Institutional Repository of Institute of Modern Physics, CAS
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Electron emission and surface etching by slow and medium highly charged ions on HOPG surface
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Highly charged (Xe-129(q+), q = 10-30) ion-induced secondary electron emission and formation of nanostructure on the surface of highly oriented pyrolytic graphite (HOPG) have been studied on the 320 kV ECR platform for Highly Charged Ion Beam at IMP-CAS, Lanzhou. The experimental data of the total secondary electron yields are used to separate contributions of kinetic and potential electron yields. The estimated kinetic electron yields are about 17 and 35 electron/ion by ions with kinetic energies of 600 keV and 5 MeV, respectively. The potential electron yield increases linearly with increasing potential energy of the incident ion. The total electron yield, however, does not depend significantly on kinetic energy. AFM analysis of the HOPG surface bombarded with Xe30+ ions revealed regular hillock like nanostructure. The relationship between hillock size (height and width) and ion's energy (including potential energy and kinetic energy) shows the same trend with the total electron yield which increases with potential energy and is independent on incident kinetic energy. (C) 2013 Elsevier B.V. All rights reserved.</span
Charge exchange and ionization cross sections of H+ + H collision in dense quantum plasmas
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The plasma screening effects of dense quantum plasmas on H+ + H charge exchange and ionization cross sections are calculated by the classical trajectory Monte Carlo method. For charge exchange cross sections, it is found that the screening effects reduce cross sections slightly in weak screening conditions. However, cross sections are reduced substantially in strong screening conditions. For ionization cross sections, with the increase of screening effects, cross sections for low energies increase more rapidly than those for high energies. When the screening effects are strong enough, it is found that ionization cross sections decrease with the increase of incident H+ energy. In addition, the cross sections have been compared with those in weakly coupled plasmas. It is found that in weak screening conditions, plasma screening effects in the two plasmas are approximately the same, while in strong screening conditions, screening effects of dense quantum plasmas are stronger than those of weakly coupled plasmas. (C) 2013 AIP Publishing LLC.</span
Kr L X-ray and Au M X-ray emission for 1.5 MeV-3.9 MeV Kr13+ ions impacting on an Au target
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Kr L X-ray and Au M X-ray emission for Kr13+ ions with energies of 1.5 MeV and 3.9 MeV impacting on an Au target are investigated at heavy ion research facility in Lanzhou (HIRFL). The L-shell X-ray yield per ion of Kr is measured as a function of incident energy. In addition, Kr L X-ray production cross section is extracted from the yield and compared with the result obtained from the classical binary-encounter approximation (BEA) model. Furthermore, the intensity ratio of the Au M-beta 3 to M-alpha 1 X-ray is investigated as a function of incident energy.</span
YAP:Ce and CsI(Tl) detectors for dielectronic recombination experiment at the CSRm
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The storage ring CSRm in Lanzhou provides good possibilities for electron-ion collision studies with cooled ion beams. To carry on the recombination experiment at the CSRm, a scintillation detector CsI(Tl) to detect the recombined ions was developed and tested. In addition, a YAP:Ce detector has been developed and installed at CSRm and capability of handling a high count rate of similar to 10(7) s(-1) has been obtained which is sufficient for the future dielectronic recombination experiment at the CSRm. The comparison of the characteristics of these two detectors is presented. (C) 2013 Elsevier B.V. All rights reserved.</span
Longitudinal Schottky spectra of a bunched Ne10+ ion beam at the CSRe
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The longitudinal Schottky spectra of a radio-frequency (RF) bunched and electron cooled Ne-22(10+) ion beam at 70 MeV/u have been studied by a newly installed resonant Schottky pick-up at the experimental cooler storage ring (CSRe), at IMP. For an RF-bunched ion beam, a longitudinal momentum spread of Delta p/p = 1.6 x 10(-5) has been reached with less than 10(7) stored ions. The reduction of momentum spread compared with a coasting ion beam was observed from Schottky noise signal of the bunched ion beam. In order to prepare the future laser cooling experiment at the CSRe, the RF-bunching power was modulated at 25th, 50th and 75th harmonic of the revolution frequency, effective bunching amplitudes were extracted from the Schottky spectrum analysis. Applications of Schottky noise for measuring beam lifetime with ultra-low intensity of ion beams are presented, and it is relevant to upcoming experiments on laser cooling of relativistic heavy ion beams and nuclear physics at the CSRe</span
