67 research outputs found
Nemlineáris lézerplazma-kölcsönhatásokban keltett gyors elektronok vizsgálata = Investigation of fast electrons generated in nonlinear laserplasma interactions
A kĂ©t legfontosabb eredmĂ©nycsoport: Hazai kĂsĂ©rleteink az SZTE KrF lĂ©zerĂ©vel a szilárdtest targeten lĂ©trehozott lĂ©zerplazma kritikus felĂĽlete körĂĽli nemlinearitásokat cĂ©lozták meg. Az elĂ©rt 1.5*1017 W/cm2 intenzitás esetĂ©n a harmonikusokat már 62 nm hullámhosszig figyeltĂĽk meg. Megmutattuk, hogy 1016 W/cm2 intenzitás fölött a harmonikusok viselkedĂ©se megváltozik, immár nem tartják meg a nyaláb polarizáciĂłját, hanem kevert polarizáciĂłjĂşakká válnak Ă©s diffĂşzan terjednek, amit a kritikus felĂĽletnek a Rayleigh-Taylor instabilitás által okozott fodrozĂłdása okoz. ElmĂ©leti modellt alkottunk a harmonikusok keltĂ©sĂ©re mĂ©rsĂ©kelt intenzitások esetĂ©re. Megmutattuk, hogy az ott tapasztalt meglepĹ‘ polarizáciĂłs tulajdonságokat az okozhatta, hogy az optikailag sűrű anyagban lecsengĹ‘ evaneszcens tĂ©rben a relativisztikus esethez hasonlĂłan a vxB erĹ‘ már kis intenzitásoknál sem elhanyagolhatĂł. A "frusztrált totálreflexiĂłn" alapulĂł modellt sikerrel alkalmaztuk egy korábbi kĂsĂ©rlet Ă©rtelmezĂ©sĂ©hez is, ahol a lĂ©zerrel fűtött vĂ©kony, de optikailag sűrű lĂ©zerplazma transzparenssĂ© vált. Gyors elektronokat közvetlenĂĽl a garchingi MPQ-val valĂł egyĂĽttműködĂ©sben vizsgáltunk. Megmutattuk, hogy a szilárdtest cĂ©ltárgyon lĂ©trehozott elĹ‘plazmában a 150 fs hosszĂş infravörös lĂ©zerimpulzus relativisztikusan önfĂłkuszálĂłdik. Az önfĂłkuszálás elĹ‘segĂti a ~3 MeV hĹ‘mĂ©rsĂ©kletű elektronnyaláb lĂ©trehozását, ami vizsgálataink szerint a szilárd targetben jĂłl kollimáltan halad. | The two most important groups of results: Experiments in Hungary were carried out with the KrF laser of the University of Szeged. We investigated nonlinear processes near to the critical density of laser plasmas on solid targets. Using 1.5*1017 W/cm2 intensity harmonics were observed to the 62 nm wavelength. It was shown that above 1016 W/cm2 intensity harmonics will not keep the polarization of the laser beam any more, their polarization will be mixed and the propagation becomes diffuse. This is caused by the rippling of the critical surface caused by the Rayleigh-Taylor instability.Our theoretical model describes harmonics behaviour at modest intensities. In the evanescent field in the optically dense matter the vxB force - similarly to the relativistic case - cannot be neglected even at week intensities. The model based on "frustrated total reflection" was successfully applied to the explanation of an earlier experiment as well, in which the thin but optically thick laser plasma became transparent for the laser radiation. Direct investigation of fast electrons was carried out in a collaboration with the MPQ, Garching. It was shown that in a preplasma on solid target the infrared laser pulse of 150 fs duration will be relativistically self-focused. Self-focusing helps in the generation of an electron beam of ~3MeV, which - according to our observation - propagates well collimated in the solid target
Cluster size distributions in gas jets for different nozzle geometries
Cluster size distributions were investigated in case of different nozzle
geometries in argon and xenon using Rayleigh scattering diagnostics. Different
nozzle geometries result in different behaviour, therefore both spatial- and
temporal cluster size distributions were studied to obtain a well-characterized
cluster target. It is shown that the generally used Hagena scaling can result
in a significant deviation from the observed data and the behaviour cannot be
described by a single material condensation parameter. The results along with
the nanoplasma model applied to the data of previous high harmonic generation
experiments allow the independent measurement of cluster size and cluster
density.Comment: 7 pages, 6 figure
Ultrarövid lágy röntgen impulzusok vizsgálata = Investigation of ultra-short soft x-ray pulses
