Heavy Ion Damage Research Articles

Deuterium retention in heavy-ion and helium-ion sequentially irradiated tungsten

Neutron irradiation as well as the presence of helium (He) significantly affects fuel inventory in plasma-facing materials. To investigate the synergistic effects of neutron and He irradiation on deuterium (D) retention behaviors in tungsten, heavy- and He-ion sequentially irradiation experiments were performed with various He fluence and/or heavy-ion damage levels, and then the samples were exposed to low-energy D plasmas at 450 K. It is shown that even a low He concentration of 0.5 atomic parts per million (appm) increases D concentration in the heavy-ion damaged region, which increases further with increasing He concentration under the parameters selected in this work (up to a maximum He concentration of 2.1 appm). The total D inventory in tungsten bulk also increases with He fluence due to the increase in D concentration both in the heavy-ion damaged region and the region irradiated by He-ion only. Furthermore, heavy-ion and He-ion successive irradiation slightly increases D retention in tungsten compared to the individual He ions irradiation. Similar to single heavy-ion damaged tungsten, the saturation of D retention is observed as heavy-ion irradiation damage above 0.2 dpa at a fixed He fluence.

Comparing deuterium retention in heavy ion damaged tungsten measured by glow discharge optical emission spectroscopy, nuclear reaction analysis and thermal desorption spectroscopy

Hot-rolled tungsten specimen were irradiated with 5 MeV gold ion and loaded with deuterium plasma sequentially. Deuterium retention was examined by glow discharge optical emission spectroscopy, nuclear reaction analysis and thermal desorption spectroscopy. The deuterium depth profiles obtained by nuclear reaction analysis show that deuterium concentration increases significantly after irradiation, and damage region could uptake most of deuterium. The results of thermal desorption spectroscopy demonstrate that heavy ion damage can produce a large number of defects which could trap deuterium. Significant deuterium saturation was observed with damage level above 0.4 dpa. Furthermore, the depth profile and total inventory of deuterium show that the result measured by glow discharge optical emission spectroscopy is in good agreement with that by nuclear reaction analysis and thermal desorption spectroscopy.

Effects of the influence of copper and zinc on living organisms (literature review)

Introduction. Scientists from Horbachevsky Ternopil National Medical University, Ternopil, and various countries, including state laboratories, have thoroughly studied the biological significance of copper and zinc ions in the body for many years. Nevertheless, the value of the shortage or excess of these metals and their compounds in the body remains mostly underestimated for health. Purpose of work: to study the pathogenesis of traumatic disease occurring due to an imbalance of copper and zinc in the body. Methods. Bibliosemantic and analytical methods were used. A literature search was conducted for the following queries as zinc, copper, heavy metals, negative impact. The investigation was performed with PubMed, Scopus, Web of Science, and Google Scholar for various articles. All publications have been analyzed and included in this review. The importance of these metals’ lack or excess and their compounds in the body remains mostly underestimated. Features of the pathogenesis of many diseases occurring due to imbalance of copper and zinc in the body have also been unexplored. The traumatic disorder was no exception, as this was not considered in experimental and clinical medicine. Conclusion. From the analysis of the available scientific literature, no messages were found about the features of the course of traumatic disease in conditions of excessive intake of copper and zinc ions in the body. We can only assume that a violation of the functional ability of the liver, lungs, brain and other organs that occurs against the background of heavy metal ion damage creates an unfavorable background for the occurrence of a serious injury.

