Antony, M

Neff, Roland

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Letters to the Editor 75The diaphragm. Two brass pieces, placed at 65.5 mm from the source, form the collimating device. They arc adjustable from 0.1 to 6 mm.PreaccelerOftion. A negative tension is applied to the source to detect electrons of very low energy. The negative electrode is a brass plate, in contact with the source. Facing the source, a grid consisting of 10 gold-wires of 50 microns, is situated at a distance of 10 mm. The maximum accelerating potential is 15KV.Conclusion, The instrument can be employed to study very low energy electrons ( <  20 Kev), using proaccelerating techniques. Tt is possible to replace emulsion by solid-state junctions.K E ¥  E R E N li:Antony, M., 1967, Thf^ais, doctorate of the Universitji hyon.R E A L I S A T I O N  O F  A  C O N S T A N T  M A G N E T IC  F IE L D , E X T E N D IN G  T O  A  D IA M E T E R  O F  8 0  C M S ,U S IN G  A IR  C O R E D  C O IL S .M. ANTONY AUD ROLAND NEFFI n s t it t j t  d e  G e o  LOGIE UNTVEI^^SITE T>E STRASBOURG, FRANCE(Received February 20, 1968)*.From the fundamental laws of magneto-static fields, Maxwell deduced that circular currents around spherical or ellipsoidal coils induce a constant magnetic field throughout the inner volume, Antony (1967) realised a homogeneous mag­netic induction over a radius of 15 ems, using oblate ellipsoidal coils for his semi­circular magnetic Bpoctrometer. He had to remove several bobbins around the median plane in order to introduce the spectrograph and compensated them by a semi-empirical method.We propose a slightly different method, yielding a constant field over a wider region. Fig. 1 indicates two semi-ellipsoids separated by a distance of 5 eras to provide the air-space. Wo divide the minor axis into 30 equal parts, each unit2Brepresenting a bobbin. Wo give below the values of contribution ofthe respective pairs o f bobbins from 0 to 40 ems at an interval of 5 cms.7 6 Letters to the EditorOinFig. (1). Two 8omi-ellipsoids with an air-space of 5 cm.bbin 0 cm 10 15 20 25 30 35 401 24,96 2r»,i4 25,56 26,72 28,32 30,76 34,62 40,56 51,202 26,02 25,22 25,60 26,80 28,42 30.84 34,56 40,46 50,02.3 26,12 25,30 25,68 26,90 28,52 30,92 34,58 40,20 48,644 26,24 25,42 25,84 27,02 28,60 30,94 34,42 39,60 46,485 26,46 25.64 26,12 27,24 28,80 31,08 .34,38 38,92 43,706 25,78 26,74 26,60 27,56 28.94 31,34 .34,32 37,88 39,127 26,30 26,48 27,08 28,02 29,62 31,74 34,28 36,00 30,588 26,90 27,08 27,68 28,70 30,18 .32,00 33,94 33,48 23,809 27,68 27,76 28,34 29,30 30,62 32,02 32,46 28,64 14,6810 28,54 28,74 29.26 30,12 31,04 31,40 29,04 20.26 6,00ll 29,46 29,62 30,04 30,56 30,68 29,64 23,22 11,58 -],.3012 30,66 30,62 30,72 30,44 28,72 25,74 13,96 3,78 -2,1213 31,14 31,00 30,28 28,40 22,66 12,22 5,62 -0,93 -2,7014 29,72 28,84 25,90 20,04 11,94 4,68 0,62 -1,20 -1,5015 14,00 12,38 8,00 3,64 1.20 0,14 0,00 0.00 0,00IB1396,78 394,98 392,60 391,46 388,26 386.36 379,82 369,2 3345,80We multiply the number of turns in the first three bobbins by 1,66 and that of the bobbin 7 by 0,5. The value of kB ia now 5LeU&rs to the Editor 7710 15 20 30 35 40432,06 431,07 429,77 4.30,.'52 429.72 430,66 431,10 431,23 429,40The mean value of fcB =  4.30,66. H e n c e =  i2.10~®. It is interestingto note that to obtain the same homogeneity over a diameter of 80 cms, the dia­meter o f a pair o f Helmoltz bobbins will be about 4 maters.The photo (fig. 2) is a model o f a small ellipsoidal coil using the principle discussed above. It was constructed to produce a field of 100 KG usingFig, 2. lSlIip8<iidal block for tho b ibbiiiM to produce pulwod magnetic field,pulsed currents o f 30KA. An advantage of ellipsoidal geometry is tho absence of radial forces, an annoying problem in intense fields.We thank Mr, Jehl for his encouragement and useful discussions.i l E F E H E N C EAntony, M., 1967, Theses, dootomt de VUniversity, L Y O N .

Realisation of a Constant Magnetic Field, Extending to a Diameter of 80 Cms, Using Air Cored Coils

http://arxiv.iacs.res.in:8080/jspui/bitstream/10821/4147/1/Realisation%20of%20a%20constant_M%20Antony.pdf

Realisation of a Constant Magnetic Field, Extending to a Diameter of 80 Cms, Using Air Cored Coils

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