic scaling law of magnetic mirror confinement is discussed. Initial startup of a mirror reactor is another problem that must be overcome. The prospects for solving these two problems are discussed. (U.S.)

[en] During 1976, new Mirror Program plans have been laid out to take into account the significant advances during the last 18 months. The program is now focused on two new mirror concepts, field reversal and the tandem mirror, that can obtain high Q, defined as the ratio of fusion power output to the neutral-beam power injected to sustain the reaction. Theoretically, both concepts can attain Q = 5 or more, as compared to Q = 1 in previous mirror designs. Experimental planning for the next 5 years is complete in broad outline, and we are turning attention to what additional steps are necessary to reach our long-range goal of an experimental mirror reactor operating by 1990. Highlights of the events that have led to the above circumstance are listed, and experimental program plans are outlined

[en] The calculations of field reversal by neutral injection carried out by Byers with the Superlayer code have thus far concentrated on varying the geometry of the injected beams. The trapped current is taken as a parameter, constant in time. Also, the only factor determining the containment of trapped ions is their orbit dynamics in the changing magnetic field. In addition, it is necessary to keep track of the actual trapping processes at a fixed injection current, and also ion losses (notably, by electron drag). Trapping and drag were studied briefly but the detailed orbit dynamics that requires the code was not carried out. Instead β greater than 1 is taken as an approximate criterion for reversal and then the question of injection current I necessary to build-up the density to the equivalent of β greater than 1 before being limited by other processes was studied. Since for the initial target plasma β < 1, it is necessary to increase either n or T (or both). (U.S.)

No abstract available

[en] In May of 1988, the long tradition of international cooperation in magnetic fusion energy research culminated in the initiation of design work on the International Thermonuclear Experimental Reactor (ITER). If eventually constructed in the 1990s, ITER would be the world's first magnetic fusion reactor. This paper discusses the background events that led to ITER and the present status of the ITER activity. This paper presents a brief summary of the technical, political, and organizational activities that have led to the creation of the ITER design activity. The ITER activity is now the main focus of international cooperation in magnetic fusion research and one of the largest international cooperative efforts in all of science. 2 refs., 12 figs

[en] The astrophysical αω dynamo converting angular momentum to magnetic energy can be interpreted as a self-excited Faraday dynamo together with magnetic relaxation coupling the dynamo poloidal field to the toroidal field produced by dynamo currents. Since both toroidal and poloidal fields are involved, the system can be modeled as helicity creation and transport, in a spheromak plasma configuration in quasi-equilibrium on the time scale of changes in magnetic energy. Neutral beams or plasma gun injection across field lines could create self-excited spheromaks in the laboratory.

No abstract available

[en] It is shown that, despite the poor global energy confinement observed in spheromak experiments to date, the long-term prospects may be favorable as spheromaks are scaled to larger size and higher temperatures. The present performance is traced to excessive magnetic energy loss at the edge compared to tokamaks and heat transport due to magnetic fluctuations, both of which should scale away as the temperature increases

[en] The Tandem Mirror Experiment (TMX) is being built at Livermore to test the principles of the new tandem mirror reactor concept. In this concept the fusion plasma is confined in a long solenoid terminated at each end by mirror machines of the magnetic-well type. High density plasmas are maintained in each of the mirror end cells by neutral injection at high energies (up to 1 MeV in a high Q reactor). The usual positive ambipolar potential that automatically develops in each mirror cell serves as an electrostatic barrier that confines ions in the solenoid for many collision times, and the very stable plasmas in these end cells ''anchor'' each flux tube, thereby assuring MHD stability of the system up to betas of order unity in the solenoid. The TMX will test these main features of the tandem mirror idea and will also investigate optimum means of suppressing loss cone instabilities in the end cells based on methods demonstrated in the 2XIIB experiment. The end cells will be similar in size and injected power to 2XIIB, but some injectors will operate at 40 kV. Expected parameters are n tau approximately 10¹¹ cm^-3 sec at ion energies of 20 keV in the end plugs and n tau approximately 1 to 3 x 10¹¹ cm^-3 sec in the solenoid at ion temperatures up to 2 keV if auxiliary beam heating is applied to the solenoid. The solenoid field will be variable up to about 4 kG and the length is 5 meters. The facility is nearing completion (18 months construction time) and experiments are expected to begin early in 1979