Depth distributions of cavities in advanced ferritic/martensitic and austenitic steels with high helium preimplantation and high damage level

The cavity depth distributions in advanced ferritic/martensitic and austenitic 316 steels were characterized after irradiation with Ni ions at 580 °C to peaked damage of ~300 dpa and 13,000 appm preimplanted helium. The swelling depth distributions for the 316 austenitic steel were determined to be ~0.0148%/dpa in helium preirradiation region, ~0.1761%/dpa in transitional region, and ~0.0363%/dpa in peak region, respectively. Inhibitory effect of swelling was observed in the peaked dpa region due to the defect imbalance. In contrast, high-level heavy ion damage was insufficient to induce the formation of voids in the helium-free region for the advanced ferritic/martensitic steel, but high density of helium bubbles with the swelling rate of ~0.0086%/dpa occurred in the helium preirradiation region. For the reduced-activation ferritic/martensitic steel, in comparison with the transitional and peak regions, preinjection helium promoted helium bubble nucleation and assisted swelling in the advanced ferritic/martensitic steel. Meanwhile, for the 316 steel, preinjection helium not only promoted nucleation of cavities but also retarded the swelling by depressing the growth of size and enhancement nucleation of small cavities.

Isolating the detrapping of deuterium in heavy ion damaged tungsten via partial thermal desorption

Partial Thermal Desorption Spectrometry (pTDS) progressively depopulated trapped deuterium (D) from heavy-ion damaged tungsten (W) to determine spatial location and detrapping energies. W samples were prepared identically: 5 MeV Cu2+ damaging ions (0.12 peak dpa dose) before D2 plasma loading (1024D/m2 fluence) held at 373 K. Each sample reached one of six pTDS peak-and-hold temperatures. Nuclear Reaction Analysis (NRA) measured the D spatial profile remaining after pTDS, before final TDS.NRA and TDS measured total D retention were in good agreement. NRA displayed three zones of D-populated defects: (I) near-surface (below 0.1 μm), (II) heavy-ion damage (peaked ∼1 μm), and (III) uniform intrinsic (bulk). D concentration in zone I reduced by ∼97% in samples with pTDS at 597 K and higher, indicating near-surface traps have low detrapping energy. The Stopping and Range of Ions in Matter (SRIM) predicts a displacement profile for zone II that coincided with measured D profile for samples with pTDS at 597 K and higher. Samples prepared with pTDS below 597 K display a distinctly different D profile in zone II. The complete cycle of D2 plasma loading, pTDS, NRA, and final TDS was modeled with Tritium Migration Analysis Program (TMAP) using a recently developed Pseudo Trap and Temperature Partition (PTTP) scheme. Differences in TDS profiles isolated traps that release between consecutive pTDS temperatures, demonstrating 6 distinct release peaks. The best fit was found with detrapping energies near 1.0, 1.2, 1.4, 1.6, 1.8, and 1.9 eV. These results show that heating at 762 K for 2.5 h released ∼99% of retained D in heavy-ion damaged W.

Molecular Dynamics Simulation of Fission Fragment Damage in Nuclear Fuel and Surrogate Material

ABSTRACTWe have performed classical molecular dynamics simulations of swift heavy ion damage, typical of fission fragments, in nuclear fuel (UO2) for energy deposition per unit length of 3.9 keV/nm. We did not observe amorphization. The damage mainly consisted of isolated point defects. Only about 1% of the displacements occur on the uranium sublattice. Oxygen Frenkel pairs are an order of magnitude more numerous than uranium Frenkel pairs in the primary damage state. In contrast, previous results show that the ratio of Frenkel pairs on the two sublattices is close to the stoichiometric ratio in ceria. These differences in the primary damage state may lead to differences in radiation response of UO2 and CeO2.

Deuterium retention in tungsten after heavy ion damage and hydrogen isotope exchange in PISCES

