Magnetic fields play a key role in driving a broad range of dynamic phenomena in the atmospheres of the Sun and other stars.Routine and accurate measurements of the magnetic fields at all the atmospheric layers are of...Magnetic fields play a key role in driving a broad range of dynamic phenomena in the atmospheres of the Sun and other stars.Routine and accurate measurements of the magnetic fields at all the atmospheric layers are of critical importance to understand these magnetic activities,but in the solar and stellar coronae such a measurement is still a challenge due to the weak field strength and the high temperature.Recently,a magnetic-field-induced transition(MIT)of Fe X at 257.26A has been proposed for the magnetic field measurements in the solar and stellar coronae.In this review,we present an overview of recent progresses in the application of this method in astrophysics.We start by introducing the theory underlying the MIT method and reviewing the existing atomic data critical for the spectral modeling of Fe X lines.We also discuss the laboratory measurements that verify the potential capability of the MIT technique as a probe for diagnosing the plasma magnetic fields.We then continue by investigating the suitability and accuracy of solar and stellar coronal magnetic field measurements based on the MIT method through forward modeling.Furthermore,we discuss the application of the MIT method to the existing spectroscopic observations obtained by the Extreme-ultraviolet Imaging Spectrometer onboard Hinode.This novel technique provides a possible way for routine measurements of the magnetic fields in the solar and stellar coronae,but still requires further efforts to improve its accuracy.Finally,the challenges and prospects for future research on this topic are discussed.展开更多
Dielectronic recombination is an important process in high temperature plasmas. In the present work, the KLn (n=L, M, N and O) DR resonance strengths of He-like to O-like xenon ions are measured at the Shanghai elec...Dielectronic recombination is an important process in high temperature plasmas. In the present work, the KLn (n=L, M, N and O) DR resonance strengths of He-like to O-like xenon ions are measured at the Shanghai electron beam ion trap using a fast electron beam energy scanning method. The experiment uncertainty reaches about 6% with significant improvement of statistics. A relativistic configuration interaction calculation is also made. Theoretical results agree with the experiment results within 15% in most cases.展开更多
In this paper,we report a newly developed Knudsen Cell injection system for SH-PermEBIT.This technique can overcome disadvantages of introducing organometallic gases and wired probes into EBIT and provide steady conti...In this paper,we report a newly developed Knudsen Cell injection system for SH-PermEBIT.This technique can overcome disadvantages of introducing organometallic gases and wired probes into EBIT and provide steady continuous injection.A specially designed vacuum line is used to ensure that the Knudsen Cell satisfies the vacuum level of SH-permEBIT.Using this system we successfully injected ytterbium into the SH-permEBIT and recorded a spectrum in the visible wavelength region.展开更多
In this work, a portable slit imaging system is developed to study both the electron beam diameter and the profile of the newly developed Shanghai Electron Beam Ion Trap (Shanghai EBIT). Images are detected by a cha...In this work, a portable slit imaging system is developed to study both the electron beam diameter and the profile of the newly developed Shanghai Electron Beam Ion Trap (Shanghai EBIT). Images are detected by a charge coupled device (CCD) sensitive to both X rays and longer wavelength photons (up to visible). Large scale ray tracings were conducted for correcting the image broadening effects caused by the finite slit width and the finite width of the CCD pixels. A numerical de-convolution method was developed to analyse and reconstruct the electron beam density distribution in the EBIT. As an example of the measured beam diameter and current density, the FWHM (full width at half maximum) diameter of the electron beam at 81 keV and 120 mA is found to be 76.2 μm and the density 2.00 × 10^3 A.cm-2, under a magnetic field of 3 T, including all corrections.展开更多
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.11825301,12103066 and12073004).
文摘Magnetic fields play a key role in driving a broad range of dynamic phenomena in the atmospheres of the Sun and other stars.Routine and accurate measurements of the magnetic fields at all the atmospheric layers are of critical importance to understand these magnetic activities,but in the solar and stellar coronae such a measurement is still a challenge due to the weak field strength and the high temperature.Recently,a magnetic-field-induced transition(MIT)of Fe X at 257.26A has been proposed for the magnetic field measurements in the solar and stellar coronae.In this review,we present an overview of recent progresses in the application of this method in astrophysics.We start by introducing the theory underlying the MIT method and reviewing the existing atomic data critical for the spectral modeling of Fe X lines.We also discuss the laboratory measurements that verify the potential capability of the MIT technique as a probe for diagnosing the plasma magnetic fields.We then continue by investigating the suitability and accuracy of solar and stellar coronal magnetic field measurements based on the MIT method through forward modeling.Furthermore,we discuss the application of the MIT method to the existing spectroscopic observations obtained by the Extreme-ultraviolet Imaging Spectrometer onboard Hinode.This novel technique provides a possible way for routine measurements of the magnetic fields in the solar and stellar coronae,but still requires further efforts to improve its accuracy.Finally,the challenges and prospects for future research on this topic are discussed.
基金supported by the National Key Research and Development Program of China under Grant No.2017YFA0402300
文摘Dielectronic recombination is an important process in high temperature plasmas. In the present work, the KLn (n=L, M, N and O) DR resonance strengths of He-like to O-like xenon ions are measured at the Shanghai electron beam ion trap using a fast electron beam energy scanning method. The experiment uncertainty reaches about 6% with significant improvement of statistics. A relativistic configuration interaction calculation is also made. Theoretical results agree with the experiment results within 15% in most cases.
基金Supported by the National Natural Science Foundation of China(No.11374061)
文摘In this paper,we report a newly developed Knudsen Cell injection system for SH-PermEBIT.This technique can overcome disadvantages of introducing organometallic gases and wired probes into EBIT and provide steady continuous injection.A specially designed vacuum line is used to ensure that the Knudsen Cell satisfies the vacuum level of SH-permEBIT.Using this system we successfully injected ytterbium into the SH-permEBIT and recorded a spectrum in the visible wavelength region.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11074049), the Chinese National Fusion Project for ITER (Grant No. 2009GB106001), and the Shanghai Leading Academic Discipline Project, China (Grant No. B107).
文摘In this work, a portable slit imaging system is developed to study both the electron beam diameter and the profile of the newly developed Shanghai Electron Beam Ion Trap (Shanghai EBIT). Images are detected by a charge coupled device (CCD) sensitive to both X rays and longer wavelength photons (up to visible). Large scale ray tracings were conducted for correcting the image broadening effects caused by the finite slit width and the finite width of the CCD pixels. A numerical de-convolution method was developed to analyse and reconstruct the electron beam density distribution in the EBIT. As an example of the measured beam diameter and current density, the FWHM (full width at half maximum) diameter of the electron beam at 81 keV and 120 mA is found to be 76.2 μm and the density 2.00 × 10^3 A.cm-2, under a magnetic field of 3 T, including all corrections.