This paper describes a simple form, the theory to determine the crystallization fraction during the phase transformation of a solid, at a constant heating rate, from data obtained by impedance spectroscopy, where the ...This paper describes a simple form, the theory to determine the crystallization fraction during the phase transformation of a solid, at a constant heating rate, from data obtained by impedance spectroscopy, where the change of the applied alternating voltage and measured current are proportional to the microstructural changes at the sample, corresponding to the volume fraction of a series layer model of two phases. To determine the volume fraction of each phase present in the sample, electrical data are obtained: conductivity and permittivity at DC, which are modeled by an electrical circuit composed by 2-RC, taking into that the permittivity and the occupied volume correspond to the filling fraction of each phase. By Cathodic Ersion or Sputtering, samples were obtained in film form of about 500 in thickness, composed of an alloy of Sb2Te3, in amorphous phase. To ensure the existence of the phase transformation in the sample, phase transition tests are performed by changes in: Reflection Optics, Electrical Resistivity and X-Ray Diffraction, showing clearly the presence of such a transformation. In the final part of this work, it completely shows the experimental results, giving a clear and precise idea of the kinetics of phase transformation of Sb2Te3 alloy, by impedance spectroscopy technique, which proves to be a simple and practical calculation tool.展开更多
The X-ray source based on Thomson scattering of ultrashort laser pulse with a relativistic electron beam is a means of generating a tunable, narrow bandwidth and ultrashort pulse of hard X-rays. Such a sub-picosecond ...The X-ray source based on Thomson scattering of ultrashort laser pulse with a relativistic electron beam is a means of generating a tunable, narrow bandwidth and ultrashort pulse of hard X-rays. Such a sub-picosecond hard X-ray source is proposed at Tsinghua University, and a preliminary experiment with a 16 MeV Backward Traveling electron linac and a 1.5 J, 6 ns Q-switched Nd：YAG laser is carried out first. A 6 ns pulse X-ray with a peak energy of 4.6 keV and an intensity of 1.Tx 104 per pulse is generated successfully in the experiment. The experimental setup, result and discussion are reported in this paper.展开更多
We try to design the lattice with 2 super periods and 4-DBA structure in order to provide more drifts for the future development of the TTX source. Due to the space limitation in the lab, the 4-DBA lattice is suitable...We try to design the lattice with 2 super periods and 4-DBA structure in order to provide more drifts for the future development of the TTX source. Due to the space limitation in the lab, the 4-DBA lattice is suitable.In the paper,we present the lattice design with a 4-DBA structure mainly for the pulse mode of the compact laser-electron storage ring （LESR）. Element parameters of the lattice are optimized with the help of the professional software and beam dynamics such as intra-beam scattering （IBS） and Compton scattering （CS） are calculated. Besides, the fringe field effect is analyzed with the numerical method.展开更多
文摘This paper describes a simple form, the theory to determine the crystallization fraction during the phase transformation of a solid, at a constant heating rate, from data obtained by impedance spectroscopy, where the change of the applied alternating voltage and measured current are proportional to the microstructural changes at the sample, corresponding to the volume fraction of a series layer model of two phases. To determine the volume fraction of each phase present in the sample, electrical data are obtained: conductivity and permittivity at DC, which are modeled by an electrical circuit composed by 2-RC, taking into that the permittivity and the occupied volume correspond to the filling fraction of each phase. By Cathodic Ersion or Sputtering, samples were obtained in film form of about 500 in thickness, composed of an alloy of Sb2Te3, in amorphous phase. To ensure the existence of the phase transformation in the sample, phase transition tests are performed by changes in: Reflection Optics, Electrical Resistivity and X-Ray Diffraction, showing clearly the presence of such a transformation. In the final part of this work, it completely shows the experimental results, giving a clear and precise idea of the kinetics of phase transformation of Sb2Te3 alloy, by impedance spectroscopy technique, which proves to be a simple and practical calculation tool.
基金Supported by National Natural Science Foundation of China(10645002)Program for New Century Excellent Talents in University(NCET)
文摘The X-ray source based on Thomson scattering of ultrashort laser pulse with a relativistic electron beam is a means of generating a tunable, narrow bandwidth and ultrashort pulse of hard X-rays. Such a sub-picosecond hard X-ray source is proposed at Tsinghua University, and a preliminary experiment with a 16 MeV Backward Traveling electron linac and a 1.5 J, 6 ns Q-switched Nd：YAG laser is carried out first. A 6 ns pulse X-ray with a peak energy of 4.6 keV and an intensity of 1.Tx 104 per pulse is generated successfully in the experiment. The experimental setup, result and discussion are reported in this paper.
基金Supported by National Natural Science Foundation of China (10735050)National Basic Research Program of China (973 Program)(2007CB815102)
文摘We try to design the lattice with 2 super periods and 4-DBA structure in order to provide more drifts for the future development of the TTX source. Due to the space limitation in the lab, the 4-DBA lattice is suitable.In the paper,we present the lattice design with a 4-DBA structure mainly for the pulse mode of the compact laser-electron storage ring （LESR）. Element parameters of the lattice are optimized with the help of the professional software and beam dynamics such as intra-beam scattering （IBS） and Compton scattering （CS） are calculated. Besides, the fringe field effect is analyzed with the numerical method.