A tervben három tĂ©macsoportot jelöltĂĽnk meg: 1. Harmonikusok keltĂ©se szilárdtest felĂĽletĂ©n: Publikáltuk korábbi, 1.5*10^17 W/cm2 intenzitásĂş KrF lĂ©zerrel kapott eredmĂ©nyeinket, amelyekben a kritikus rĂ©teg fodrozĂłdására adtunk kĂsĂ©rleti bizonyĂtĂ©kot. Az intenzitást sikerrel növeltĂĽk meg ötszörösĂ©re, de a gyengĂ©bb kontraszt miatt nem láttunk a a korábbiaknál magasabb harmonikusokat. A kontraszt javĂtandĂł elĹ‘ször demonstráltuk a plazmatĂĽkör effektus fellĂ©pĂ©sĂ©t KrF lĂ©zernĂ©l. Az MPQ-ban vĂ©gzett kĂsĂ©rletben sikerrel vizsgáltuk meg a 3 ciklusĂş impulzussal keltett plazmaharmonikusok polarizáciĂłfĂĽggĂ©sĂ©t. 2. Az Ar rezonanciát felhasználĂł nagy hatásfokĂş 3. harmonikus keltĂ©sĂ©t vizsgáltuk kĂĽlönbözĹ‘ gázjet konfiguráciĂłkkal. SikerĂĽlt a fázisillesztĂ©st a geometriailag lehetsĂ©ges optimális hosszig megvalĂłsĂtani. A konverziĂł alacsonyabb a korábbi publikáciĂłknál, mĂ©rĂ©seink abszolĂşt kalibráciĂłja folyamatban van. 3. A LiF spektroszkĂłpiájával megmutattuk, hogy az intenzitás növelĂ©sĂ©vel hogyan keletkeznek az egymást követĹ‘ ionizáciĂłs állapotok, Ă©s megbecsĂĽltĂĽk a plazmatĂĽkör optimum esetĂ©n a plazmahĹ‘mĂ©rsĂ©kletet. TranszmissziĂłs rács spektromĂ©tert kĂ©szĂtettĂĽnk a PALS lĂ©zeren vĂ©gzett kĂsĂ©rleteknĂ©l is az 1 keV körĂĽli spektrumok vizsgálatához. Emellett a kapcsolĂłdĂł lĂ©zerkutatásainkban sikerĂĽlt a KrF lĂ©zerkisĂĽlĂ©s mĂ©retĂ©t, Ăgy az elĂ©rhetĹ‘ energiát megnövelni Ăşgy, hogy a kisĂĽlĂ©s homogĂ©n maradt. Ăšj elrendezĂ©st javasoltunk gyorsbegyĂşjtásos termonukleáris fĂşziĂłra KrF lĂ©zerrel. | Three topics were assigned in the project: 1. Harmonics on solid surfaces: Publication of previous results on the rippling of critical surface with 1.5*10^17 W/cm2 KrF laser intensity occurred during the present project. Laser intensity was successfully increased with a factor of 5, but due to the weaker contrast no higher order harmonics were observed. In order to improve the contrast plasma mirror effect was demonstrated the first time for KrF lasers. In an experiment carried out in the MPQ polarization dependence of harmonics was investigated using a 3 cycle laser beam. 2. Third harmonics generation was observed using the Ar resonance with different gas jet configurations. Phase matching was successfully obtained up to the geometrical limit. The conversion was however lower than previously. The absolute calibration of our measurements are under progress. 3. Spectroscopic investigation of LiF plasmas showed the progress of ionization with the appearing subsequent ionization states. Plasma temperature was estimated for the optimal plasma mirror conditions. A transmission grating spectrometer was prepared for the experiments at the PALS laser for spectroscopy around 1 keV. Furthermore our KrF laser researches successfully increased the size of the homogeneous discharge, and thus the obtainable energy. We suggested a new scheme for fast ignition inertial fusion using KrF lasers
Dr. Hoóz István : Baranya megye nemzetiségeinek jogállása, oktatási és kulturális helyzete : Pécs, Baranya Megyei Közgyűlés, 1993
Kisüléssel gerjesztett lágy-röntgen lézer kutatása = Investigation of soft x-ray laser excited by discharge
A ËťKisĂĽlĂ©ssel gerjesztett lágyröntgen lĂ©zer kutatásaËť cĂmű kutatási projekt (OTKA T/F 046811, 2004-2006) keretĂ©ben lĂ©trehoztunk Magyarországon (PTE-en) egy működĹ‘, kapilláris z-pinch kisĂĽlĂ©ssel gerjesztett lágy röntgen (46.9 nm) lĂ©zert Ă©s hozzá a diagnosztikai rendszert, nevezetesen plazma diagnosztikai rendszert (áramerĹ‘ssĂ©g mĂ©rĂ©se Rogowsky tekercs segĂtsĂ©gĂ©vel), spektroszkĂłpiai diagnosztika (röntgen monokromátorral), lĂ©zer intenzitás eloszlásának diagnosztikája foszfor ernyĹ‘ konverterrel (röntgen -> láthatĂł), tĂ©rbeli koherencia mĂ©rĂ©sĂ©hez Young-fĂ©le kettĹ‘s apertĂşra interferenciás mĂłdszer. | In the frame of the project ËťSoft x-ray laser by capillary dischargeËť (OTKA T/F 046811), an operating capillary-discharge soft x-ray laser and diagnostics was built in Hungary (PTE). The laser beam and plasma diagnostics system includes: the time-resolved measurements of electrical current with Rogowsky coil, spectroscopic diagnostics with x-ray monochromator, optical diagnostics of the laser beam intensity with help of phosphor screen converter (x-ray radiation - visible light), measurements of laser beam spatial coherency by using Young-type double aperture interferometric method