The effect of H isotope exchange and radiation damage on the retention of D in W was examined in the PISCES linear plasma device. W samples were treated with D plasma at low sample temperatures (473K), with a fluence of 1026ions/m2 and ion energies of 150eV. Each sample was then exposed to varying doses of H plasma with similar sample temperature and plasma conditions to fluences ranging from 0 to 1026ions/m2, to examine the effectiveness of isotope exchange as a means of tritium removal. The D(3He, p)4He nuclear reaction was used to measure D concentration profiles up to a depth of 7.7μm. Thermal desorption spectroscopy (TDS) was used to determine the D retained throughout the bulk of the sample. Isotope exchange allows for a unique study of atomic migration by separately examining the diffusion of implanted atoms from those bombarding the surface. D atoms are exchanged out of traps as a result of H plasma bombardment and diffuse until either falling into another trap or reaching the surface to recombine and escape. Radiation damage at levels of 0.01, 0.1, and 1 displacements per atom (dpa) was carried out before plasma exposure on some samples with 2MeV Cu ions as a surrogate for damage caused by fusion neutrons. The Cu ion damage was compared to damage induced by 6MeVW ions to see if there is an effect of Cu contamination on retention. We saw little difference in Cu versus W ion damage at low dpa, but at 1dpa, where Cu content reached 65appm, contamination seems to be significant. Retention measurements showed that ion damage has little effectiveness on isotope removal at these sample temperatures; however, there is evidence to suggest that the trapping mechanisms in W change as damage is increased.

Eighth Warren K. Sinclair Keynote Address

Heavy charged particles produce biological damage that is different from that normally produced by sparsely ionizing radiation, such as x- or gamma-rays, which are a large component of the natural radiation background. In fact, as a result of the different spatial distribution of the energy deposited along the core and penumbra of the track, DNA lesions are exquisitely complex and difficult to repair. Relative biological effectiveness (RBE) factors are normally used to scale from x-rays to heavy ion damage, but it should be kept in mind that RBE depends on several factors (dose, dose rate, endpoint, particle energy, and charge, etc.), and sometimes heavy ions produce special damages that just cannot be scaled by x-ray damage alone. These special characteristics of heavy ions can be used to treat tumors efficiently, as it is currently done in Japan and Germany, but they represent a threat for human space exploration.

Swift heavy ion damage to sodium chloride: synergy between excitation and thermal spikes

Systematic data on the effect of irradiation with swift ions (Zn at 735 MeV and Xe at 929 MeV) on NaCl single crystals have been analysed in terms of a synergetic two-spike approach (thermal and excitation spikes). The coupling of the two spikes, simultaneously generated by the irradiation, contributes to the operation of a non-radiative exciton decay model as proposed for purely ionization damage. Using this scheme, we have accounted for the π-emission yield of self-trapped excitons and its temperature dependence under ion-beam irradiation. Moreover, the initial production rates of F-centre growth have also been reasonably simulated for irradiation at low temperatures ( < 100 K), where colour centre annealing and aggregation can be neglected.

The temperature dependence of heavy-ion damage in iron: A microstructural transition at elevated temperatures

A transition is reported in the dislocation microstructure of pure Fe produced by heavy-ion irradiation of thin foils, which took place between irradiation temperatures (T irr) of 300°C and 500°C. At T irr ≤ 400°C, the microstructure was dominated by round or irregular non-edge dislocation loops of interstitial nature and with Burgers vectors b = ½ ⟨111⟩, although interstitial ⟨100⟩ loops were also present; at 500°C only rectilinear pure-edge ⟨100⟩ loops occurred. At intermediate temperatures there was a gradual transition between the two types of microstructure. At temperatures just below 500°C, mobile ½⟨111⟩ loops were seen to be subsumed by sessile ⟨100⟩ loops. A possible explanation of these observations is given.

Dynamic observations of heavy-ion damage in Fe and Fe–Cr alloys

We give an overview and summary of recent in-situ heavy-ion irradiation experiments on Fe and Fe–Cr alloys carried out on the Argonne IVEM Facility at irradiation temperatures up to 500 °C. Several new and unexpected observations were made. At low doses the contrast of new irradiation-induced dislocation loops sometimes developed over time intervals as long as 0.2 s, many orders of magnitude longer than expected for a process of cascade collapse. In addition at temperatures ⩽300 °C, “hopping” of 1/2<1 1 1> loops was induced by the ion or electron beams, especially in UHP Fe. At high doses complex microstructures developed in all materials, involving the formation of large interstitial loops. At 300 °C and RT these loops had Burgers vectors of type b = 1/2<1 1 1> and large shear components. At 500 °C only edge loops with b = <1 0 0> were produced.

