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You can generate and download free printable calendars for , and Each monthly and yearly calendar is adjusted in to a page neatly and can be printed on any paper. It is another 4object of this invention to provide a vapor for a MHD generator which may be used in outer space. It is still another object of this invention to provide a vapor for a MHD generator which may be utilized as a topping device for steaml power plants.
It is still a further object of this invention to provide a mixture for MHD generators wherein the resultant degree of ionization and conductivity will be greater than the thermal equilibrium value. It is another object of this invention to. It is another object of the invention to provide a vapor for a MDH generator which is economical to produce and utilizes conventional, currently available components that lend themselves to standard mass production manufacturing techniques.
These and other advantages, features and objects of the invention will become more apparent from the following description taken in connection with the illustrative embodiments in the accompanying drawings, where- 1n:. With the increased use of earth satellites and interplanetary space probes a serious problem has arisen attempting to sustain reliable electrical power for the instrumentation aboard such vehicles for extended periods.
The nuclear reactor is one answer to this problem. In utilizing nuclear reactors for MHD power generation in outer space a radiator is needed to reject the heat. The MHD generator utilizes a high inlet and outlet temperature, however, due to the possibility of core melt down and other metallurgical requirements, the nuclear reactor is limited to a relatively low temperature, in the order of K. Ordinarily, at this temperature, the thermal degree of ionization of the seed and the overall gas conductivity would be low, but by utilizing the induced electric field of the MHD generator the electrons will be heated enough to raise the conductivity to usable proportions.
It can be shown that a vapor cycle is more eicient than a gas cycle for MHD operation in outer space. I have discovered that by using mercury vapor seeded with a small amount of barium one percent has been found adequate as the working fluid, added conductivity is obtained. This is explained as follows: In the MHD generator there exists two electric fields called the Faraday and Hall fields. The former is given by the expression X ,. The latter depends on the generator electrode configuration.
Its maximum value is obtained in the infinitely segmented electrode generator operated under short circuited conditions. At high enough elds the Hall field can be as much as an order of magnitude greater than the Faraday field.
It is this field which will be utilized to heat the electrons suiciently to excite the 3PZ state of Hg which has an excitation potential of 5. This reaction proceeds thusly:. The 3P2 state is metastable and can lose its energy only by collision with an electron or an atom. Barium has an ionization potential of 5. This mixture satisfies Wigners rule of spin conservation, hence, the cross section for this process should be large.
Quantum mechanically, the mixture of krypton and mercury would work, but for MHD operation it is undesirable because in the mixture 3Pn krypton plus one percent mercury the ionization potential of mercury is too high. Another possible seeding material for mercury is potassium. Generally, the alkali metals do not satisfy Wigners conservation in all collisions, for example, in Hg-i-K the two consecutive reactions are:.
Examining the spins in reaction 2 , it is found that in only 50 percent of the collisions will spin be conserved. Since the ionization potential of potassium is 4.
However, since the spins are not always conserved the etlcency is lower than in a mercury-barium mixture even though the ionization potential of potassium is 0.
Mercury plus cesium is also unsatisfactory due to the large energy discrepancy between them. Furthermore, it has been found that mercury plus alkali metals may amalgamate explosively.
While it is envisaged that the induced iields in the MHD generator will heat the electrons, the use of the mercury-barium working uid is not restricted to this mode of electron heating. An externally applied electric field at the entrance of the generator or an electron beam can also be utilized to heat the electrons and populate the mercury metastables.
Referring now to FIG. The nuclear reactor Iproduces suiiicient heat to circulate the coolant 11 through a closed loop to the heat exchanger The heat is transferred to the mercury seeded with about one percent barium 14 which becomes somewhat ionized.
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