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Charge transfer of 4.3 MeV/u chlorine ions passing through a discharge plasma target is used as a probe to determine the plasma density and the ratio of impurities inside the plasma column. Charge-state distributions of 2 MeV/u chlorine ions passing through the plasma are then measured and compared to corresponding measurements in the cold gas. Stopping power measurements are also performed in both cases.

Stigmatic configurations for spherical holographic gratings are generally explained by the properties of the harmonic conjugate points; this global approach, however, does not explain how the various aberrations generated by the blank are cancelled by the hologram. In this paper, light path function analysis is used to explain this balancing effect and to derive practical VUV configurations.

This paper deals first with the basic concept of luminous intensity and the laws of propagation of the elec­ tromagnetic waves. CLE. terminology is used, in the second part, to describe the performances of vacuum ultraviolet sources.

Optical properties of spherical or aspherical holographic gratings are investigated from the imaging point of view. Basic conditions for aplanetism are first expressed, the object image and recording point sources being located on circles centered on the grating tangent. The performances (resolution, anamorphism) of some imaging configurations are described.

Various aplanatic flat field spectrometers fitted with spherical or aspherical holographic gratings are described. Basic conditions for stationary anastigmatism are first expressed, the object and image being located on the sagittal focus. Optical performances of some coma corrected configurations are finally described.

This paper deals with the opto-mechanical design and some experimental results of a new anastigmatic normal incidence monochromator. The configuration involves a plane holographic grating used in convergent light, and the first part of this paper will be devoted to the optimization of the Line Spread Function.

In this paper we investigate the optical design criteria of an VUV or XUV three beam grating interferometer whose performances has been experimentally checked in the visible spectral region.

Influence of target temperature, density and atomic number on the charge state of swift heavy ions interacting with hot and dense plasma is considered. Hydrogen targets exhibit strong temperature effects and large non-equilibrium charges, whereas interactions with heavy material are more sensitive to the density effect. Our new average correlated hydrogenic atom model (ACHAM) is presented. It enables us to cover the whole range of target densities of interest for swift heavyion-plasma interaction experiments.

Charge exchange of chlorine ions traversing a discharge plasma target is used as a probe to determine the rati of heavy impurities inside a plasma column. The rate coefficient of the recombination process is strongly related to the atomic number of the target atoms. High-Z impurities are much more efficient to modify the charge state distribution of the incoming chlorine ions. The ragne of detection could reach about 1‰ of the total number of atoms.

We describe a new grazing angle monochromator specially designed for undulator sources. A holographic plane grating is used in conjunction with a refocusing mirror, at a constant include angle of 174°. Astigmatism is eliminated and the odd aberration is reduced to second order terms in the scan angle. Spherical aberration is the main aberration left, and the small emittance of the undulator is used to keep this term small. Scanning is achieved simply by the rotation of the grating. The mount shows a line resolving power of 13 000 at 20 A, as confirmed by exact ray-tracing. An application of the monochromator to an undulator installed in Aladdin is discussed.

