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
SSC-Linac[1] as the injector for the Separated Sector Cyclotron (SSC), is being constructed at national labo-ratory Heavy Ion Research Facility at Lanzhou (HIRFL). The injection and extraction energy are 3.7 keV/u and...SSC-Linac[1] as the injector for the Separated Sector Cyclotron (SSC), is being constructed at national labo-ratory Heavy Ion Research Facility at Lanzhou (HIRFL). The injection and extraction energy are 3.7 keV/u and1.025 MeV/u, respectively. Fig. 1 shows the front end section of the SSC-Linac. The high charges state continuswave (CW) 4-rod RFQ has been designed and fabricated for some years. From the end of 2013, the commissioningof the RFQ was performed and the beam test was carried out in April 2014. In this paper the experiment resultwill be presented.展开更多
Multi-charged helium ion beam He2＋ is useful for helium accelerator to obtain a higher energy with lower cost and for deuterium accelerator to avoid neutron activation during machine commissioning. An attempt to gene...Multi-charged helium ion beam He2＋ is useful for helium accelerator to obtain a higher energy with lower cost and for deuterium accelerator to avoid neutron activation during machine commissioning. An attempt to generate milliampere multi-charged helium He2＋ ion beam with a 2.45 GHz electron cyclotron resonance ion source （ECRIS） was tested recently. A design using a specfic permanent magnet 2.45 GHz ECRIS （PMECRIS） source （ERCIS） is reported and the He2~ beam production ability is described. With this source, we produced a total helium beam of 40 mA at 40 kV with 180 W of net microwave power and a gas flow of less than 0.5 seem. At steady state the He2＋ beam intensity is 4.4 rnA, that being the fraction of multi-charged he- lium ion beam is at approximately 11%.展开更多
Three sets of High Intensity Beam Emittance Measurement Units (HIBEMUs) are being developed at Peking University. They are HIBEMU-2 (slit-wire type, one direction), HIBEMU-3 (Allison scanner type, one direction) and H...Three sets of High Intensity Beam Emittance Measurement Units (HIBEMUs) are being developed at Peking University. They are HIBEMU-2 (slit-wire type, one direction), HIBEMU-3 (Allison scanner type, one direction) and HIBEMU-4 (slit-wire type, two directions). For HIBEMU-2 and HIBEMU-3, more recent work has been done on software redesign in order to measure beam emittance and to draw phase diagram more efficiently and precisely. Software for control and data processing of them were developed in Labveiw environment, trying to improve calculation rationality and to offer user-friendly interface. Mechanical modification was also done for HIBEMU-3, mainly concentrating on the protection of Faraday cups from being overheated by the high intensity beam and also from interference of secondary electrons. This paper will also cover the mechanical structure as well as the software development of HIBEMU-4, which is a two-direction emittance scanner newly designed and manufactured for the high energy beam transport (HEBT) of Peking University Neutron Imaging FaciliTY (PKUNIFTY). At the end of this paper, comparison and analysis of the three HIBEMUs are given to draw forth better design of the future emittance measurement facility.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
The 53.667 MHz continuous-wave heavy ion RFQ has been designed and manufactured for the SSC-LINAC project.This four-rod RFQ accelerates ions with maximum mass to charge ratio of 7 from 3.728 keV/u to 143 keV/u.Measure...The 53.667 MHz continuous-wave heavy ion RFQ has been designed and manufactured for the SSC-LINAC project.This four-rod RFQ accelerates ions with maximum mass to charge ratio of 7 from 3.728 keV/u to 143 keV/u.Measurements have been carried out to check the RF performance of the cavity and the quality of the electric field.The S11 of the power coupler is adjusted to better than-44 dB,and the Q0 of the cavity is 6440.The quality of the electric field is evaluated by the perturbation method.The measurement procedure and data analysis will be discussed in detail.The error due to gravity of the perturbation bead has been corrected by averaging the fields in different quadrants.As a result,the unflatness of the electric field is±2.5%,and the dipole field component distributes from 0%to 20%in different longitudinal positions,which indicates the asymmetry of the quadrupole field.The unflatness of the quadrupole field distribution represents a good agreement with the simulation results.High power RF test and beam commissioning of the RFQ are on schedule in early 2014.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National Natural Science Foundation of China (10635090, 11375243)
文摘SSC-Linac[1] as the injector for the Separated Sector Cyclotron (SSC), is being constructed at national labo-ratory Heavy Ion Research Facility at Lanzhou (HIRFL). The injection and extraction energy are 3.7 keV/u and1.025 MeV/u, respectively. Fig. 1 shows the front end section of the SSC-Linac. The high charges state continuswave (CW) 4-rod RFQ has been designed and fabricated for some years. From the end of 2013, the commissioningof the RFQ was performed and the beam test was carried out in April 2014. In this paper the experiment resultwill be presented.
