Recent research activities relevant to high energy density physics(HEDP) driven by the heavy ion beam at the Institute of Modern Physics, Chinese Academy of Sciences are presented. Radiography of static objects with the fast extracted high energy carbon ion beam from the Cooling Storage Ring is discussed. Investigation of the low energy heavy ion beam and plasma interaction is reported. With HEDP research as one of the main goals, the project HIAF(High Intensity heavy-ion Accelerator Facility), proposed by the Institute of Modern Physics as the 12 th five-year-plan of China, is introduced.
An analytical description for guiding of ions through nanocapillaries is given on the basis of previous work. The current entering into the capillary is assumed to be divided into a current fraction transmitted through the capillary, a current fraction flowing away via the capillary conductivity and a current fraction remaining within the capillary, which is responsible for its charge-up. The discharging current is assumed to be governed by the Frenkel–Poole process. At higher conductivities the analytical model shows a blocking of the ion transmission, which is in agreement with recent simulations.Also, it is shown that ion blocking observed in experiments is well reproduced by the analytical formula. Furthermore, the asymptotic fraction of transmitted ions is determined. Apart from the key controlling parameter(charge-to-energy ratio), the ratio of the capillary conductivity to the incident current is included in the model. Differences resulting from the nonlinear and linear limits of the Frenkel–Poole discharge are pointed out.
The K-shell x-rays of Ti, V, Fe, Co, Ni, Cu, and Zn induced by 424-MeV/u C^(6+) ion impact are measured. It is found that the K x-ray shifts to the high energy side and the intensity ratio of Kβ/Kα is larger than the atomic data, owing to the L-shell multiple-ionization. The x-ray production cross sections are deduced from the experimental counts and compared with the binary encounter approximation(BEA), plane wave approximation(PWBA) and energy-loss Coulomb-repulsion perturbed-stationary-state relativistic(ECPSSR) theoretical predictions. The BEA model with considering the multipleionization fluorescence yield is in better consistence with the experimental results. In addition, the cross section as a function of target atomic K-shell binding energy is presented.
Fe K-shell ionization cross sections induced by 2.4–6.0 MeV Xe20+are measured and compared with different binaryencounter-approximation(BEA)models.The results indicate that the BEA model corrected both by the Coulomb repulsion and by the effective nuclear charge(Zeff)agrees well with the experimental data.Comparison of Fe K-shell X-ray emission induced by 5 MeV xenon ions with different initial charge states(20+,22+,26+,30+)verifies the applicability of the effective nuclear charge(Zeff)correction for the BEA model.It is found that Zeffcorrection is reasonable to describe direct ionization induced by xenon ions with no initial M-shell vacancies.However,when the M shell is opened,the Zeffcorrected BEA model is unable to explain the inner-shell ionization,and the electron transfer by molecular-orbital promotion should be considered.
The interaction process of ions and plasmas is an important topic in Ion-Beam-Driven High Energy DensityPhysics and Inertial Confinement Fusion research. Due to the strong non-linear effects and the special importancein ICF research, more and more emphasis has been given to the investigations for ion beam in low energy rangeand/or for plasma with high intensity[1;2]. Here, we address the newly measured results of the energy loss by slowions penetrating the fully ionized hydrogen plasma target.
Highly charged ions (HCIs) carrying amount of potential energy will produce some new physical phenomenabecause the potential energy will be deposited into a very small volume within a very short time. We wouldapply the calorimetric method to study the energy deposition of HCIs [1;2]. Herein we introduce the new setup forcalorimetric measurement for the potential energy deposition of highly charged ions at 320 kV Highly Charged IonsPhysics Experimental Platform.The setup was constructed by 3 parts: the Dewar, the electrical temperature controller and the main part. Thediamond target was connected to the LN2 cooled heat sink by 4 copper wires and a Platinum temperature sensorwas glued to the rear side of the target. As shown in Fig. 1.
Graphene is two dimensional materials which is made of honeycombed carbon atoms. It attracts extensiveinterests for its wonderful characteristics that make the graphene a potential candidate in fields of microelectronicsproduction, molecule detection, desalination and DNA sequencing. Highly charged ion (HCI) has huge potentialenergy for peeling off electrons. When interacting with solid surface, the HCI distorted the solid lattice via potentialdeposition and then the nanostructures were formed on the solid surface. The HCI was expected as a tool for surfacemodification. In this work, HOPG and grapheme were irradiated with Xeq+ and Arq+ ions. The typical Ramanspectra of graphene and HOPG irradiated with highly charged ions were shown in Fig. 1. The D peak appeared at1 335 cm??1 on the spectra of graphene irradiated with highly charged ions. The intensity of D peak increased withfluence. The ratio of intensity of D peak to that of G peak varied with fluence in Fig. 2. The ratio rose linearlywith the square root of fluence when fluence was low. The ratio saturated when the irradiation fluence was high.The critical fluence depended on the charge state of ion. The higher charge state it was, the lower critical fluenceit would be.
High energy density is generally defined as a state with energy content larger than 1011 J/m3,or equivalently with pressure higher than 1 Mbar.High energy density matter widely exists in the universe,like the cores of Jupiter,Sun and Earth,as well as inertial confinement fusion.The creation of high energy density state in the laboratory and the research on its properties are very important in astrophysics,planetary sciences,geophysics,inertial fusion sciences and so on.Related to high energy density physics,we carried out a series of research activities including simulation of the state of warm dense matter at HIAF,ion-plasma interaction,highly charged ions induced nanoscale defect on surface and X-ray emission,as well as developing a new multi-channel pyrometer and high energy electron radiography.
Warm dense matter,an intermediate state of matter between a solid and an ideal plasma,has a density as a solid,a temperature of a few eV,and a pressure of some Mbar,which exists in the cores of large planets and the path to inertial confinement fusion.However,in this state,because of the strongly coupled particles,the assumptions of both condensed matter theory and ideal-plasma theory break down,the quantum mechanics and other effects become of the importance as well.
