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The effect of electromagnetic fields on the evaporation of metals
Volume 24A. n u m b e r 9
THE
EFFECT
PHYSICS
OF
LETTERS
ELECTROMAGNETIC
24 April 1967
FIELDS OF
ON
THE
E VAPCRATION
METALS
K. SCHRETZMANN I n s t i t u t e of N e u t r o n P h y s i c s and R e a c t o r T e c h n i c a l S c i e n c e Nuclear Research Center Karlsruhe
Received 16 March 1967
E x p e r i m e n t s with heat pipes heated by induction have shown the evaporation of m e t a l s in vacuum is r e duced by one third where an e l e c t r o m a g n e t i c field of about 0.6 V / e m and 60 g a u s s is p r e s e n t .
A h e a t p i p e [ 1 , 2 ] m a n u f a c t u r e d of s t a i n l e s s s t e e l and filled with s o d i u m w a s put into an e v a c u a t e d g l a s s t u b e c o o l e d by w a t e r a n d w a s h e a t e d b y i n d u c t i o n , s e e fig. 1. T h e i n d u c t i o n c o i l w a s 4 c m a b o v e t h e l o w e r e n d of t h e h e a t p i p e a n d w a s c o n n e c t e d to a 15 k W - g e n e r a t o r w o r k i n g a t a b o u t 4 0 0 k H z . T h e t u b e r a d i a t e s t h e p o w e r on t h e
Io~
~ '-~,,.
SICM
J0
I -30
q TOVACUUM PUMP 8) SECONDEVAPORATION
40. "G"R-/CM2
20, 10.
I
-30
[
C) THIRD EVAPORATION
HEAT PiPE
S/CM I
I
I B
D
4o P-G'E-"C:M2
10 CM
4CM
t
B
-30
A
q
30
J
INDUCTION COIL
Fig, 2. T h i c k n e s s of a cover m a d e by the evaporation of a s t a i n l e s s steel tube in a e l e c t r o m a g n e t i c field. O middle of the tube, A position of the coil during the e v a poration, B position of coil during the p r e v i o u s evaporation. WAT~I~ET
Fig. 1. A r r a n g e m e n t of the evaporation e x p e r i m e n t (A). 478
whole surface. The power was completely s o r b e d by the w a t e r and w a s m e a s u r e d by a n d r i s e of t e m p e r a t u r e . The temperature h e a t p i p e m e a s u r e d by t h e r m o c o u p l e s w a s
abits flow of t h e almost
Volume 24A, number 9
PHYSICS LETTERS
the s a m e all o v e r the s u r f a c e of the tube - 930 to 1055°C - with the e x c e p t i o n of the r e g i o n n e a r the c o i l , w h e r e it w a s h i g h e r by 57 to 77°C on a c c o u n t of the high s p e c i f i c i n w a r d h e a t flow. A f t e r one h o u r the g l a s s tube was s l i g h t l y c o v e r e d with m e t a l . The d e p o s i t was not s y m m e t r i c a l a r o u n d the m i d d l e of the h e a t pipe. On the s i d e of the h e a t e d r e g i o n it was l e s s d e n s e than on the o t h e r s i d e at the s a m e d i s t a n c e f r o m the m i d d l e . The o b s e r v a t i o n w a s c o n f i r m e d by p h o t o m e t r i c m e a s u r e m e n t s of the t h i c k n e s s of the c o v e r . With the t o t a l m a s s of the d e p o s i t e d m e t a l o b t a i n e d by c h e m i c a l a n a l y s i s we got the t h i c k n e s s in ~g/cm 2, shown in fig. 2 (A). The dashed line is the thickness on the left side. Thickness is reduced by one third near the coil. The peak above A is caused by the higher temperature near the coil. To test whether the observed effect is due to a not homogeneous tube material the heat pipe was turned and the experiment was repeated. We again obtain less deposit in the heated part of the tube than in the other part, see fig. 2 (B).