Egzotikus atomfizikai folyamatok plazmákban és szilárdtestek felületén = Exotic Atomic Processes in Plasmas and on Solid Surfaces
Kutatási eredmĂ©nyeink többsĂ©ge a debreceni elektron-ciklotronrezonanciás (ECR) plazma- Ă©s ionforrás folyamatos fejlesztĂ©sĂ©n Ă©s többcĂ©lĂş, a plazmafizikátĂłl az asztrofizikáig, a nanotechnolĂłgiátĂłl az orvostudományig terjedĹ‘ alkalmazásán alapul. A kĂsĂ©rleti elrendezĂ©sek fĂĽggvĂ©nyĂ©ben vizsgáltuk az előállĂtott nagytöltĂ©sű nehĂ©zionok, plazmák, ionnyalábok (Ne1+-8+, Ar1+-16+, Xe1+-24+, C601+-3+, ....) paramĂ©tereit (ionizáciĂłs összetĂ©tel, sűrűsĂ©g, röntgenspektrumok, potenciális Ă©s kinetikai energia) Ă©s azokat összehasonlĂtottuk más plazmafizikai kutatások adataival, elĹ‘segĂtve a kozmikus vizsgálatok eredmĂ©nyeinek a teljesebb megĂ©rtĂ©sĂ©t is. A nagytöltĂ©sű ionok Ă©s a bizonyos speciális szilárdtestek (funkcionális amorf kalkogenid alapĂş fĂ©lvezetĹ‘ rĂ©tegek, kapillárisokat tartalmazĂł polimer rĂ©tegek, titán implantátumok, stb.) kölcsönhatásainak specifikus, mikro- Ă©s nanoskálán jelentkezĹ‘ tulajdonságait Ă©s mechanizmusát kutattuk, kĂĽlönös tekintettel az ionok töltĂ©se által keltett átalakulásokra Se, AsSe rĂ©tegekben, Ti felĂĽleten, valamint mikrokapillárisok belsejĂ©ben. Ezek alapján cĂ©loztuk meg a vizsgált ionnyalábok potenciális alkalmazásait felĂĽleti fĂ©lvezetĹ‘ mikro- Ă©s nanostruktĂşrák in situ előállĂtására, biokompatibilis implantátumok felĂĽleti mĂłdosĂtására, ionnyaláb fĂłkuszálĂł, irányĂtĂł mikroeszközök kialakĂtására. EredmĂ©nyeink többsĂ©ge az ECR ionforrás alkalmazására Ă©pĂĽlĹ‘ Ăşj kutatási-fejlesztĂ©si tĂ©mákat (pl. funkcionizált biokompatibilis anyagok, integrált ionoptika) alapoz meg. | Majority of our research results base on continuous development of the Electron Cyclotron Resonance (ECR) plasma and ion source and its multipurpose application from plasma physics to astrophysics and from nanotechnology to medical sciences. The parameters (composition, density, X-ray spectra, potential and kinetic energy) of the generated highly charged heavy ions (Ne1+-8+, Ar1+-16+, Xe1+-24+, C601+-3+, ....) have been investigated in dependence from the experimental conditions and the results were compared with data of other plasma physics research which enabled understanding more deeply some cosmic phenomena. The specific characteristics and mechanisms of interaction of highly charged ions with solid surfaces (functional amorphous chalcogenide-based semiconductor layers, polymer layers with capillaries, titanium implants, etc.) at micro- and nano-scale dimensions were investigated with a special attention to ion-charge induced transformations in Se, AsSe layers and on Ti surfaces, as well as to the ion transport inside the micro-capillaries. It was the basis of our targeted research on the possibilities of applications of these ion beams for the in situ creation of surface micro- and nanostructures on given semiconductors, for surface modification of biocompatible implants, as well as for development of micro-tools for guiding and focusing ion beams. Most of our results serve a good basis for new ECR-based R&D themes like new biocompatible materials, integrated ion optics
Homologies between a brain-specific identifier (ID) sequence and regions of Harvey murine sarcoma virus and Rous sarcoma virus genomes Putative role of identifier sequences in the tissue specificity of malignant transformation by RNA tumor viruses
AbstractAs a step toward understanding of the tissue specificity of cellular transformation by RNA tumor viruses we looked for the presence of a putative brain specific regulatory (identifier) sequence (C82B) in the genome of various oncornaviruses. The genomes of Harvey murine sarcoma virus and Rous sarcoma virus contain sequences flanking the viral oncogenes with > 80% and > 60% homology to C82B, respectively. We suggest that identifier sequences acquired by oncoviruses may determine the potential target cells of malignant transformation after virus penetration.Nucleic acid homologyRNA tumor virusIdentifier sequenceCell transformationTissue specificit
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