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Angular distribution of emitted and reflected radiant energy from diffuse gray asymmetric grooves
fer I n R a d i a t i n g F i n s " , N A S A T e c h n i c a l N A S A T N D-1878, O c t o b e r 1963, 43 pgs.
Note,
An equation is derived for the temperature distribution in a rectangular fin of infinite width and of finite length and thickness that assumes one-dimensional conduction along the finite length and radiation from both sides to an equivalent sink temperature, with material emissivity and conductivity given as functions of temperature. Results in the form of a radiating effectiveness and temperature distribution are presented fox' several materials and surface coatings with linearly wtrying conductivity and emissivity. The percent error in radiating effectiveness as '~ result of assuming constant properties is also given fox" these eases. A correlation is obtained that permits simple calculation of the heat rejected by a fin of variable conductivity and variable einissivity from the readily awdlable data for a fin with constant properties.
X I - - R a d i a t i o n Mechanics and Availability: Insolation, Spectroscopy and Spectral Distribution P e r l m u t t e r , Morris, a n d J o h n R. Howell, Lewis Research C e n t e r , " A n g u l a r D i s t r i b u t i o n of E m i t t e d an d R e f l e c t e d R a d i a n t E n e r g y f r o m Diffuse G r a y A s y m metric Grooves", NASA Technical Note, NASA TN D-1987, O c t o b e r , 1963, 43 p. The directional emissivity and directional refleetivity of an infinitely long isothermal asymmetric groove with diffusely emitting and reflecting gray walls are analyzed, and numerical results are given. The directional emissivity is presented as a function of the groove parameters and material emissivity, while the directional refleetivity is presented as a function of these parameters and the angle of incident radiation. The directional refleetivity was found to be greatest at angles close to the angle of the incident beam in sharp contrast to the commonly assumed diffuse or specular modes of reflection. The directional emissivity was greatest elose to the angle bisecting the groove. The results thus indicate that the surface struelure has a strong effect on the radiative properties. Some extimples of radiant-energy interchange between surfaces with directional radiative properties are used to illustrate the large effects of these surfaces on the energy interchange. The ex alnples also illustrate how the radiant interchange can be controlled to some extent by proper design of these surfaces. The analysis is restricted to grooves with dimensions that are large in comparison to the wavelengths of the radiation considered. Billings, D o n a l d E. a n d Carl G. Lilliequist, H i g h Altit u d e O b s e r v a t o r y a n d D e p a r t m e n t of A s t r o - G e o physics, U n i v . of Colorado, Boulder, Colo., " C o r o n a l T e m p e r a t u r e G r a d i e n t a n d t h e Solar W i n d " , The Astrophysical Journal, 137, No. 1, J a n . , 1963, 5 pgs. Evidence is presented for a negative temperature gradient in the inner corona. The significance of such "~ t:emoer.'ltnro gradient to solar wind theories is discussed. Castelli, J o h n P., Space P h y s i c s L a b o r a t o r y , A F C R L , Office of A e r o s p a c e R e s e a r c h , U S A F , L. G. H a n s c o m Field, Mass., "Solar Flux Measurements, April 1962, an d A n t e n n a C o n s i d e r a t i o n s " , A F C R L 621111, D e c e m b e r , 1962, 17 p. For ten days in April, 1962, solar-power flux density was Ineasured simultaneously at four frequencies using the 84 ft diameter radio telescope at Halnilton, Mass. The frequencies were 2965 Mc, 1200 Mc, 400 Mc, and 225 Mc. In addition, data were available for several days at 94 kMc through the courtesy of C. W. Tolbert of the University of Texas. Data at 9180 Mc were taken at Hamilton, Mass. with an 8-ft antenna. Apart from the solar data presented, various antenna parameters of the 84-ft parabola are reviewed and presented along with the
Vol. 8, No. 2, 1964
