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Trends in heavy ion interaction with plasma
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);">In this work, we review current trends in China to investigate beam plasma interaction phenomena. Recent progresses in China on low energy heavy ions and plasma interaction, ion beam-plasma interactions under the influences of magnetic fields, high energy heavy ion radiography through marginal range method, energy deposition of highly charged ions on surfaces and Raman spectroscopy of surfaces after irradiation of highly charged ions are presented.</span
K shell hyper-satellite lines of Cu induced by 300MeV/u C ions
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);">X-ray emission induced by 300 MeV/u C ions impacting on copper was investigated at the Heavy Ion Research Facility in Lanzhou (HIRFL). The results showed a very high yield of K hyper-satellite emission comparing to the satellite emission.</span
Development of DRAGON electron cyclotron resonance ion source at Institute of Modern Physics
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Annealing effects on the photoluminescence of Pb-ion irradiated He-doped sapphire
No full textIn the present work, the photoluminescence (PL) character of single crystal sapphire (Al2O3) samples with and without implantation by 110 keV He and/or irradiation by 230-MeV Pb ions, as well as subsequently annealing at 600, 900 and 1100 K (T (A)) was studied. The modification of the structure and optical properties induced by ion irradiation were analyzed by using PL and FTIR spectra. The PL measurements showed that luminescence peaks located at 390, 413, 450, and 564 nm appeared in irradiated samples. The luminescence peaks appeared at 360, 380, and 516 nm after annealing. Infrared spectra showed a broadening of the absorption band between 460 cm(-1) and 510 cm(-1), which indicated the formation of strongly damaged regions in the Al2O3 samples. The position shift of the absorption band in 1000-1300 cm(-1) tended towards to a higher wavelength
Lattice damage and nanohardness in 6H-SiC implanted with multiple-energy Xe ions
No full textSpecimens of 6H-SiC were implanted with Xe ions with multiple kinetic energies at room temperature to obtain nearly uniform Xe concentrations of 7.5, 30, 150 at. ppm, respectively, and were subsequently thermally annealed under high vacuum. The lattice damage and nanohardness of specimens were studied with high resolution X-ray diffraction spectrometry and nanoindentation measurements. In the low dose specimen (7.5 at. ppm), the occurrence of a plateau (with sub-peaks) at low angle side of the SiC (0 0 0 1 2) peak suggests a strain gradient in the direction normal to the specimen surface. Upon subsequent thermal annealing the strain relaxes gradually. The relaxation activation energy of the strain was estimated with Arrhenius law. For the specimens implanted to 30 and 150 at. ppm Xe, the disappearance of the plateau or peak indicates that the implanted region has been amorphized. However, a satellite peak near the main peak reappears after the thermal annealing. In addition, the main peak broadens toward high angle side after the annealing as the result of a shrinkage of crystal lattice. The nanohardness value of the specimen implanted to 7.5 at. ppm exceeds that of virgin SiC, whereas it is opposite for the case of 30 and 150 at. ppm implantation due to the formation of amorphous regions. Changes of nanohardness with thermal annealing temperature were studied. Underlying mechanisms were discussed. (C) 2011 Elsevier B.V. All rights reserved
A HRXRD and nano-indentation study on Ne-implanted 6H-SiC
No full textSpecimens of 6H-SiC single crystal were irradiated at room temperature with 2.3 MeV neon ions to three successively increasing fluences of 2 x 10(14), 1.1 x 10(15) and 3.8 x 10(15) ions/cm(2) and then annealed at room temperature, 500, 700 and 1000 degrees C, respectively. The strain in the specimens was investigated with a high resolution XRD spectrometer with an omega-20 scanning. And the mechanical properties were investigated with the nano-indentation in the continuous stiffness measurement (CSM) mode with a diamond Berkovich indenter. The XRD curves of specimens after irradiation show the diffraction peaks arising at lower angles aside of the main Bragg peak Theta(Bragg), indicating that a positive strain is produced in the implanted layer. In the as-implanted specimens, the strain increases with the increase of the ion fluence or energy deposition. Recovery of the strain occurs on subsequent thermal annealing treatment and two stages of defects evolution process are displayed. An interpretation of defects migration, annihilation and evolution is given to explain the strain variations of the specimens after annealing. The nano-indentation measurements show that the hardness in as-implanted specimens first increases with the increase of the ion fluence, and a degradation of hardness occurs when the ion fluence exceeds a threshold. On the subsequent annealing, the hardness variations are regarded to be a combined effect of the covalent bonding and the pinning effect of defect clusters. (C) 2012 Elsevier B.V. All rights reserved
A particle-in-cell mode beam dynamics simulation of medium energy beam transport for the SSC-Linac
No full textA new linear accelerator system, called the SSC-Linac injector, is being designed at HIRFL (the heavy ion research facility of Lanzhou). As part of the SSC-Linac, the medium energy beam transport (MEBT) consists of seven magnetic quadrupoles, a re-buncher and a diagnose box. The total length of this segment is about 1.75 m. The beam dynamics simulation in MEBT has been studied using the TRACK 3D particle-in-cell code, and the simulation result shows that the beam accelerated from the radio frequency quadrupole (RFQ) matches well with the acceptance of the following drift tube linac (DTL) in both the transverse and longitudinal phase spaces, and that most of the particles can be captured by the final sector focusing cyclotron for further acceleration. The longitudinal emittance of the RFQ and the longitudinal acceptance of the DTL was calculated in detail, and a multi-particle beam dynamics simulation from the ion source to the end of the DTL was done to verify the original desig
Multipacting simulation and analysis of a taper quarter wave cavity by using Analyst-PT3P
No full textSince the tapered quarter wave resonator (QWR) cavity is proven to have a much lower peak surface magnetic field in the short plate and a lower peak surface electric field near the beam tube compared with the straight outer conductor QWR, it has been recommended for the separated sector cyclotron linac injector system in the heavy ion research facility in Lanzhou. This paper is focused on the multipacting (MP) analysis for the tapered QWR with a frequency of 80.5 MHz and beta of 0.085. Using the Analyst program, MP bands can be simulated and analyzed with the Particle Tracking module to identify potential problems in the cavity design. This paper will present the simulation results of MP for the tapered QWR cavity.National Nature Science Foundation of Chin