THE
QUINTET
STATE
OF
24April 1967
To t e s t w h e t h e r the e f f e c t is due e i t h e r to an e q u a l i n n e r d i a m e t e r of the g l a s s tube o r to the r i s e in t e m p e r a t u r e of the c o o l i n g w a t e r (4°C) o r to the c h a n g e a b l e p r e s s u r e in the e v a c u a t e d s p a c e b e t w e e n h e a t p i p e and g l a s s tube, the g l a s s tube and the w a t e r f l o w w e r e turned. H e r e , too, we obtain an u n s y m m e t r i c a l c o v e r a s in the f i r s t and s e c o n d e v a p o r a t i o n , s e e fig. 2(C). The s m a l l e r t h i c k n e s s n e a r the c o i l is a c c o u n t e d to the e l e c t r o m a g n e t i c field. E l e c t r i c and m a g n e t i c f i e l d s t r e n g t h e v a l u a t e d f r o m p o w e r [3] w e r e about 0.6 V / c m and 60 g a u s s . I e x p r e s s my thanks to Dr. H e l g a S c h n e i d e r , N. R. C. K a r l s r u h e , f o r c h e m i c a l a n a l y s i s .
1 . G . M . G r o v e r . T . P . C o t t e r and G.F.Erickson. J.Appl. Phys.35 (1964) 1990. 2.S.Dorner, F . R e i s s and K.Schretzmann. KFK 512 (1966). 3.K. Schretzmann, Elektrow~lrme (Germany) 24 (1966) 415.
THE
PYRENE
EXCIMER
J. B. BI1RKS
Departrnent of Physics, Uniz,ersity of Baghdad, Baghdad. Iraq Received 16 March 1967 5D*, 3D* and 1D*, the quintet, dissociated triplet, and singlet excimer states of pyrene are produced by triplet-triplet association. 5D* is long-lived and undergoes intersystem crossing, after thermal activation. into 1D*. The experimental data agree with the theory.
The d e l a y e d f l u o r e s c e n c e of p y r e n e (M) in s o l u tion is due to t r i p l e t - t r i p l e t (3M* +3M*) a s s o c i a tion [1] to p r o d u c e an e x c i t e d e x c i m e r D** [2]. A f r a c t i o n a/(1 +a) of D** is c o n v e r t e d to the l o w e s t e x c i m e r s i n g l e t s t a t e 1D*, and the r e m a i n i n g f r a c t i o n 1/(1 + a ) d i s s o c i a t e s r a p i d l y into 1M* + M. In e t h a n o l [1,2] o r e y c l o h e x a n e [3] s o l u t i o n s at T >i 2 9 0 ° K , a = 2.0; at l o w e r t e m p e r a t u r e s a is r e d u c e d [4]. A s i m p l e m u l t i p l i c i t y a r g u m e n t [5] e x p l a i n s the On short leave of absence from Atomic and Molecular Physics Group, The Schuster Laboratory, University of Manchester, England (from which address reprints should be requested).
v a l u e of a = 2.0. T h e r e a r e 9 s t a t e s of D**, 1 s i n g l e t 1D**, 3 t r i p l e t s 3D**, and 5 q u i n t e t s 5D**, which it is a s s u m e d a r e f o r m e d with e q u a l p r o b a b i l i t y . 3D** (i. e. ~ of D**) d i s s o c i a t e s i m m e d i a t e l y into 1M* + M , as the l o w e s t e x c i m e r t r i p l e t s t a t e 3D* is d i s s o c i a t e d [6]. 1D** and 5D** are internally converted through their respective m a n i f o l d s into the c o r r e s p o n d i n g l o w e s t e x c i t e d s t a t e s 1D* and 5D*. If, at T >/ 2 9 0 ° K , 5D* c o n ~ e r t s c o m p l e t e l y into 1D*, then ~ of D** y i e l d D*, i . e . a = 2 . 0 . A r e d u c t i o n in t e m p e r a t u r e is u n l i k e l y to a f f e c t the b e h a v i o u r of 3D** of 1D**, s o that the e f f e c t of T on a is to be a t t r i b u t e d to 5D**. By 479
THE
EFFECT
PHYSICS
OF
LETTERS
ELECTROMAGNETIC
24 April 1967
FIELDS OF
ON
THE
E VAPCRATION
METALS
K. SCHRETZMANN I n s t i t u t e of N e u t r o n P h y s i c s and R e a c t o r T e c h n i c a l S c i e n c e Nuclear Research Center Karlsruhe
Received 16 March 1967
E x p e r i m e n t s with heat pipes heated by induction have shown the evaporation of m e t a l s in vacuum is r e duced by one third where an e l e c t r o m a g n e t i c field of about 0.6 V / e m and 60 g a u s s is p r e s e n t .
