Beam Tube Research Articles

Fabrication of the Fermilab Pre-Series Cold Mass for the HL-LHC Accelerator Upgrade Project

Fermilab is fabricating ten full length cold masses for the high-luminosity Large Hadron Collider Accelerator Upgrade Project (HL-LHC AUP). One practice assembly and one pre-series assembly have been completed. This paper summarizes the construction details. Topics include incoming inspection, bus assembly, component machining, shell forming, beam tube insertion, bus expansion loop installation, instrumentation installation, electrical testing, heat exchanger installation and final assembly welding. In-process surveys, alignment measurements and testing are presented and explained. Problems encountered during construction and their solutions are discussed.

X-ray beam experiment for the Hard X-ray Imager onboard ASO-S

The Hard X-ray Imager (HXI) is one of the scientific payloads onboard the Advanced Space-based Solar Observatory. As a telescope using Fourier space modulation, it contains fine sub-collimators to reach high angular resolution. The X-ray resolution of HXI needs to be verified on the ground before its launch. Therefore, an X-ray beam experiment was performed to evaluate the modulation capabilities of each sub-collimator in HXI.The X-ray beam facility for this experiment consisted of an X-ray machine with a 0.4 mm-diameter spot, a 26-meter beam tube with an adjustable diaphragm at the end to control the parallelism of the beam, and an experimental platform that could translate and horizontally rotate the instrument on it with high precision. A strategy for measuring these sub-collimators was then developed theoretically. Additionally, the stability of the instrument and the environment were monitored throughout the experiment.The results of the successful experiment are presented in this paper. The relevant parameters fitted from the measured modulation functions agree well with theoretical predictions. This proves the resolving ability of the HXI meets the requirements. The research also illustrates some side effects due to different incident energies and strengtheners.

Study on the application of coal spontaneous combustion positive pressure beam tube classification monitoring and early warning.

To improve the accuracy of early warning on coal spontaneous combustion (CSC), this paper, on the basis of the principle of preferential selection of index gases in CSC process, carries out fitting analysis of the variation curve of index gas data with coal temperature by combining logistic fitting model, then establishes a CSC graded warning system based on positive pressure beam tube monitoring, and determines CO, O2, φ(CO)/φ(O2), C2H4, C2H6, φ(C2H4)/φ(C2H6) as the index gases for predicting and forecasting CSC, and accurately divides the CSC process into seven levels of early warning: safe, gray, blue, yellow, orange, red, and black. Applying the CSC positive pressure beam tube monitoring system to Dongtan coal mine and analyzing the error by manual sampling and sampling by positive pressure beam tube system, we find that the error is less than 0.1%. Monitoring of several working faces, we get that the CO and CH4 concentrations of 14,320 working face are higher than the normal level at the beginning of mining, and the 100 × CO/ΔO2 value is higher than the gray warning threshold of 0.1, and the warning level is gray warning. After taking timely preventive measures against coal oxidation and warming, the CO and CH4 concentrations return to the normal level and the warning level drops to the safe level. This paper improves the monitoring, identifying and early warning capabilities of underground CSC in its early stage.

Experimental and numerical study on the prefabricated double L-shaped beam-column joint with triangular stiffener

This study proposes an innovative prefabricated double L-shaped beam-column joint with triangular stiffener (double L-shaped joint) for low-rise residential buildings. The double L-shaped joint consists of the L-shaped connector with triangular stiffener, web side plate connection, H-shaped beam, and concrete-filled lightweight steel tube (CFLST) column or square hollow steel tube (SHS) column. Twelve double L-shaped joints are manufactured and experimented. The design parameters include the column types (CFLST or SHS), triangular stiffener height, perforated end plate (with or without), and the web side plate connection (with or without). In addition, the failure modes, hysteretic performances, ultimate capacity, stiffness degradation, deformation capacity, energy dissipation, and strain responses of joint specimens are analyzed. The experimental results show that the failure modes include steel tube local buckling, weld cracking, and bolts fracture in the area of the L-shaped connector. The ultimate moment of the CFLST column joints rises from 4.53% to 13.05% compared to the SHS column joints, while the initial stiffness increases from 2.16% to 26.46%. The perforated end plate grows at the ultimate moment, but the ductility index reduces. The initial stiffness and deformation capacity of the specimens without a web side plate connection decreases significantly. The finite element model is developed, and the numerical simulation is conducted. The experimental results are consistent with failure modes and bending moment versus rotation angle curves obtioned by numerical simulation.