Due to the lack of highly transparent materials monochromators for the vacuum ultraviolet spectral range are therefore normally equipped with just one optical element, namely a ruled spherical grating. Further, three additionnal properties of such type of mounting would be useful. First would be a single grating motion, an attractive possibility being a simple rotation of the grating. Second, fixed entrance and exit slits would simplify the mechanical aspects of many experimentals set up, particularly when using experimental chambers for optical testing in this spectral range. A last feature would be to use the grating either at normal incidence to avoid an excess amount of astigmatism in the spectral range 4 000 to 500 A either at large angle of incidence, attempting to extend the short wavelenght limit, through the increased reflectivity associated with the total reflection phenomenon. The first order focusing properties of ruled concuve gratings, derived from Fermat's principle, are then well known and various mountings working in the gaussian image plane are currently used in this spectral range. If the well known Seya Namioka monochromator fulfil the two first conditions, the angle 2 Θ between the incident and diffracted beam is a constant equal to 70° 30'. This angle is chosen to minimize the deviations from the rowland conditions and therefere this mounting satisfy approximatively to the condition T + T' = 0 (eq. 3), T and T' being respectively the equation for the object and image tangential focus. In this mounting as in the Rowland circle or Wadsworth mounting the high order terms in the equations of Fermat's principle as well as the possibility of balancing different aberration terms has been ignored. It is well known, however, from lens design studies that a great improvement of an optical element can be achived, by using the phase balancing method and by a proper consideration of the focussing properties in both geometrical and diffraction theories. The principle of this method is to replace the spherical reference sphere centered about the gaussian image by a new reference sphere centred about the brightest part of a line at the best plane of focus. This method involves, then, a change of focus in order to decrease the amount of aberration (eq. 7) and consequently ignores all mathematical solutions of the first order focussing condition. If the wavefront aberration over the pupil is small with respect to the wavelength λ, the diffraction pattern is only slightly modified. Then by using the strehl criterion we obtain first the value of the parameters characterizing the change of focus and second the optimum ruled width W0 for a given height L0 of the ruled area for which the residual aberrations 01 (W2/R2) can be neglected. A generalized focussing condition in which the main aberration terms (except for astigmatism) are balanced by the defocussing term is consequently derived from the Fermat's principle (eq. 4). For large phase-errors we have defined a quality factor Q (eq. 8) characterizing the r. m. s. value of the width of the image pattern which is connected to the slope of the wavefront deviation. Such image evaluation implying an association of ray density and energy flux, the averaging in the image plane uses the geometrical intensity distribution in the image plane as a weighting factor. Using the same procedure as above we have obtained for each value of W0 and L0 the limiting resolution, a second expression for the generalized focussing condition (eq. 5, table 1). Generallly the tilt of defocus coefficients and then the type of correction are different for the physical optics and the geometrical optics limit (fig. 1 to 5). Using an iterative process the equation 5, has been solved for two particular wavelengths λi and λf and for an one meter 1 831,8 lines/mm concave grating. Figure 6 shows in function of θ, the variations of the object and image distance and leads to the design of a two entrance beams monochromator. Indeed to one image distance r' = Re' correspond two θ values θ1 = 10° and θ2 = 49° 48' 45" at which occur a perfect focus. For other λ values the instrumental defocusing (eq. 15) limit the useful spectral range and the practical resolution (fig. 7) which can be obtain. Indeed this defocussing must remain inferior to a tolerated value (equivalent to the deep of the focus of a lens) arising from the quality factor (eq. 16-16'). The A. S. M. 100/2E mounting made by creusot Loire Instrumentation using a single rotation of the grating gives in a fixed direction diffracted beams of spectral width of 3 to 5 A from 256 to 4 000 A. This mounting has been used in particular to test the efficiency of various holographic gratings and some results are summarized on figures 10 to 13.

In this paper we describe new STIGMATIC XUV POLYCHROMATORS specially designed for hot plasmas diagnostics. Fixed horizontal and vertical diffracted beam divergences, as well as ERECTED FLAT FIELD are allowed imorehower solutions occur for various grooves density.In ‘GRAZING INCIDENCE ULTIMATES POLYCHROMATORS’ (UGP), the focusing is achieved by a stigmatic toroidal mirror (unit magnification), and the dispersion of the radiation, by a simple rotation of a plane type V holographic grating WORKING AT MINUS ONE MAGNIFICATION. If the point sources used to record the hologram are located at the same distance from the grating pole STIGMATIC images are located on a circle centered on the grating pole. Erected FLAT FIELD may be then considered in so far as the corresponding broadening of the line spread function is less tha the pixel size.

In this paper I describe new stigmatic VUV and XUV monochromators specially designed to match the “etendue” of Super ACO. Fixed horizontal and vertical diffracted beam divergences, as well as uniform sample illumination are allowed; moreover, particular gratings delivering diffraction limited monochromatic convergent beams also allow image evaluation of optical instruments.

In laser induced confinement fusion or in ion driven fusion the understanding of the physical process taking place in the plasma atmosphere surrounding the target is extremely important. Plasma diagnostics requires line ratios and line broadening measurements to be made at very short wavelengths. The author presents the design of stigmatic normal and grazing incidence devices fitted with spherical holographic gratings.

The Strehl criterion can be satisfied for particular symmetrical mounts fitted with toroidal holographic gratings having a non-uniform groove distribution if the latter does not introduce any defect in focus or astigmatic correction.

Design rules using geometrical optics and physical optics associated with the phase balancing method are discussed for stigmatic toroidal grazing incidence monochromators. To determine the optical performance of devices involving mirrors and/or gratings, ray tracing programs using exact geometry are quite widely used. It is then desirable to have some way to infer the practical performance of an instrument from a spot diagram created by tracing a limited number of rays. We propose a first approach to this problem involving an estimation of the geometrical intensity distribution in the image plane and the corresponding line spread function.

In a recent paper (ibid., vol.14, p.235, 1983) the author described some new stigmatic properties of spherical holographic gratings. This paper describes some specific diffraction limited configurations, as well as spectrometers for line profile measurements.