A h e a t p i p e [ 1 , 2 ] m a n u f a c t u r e d of s t a i n l e s s s t e e l and filled with s o d i u m w a s put into an e v a c u a t e d g l a s s t u b e c o o l e d by w a t e r a n d w a s h e a t e d b y i n d u c t i o n , s e e fig. 1. T h e i n d u c t i o n c o i l w a s 4 c m a b o v e t h e l o w e r e n d of t h e h e a t p i p e a n d w a s c o n n e c t e d to a 15 k W - g e n e r a t o r w o r k i n g a t a b o u t 4 0 0 k H z . T h e t u b e r a d i a t e s t h e p o w e r on t h e
Io~
~ '-~,,.
SICM
J0
I -30
q TOVACUUM PUMP 8) SECONDEVAPORATION
40. "G"R-/CM2
20, 10.
I
-30
[
C) THIRD EVAPORATION
HEAT PiPE
S/CM I
I
I B
D
4o P-G'E-"C:M2
10 CM
4CM
t
B
-30
A
q
30
J
INDUCTION COIL
Fig, 2. T h i c k n e s s of a cover m a d e by the evaporation of a s t a i n l e s s steel tube in a e l e c t r o m a g n e t i c field. O middle of the tube, A position of the coil during the e v a poration, B position of coil during the p r e v i o u s evaporation. WAT~I~ET
Fig. 1. A r r a n g e m e n t of the evaporation e x p e r i m e n t (A). 478
whole surface. The power was completely s o r b e d by the w a t e r and w a s m e a s u r e d by a n d r i s e of t e m p e r a t u r e . The temperature h e a t p i p e m e a s u r e d by t h e r m o c o u p l e s w a s
abits flow of t h e almost
Volume 24A, number 9
PHYSICS LETTERS
the s a m e all o v e r the s u r f a c e of the tube - 930 to 1055°C - with the e x c e p t i o n of the r e g i o n n e a r the c o i l , w h e r e it w a s h i g h e r by 57 to 77°C on a c c o u n t of the high s p e c i f i c i n w a r d h e a t flow. A f t e r one h o u r the g l a s s tube was s l i g h t l y c o v e r e d with m e t a l . The d e p o s i t was not s y m m e t r i c a l a r o u n d the m i d d l e of the h e a t pipe. On the s i d e of the h e a t e d r e g i o n it was l e s s d e n s e than on the o t h e r s i d e at the s a m e d i s t a n c e f r o m the m i d d l e . The o b s e r v a t i o n w a s c o n f i r m e d by p h o t o m e t r i c m e a s u r e m e n t s of the t h i c k n e s s of the c o v e r . With the t o t a l m a s s of the d e p o s i t e d m e t a l o b t a i n e d by c h e m i c a l a n a l y s i s we got the t h i c k n e s s in ~g/cm 2, shown in fig. 2 (A). The dashed line is the thickness on the left side. Thickness is reduced by one third near the coil. The peak above A is caused by the higher temperature near the coil. To test whether the observed effect is due to a not homogeneous tube material the heat pipe was turned and the experiment was repeated. We again obtain less deposit in the heated part of the tube than in the other part, see fig. 2 (B).
