The Electrophysics program is devoted to obtaining new knowledge of the behavior of nuclei, atoms and molecules under the influence of electric and magnetic force fields; as such, it provides basic information needed to extend the capabilities for the utilization and transfer of energy so vital to the future of space. For example, the research results show the way to achieving higher temperature superconductors, high energy lasers and magnetoplasma dynamic devices, all being important in bringing about newer and better space power and propulsion systems for future missions. Research in the Electrophysics program is conducted at several NASA Centers, e.g., Ames Langley and Lewis; at the Jet Propulsion Laboratory; and in Universities and Industry.

SUPERCONDUCTIVITY

Research in superconductivity is aimed at ultimately providing higher temperature superconductors which would simplify the construction and use of high-field-strength magnets for power generation and propulsion systems of the future. The current program has the goal of extending the understanding of the phenomenon of superconductivity and developing a theoretical approach for making higher temperature superconductors. We also support measurements of the superconducting characteristics of new substances and the evaluation of the performance of newer types of superconducting magnets.

While engaged in explaining the transport of superconducting electron pairs from a tin superconductor through a non-superconducting gold film, it was noted that an electronic circuit device consisting of tin-gold-tin has a voltagecurrent characteristic like that of the usual transistor. This was a provocative discovery as it might be possible to provide transistor operation at a very low temperature, 1.5°K or -456.7°F, by an entirely new arrangement of atomic substances with the advantage of very low intrinsic noise background. Despite the need for cryogenic equipment, such a feature could be very useful in communication and computer systems where very weak signals must be detected and. processed. Work is continuing to determine if the superconducting array does indeed operate like a transistor, especially as an amplifier.

PLASMADYNAMICS

The purpose of the research into plasma dynamics is to develop the scientific understanding of the interactions between an ionized gas flow (plasma) and electric and magnetic fields for producing thrust or generating electrical power. It also investigates the plasmadynamic phenomena such as instabilities and non-equilibrium radiation in a plasma consisting of an ionized fissionable gas. A discussion of a reactor powered magnetohydrodynamic-dynamic energy conversion system is a useful means to relate this research on plasmadynamics to practical problems. The MHD concept is shown in figure 29 (NASA NSO 71–3463). In this example, argon gas is heated in a reactor to 4600°F and then passed through an MHD power generator in which 200 megawatts of electrical power is extracted. The argon gas is cooled in a heat exchanger and recirculated by a turbine driven compressor. Waste heat is rejected in a radiator. A space power system results which offers an order of magnitude improvement of specific mass as compared with other space power systems.

This closed cycle generator operates at a temperature of 4600° F. for compatibility with a nuclear heat source. At this temperature, the degree of ionization has to be enhanced by means of plasmadynamics phenomena that occurs when the slightly ionized gas traverses the magnetic field present in the generator channel. The cross-field motion of the gas generates an electrical potential which not only drives an electrical current for output power but also heats the electrons above the gas temperature for increased ionization. At the same time, there is a tendency that such a non-equilibrium energy distribution of the electrons drives instabilities within the plasma, and that the induced electric voltage causes electrical shorts along the inner surfaces of the channel. In fundamental plasmadynamics research, the detailed mechanisms of such instabilities have been elucidated and were found to depend strongly on the presence of traces of inpurities in the plasma. Efforts to remove such impurities have led to success, and instabilities can now be kept at a tolerable level. Electrical shorts along the inner surface of the channel involve boundary layer phenomena, which in the case of a streaming plasma, are appreciably more complex than those of a neutral gas flow. In the Electrophysics program a concerted research effort is underway for MHD boundary layer analysis. It is found that the characteristics

of the boundary layer, such as velocity and conductivity profiles, depend strongly on the microscopic processes which occur at the plasma-wall interfaces. Other emphasis is put on elaborating a general analytical framework which eventually will be applicable to various plasma boundary layer problems that occur in plasma accelerators for propulsion and re-entry simulators, and in plasma flow configurations through a nuclear energy source. The possibility of controlling the boundary layer characteristics, particularly the rates of heat flux from and to surface structures, will result in increasing operating temperatures with higher thermodynamic efficiencies of the cycle.

HIGH ENERGY LASERS

We have experimentally shown that the output of a gas laser using carbon dioxide as the lasing material, nitrogen and the helium isotope He3 can be increased when operated in a neutron flux field. The experiment and general principles involved are shown in figure 30 (NASA NSO 71-3464). The laser operates by means of an electrical discharge at which electrons excite metastable states of the nitrogen, which in turn can excite lasing levels of the carbon dioxide. The helium serves to depopulate the lower energy levels of the carbon dioxide. However, in the presence of neutrons, some of the He atoms undergo nuclear reactions, producing tritium atoms and high energy protons. Such protons act as an agent for increased ionization and excitation, and the laser output is increased.

Conceptually, lasers of sufficiently high energy can radiate energy to a satellite which can transform the radiation to electrical power. Also, a high energy laser can energize deuterium or tritium to form deuterons and tritons which are necessary in a controlled thermonuclear reaction to provide power.

Only a few low neutron flux was available in experiments done so far and the increase in power was accordingly small (10%). However, the principle was demonstrated. An improved laser of this kind is presently under construction which will operate at a much higher neutron flux close to the core of a nuclear reactor. Our current calculations indicate that we should be able to increase the laser power by a factor of two to three.

We are also exploring the potential of producing high energy ions by vaporization of targets with a high-powered laser beam. Figure 31 (NASA RR 71

3766) shows an experiment in which a very thin gold film (200 angstroms) was used as the target for a ruby laser. Measurements to date indicate that the ion energy in the plasma produced was from 2000 to 7000 electron volts. This technique may find application in controlled thermonuclear fusion (CTF) where production of ions (deuterons and tritons) is an important problem and ion energies of tens of thousands of electron volts are necessary. As is well known, CTF has a promise of tremendous electric power. Our future plans are to continue experiments with a high power laser to irradiate films of different compositions and to obtain data on the plasma characteristics and ion and electron energies.

