| Radiative opacity is a significant physical parameter in plasma simulation for theresearch on the inertial confinement fusion(ICF),and it requires precise theoreticalcalculation and experimental measurement.X-ray spectrum diagnosis is a powerful tool tocarry out the measurement of plasma temperature and density in extreme plasma condition.In this paper,space-and time-resolving measurements are developed to achieve reliablehigh resolution transmission spectrum,and it has been compared with the calculationresults of a detailed level accounting opacity code.In filed of plasma diagnostics themethod of X-ray spectrum diagnosis is studied in details both experimentally andtheoretically.The following is the main contents of the present paper:(1)The wavelength determination method of X-ray spectral line with planar crystalspectrometer is studied,the curvature of spectral line was used to determine the anglebetween crystal and recording plane in order to develop the auxiliary diaphragm method.And a novel method of directly wavelength determination by using the curvature of spectralline is proposed and it is analyzed both experimentally and theoretically.Calibration ofabsolute response curves between 1.0keV and 1.5keV for X-ray film is accomplished onBeijing synchrotron radiation 3W1B facility,and it can provide quantitative measurementin opacity experiment.(2)The point-projection method is adopted to measure the transmission spectrum inopacity experiment on ShenguangⅡlaser facility.A half sample sandwich target has beendesigned to perform space-resolved measurement.Simultaneous measurements of theself-emission spectrum,the backlighting source spectrum and the transmission spectrum inone shot,can reduce the experimental uncertainties from shot-to-shot fluctuation andachieve reasonable data.Short backlighter generated by the ninth laser beam has been usedto provide temporal resolution and absorption measurement in a unitary plasma state and itis helpful to make comparison between experimental transmission spectrum and theoreticalmodel at a certain temperature and density.Side-on imaging technique is applied tomeasure the thickness of the expanded A1 plasma layer and the density,and the result arecompared with the hydrodynamic simulations(3)A steady collisional-radiative model(CRM),which separates the set of equations for a determination of excited level populations(considering fast processes of excitationand spontaneous radiative transitions)and for calculation of ion concentrations(slowprocesses of ionization and recombination),is established.Emission spectrum under nonlocal thermal equilibrium is studied,and the X-ray spectra emitted from laser-produced A1plasma are modeled.(4)Plasma state diagnostics is a significant subject in the research of ICF.Based onthe opacity experiment on ShenguangⅡfacility,theoretical method of plasma densitydiagnostics by using shift of the L edge is established.On Xingguang facility,the nonequilibrium K-shell emission spectra of laser-produced A1 plasma are measured by thespace-resolved spectrometer,which is constructed by a flat crystal spectrometer with slit.By using the established steady collisional-radiative model,the interstage line intensityratio of He-α/Ly-αis given as a function of electron temperature.The real intensity of1s-2p resonance line is decomposed by fitting experimental spectra with the satellites andparent resonance line,and the precision of temperature diagnostics is improved.
|
PDF Full Text Request