- ROUND TABLE -NEW U.V. RADIATION SOURCES AND THEIR APPLICATION TO COLLISION STUDIES

HAL Id: jpa-00224485

https://hal.archives-ouvertes.fr/jpa-00224485

Submitted on 1 Jan 1985

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

- ROUND TABLE -NEW U.V. RADIATION SOURCES AND THEIR APPLICATION TO COLLISION

STUDIES

Y. Petroff

To cite this version:

Y. Petroff. - ROUND TABLE -NEW U.V. RADIATION SOURCES AND THEIR APPLICA- TION TO COLLISION STUDIES. Journal de Physique Colloques, 1985, 46 (C1), pp.C1-147-C1-148.

�10.1051/jphyscol:1985114�. �jpa-00224485�

JOURNAL DE PHYSIQUE

Colloque C1, suppliment au n O l , Tome 46, janvier 1985 page C1-147

- ROUND T A B L E -

NEW UmVa R A D I A T I O N SOURCES AND T H E I R A P P L I C A T I O N TO C O L L I S I O N S T U D I E S

Y . P e t r o f f

Laboratoire pour Z'UtiZisation du Rayonnement ~~eetroma~ndti~ue', Biitiment 209c, Universit6 de Paris-Sud, 91405 Orsay Cedex, France

The purpose of t h i s round t a b l e was t o review t h e d i f f e r e n t p o s s i b l e methods t o produce c o h e r e n t r a d i a t i o n i n t h e vacuum u l t r a - v i o l e t .

The f i r s t t a l k , g i v e n b y J . Lukasik, d e a l t with t h e g e n e r a t i o n of c o h e r e n t and t u n a b l e VUV/XUV r a d i a t i o n by non l i n e a r o p t i c a l m e t h o d s / l / . T h e s e m e t h o d s h a v e beenim- proved r e c e n t l y by u s i n g p u l s e d s u p e r s o n i c j e t . The use o f d i f f e r e n t g a s e s (CO, H 2 , D2, A r , K r , Xe. ..) has allowed t o cover t h e range 800-2000

a.

'-

The second t a l k , p r e s e n t e d by H . Brunet, d e s c r i b e d t h e r e s e a r c h underway a t C . G . E . on U . V . l a s e r s . Recent advances i n performance and r e l i a b i l i t y of excimer l a s e r s were r e p o r t e d . Hollow cathode glow d i s c h a r g e s and chemical pumping of an e l e c - t r o n i c t r a n s i t i o n have been i n v e s t i g a t e d f o r t h e production o f cw UV l a s e r r a d i a t i o n . Laser emission was r e c e n t l y o b t a i n e d on CU' a t 260 nm.

The next t a l k ( P e t r o f f ) d e s c r i b e d t h e p o s s i b i l i t y t o o b t a i n coherent r a d i a t i o n w i t h r e l a t i v i s t i c e l e c t r o n s / 2 / . Threemethodswere reviewed.They a r e based on low emi- t t a n c e s t o r a g e r i n g and a magnetic device c a l l e d u n d u l a t o r . I f t h e f e a s i b i l i t y of t h e f r e e e l e c t r o n l a s e r has been demonstrated, it w i i l t a k e a t l e a s t two o r t h r e e y e a r s b e f o r e t o have a l a s e r i n t h e range 1200 - 3000 A. The production o f harmonics by an e x t e r n a l l a s e r i n a way very s i m i l a r t o t h e one d e s c r i b e d by Lukasik (excepted t h a t t h e g a s i s r e p i a c e d by an e l e c t r o n beam) i s very promising f o r t h e f u t u r e togodown t o 200 o r 300 A.

The l a s t t a l k was given by P. J a e g l 6 and was a d e s c r i p t i o n o f experiments performed with l a s e r s i n recombinating plasmas. I t was shown t h a t p o p u l a t i o n i n v e r - s i o n can occur between t h e l e v e l s n = 3, 4, 5 of l i t h i u m - l i k e i o n s . The experimental svidence has been c l e a r l y e s t a b l i s h e d and a good t h e o r e t i c a l i n t e r p r e t a t i o n of popu- l a t i o n i n v e r s i o n e x i s t s . The main problem i s t o o b t a i n a s u f f i c i e n t gain (5-10 cm -') f o r l a s e r o s c i l l a t i o n . We should mention t h a t a f t e r t h e conference, Matthews e t a l . /3/ .from Livermore have r e p o r t e d t h e o b s e r v a t i o n of a m p l i f i e d spontaneous emission of s o f t X-ray wavelengths of t h e neon l i k e Se c o l l i s i o n a l e x c i t a t i o n . The a m p l i f i c a t i o n .ras o b s e r v e d f o r t h e 2p53p-2p53s t r a n s i t i o n , with t h e l a r g e s t g a i n being observed f o r the J = 2 t o 1 l i n e s a t 206.3 and 209.6 8 with a g a i n c o e f f i c i e n t o f 5.0 ? 1 . 0 cm-l.

I n conclusion we can say t h a t t h i s f i e l d i s moving very f a s t : however we nust mention t h a t t h e experiments 3 and 4 a r e s t i l l p r o t o t y p e s whereas t h e methods i e s c r i b e d by Lukasik and Brunet a r e a l r e a d y o p e r a t i o n a l .

REFERENCES

/1/ J . LUKASIK, t h i s volume, p. 149

k L . P . CNRS 008

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1985114

C1-148 J O U R N A L DE PHYSIQUE

/ 2 / Y. PETROFF, this volume, p. 153

/3/ D.L. MATTHEWS e t al., Phys. Rev. Lett. 54, 110 (1985)