Kr L X-ray and Au M X-ray emission for 1.5 MeV-3.9 MeV Kr~(13+) ions impacting on an Au target
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Kr L X-ray and Au M X-ray emission for Kr13+ ions with energies of 1.5 MeV and 3.9 MeV impacting on an Au target are investigated at heavy ion research facility in Lanzhou (HIRFL). The L-shell X-ray yield per ion of Kr is measured as a function of incident energy. In addition, Kr L X-ray production cross section is extracted from the yield and compared with the result obtained from the classical binary-encounter approximation (BEA) model. Furthermore, the intensity ratio of the Au M-beta 3 to M-alpha 1 X-ray is investigated as a function of incident energy.</span
Magnetic Field and Strain Measurements of a Superconducting Solenoid Magnet for C-ADS Injector-II During Excitation and Quench Test
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">A superconducting solenoid magnet has been fabricated and tested for the Accelerator Driven System (ADS), which is a dedicated burner reactor in a double strata fuel cycle to incinerate nuclear waste, at the Institute of Modern Physics of Chinese Academy of Science (IMPCAS). The magnetic field of the superconducting solenoid was measured with hall probes during the magnet excitation and spontaneous quench test. The strains in the superconducting solenoid magnet and its cryogenic support structures were measured by using a compensation bridge of low-temperature strain gauges and a wireless strain acquisition system. The transient strains and their abrupt changes were recorded and compared with the collected signals of the transport current and temperature of the superconducting solenoid during a spontaneous quench test. It indicates that, not only the mechanical behaviors of the superconducting solenoid and the support structures during the excitation can be captured effectively, but also the quench feature can be detected with observations of abrupt strain variations as a quench occurs. The predictions of the magnetic and strain field by means of a coupled finite element analysis were also performed and compared with the experimental measurements resulting in a good agreement</span
2.45 GHz ECR离子源的微波阻抗匹配
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">ECR离子源的等离子体阻抗对其微波传输与阻抗匹配设计至关重要。在中国科学院近代物理研究所现有的2.45 GHz ECR质子源上,对等离子体阻抗进行了测量。首先用水吸收负载代替等离子体负载测量得到了所用微波窗阻抗,然后根据质子源测量数据,推算得到了等离子体阻抗。实验结果表明,脊波导输出端阻抗与后续负载不完全匹配,等离子体阻抗随微波功率变化呈非线性。这些结果为ECR离子源过渡匹配和微波窗的设计提供了参考依据。</span><span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Plasma impedance of an ECR ion source is important for microwave transmission and impedance matching design. Plasma impedance was measured indirectly with the 2.45 GHz ECR proton source at the Institute of Modern Physics, Chinese Academy of Sciences. In the test, we got microwave window impedance by using water absorption load instead of plasma load, and the source plasma impedance was derived from the test data with the 2.45 GHz ECR proton source and microwave window impedance. The experimental results show that ridge waveguide output impedance and the subsequent load does not exactly match, plasma impedance variation is nonlinear with microwave power. The achieved result is useful in the design of ridged waveguide and microwave window.</span
Charge state distribution analysis of Al and Pb ions from thelaser ion source at IMP
No full text<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">A prototype laser ion source that could demonstrate the possibility of producing intense pulsed high charge state ion beams has been established with a commercial Nd:YAG laser (E-max=3 J, 1064 nm, 8-10 ns) to produce laser plasma for the research of Laser Ion Source (LIS). At the laser ion source test bench, high purity (99.998%) aluminum and lead targets have been tested for laser plasma experiment. An Electrostatic Ion Analyzer (EIA) and Electron Multiply Tube (EMT) detector were used to analyze the charge state and energy distribution of the ions produced by the laser ion source. The maximum charge states of Al12+ and Pb7+ were achieved. The results will be presented and discussed in this paper.</span