In this paper we describe new types of VUV monochromators using only spherical or plane type V holographic gratings. New design rules using physical optics associated with the phase balancing method are suggested to achieve diffraction limited performances.

In this paper we describe new STIGMATIC XUV monochromators specially designed to fit the "Etendue" of SUPER ACO. Fixed horizontal and vertical diffracted beam divergences, as well as uniform photometric illumination are allowed ; comparison with TGM show the improvements that might be expected from the case of Plane type V grating used in convergent light.

On montre theoriquement que le coefficient de reflexion diffuse est la somme de deux termes dont l'un caracterise uniquement la direction de reflexion speculaire, et dont l'autre fait intervenir la pente des rugosites. Lorsque la hauteur de ces dernieres est inferieure a la longueur d'onde, l'expression de l'energie renvoyee comporte un terme proportionne la 1/Λ4, qui tendrait a faire croire que pour les courtes longueurs d'ondes l'energie diffusee est tres importante. En fait on demontre que si σ/Λ≫ 1, le second terme ne fait intervenir, dans le cas de distribution ‘normale’ des irregularites, que la valeur moyenne de leur pente. La premiere partie de ces experiences comporte letude de surfaces metalliques et les resultats obtenus permettent de souligner l'importance de ce facteur.

Une serie de mesures de diffusion ont ete effectuees a 1608 A sur des echantillons varies dans le but d'obtenir des materiaux ou des depots susceptibles de posseder des proprietes photometriques regies par la loi de Lambert. Plusieurs echantillons depolis de verre et de metaux differents ont ete etudies ainsi que des depots de ‘velvet coating’ noir et blanc, et de salicylate de sodium. Un detecteur a surface delimitee decrit un arc de cercle centre sur l'echantillon, et l'energie detectee est enregistree dans le cas de differents angles d'incidence. Le profil angulaire de l'energie reflechie de facon diffuse est donne pour des echantillons types. Les resultats obtenus montrent qu'un depot de salicylate sur de la magnesie peut jouer le role d'un diffuseur parfait dans l'ultraviolet lointain.

The purpose of this communication is to give quantitative values for the gain in luminosity which arises from optical corrections in the case of any far ultraviolet mounting. Using the Strehl criterion applied in the case of a line image given by a rectangular pupil, we have expressed the luminosity as a function of the optimum value of the resolving power. The results show the high luminosity of corrected symmetrical mounting.

The purpose of this communication is to design the optimum optical parameters of far ultraviolet corrected symmetrical monochromators using concave gratings.

A review of the principal features of reflected intensity distributions in the vacuum ultraviolet is given. The results can be explained in terms of the characteristic function of the distribution of the slope of the irregularities, when the rms height σ of the irregularities is very large relative to the wavelength λ.

On presente une etude experimentale de la distribution spatiale du rayonnement de fluorescence diffuse dans 4π sr par des depots de salicylate de sodium de diverses epaisseurs. Les resultats obtenus sont independants de la longueur d'onde du rayonnement primaire dans l'ultraviolet lointain; la distribution angulaire, differente suivant la face de l'echantillon observee, depend peu de l'angle d'incidence du faisceau primaire, mais varie avec l'epaisseur. Les couches epaisses constituent des diffuseurs parfaits.

The purpose of this communication is to design the optimum optical parameters of a corrected Seya-Namioka mounting, by using the Strehl criterion.

To improve the resolution of grazing incidence XUV devices precise evaluation of the broadening parameters of the Line Spread Function are required. In this respect, transverse ray aberrations must be first evaluated for an oblique exit pupi1-aperture stop not centered al the grating pole-geometrical optical criterion clearly shows then the competitive action of the defect of focus vs astigmatism and astigmatic coma.

A vacuum reflectometer for the UV and VUV spectral range was developed for qualification of optical components below 400 nm. Typical performances, in the 120-320 nm spectral range, of filters and mirrors offered by MATRA will be presented. Fitted with various gratings and sources this device allows reflecting, transmitting power as well as scattered or diffracted flux measurements (gratings efficiency measurements) until 25 nm.

The problem of image evaluation in vuv optical mountings of ruled concave gratings has been treated by means of the method of phase-error balancing. In the classical diffraction limit, the tolerances on the aberrations of normal-incidence mounts are evaluated by means of a modified Strehl criterion. For large phase errors, a quality factor that implies an association of ray density with energy flux, leads to determination of the tolerated magnitude of large aberrations. In addition, we give the related generalized focusing conditions that include shifts, off the gaussian image plane, as functions of the amounts of aberrations.