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The beam commissioning of a CW high charge state heavy ion RFQ
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 SSC-LINAC project is launched at Institute of Modern Physics in China to develop one new linear accelerator (LINAC) injector for separated sector cyclotron (SSC). It includes a high charge state ion source, a CW RFQ and a DTL section, and is designed to accelerate ions up to 580 keV/u, Now the ion source and the RFQ cavity have been installed in the main hall and the beam commissioning has been carried out. Two kinds of ions have been tested, O-16(5+) and Ar-40(8+). The experiment result of O-16(5+) is: the measured beam current is 180 mu A at entrance of RFQ and 150 mu A at exit of RFQ. The output energy of O-16(5+) is 141.89 keV/u. The measured beam current is 210 mu A at entrance of RFQ and 198 mu A at exit of RFQ for Ar-40(8+). The output energy of Ar-40(8+) is 142.78 keV/u, The experiment results agree with the design parameters of RFQ very well. This paper presents: the design consideration of beam dynamics, RF and cooling structure design; measurement of the cold model; high power test of RFQ and beam commissioning result. (C) 2015 Elsevier B.V. All rights reserved.</span
Fractal characteristics of fracture morphology of steels irradiated with high-energy ions
No full textA fractal analysis of fracture surfaces of steels (a ferritic/martensitic steel and an oxide-dispersion-strengthened ferritic steel) before and after the irradiation with high-energy ions is presented. Fracture surfaces were acquired from a tensile test and a small-ball punch test (SP). Digital images of the fracture surfaces obtained from scanning electron microscopy (SEM) were used to calculate the fractal dimension (FD) by using the pixel covering method. Boundary of binary image and fractal dimension were determined with a MATLAB program. The results indicate that fractal dimension can be an effective parameter to describe the characteristics of fracture surfaces before and after irradiation. The rougher the fracture surface, the larger the fractal dimension. Correlation of the change of fractal dimension with the embrittlement of the irradiated steels is discussed. (C) 2015 Elsevier B.V. All rights reserved
Rydberg-to- M -shell x-ray emission of hollow Xeq+ (q=27-30) atoms or ions above metallic surfaces
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 rays originating from transitions from high Rydberg states to the M shell (here called Rydberg-to-M-shell x rays) have been measured in the interaction of Xeq+ (q = 27-30) ions with aluminum, molybdenum, and beryllium surfaces in the energy range of 350-600 keV, by using a Si(Li) detector. The transition energy calculation by Cowan's program with relativistic correlation indicates that such x rays are mainly from the transition of the higher quantum states, with the principal quantum number from 6 up to 30, directly to M shell of xenon. The yield of the x ray per vacancy in M shell decreases slightly with increasing the projectile energies and is inversely proportional to the work functions of metallic surfaces used. However, it increases rapidly with the increase of the projectile charge states. All of these experimental facts combined with the transition rate calculations indicate that the measured Rydberg-to-M-shell x rays come from the "above the surface" hollow Xe atoms or ions deexcitation, when the inner shells such as N and O have not been filled.</span