基金supported by the National Natural Science Foundation of China(Grant Nos.11075008 and 11175009)
文摘Multi-charged helium ion beam He2＋ is useful for helium accelerator to obtain a higher energy with lower cost and for deuterium accelerator to avoid neutron activation during machine commissioning. An attempt to generate milliampere multi-charged helium He2＋ ion beam with a 2.45 GHz electron cyclotron resonance ion source （ECRIS） was tested recently. A design using a specfic permanent magnet 2.45 GHz ECRIS （PMECRIS） source （ERCIS） is reported and the He2~ beam production ability is described. With this source, we produced a total helium beam of 40 mA at 40 kV with 180 W of net microwave power and a gas flow of less than 0.5 seem. At steady state the He2＋ beam intensity is 4.4 rnA, that being the fraction of multi-charged he- lium ion beam is at approximately 11%.
基金supported by the National Natural Science Foudation of China (Grant No. 11075008)
文摘Three sets of High Intensity Beam Emittance Measurement Units (HIBEMUs) are being developed at Peking University. They are HIBEMU-2 (slit-wire type, one direction), HIBEMU-3 (Allison scanner type, one direction) and HIBEMU-4 (slit-wire type, two directions). For HIBEMU-2 and HIBEMU-3, more recent work has been done on software redesign in order to measure beam emittance and to draw phase diagram more efficiently and precisely. Software for control and data processing of them were developed in Labveiw environment, trying to improve calculation rationality and to offer user-friendly interface. Mechanical modification was also done for HIBEMU-3, mainly concentrating on the protection of Faraday cups from being overheated by the high intensity beam and also from interference of secondary electrons. This paper will also cover the mechanical structure as well as the software development of HIBEMU-4, which is a two-direction emittance scanner newly designed and manufactured for the high energy beam transport (HEBT) of Peking University Neutron Imaging FaciliTY (PKUNIFTY). At the end of this paper, comparison and analysis of the three HIBEMUs are given to draw forth better design of the future emittance measurement facility.
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.11079001 and 10905003)the Linear Accelerator Center of PKU-IMPCAS
文摘The 53.667 MHz continuous-wave heavy ion RFQ has been designed and manufactured for the SSC-LINAC project.This four-rod RFQ accelerates ions with maximum mass to charge ratio of 7 from 3.728 keV/u to 143 keV/u.Measurements have been carried out to check the RF performance of the cavity and the quality of the electric field.The S11 of the power coupler is adjusted to better than-44 dB,and the Q0 of the cavity is 6440.The quality of the electric field is evaluated by the perturbation method.The measurement procedure and data analysis will be discussed in detail.The error due to gravity of the perturbation bead has been corrected by averaging the fields in different quadrants.As a result,the unflatness of the electric field is±2.5%,and the dipole field component distributes from 0%to 20%in different longitudinal positions,which indicates the asymmetry of the quadrupole field.The unflatness of the quadrupole field distribution represents a good agreement with the simulation results.High power RF test and beam commissioning of the RFQ are on schedule in early 2014.
