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1

Numerical modeling of polarization effects in a plasma at the W7-X stellarator

Bieg B., Hirsch M., Kravtsov Y. A.

Zeszyty Naukowe / Akademia Morska w Szczecinie

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2011

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nr 26 (98)

5-9

EN

The interferometer-polarimeter in the stellarator W7-X will operate in the far infrared band in the double passage regime: the electromagnetic beam will be reflected back from a corner cube retroreflector and thus pass through the magnetized plasma twice. Evolution of the polarization state of the beam along the polarimeter sightline in the standard magnetic field configuration of W7-X is analyzed on the basis of differential equations, for traditional polarization parameters – azimuthal angle [psi] and ellipticity angle [chi]. The influence of the Faraday and the Cotton-Mouton phenomena on polarization parameters [psi] and [chi] are analyzed. Calculations are performed for different plasma densities. Finally the potential sources of inaccuracy are considered, such as the shift in the probing beam position.

PL

W interfero-polarymetrycznym systemie diagnostycznym stellaratora W7-X podczerwona wiązka pomiarowa ulega podwójnemu przejściu przez obszar namagnesowanej plazmy. Ewolucja stanu polaryzacji fali elektromagnetycznej, podczas jej propagacji w plazmie o standardowej konfiguracji pola magnetycznego, analizowana jest na podstawie równań różniczkowych, opisujących zmiany tradycyjnych parametrów polaryzacyjnych: kąta azymutu [psi] i kąta eliptyczności [chi]. Przeanalizowano wpływ zjawiska Faradaya i Cottona-Moutona na zmiany wartości parametrów [psi] i [chi] przy różnych gęstościach plazmy w stellaratorze. Zbadano również wpływ przesunięcia przestrzennego pozycji wiązki pomiarowej na obserwowane zmiany polaryzacji fali elektromagnetycznej.

2

Studies of ion fluxes emitted from picosecond and nanosecond laser-produced plasmas

Badziak J., Parys P., Wołowski J., Woryna E.

Journal of Technical Physics

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2004

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Vol. 45, no 1

3-20

EN

Energetic ions emitted from plasmas produced by the interaction of intense laser pulses with solid targets are currently a subject of growing interest due to the possibility of unique applications in accelerator technology, nuclear physics, material science and medicine. Depending on the kind of application, different parameters of the ion fluxes are required, and various conditions of laser-target interaction must be considered. In this paper, selected results of our recent studies of ion emission from plasmas produced by laser pulses of duration from ~ 1 ps to ~ 1 ns and of intensities from 10^10 W/cm^2 to 10^17 W/cm^2 are reviewed. The characteristics of both heavy ion fluxes emitted from massive high-Z targets and proton beams generated from thin foil targets of various structures are presented. Some basic properties of ion fluxes produced in various experimental conditions are discussed. The effect of external magnetic field on the ion emission is demonstrated.

3

Application of automated interferometric system for investigation of the behaviour of a laser-produced plasma in strong external magnetic fields.

Kasperczuk A., Pisarczyk T.

Optica Applicata

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2001

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Vol. 31, nr 3

571-597

EN

Achievements of the authors in the field of technical and numerical problems of multi-frame interferometry are presented. A three-channel interferometric system with an automatic image processing for laser-produced plasma is described. The measurements of electron density distributions in a plasma generated by a laser and confined by a strong magnetic field (up to 15 T) are the main part of this work. Numerical analysis of interferograms of the plasma and numerical methods of the reconstruction of electron density spatial profiles, both in an axially symmetrical plasma and in a plasma stream of disturbed axial symmetry are presented in more detail.