method of determination. Fin,dly, tile meth,)d is presented by widch the recorded data were corrected for these in deterinining true flux. N e w k i r k , G o r d o n , ,Jr., H i g h A l t i t u d e O b s e r v a t o r y , U n i v e r s i t y of Colorado, " T h e Solar C o r o n a in A c t i v e R e g i o n s and t h e T h e r m a l Origin of t h e Slowly V a r y ing C o m p o n e n t of Solar R a d i o R a d i a t i o n " , R e p r i n t e d from A s t r o p h y s i c a l J o u r n a l , 133, 3, M a y lq61, 31 pgs. Using as a basis previously pul)lished K-corona observations made at Climax, Coh)rado, a nn)del is derived for the enhancement of electron density in the corona at>ove an aclive region. The electron densities in the quiet corona during tim sunspot maxinmln 1957-1958 were found to be about twice those reported by van de Hulst for a maximmn corona, while densities along the axis of the active region were found to be about twice those in the quiet corona at the same height. The several models advanced in the past to explain the slowly varying component of solar radio radiation are criticized mainly on the basis that they require coronal temperatures of from 6 to 10 X 106 deg K, while there is no evidence fox" the existence of such temperatures. The electron densities deterinined in the first section are combined with models of the chromosphere arid of a plage to determine the appearance of the active region at radio wave lengths. Detailed calculations of the appearance of the active region 'it various radio frequencies were carried out arid include the effect of refraction but neglect the effects of magnetic fields. Profiles of the solar disk at various radio frequencies for three coronal inodels with the active region at various positions on the solar disk are presented. These profiles are then used to predict such characteristics of the slowly varying component as its spectrum, apparent size, "height", and directivity. The comptiri son of these predictions with the observed properties leads to the conclusion that the slowly varying component is due solely to the enhancement (if densities in the corona arid in the chromospheric plage. There is no evidence that the temperature of the corona is modified from its normal value of about 2 X 10 ~ deg K. A brief examination of the therinal radiation from an idealized look prominence shows that temperatures of 3 4 X 10" deg K are sufficient to explain some of the features of the radio event called "gradual rise 'rod fall." Lu si g n an , B. B., R a d i o s c i c n c e L a b o r a t o r y , S t a n f o r d U n i v e r s i t y , " D e t e c t i o n of Solar P a r t i c l e S t r e a m s b y H i g h - F r e q u e n c y R a d i o W a v e s " , Join'hal of Geophysical Research, 68, 20, O c t o b e r 15, 1963, 16 pages. Interactions between radio waves and charged particles change their character when the p'irticles have high "lverage velocities. Investigation has been made of the nature of such interactions "~ssmning no collisions, no external magnetic field, and low particle densities. A stream
Note,
An equation is derived for the temperature distribution in a rectangular fin of infinite width and of finite length and thickness that assumes one-dimensional conduction along the finite length and radiation from both sides to an equivalent sink temperature, with material emissivity and conductivity given as functions of temperature. Results in the form of a radiating effectiveness and temperature distribution are presented fox' several materials and surface coatings with linearly wtrying conductivity and emissivity. The percent error in radiating effectiveness as '~ result of assuming constant properties is also given fox" these eases. A correlation is obtained that permits simple calculation of the heat rejected by a fin of variable conductivity and variable einissivity from the readily awdlable data for a fin with constant properties.
X I - - R a d i a t i o n Mechanics and Availability: Insolation, Spectroscopy and Spectral Distribution P e r l m u t t e r , Morris, a n d J o h n R. Howell, Lewis Research C e n t e r , " A n g u l a r D i s t r i b u t i o n of E m i t t e d an d R e f l e c t e d R a d i a n t E n e r g y f r o m Diffuse G r a y A s y m metric Grooves", NASA Technical Note, NASA TN D-1987, O c t o b e r , 1963, 43 p. The directional emissivity and directional refleetivity of an infinitely long isothermal asymmetric groove with diffusely emitting and reflecting gray walls are analyzed, and numerical results are given. The directional emissivity is presented as a function of the groove parameters and material emissivity, while the directional refleetivity is presented as a function of these parameters and the angle of incident radiation. The directional refleetivity was found to be greatest at angles close to the angle of the incident beam in sharp contrast to the commonly assumed diffuse or specular modes of reflection. The directional emissivity was greatest elose to the angle bisecting the groove. The results thus indicate that the surface struelure has a strong effect on the radiative properties. Some extimples of radiant-energy interchange between surfaces with directional radiative properties are used to illustrate the large effects of these surfaces on the energy