THE
QUINTET
STATE
OF
24April 1967
To t e s t w h e t h e r the e f f e c t is due e i t h e r to an e q u a l i n n e r d i a m e t e r of the g l a s s tube o r to the r i s e in t e m p e r a t u r e of the c o o l i n g w a t e r (4°C) o r to the c h a n g e a b l e p r e s s u r e in the e v a c u a t e d s p a c e b e t w e e n h e a t p i p e and g l a s s tube, the g l a s s tube and the w a t e r f l o w w e r e turned. H e r e , too, we obtain an u n s y m m e t r i c a l c o v e r a s in the f i r s t and s e c o n d e v a p o r a t i o n , s e e fig. 2(C). The s m a l l e r t h i c k n e s s n e a r the c o i l is a c c o u n t e d to the e l e c t r o m a g n e t i c field. E l e c t r i c and m a g n e t i c f i e l d s t r e n g t h e v a l u a t e d f r o m p o w e r [3] w e r e about 0.6 V / c m and 60 g a u s s . I e x p r e s s my thanks to Dr. H e l g a S c h n e i d e r , N. R. C. K a r l s r u h e , f o r c h e m i c a l a n a l y s i s .
1 . G . M . G r o v e r . T . P . C o t t e r and G.F.Erickson. J.Appl. Phys.35 (1964) 1990. 2.S.Dorner, F . R e i s s and K.Schretzmann. KFK 512 (1966). 3.K. Schretzmann, Elektrow~lrme (Germany) 24 (1966) 415.
THE
PYRENE
EXCIMER
J. B. BI1RKS
Departrnent of Physics, Uniz,ersity of Baghdad, Baghdad. Iraq Received 16 March 1967 5D*, 3D* and 1D*, the quintet, dissociated triplet, and singlet excimer states of pyrene are produced by triplet-triplet association. 5D* is long-lived and undergoes intersystem crossing, after thermal activation. into 1D*. The experimental data agree with the theory.
The d e l a y e d f l u o r e s c e n c e of p y r e n e (M) in s o l u tion is due to t r i p l e t - t r i p l e t (3M* +3M*) a s s o c i a tion [1] to p r o d u c e an e x c i t e d e x c i m e r D** [2]. A f r a c t i o n a/(1 +a) of D** is c o n v e r t e d to the l o w e s t e x c i m e r s i n g l e t s t a t e 1D*, and the r e m a i n i n g f r a c t i o n 1/(1 + a ) d i s s o c i a t e s r a p i d l y into 1M* + M. In e t h a n o l [1,2] o r e y c l o h e x a n e [3] s o l u t i o n s at T >i 2 9 0 ° K , a = 2.0; at l o w e r t e m p e r a t u r e s a is r e d u c e d [4]. A s i m p l e m u l t i p l i c i t y a r g u m e n t [5] e x p l a i n s the On short leave of absence from Atomic and Molecular Physics Group, The Schuster Laboratory, University of Manchester, England (from which address reprints should be requested).
v a l u e of a = 2.0. T h e r e a r e 9 s t a t e s of D**, 1 s i n g l e t 1D**, 3 t r i p l e t s 3D**, and 5 q u i n t e t s 5D**, which it is a s s u m e d a r e f o r m e d with e q u a l p r o b a b i l i t y . 3D** (i. e. ~ of D**) d i s s o c i a t e s i m m e d i a t e l y into 1M* + M , as the l o w e s t e x c i m e r t r i p l e t s t a t e 3D* is d i s s o c i a t e d [6]. 1D** and 5D** are internally converted through their respective m a n i f o l d s into the c o r r e s p o n d i n g l o w e s t e x c i t e d s t a t e s 1D* and 5D*. If, at T >/ 2 9 0 ° K , 5D* c o n ~ e r t s c o m p l e t e l y into 1D*, then ~ of D** y i e l d D*, i . e . a = 2 . 0 . A r e d u c t i o n in t e m p e r a t u r e is u n l i k e l y to a f f e c t the b e h a v i o u r of 3D** of 1D**, s o that the e f f e c t of T on a is to be a t t r i b u t e d to 5D**. By 479