The multiple filamentation of terawatt femtosecond （fs） laser pulses is experimentally studied in a natural environment. A more than 30-m long plasma filament with a millimeter diameter is formed by the collimated f...The multiple filamentation of terawatt femtosecond （fs） laser pulses is experimentally studied in a natural environment. A more than 30-m long plasma filament with a millimeter diameter is formed by the collimated fs laser pulse freely propagating in an open atmosphere. This study provides the first quantitative experimental data about the electron density of a long range light filament in the atmosphere. The electron density of such a filament is quantitatively detected by using an electric method, showing that it is at the 1011-cm -3 level.展开更多
In this work,we optimized a clean,versatile,compact source of soft X-ray radiation(Ex-ray∼3 keV)with an yield per shot up to 7×10^11 photons/shot in a plasma generated by the interaction of high-contrast femtose...In this work,we optimized a clean,versatile,compact source of soft X-ray radiation(Ex-ray∼3 keV)with an yield per shot up to 7×10^11 photons/shot in a plasma generated by the interaction of high-contrast femtosecond laser pulses of relativistic intensity(Ilas∼10^18-10^19 W/cm^2)with supersonic argon gas jets.Using high-resolution X-ray spectroscopy approaches,the dependence of main characteristics(temperature,density and ionization composition)and the emission efficiency of the X-ray source on laser pulse parameters and properties of the gas medium was studied.The optimal conditions,when the X-ray photon yield reached a maximum value,have been found when the argon plasma has an electron temperature of Te∼185 eV,an electron density of Ne∼7×10^20 cm^-3 and an average charge of Z∼14.In such a plasma,a coefficient of conversion to soft X-ray radiation with energies Ex-ray∼3.1(±0.2)keV reaches 8.57×10^-5,and no processes leading to the acceleration of electrons to MeV energies occur.It was found that the efficiency of the X-ray emission of this plasma source is mainly determined by the focusing geometry.We confirmed experimentally that the angular distribution of the X-ray radiation is isotropic,and its intensity linearly depends on the energy of the laser pulse,which was varied in the range of 50-280 mJ.We also found that the yield of X-ray photons can be notably increased by,for example,choosing the optimal laser pulse duration and the inlet pressure of the gas jet.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574387,11404335,11474002,and 11535001)the National Basic Research Program of China(Grant Nos.2013CBA01501 and 2013CB922401)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grants Nos.XDB16010200 and XDB07030300)the Science Challenge Project,China(Grant No.TZ2016005)
文摘The multiple filamentation of terawatt femtosecond （fs） laser pulses is experimentally studied in a natural environment. A more than 30-m long plasma filament with a millimeter diameter is formed by the collimated fs laser pulse freely propagating in an open atmosphere. This study provides the first quantitative experimental data about the electron density of a long range light filament in the atmosphere. The electron density of such a filament is quantitatively detected by using an electric method, showing that it is at the 1011-cm -3 level.
基金The reported study was funded by RFBR according to the research project No.18-52-53033National Natural Science Foundation of China(No.11811530076).
文摘In this work,we optimized a clean,versatile,compact source of soft X-ray radiation(Ex-ray∼3 keV)with an yield per shot up to 7×10^11 photons/shot in a plasma generated by the interaction of high-contrast femtosecond laser pulses of relativistic intensity(Ilas∼10^18-10^19 W/cm^2)with supersonic argon gas jets.Using high-resolution X-ray spectroscopy approaches,the dependence of main characteristics(temperature,density and ionization composition)and the emission efficiency of the X-ray source on laser pulse parameters and properties of the gas medium was studied.The optimal conditions,when the X-ray photon yield reached a maximum value,have been found when the argon plasma has an electron temperature of Te∼185 eV,an electron density of Ne∼7×10^20 cm^-3 and an average charge of Z∼14.In such a plasma,a coefficient of conversion to soft X-ray radiation with energies Ex-ray∼3.1(±0.2)keV reaches 8.57×10^-5,and no processes leading to the acceleration of electrons to MeV energies occur.It was found that the efficiency of the X-ray emission of this plasma source is mainly determined by the focusing geometry.We confirmed experimentally that the angular distribution of the X-ray radiation is isotropic,and its intensity linearly depends on the energy of the laser pulse,which was varied in the range of 50-280 mJ.We also found that the yield of X-ray photons can be notably increased by,for example,choosing the optimal laser pulse duration and the inlet pressure of the gas jet.