interchange. The ex alnples also illustrate how the radiant interchange can be controlled to some extent by proper design of these surfaces. The analysis is restricted to grooves with dimensions that are large in comparison to the wavelengths of the radiation considered. Billings, D o n a l d E. a n d Carl G. Lilliequist, H i g h Altit u d e O b s e r v a t o r y a n d D e p a r t m e n t of A s t r o - G e o physics, U n i v . of Colorado, Boulder, Colo., " C o r o n a l T e m p e r a t u r e G r a d i e n t a n d t h e Solar W i n d " , The Astrophysical Journal, 137, No. 1, J a n . , 1963, 5 pgs. Evidence is presented for a negative temperature gradient in the inner corona. The significance of such "~ t:emoer.'ltnro gradient to solar wind theories is discussed. Castelli, J o h n P., Space P h y s i c s L a b o r a t o r y , A F C R L , Office of A e r o s p a c e R e s e a r c h , U S A F , L. G. H a n s c o m Field, Mass., "Solar Flux Measurements, April 1962, an d A n t e n n a C o n s i d e r a t i o n s " , A F C R L 621111, D e c e m b e r , 1962, 17 p. For ten days in April, 1962, solar-power flux density was Ineasured simultaneously at four frequencies using the 84 ft diameter radio telescope at Halnilton, Mass. The frequencies were 2965 Mc, 1200 Mc, 400 Mc, and 225 Mc. In addition, data were available for several days at 94 kMc through the courtesy of C. W. Tolbert of the University of Texas. Data at 9180 Mc were taken at Hamilton, Mass. with an 8-ft antenna. Apart from the solar data presented, various antenna parameters of the 84-ft parabola are reviewed and presented along with the
Vol. 8, No. 2, 1964
method of determination. Fin,dly, tile meth,)d is presented by widch the recorded data were corrected for these in deterinining true flux. N e w k i r k , G o r d o n , ,Jr., H i g h A l t i t u d e O b s e r v a t o r y , U n i v e r s i t y of Colorado, " T h e Solar C o r o n a in A c t i v e R e g i o n s and t h e T h e r m a l Origin of t h e Slowly V a r y ing C o m p o n e n t of Solar R a d i o R a d i a t i o n " , R e p r i n t e d from A s t r o p h y s i c a l J o u r n a l , 133, 3, M a y lq61, 31 pgs. Using as a basis previously pul)lished K-corona observations made at Climax, Coh)rado, a nn)del is derived for the enhancement of electron density in the corona at>ove an aclive region. The electron densities in the quiet corona during tim sunspot maxinmln 1957-1958 were found to be about twice those reported by van de Hulst for a maximmn corona, while densities along the axis of the active region were found to be about twice those in the quiet corona at the same height. The several models advanced in the past to explain the slowly varying component of solar radio radiation are criticized mainly on the basis that they require coronal temperatures of from 6 to 10 X 106 deg K, while there is no evidence fox" the existence of such temperatures. The electron densities deterinined in the first section are combined with models of the chromosphere arid of a plage to determine the appearance of the active region at radio wave lengths. Detailed calculations of the appearance of the active region 'it various radio frequencies were carried out arid include the effect of refraction but neglect the effects of magnetic fields. Profiles of the solar disk at various radio frequencies for three coronal inodels with the active region at various positions on the solar disk are presented. These profiles are then used to predict such characteristics of the slowly varying component as its spectrum, apparent size, "height", and directivity. The comptiri son of these predictions with the observed properties leads to the conclusion that the slowly varying component is due solely to the enhancement (if densities in the corona arid in the chromospheric plage. There is no evidence that the temperature of the corona is modified from its normal value of about 2 X 10 ~ deg K. A brief examination of the therinal radiation from an idealized look prominence shows that temperatures of 3 4 X 10" deg K are sufficient to explain some of the features of the radio event called "gradual rise 'rod fall." Lu si g n an , B. B., R a d i o s c i c n c e L a b o r a t o r y , S t a n f o r d U n i v e r s i t y , " D e t e c t i o n of Solar P a r t i c l e S t r e a m s b y H i g h - F r e q u e n c y R a d i o W a v e s " , Join'hal of Geophysical Research, 68, 20, O c t o b e r 15, 1963, 16 pages. Interactions between radio waves and charged particles change their character when the p'irticles have high "lverage velocities. Investigation has been made of the nature of such interactions "~ssmning no collisions, no external magnetic field, and low particle densities. A stream