TECHNOLOGY UTILIZATION (TU)

We are continuing to experience gratifying results in our work to report technology of potential value to activities outside the space program. This is evidenced in three ways. First, by the high number of inquiries we are processing to provide readers with details on how to use the ideas announced in AEC-NASA Tech Briefs Second, by the confirmed proof that our ideas are, in fact, being put to use Third, by the emergence of technologies which we have come to recognize as have considerable promise for new industries or for significant commercial application.

Our TU inquiry volume at 8% of the total for NASA is significantly larger than the percentage of the space budget devoted to nuclear propulsion Similarly, two of the five "best selling" Tech Briefs in the history of the NASA program, covering a seven-year span, were originated in the Nuclear Rocket Program. The Welding Manual achieved instant popularity and, although we have reported examples of its application previously, two new casses are of interest. Weld corrosion was being experienced in food processing equipment used by a West Coast company. Information in our manual solved many questions regarding welding standards and requirements imposed upon equipment suppliers. The corrosion problem was eliminated, and the company indicates "significant" monetary savings. In other case, the Foster Joseph Sayers Dam project in Pennsylvania experienced substantially reduced construction costs through the benefit of the manual. A subcontractor had trouble meeting the weld qualification requirements, and faced a cost overrun. The manual showed that new welding methods could be employed which allowed for the use of lower grade roller track steels in place of stainless steel.

In last year's statement we mentioned a radio frequency induction torch which was developed in the evaluation of gas-core reactors. It produces a steady flow of almost totally clean gas at temperatures up to 10,000° F. The fundamental technology for this torch has been known in plasma physics for a number of years. and was not funded by NASA. Our contribution has been the scaling-up of what has ben described as a low power "lab toy" to a device which now operates at 1 million watts and is capable of improvement to at least 10 million watts. The contractor whom we have sponsored has announced a ball processing plant capable of turning out 6 million pounds per year of iron and steel spheres, ranging in diameter from four ten-thousandths to four thousandths of an inch. Articles appearing in commercial and technical journals during 1970 described the features of the system and postulated a sales volume of $10-million by 1975. In a dramatically different application, the Lewis Research Center advises that the torch is a good candidate for ultra-sensitive spectroscopic analysis of tract elements in blood serum, food, industrial wastes, pollutants, etc. The very clean, very high temperature which is unique to the torch has provided readings 10 times more sensitive than those available by the prior method, the gas flame spectroscope.

The nuclear rocket program technology activity support several investigations which could have a positive impact on environmental quality. One direct activity of this nature is the effluent cleanup system (scrubber) for the reactor exhaust of the so-called Nuclear Furnace. The scrubber is intended to remove radioactive components from the exhaust stream. When the Nuclear Furnace is in operation with the scrubber, much valuable data will be obtained on the efficacy of such systems in cleaning up high-temperature reactor exhaust streams. Such knowledge and experience will directly effect control emissions from any systems involving high-temperature combustible effluents which contain soluble, particulate, and inert substances.

A less direct and longer range benefit may result from investigations underway on higher temperature nuclear reactors and improved power conversion systems. In combination, these technology advancements will result in higher

cycle efficiencies, and therefore lower heat rejection rates to the environment, Eventually, ultrahigh-temperature power systems may be developed which may permit radiating the waste heat to outer space, thus eliminating any atmospheric Interaction or thermal pollution.

The Space Nuclear Systems Office has sponsored vortex flow research in support of the gaseous core reactor system since 1963. As a result of the understanding of vortex flows obtained by this research. United Aircraft Research Laboratories has devised a unique water/oil vortex separator which shows great promise for cleaning up oil spills. Feasibility of the separators has been demonstrated using sub-scale hardware. UARL has recently submitted a proposal to the U.S. Coast Guard for the construction of a complete oil-spill cleanup system based on this vortex separator. The proposed system would weigh approximately 10,000 pounds, could be air deployed using a helicopter for distances to 150 miles and is to have a cleanup capability for spills up to 20,000 tons. It is anticipated that 2500 gallons/minute of a water/oil mixture could be processed. For a slick one-tenth of an inch thick, this would result in approximately 500 gallons/ minute of the oil being recovered. Thus a spill of one million gallons could be processed in approximately 35 hours.

CONCLUDING REMARKS

During the past year, the utility of nuclear power in space has been dramatically demonstrated by the very successful long-term lunar operation of the SNAP-27 isotope generator, the only type of power source which could have met the Apollo scientific station requirements, and by the operation of the SNAP-19 generator which has provided needed supplemental power to the NASA Nimbus weather satellite. In the near future other RTG's, being provided by the AEC, will be used on a new and improved Navy navigational satellite, NASA Jupiter probe missions, and in the unmanned exploration of Mars. Moreover, nuclear power will be the only way to meet many of the electrical requirements of missions to the outer planets and other potential missions of the late seventies and beyond.

We have continued to make progress during the past year in the development of the NERVA engine, definition of the companion vehicle and in rocket reactor fuel element technology. Our mission studies have shown that a NERVApropelled stage is capable of performing nearly all foreseeable complex missions beyond those of low Earth orbit during the next few decades.

Unfortunately, the FY 1972 budget levels prevent us from progressing at the rate technology would allow; however, the potential of space nuclear systems makes it essential that these activities continue in order to apply the energy of the atom to the accomplishment of the Nation's goals in space.

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