ISSN:0031-9228    

DOI:10.1063/1.2995572

出版商:AIP    

年代:1979

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2995541

出版商:AIP    

年代:1979

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2995544

出版商:AIP    

年代:1979

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2995546

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Of the many ionic species that normally emerge from the ion source of an electrostatic accelerator, it has traditionally been only the monatomic ions that are considered to provide “useful” beams. The remaining beams of molecular ions (H2+,H3+,HeH+,OH+,etc.), which frequently constitute as much as 90&percent; of the total ion‐beam current, are seldom used in a nuclear‐physics experiment.

ISSN:0031-9228    

DOI:10.1063/1.2995547

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Although most physicists have long been convinced that gravity waves would ultimately be detected, there has yet been no unambiguous experimental confirmation of their existence. Recent work by Joseph Taylor and Lee Fowler of the University of Massachusetts at Amherst and Peter McCulloch of the University of Tasmania, however, provides further evidence for the reality of these elusive waves. In the 8 February issue ofNature(277, page 437), Taylor, Fowler and McCulloch report that the orbital period of the only known binary pulsar is diminishing at a rate of about 3 parts in1012,which is consistent with quadrupole radiation of gravity waves by the system.

ISSN:0031-9228    

DOI:10.1063/1.2995548

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The resolving power of the scanning acoustic microscope now rivals that of the optical microscope. Since Calvin Quate and Ross Lemons reported building the first scanning acoustic microscope in 1974, Quate's group at Stanford has been able to improve the resolution of this instrument every year by about a factor of two; they now report they have achieved resolutions of about half a micron. Quate recently described his progress in an invited paper at the March meeting of The American Physical Society in Chicago. Quate's group has also recently reported the results of the first experiment with a photoacoustic microscope, a new instrument that generates sound waves by heating a sample with a pulsed laser.

ISSN:0031-9228    

DOI:10.1063/1.2995549

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

One of the fundamental postulates of the special theory of relativity is that the speed of light is uniform in all directions, and is independent of the motion of the emitter or the observer. A recent report from the Joint Institute for Laboratory Astrophysics (National Bureau of Standards and the University of Colorado) in Boulder has greatly increased the precision with which we know that the postulate agrees with experiment.

ISSN:0031-9228    

DOI:10.1063/1.2995550

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

At the 1968 conference on controlled fusion in Novosibirsk a group from Kurchatov, USSR, led by L. A. Artsimovitch, presented convincing evidence that one conceptually simple method for confining plasmas in a ring showed great promise for future developments. The name for their early machine, the tokamak, has now become the generic name for all such devices. The Russian successes led to a rapid expansion of research with tokamaks, so that while in 1968 there were only nine of them, all in the USSR, there are now more than a hundred; they are in the USSR, the US, Europe, Japan, and elsewhere.

ISSN:0031-9228    

DOI:10.1063/1.2995551

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The tokamak is a marvelous device for plasma confinement, but can it be made into a commercially viable reactor? This is a question being asked more and more often by the electric utilities and the informed public. As a magnetic container of hot plasma, the tokamak is without peer. Now that the complicating factor of impurity radiation has been removed, the self‐healing properties of the tokamak discharge, leading to good confinement scaling in both the collisional (MIT Alcator) and the collisionless (Princeton Large Torus) regimes, have become apparent. But satisfying the temperature, density and confinement time conditions for fusion is only a part of the story. The ultimate users of fusion—the electric utilities—are even more vitally interested in such factors as engineering feasibility, reliability and ease of maintenance, overall efficiency, total plant cost, small plant size, and safety and environmental impact. Since the tokamak was developed from the standpoint of plasma stability, there is concern that it may not be ideal from those other viewpoints. Indeed, there may be room for improvement in the accessibility allowed by a tight torus, in the high technology required for auxiliary heating, fueling, and treatment of wall surfaces, and in the costly equipment needed in breeding and containing tritium. Feasible solutions to these difficult engineering problems have been suggested—but are there better solutions?

ISSN:0031-9228    

DOI:10.1063/1.2995552

出版商:AIP    

年代:1979

数据来源: AIP