摘要:

The current generation of communications satellites are located primarily in geosynchronous Earth orbit (GEO). Over the next decade, however, a new generation of communications satellites will be built and launched, designed to provide a world−wide interconnection of portable telephones. For this mission, the satellites must be positioned in lower polar‐ and near‐polar orbits. To provide complete coverage, large numbers of satellites will be required. Because of the required number of satellites decreases as the orbital altitude is increased, fewer satellites would be required if the orbit chosen were raised from Low to intermediate orbit.However, in intermediate orbits, satellites encounter significant radiation due to trapped electrons and protons. Radiation tolerant solar cells may be necessary to make such satellites feasible. We analyze the amount of radiation encountered in low and intermediate polar orbits at altitudes of interest to next−generation communication satellites, calculate the expected degradation for silicon, GaAs, and InP solar cells, and show that the lifetimes can be significantly increased by use of advanced solar cells. ©American Institute of Physics 1995

ISSN:0094-243X    

DOI:10.1063/1.47215

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

InP‐based multijunction tandem solar cells show great promise for high conversion efficiency and high radiation resistance. In this work, we present results on an InGaAs solar cell with a very high current density, 60 mA/cm2(the highest ever reported), and an efficiency (&eegr;) of 10.2% under natural sunlight, and InP solar cell with &eegr;=18% under AM1 simulator, and InGaAs tunnel junctions with peak current densities exceeding 1000 A/cm2. Preliminary results on an InP/InGaAs tandem solar cell show the possibility of no interconnect voltage loss and that a patterned tunnel junction is necessary to allow current matching in the tandem by avoiding photons absorption in the InGaAs tunnel junction. Finally, our preliminary investigation on new multiquantum well InP cells indicates the strength of this alternative approach. ©American Institute of Physics 1995

ISSN:0094-243X    

DOI:10.1063/1.47216

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The possibility of power module development as the first step for the development of an orbital power state (OPS) is reviewed in this report. The most probable OPS scheme is a laser system with direct nuclear pumping. Since this task is not yet been defined well enough in its technical form, a better developed prototype has been selected in the form of a free electron laser with the power system on the basis of a gas core nuclear reactor (MGD)—generator and multi‐modular closed gas turbine system. Taking into consideration that many of the elements of this orbital complex are in the stage of advanced development within current programs in different countries, we propose to continue the research and development of the remainder of the key elements.This work was carried out earlier for military purposes but was halted after the end of the cold war. It is proposed to perform this work within the framework of international cooperation, and a lot of the achievements of the Russian nuclear and aerospace technology will be utilized in the project. It will be a worthwhile task to achieve within 6−8 years the development of an orbital power module with a shortwave laser having the power of NL=100 kW for short−time periodical energy transmision from the 500 km orbital to a stationary site in Eastern Siberia. The power supply for this laser is based upon a closed high temperature gas turbine system with a graphite heat accumulator, which is charged with electricity generated by the ‘‘Topaz’’‐type nuclear power system. ©American Institute of Physics 1995

ISSN:0094-243X    

DOI:10.1063/1.47218

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Governments presently have little individual or collective interest in financing large scale lunar enterprises, either for science or potential resource utilization. For example, preliminary technical and economic considerations of the return of lunar helium−3 (3He) for terrestrial fusion power plants suggest positive economic and enviromental returns, however, no significant governmental activity has been focused on this or other space related energy options.General analysis of both short and long term returns on investment for a lunar helium−3 enterprise, including considerations of future launch costs, strongly suggests that private financing may be attracted to this endeavor. A privately organized ‘‘catalytic financing’’ approach to providing start‐up capital for a lunar helium−3 enterprise appears to be worth consideration. ©American Institute of Physics 1995

ISSN:0094-243X    

DOI:10.1063/1.47219

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The productive efficiency potential of solar power vis‐a‐vis five other electric generation technologies is examined as a prototype analysis. Environmental externalities are considered as a fundamental component of the problem. The analysis is completed by the modern operations research method Data Envelopment Analysis (DEA). Lunar solar power (LSP) is shown to be considerably more efficient than fossil, nuclear, and solar terrestrial alternatives. This relationship holds even if resource costs are much greater than estimated. ©American Institute of Physics 1995

ISSN:0094-243X    

DOI:10.1063/1.47220

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The technical competitiveness of the US economy versus other leading nations, as measured by relative efficiency, is examined given a US policy commitment to develop Lunar Solar Power (LSP) as a new energy technology. The impact of LSP is quantified in terms of the effect on national income, the balance of trade, capital investment, and primary energy consumption. The analysis uses Data Envelopment Analysis (DEA) to measure the effect of the strategy on US technical competitiveness for two scenarios reflecting different stages of technology implementation. DEA evaluates the relative efficiency of producers and identified the ‘‘best practice’’ production frontier. In this application, the producers are nations. The results show the US economy remains technically competitive during all periods of the early and mature phases of LSP development. ©American Institute of Physics 1995

ISSN:0094-243X    

DOI:10.1063/1.47221

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Experts have achieved tremendous success in space technologies, as well as in the field of electrical energy Earth supply systems. It is time to join efforts of scientists who work in both spheres because these problems are tightly connected. This paper is an attempt to show that studies concerned with power system development, including the formation of a Global Power System (GPS) should be considered as an important part of studies concerned with transmitting clean energy from space to Earth. Some results of investigations on specific features of a power system in different regions of the world are addressed by experts who look for suitable sites for the reception of Space‐Earth electricity transmission systems. ©American Institute of Physics 1995

ISSN:0094-243X    

DOI:10.1063/1.47222

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

This paper will analyze the legal aspects of alternative power systems in space. The initial question is the legal status and rights to ownership of space resources, including helium ‐ 3, solar energy and other resources, used in these power systems. It is suggested that, although existing space law does raise questions about ownership and use, the official American understanding of the extant space treaties will permit the actual exploitation of these resources for space ‐ and earth ‐ based needs. ©American Institute of Physics 1995

ISSN:0094-243X    

DOI:10.1063/1.47223

出版商:AIP    

年代:1995

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.47198

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A particle accelerator‐driven spallation target and corresponding blanket region are proposed for the ultimate disposition of weapons‐grade plutonium being retired from excess nuclear weapons in the U.S. and Russia. The highly fissle plutonium is contained within .25 to .5 cm diameter silicon‐carbide coated graphite beads, which are cooled by helium, within the slightly subcritical blanket region. Major advantages include very high one‐pass burnup (over 90%), a high integrity waste form (the coated beads), and operation in a subcritical mode, thereby minimizing the vulnerability to the positive reativity feedbacks often associated with plutonium fuel. ©American Institute of Physics 1995

ISSN:0094-243X    

DOI:10.1063/1.47199

出版商:AIP    

年代:1995

数据来源: AIP