TEM characterisation of heavy-ion irradiation damage in FeCr alloys

Heavy-ion damage in a series of FeCr binary alloys and pure Fe has been investigated by TEM. Specimens were irradiated in bulk with 1.5 MeV Fe + ions at an irradiation temperature of 300 °C. A TEM specimen preparation technique has been developed to access the peak of the buried damage region. The damage took the form of dislocation loops with sizes ranging up to a few tens of nanometres. Loops with Burgers vectors of type b = <1 0 0> and b = ½<1 1 1> were both present in all the specimens, but the proportion of <1 0 0> loops was higher in FeCr alloys than in pure Fe. In Fe–8%Cr the loop number density was determined to be (1.6 ± 0.2) × 1021 m-2. Nature determinations showed that <1 0 0> loops in Fe–11Cr and ½<1 1 1> loops in Fe–8Cr were of interstitial type.

Atomic Displacement Effects in Single-Event Gate Rupture

Swift heavy ion (SHI) damage, including single-event gate rupture (SEGR), radiation-induced soft breakdown (RISB), and long-term reliability degradation (LTRD), plays an important role in limiting device lifetime and reliability. However, the atomic-scale physical origins of these phenomena have not been elucidated. In this work, we explain the underlying physical processes responsible for SHI-induced effects in oxides, providing a direct link between atomic motion and macroscopic electrical effects. SRIM 2008 calculations show that SHIs produce low-energy atomic recoils in SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Using parameter-free quantum mechanical calculations, we probe the atomic-scale dynamics of the resulting low-energy atomic displacements. We show that low-energy displacements in SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> produce pockets containing high densities of network defects, and that these defects generate electronic states throughout the SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> band gap. These spatially correlated defect states represent a low-resistivity ldquoconducting piperdquo through SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> layers, and provide an atomistic mechanism for the formation of electrically-active damage that does not rely on thermal spike effects. In the case of SEGR, the conducting pipe allows energy stored on the gate capacitance to be discharged into the oxide, resulting in the permanent damage observed experimentally. The persistence of defects resulting from SHI-induced atomic displacements provides a physical explanation for percolation models of LTRD and RISB.

Heavy-ion irradiations of Fe and Fe–Cr model alloys Part 2: Damage evolution in thin-foils at higher doses

A study of heavy-ion damage in Fe and Fe–Cr alloys started in Part 1 1 was continued with an investigation of damage development in UHP Fe and Fe–8%Cr at higher doses up to 2 × 1019 ions m−2 (∼13 dpa). In thin-foil irradiations with 150 keV Fe+ ions at 300°C and room temperature (RT), more complex microstructures started to develop in thicker regions of the foils at doses greater than about 2 × 1018 ions m−2, apparently involving cooperative interaction, alignment and coalescence of smaller loops. First strings of loops all with the same ½⟨111⟩ Burgers vectors formed. In UHP Fe irradiated at 300°C the damage then developed into colonies of resolvable interstitial loops with ½⟨111⟩ Burgers vectors. By a dose of 2 × 1019 ions m−2, large (several hundred nanometre) finger-shaped loops with large shear components had developed by the growth and subsequent coalescence of smaller loops. Similar but finer-scale damage structures developed in UHP Fe irradiated at RT and in Fe–8%Cr irradiated at both RT and 300°C.

Novel apparatus to measure hyperthermal heavy ion damage to DNA: Strand breaks, base loss, and fragmentation

We have developed a novel apparatus that allows us to irradiate nonvolatile organic films of high mass (1-100 microg range) spread out over a large surface area (42 cm(2)) with low energy (kT-100 eV) heavy ions and to quantitatively analyze the film substance via standard biochemical techniques afterwards. Here we discuss the details of the apparatus and method and show that it allows us to measure substantial damage to double stranded DNA molecules (plasmids) and its fundamental subunits induced by heavy ions with unprecedented low energies, i.e., 2.5 eV/amu; these energies correspond to track end energies of stopping ions or secondary ions created along primary ion tracks. We find that hyperthermal Ar(+) ions interacting with plasmid DNA will lead to the formation of single and double strand breaks, as well as fragmentation of nucleosides, which also involve chemical modifications and site specific rupture along the N1-C1 glycosidic bond, resulting in base release. In cells, such localized clustered damage will enhance the severity of DNA strand lesions, thus making them harder to repair.

