Irradiated by femtosecond laser pulses with different energies, opened cone targets behave very differently in the transmission of incident laser pulses. The targets, each with an opening angle of 71° and an open...Irradiated by femtosecond laser pulses with different energies, opened cone targets behave very differently in the transmission of incident laser pulses. The targets, each with an opening angle of 71° and an opening of 5 μm, are fabricated using standard semiconductor technology. When the incident laser energy is low and no pre-plasma is generated on the side walls of the cones, the cone target acts like an optical device to reflect the laser pulse, and 15% of the laser energy can be transmitted through the cones. In contrast, when the incident laser energy is high enough to generate pre-plasmas by the pre-pulse of the main pulse that fills the inner cone, the cone with the plasmas will block the transmission of the laser, which leads to a decrease in laser transmission compared with the low-energy case with no plasma. Simulation results using optical software in the low-energy case, and using the particle-in-cell code in the high-energy case, are primarily in agreement with the experimental results.展开更多
The paper has studied the influence of target material and thickness on energy and angular distributions of the protons generated by using an 800 rim, 60 fs, 0.24 J laser pulse to irradiate solid target foils. The res...The paper has studied the influence of target material and thickness on energy and angular distributions of the protons generated by using an 800 rim, 60 fs, 0.24 J laser pulse to irradiate solid target foils. The results show that the initial density and thickness of the targets will affect the formation of the acceleration sheath fields in the target normal direction. For the same target thickness, using lower density target materials can obtain a higher proton maximum energy. However, lower density targets tend to be deformed due to the shock waves launched by the laser pulses, making the proton spatial distribution more divergent.展开更多
A powerful terahertz(THz) pulse was produced by a p-polarized,70 fs,800 nm laser interacting with solid targets at an incident angle of 45°.The polarization of the THz emission was measured out of the laser incid...A powerful terahertz(THz) pulse was produced by a p-polarized,70 fs,800 nm laser interacting with solid targets at an incident angle of 45°.The polarization of the THz emission was measured out of the laser incident plane.The results showed that it was linearly polarized.We established a surface current model to explain this phenomenon,assuming that the transient current moving along the plasma surface was responsible for the generation of the THz emission.The model expectation and the experimental result were in good agreement.展开更多
The proton spectral and angular distributions simultaneously within the target normal direction and laser propagation direction by using an angle-resolved proton energy spectrometer are studied.For the protons generat...The proton spectral and angular distributions simultaneously within the target normal direction and laser propagation direction by using an angle-resolved proton energy spectrometer are studied.For the protons generated in the interactions of 100 fs,800nm laser pulses with aluminum foil targets,the deviations of proton beam centers of different energies from the target normal direction towards the laser propagation direction are different.This is probably because of the toroidal magnetic fields generated at the rear target surface,which deflect protons transversely.As a result,protons in low energy range have large deviation angles,protons in middle energy range have the smallest deviation angles,while protons in high energy tail have large deviation angles.展开更多
基金supported by National Natural Science Foundation of China(Nos.10925421,10735050,10974250,10935002)
文摘Irradiated by femtosecond laser pulses with different energies, opened cone targets behave very differently in the transmission of incident laser pulses. The targets, each with an opening angle of 71° and an opening of 5 μm, are fabricated using standard semiconductor technology. When the incident laser energy is low and no pre-plasma is generated on the side walls of the cones, the cone target acts like an optical device to reflect the laser pulse, and 15% of the laser energy can be transmitted through the cones. In contrast, when the incident laser energy is high enough to generate pre-plasmas by the pre-pulse of the main pulse that fills the inner cone, the cone with the plasmas will block the transmission of the laser, which leads to a decrease in laser transmission compared with the low-energy case with no plasma. Simulation results using optical software in the low-energy case, and using the particle-in-cell code in the high-energy case, are primarily in agreement with the experimental results.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10935002,10925421,and 10974250)the National Basic Research Program of China (973 Program,Grant No.2007CB815102)
文摘The paper has studied the influence of target material and thickness on energy and angular distributions of the protons generated by using an 800 rim, 60 fs, 0.24 J laser pulse to irradiate solid target foils. The results show that the initial density and thickness of the targets will affect the formation of the acceleration sheath fields in the target normal direction. For the same target thickness, using lower density target materials can obtain a higher proton maximum energy. However, lower density targets tend to be deformed due to the shock waves launched by the laser pulses, making the proton spatial distribution more divergent.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10925421 and 10734130)
文摘A powerful terahertz(THz) pulse was produced by a p-polarized,70 fs,800 nm laser interacting with solid targets at an incident angle of 45°.The polarization of the THz emission was measured out of the laser incident plane.The results showed that it was linearly polarized.We established a surface current model to explain this phenomenon,assuming that the transient current moving along the plasma surface was responsible for the generation of the THz emission.The model expectation and the experimental result were in good agreement.
基金supported by the National Basic Research Program of China(Grant No.2013CBA01501)the National Natural Science Foundation of China(Grant Nos.11375262 and 11135012)
文摘The proton spectral and angular distributions simultaneously within the target normal direction and laser propagation direction by using an angle-resolved proton energy spectrometer are studied.For the protons generated in the interactions of 100 fs,800nm laser pulses with aluminum foil targets,the deviations of proton beam centers of different energies from the target normal direction towards the laser propagation direction are different.This is probably because of the toroidal magnetic fields generated at the rear target surface,which deflect protons transversely.As a result,protons in low energy range have large deviation angles,protons in middle energy range have the smallest deviation angles,while protons in high energy tail have large deviation angles.
