Tofms Of Gas Media In Femtosecond Laser Field And Measurement Of Soft X-Ray Spectrum

With the developing of ultrashort pulse laser technology,the interaction between laser and gas,solid,cluster and droplet gives birth to many new phenomenon which can not be explained by general perturbation theory,and such becomes a research focus of high-intensity physics.In this paper,a multifunctional target chamber system is designed,which can be simultaneously used to study the ionization(time of flight mass spectrum and electron energy spectrum) of gas atom,molecule and soft X-ray spectrum. Mainly with a Spectra-Physics laser system with the output parameters of 12mJ/pulse,100fs,and 10Hz repetition rate as pump source,ionization of gas media in the ultrashort pulse laser fields are studied in this paper.Besides,a soft X-ray flat-field spectrograph is built,and it has been tested and demarcated.The target chamber system structurally consists of a big target chamber and a small one,and functionally includes a time of flight mass spectrograph and electron energy spectrometer,a flat-field spectrograph and other modules.With this system,the interactions of laser pulse with different state materials can be observed;the dynamical data of ions and photoelectrons generated in the intense fields,the space distribution of photoelectrons and their angular distribution related to the polarization of laser can be measured;Soft X-ray and high-order harmonic generation can also be detected.According to working condition,the parameters of the spectrograph have been calculated at 1140mm incident distance,and the spectrograph has been demarcated by using a hollow cathode gaseous discharge source filled with He. When the cursor of CCD is 8.4mm,the measuring range of the spectrograph is 14.72～36.15nm,the width of 30.38nm spectrum is 0.054mm and the spectral resolution is better than 0.001 around 30nm with a 120μm incident slit.The spectrograph system will be used to detect the X-ray spectrum in the future.The processes of ionization and Coulomb explosion of Kr,N₂ and CO₂ in horizontal polarization Femtosecond pulse intense laser field are studied by using a time of flight mass spectrometer.When the power density is 2×10¹⁵W/cm², Kr⁺,Kr²⁺ and Kr⁴⁺ are found.The spectral peak disruption of N⁺ and N²⁺ are detected which means Coulomb explosion.Through deducing,the main explosion pathway of N⁺ is N₂³⁺→N⁺+N²⁺.Besides,C²⁺,O²⁺,C⁺,O⁺, CO⁺ and CO₂⁺ are detected in the CO₂ experiment.