Effects of Gamma and Heavy Ion Damage on the Impulse Response and Pulsed Gain of a Low Breakdown Voltage Si Avalanche Photodiode

Effects of displacement and ionization damage on the impulse response of a high-bandwidth low breakdown voltage Si Avalanche Photodiode was investigated using a picosecond laser system. Damage was generated using either Co60 gamma-irradiation or by scanning the device with an MeV ion microbeam. No shift in the impulse response characteristics and gain was observed for gamma doses as high as 100 kGy(Si). However, dark current measurements for irradiations with biases close to typical operating levels, exhibited enhanced ionization damage orders of magnitude higher than for no bias. Displacement damage introduced by the microbeam was used to differentiate between ionization damage in the guard ring isolation oxide and bulk damage. The absence of any marked change in the impulse response is discussed, as are possible mechanisms for the enhanced ionization damage

The Simulation of damage tracks in silicon

We describe an analytical model for deriving heavy ion damage tracks using nonionizing energy loss (NIEL) and range-energy relations. NIEL is directly calculated for heavy ions based upon screened Coulomb potentials in the nonrelativistic limit and the projected range algorithm (PRAL) is used to obtain the range relationship. Examples of damage track calculations are given for incident ions on silicon.

Microprobe analysis of light elements in nanoporous surfaces produced by helium ion implantation

Helium ion implantation into surfaces can be used to form nanoporous cavity structures with unique features, of interest for applications. The ingress of desired dopant atoms into the material could be enhanced by producing cavity layers that extend to the surface. Ti and Co targets were implanted with He using pulsed plasma-immersion ion implantation (PI 3 TM) and monoenergetic accelerator ion implantations. Spatially resolved elemental mapping of C, N and O, using microprobe nuclear reaction analysis was done with a scanned 20 μm diameter deuteron beam. This spatial resolution has enabled several important new results to be obtained. It is demonstrated for the two materials that He implanted surfaces take up more O from the atmosphere than unimplanted surfaces. In Ti, the nanoporous surface exposed by heavy ion damage in a prior heavy ion elastic recoil detection analysis measurement takes up twice as much O and over ten times as much N as the immediately adjacent undisturbed He implanted surface.

Modeling high-energy heavy-ion damage in silicon

We identify a discrepancy between experimental data and model predictions by a widely used radiation transport code, SRIM. We describe a method for determining the implant and damage profiles of energetic heavy ions that better agrees with experimental data than SRIM Monte Carlo predictions. Results of our method are given and compared to experimental data for a range of ion types and energies. Finally, the reason for discrepancy is discussed.

Swift heavy ion and fission damage effects in UO2

Irradiations of uranium dioxide, UO2 with different swift heavy ions were performed using wide ranges of energies and fluences from 72 MeV to 2.7 GeV in the range 5×109–1017 ions/cm2. The ions were Zn, Mo, Cd, Sn, Xe, I, Pb, Au and U. The threshold energy loss for formation of visible tracks in UO2 could be determined to be in the range 22–29 keV/nm. Fission products of fission energy are below this threshold but nevertheless form thermal spikes in UO2. Observable tracks are only found at the surface. By using 127I-beams of 72 MeV energy the consequences of fission product impact, i.e., lattice parameter increase, fission gas bubble formation, resolution of fission gas from bubbles and fission-enhanced diffusion were all observed and measured. The swelling of UO2 was confirmed to be small and the technologically important process of polygonization (grain subdivision, also called rim-effect in operating UO2-fuel) could be simulated. The results obtained are important in understanding the operating behavior of UO2, today’s fuel in nuclear electricity-producing power stations.