We report on the expected sensitivity of dedicated scintillator-based detectors at the LHC for elementary particles with charges much smaller than the electron charge. The dataset provided by a ...prototype scintillator-based detector is used to characterize the performance of the detector and provide an accurate background projection. Detector designs, including a novel slab detector configuration, are considered for the data taking period of the LHC to start in 2022 (Run 3) and for the high luminosity LHC. With the Run 3 dataset, the existence of new particles with masses between 10 MeV and 45 GeV could be excluded at 95% confidence level for charges between 0.003 e and 0.3 e, depending on their mass. With the high luminosity LHC dataset, the expected limits would reach between 10 MeV and 80 GeV for charges between 0.0018 e and 0.3 e, depending on their mass.
We report on a search for elementary particles with charges much smaller than the electron charge using a data sample of proton-proton collisions provided by the CERN Large Hadron Collider in 2018, ...corresponding to an integrated luminosity of 37.5 fb−1 at a center-of-mass energy of 13 TeV. A prototype scintillator-based detector is deployed to conduct the first search at a hadron collider sensitive to particles with charges ≤ 0.1 e . The existence of new particles with masses between 20 and 4700 MeV is excluded at 95% confidence level for charges between 0.006 e and 0.3 e , depending on their mass. New sensitivity is achieved for masses larger than 700 MeV.
An extensive program on the development of the joining technologies between armor (beryllium, tungsten and carbon fibre composites) and copper alloys heat sink materials for ITER plasma facing ...components (PFCs) has been carried out by ITER home teams. A brief review of this R&D program is presented in this paper. The critical problems related to these joints are described. Based on the results of this program and new requirements on the reduction the manufacturing cost of ITER PFC, reference technologies for use in ITER have been selected and recommended for further development.
An attempt was made to review the current joining techniques being considered for the ITER plasma facing components (PFC). This review describes the general characteristics of two of the joining ...techniques (brazing and diffusion bonding) being used to joint a beryllium armor to a copper alloy heat sink and describes the issues associated with these joining processes. Much of the information is relevant to the other ITER material candidates. Most important is a list of the relevant activities either completed or in progress addressing the beryllium—copper joining issues.
The potential use of high temperature coolant (e.g. 900°C He) in first wall structures would preclude the applicability of copper alloy heat sink materials and refractory metals would be potential ...replacements. Brazing trials were conducted in order to examine techniques to join tungsten armor to high tungsten (90–95 wt%) or molybdenum TZM heat sink materials. Palladium-, nickel- and zirconium-based filler metals were investigated using brazing temperatures ranging from 1000°C to 1275°C. Palladium–nickel and palladium–cobalt braze alloys were successful in producing generally sound metallurgical joints in tungsten alloy/tungsten couples, although there was an observed tendency for the pure tungsten armor material to exhibit grain boundary cracking after bonding. The zirconium- and nickel-based filler metals produced defect-containing joints, specifically cracking and porosity, respectively. The palladium–nickel braze alloy produced sound joints in the Mo TZM/tungsten couple. Substitution of a lanthanum oxide-containing, fine-grained tungsten material (for the pure tungsten) eliminated the observed tungsten grain boundary cracking.
The following document describes the processing, testing and post-test analysis of two Be-Cu assemblies that have successfully met the heat load requirements for the first wall and dome sections for ...the International Thermonuclear Experimental Reactor (ITER) fusion reactor. Several different joint assemblies were evaluated in support of a manufacturing technology investigation aimed at diffusion bonding or brazing a beryllium armor tile to a copper alloy heat sink for fusion reactor applications. Judicious selection of materials and coatings for these assemblies was essential to eliminate or minimize interactions with the highly reactive beryllium armor material. A thin titanium layer was used as a diffusion barrier to isolate the copper heat sink from the beryllium armor. To reduce residual stresses produced by differences in the expansion coefficients between the beryllium and copper, a compliant layer of aluminum or aluminum-beryllium (AlBeMet-150) was used. Aluminum was chosen because it does not chemically react with, and exhibits limited solubility in, beryllium. Two bonding processes were used to produce the assemblies. The primary process was a diffusion bonding technique. In this case, undesirable metallurgical reactions were minimized by keeping the materials in a solid state throughout the fabrication cycle. The other process employed an aluminum-silicon layer as a brazing filler material. In both cases, a hot isostatic press (HIP) furnace was used in conjunction with vacuum-canned assemblies in order to minimize oxidation and provide sufficient pressure on the assemblies for full metal-to-metal contact and subsequent bonding. The two final assemblies were subjected to a suite of tests including: tensile tests and electron and optical metallography. Finally, high heat flux testing was conducted at the electron beam testing system (EBTS) at Sandia National Laboratories, NM. Here, test mockups were fabricated and subjected to normal heat loads to 10 MW/m
2 (3 Hz) and abnormal heat loads to 250 MJ/m
2 (0.5 s) to determine their performance under simulated fusion reactor conditions for first wall components. Both assemblies survived the normal heat loads with no visual damage. Optical and electron microscopy were used to evaluate the extent of the damage at the interfaces following the VDE simulations.
Five different brazing techniques were evaluated in the process of joining beryllium to copper. Aluminum-based filler metals were used in conjunction with aluminum coatings on both beryllium and ...copper substrates. This innovative approach was born out of the necessity to inhibit the formation of oxides and intermetallics on the aluminum and beryllium surfaces both before and during the joining process. Several bonding techniques, diffusion barriers, and oxide inhibitors were employed to reduce the bonding problem to that of joining aluminum to aluminum. The volume of aluminum in the joint was found to be an important factor in reducing the segregation of secondary alloying elements at the beryllium interface. Plasma sprayed aluminum coatings were too porous to use in the as-sprayed condition and were further processed using a hot isostatic press (HIP) to accomplish full density. The use of plasma sprayed aluminum coatings, Al-12%Si filler metal (Alloy 718), and the HIP process produced excellent bonds between the aluminum coated beryllium and 1100-Al alloy plate which was explosively bonded to a copper alloy. Bond strengths were measured at 100% of the strength of the 1100-Al plate strength (90 MPa). The ductility of the aluminum bond was sufficient to produce extensive necking prior to fracture.
This paper is a review of the current joining technologies for plasma facing components in the US for the International Thermonuclear Experimental Reactor (ITER) project. Many facilities are involved ...in this project. All of those facilities are not represented in the authors list but all contributions will be noted throughout the report and in the acknowledgements. Many unique and innovative joining techniques are being considered in the quest to join two candidate armor plate materials (beryllium and tungsten) to a copper base alloy heat sink (Glidcop, Elbrador). These techniques include brazing and diffusion bonding, compliant layers at the bond interface, and the use of diffusion barrier coatings and diffusion enhancing coatings at the bond interfaces. The development and status of these joining techniques will be detailed in this report.
Beryllium–copper reactivity was studied using test parameters being considered for use in the ITER reactor. In this application, beryllium–copper tiles are produced using a low-temperature ...copper–copper diffusion bonding technique. Beryllium is joined to copper by first plating the beryllium with copper followed by diffusion bonding the electrodeposited (ED) copper to a wrought copper alloy (CuNiBe) at 450°C, 1–3 h using a hot isostatic press (HIP). In this bonded assembly, beryllium is the armor material and the CuNiBe alloy is the heat sink material. Interface temperatures in service are not expected to exceed 350°C. For this study, an ED copper–beryllium interface was subjected to diffusion bonding temperatures and times to study the reaction products. Beryllium–copper assemblies were subjected to 350, 450 and 550°C for times up to 200 h. Both BeCu and Be
2Cu intermetallic phases were detected using scanning electron microscopy and quantitative microprobe analysis. Growth rates were determined experimentally for each phase and activation energies for formation were calculated. The activation energies were 66 mol and 62 kJ mol
−1 for the BeCu and Be
2Cu, respectively. Tensile bars were produced from assemblies consisting of coated beryllium (both sides) sandwiched between two blocks of Hycon-3. Tensile tests were conducted to evaluate the influence of these intermetallics on the bond strength. Failure occurred at the beryllium–copper interface at fracture strengths greater than 300 MPa for the room-temperature tests. At 300°C, the fracture strength was decreased significantly and, in contrast to the room-temperature tests, the fracture initiated in the copper–copper bond. The change in fracture initiation is attributed to a decrease in the residual stresses at the beryllium–copper interface at the higher temperatures and a decrease in the intrinsic fracture strength of the ED copper.
Very High Power IGCT PEBB technology Steimer, P.K.; Odegard, B.; Apeldoorn, O. ...
2005 IEEE 36th Power Electronics Specialists Conference,
2005
Conference Proceeding
In the field of power electronics the power electronics building block (PEBB) is a key functional component. With regard to the applications, it is of outmost importance that the PEBB technology used ...is compact, cost-effective and reliable. The IGCT is at the forefront of technology in high power, medium-voltage applications. For further improvement in size and costs a new ANPC IGCT PEBB has been developed. The main new technologies to achieve higher powers are the new low-inductive gate-unit to maintain hardswitched operation up to more than 6000 A, the increased SOA of the 91 mm asymmetric IGCT (4 inch technology) and the antiparallel diode up to more than 6000 A and the active NPC technology, which allows an optimum and equal loss balancing in all power semiconductors. The maximum inverter output power has been increased by 80% with a parallel increase in the power density and reduced costs per kVA
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