Development and characterization of a large thermal neutron beam for neutron radiography at Isfahan MNSR

The feasibility study of performing neutron radiography (NR) at the Isfahan Miniature Neutron Source Reactor (MNSR) was carried out in the previous work that was including calculations and experiments in support of the implementation of a prototype NR beam tube. Results were shown the obtained neutron beam from that prototype beam tube had appropriate conditions for NR and it is possible to obtain a large NR beam at this low power research reactor. The main disadvantage of the prototype beam tube was the small size of the beam port with diameter of 5 cm. In this study, a large diameter beam tube is designed and installed at the reactor. This beam tube has a telescopic divergent shape and is installed in the west side of the reactor pool. The neutron beam parameters and image quality of the obtained beam from this beam tube are measured based on ASTM-E545. Results showed that this neutron beam has good quality for NR experiments over a beam diameter of about 25 cm. Also, a simple and practical system, for fill and drain water to the beam tube, is designed and incorporated as a beam shutter in order to maintain the radiation safety.

The design and construction of a collimator holder to equip beam tube D of the Tehran research reactor

The continued safe and efficient operation of a research reactor depends on the behavior of the structural materials making up its main components. Many of these materials are difficult to replace in view of hard-to-reach locations after installation or even storage after years of use due to radiation from high exposure to neutrons inside the research reactor structure. The neutron collimator is a major part of the beam-related devices used in a research reactor. This device is installed in the beam tube via a holder. The collimator holder used as a structural component of beam tube D in the Tehran Research Reactor (TRR) has been made of cast iron. This component has been installed inside the beam tube and subjected to irradiation for 30 years. As a result, it has become severely damaged and must be transferred to radioactive waste storage. A necessary measure to recommission beam tube D in TRR is selecting a replacement with higher quality. Suitable candidates for this purpose would be materials that retain the neutron beam quality in addition to being adequate for long lifetime management. In this case, lower induced activity, shorter half-life of produced radioisotopes, and shorter cooling time are desirable. The present work used ORIGEN2 and MCNPX2.6 computational codes to compare various materials, such as barite concrete (type BA), Portland iron concrete, and stainless steel (316), in terms of the induced activity for various reactor operation periods, radiation level for various cooling periods, and neutron and photon beam parameters at the beam tube nozzles. The results indicated that replacing cast iron with Barite concrete (type BA) retains the quality of the neutron beam. In addition, 11.2, 2.81, and 3.63 times more activity was induced in stainless steel, Portland iron concrete, and cast iron, respectively, compared to type-BA barite concrete after 30 years under identical conditions. Since barite concrete is economical and simpler to manufacture, it was a suitable replacement for cast iron as the material for the collimator holder in beam tube D in TRR. In addition, Barite concrete holder was constructed based on the calculations made in this research. The results showed a good agreement between dosimetry experimental data and calculation results with a 3 % error.

Thermal-Hydraulic Transient Analyses for Primary Coolant System of HFRR Using RELAP5

The High Flux Research Reactor (HFRR) is a 40 MW pool-type nuclear research reactor developed for neutron beam tube research, material and fuel irradiation studies, and advanced research using a cold neutron source. As a part of safety analyses, thermal-hydraulic transient analyses were carried out using the computer coder RELAP5 for the primary coolant system of the HFRR. This technical note presents various analyses that were carried out such as loss of normal electric power supply, loss of heat sink, main coolant pump seizure, inadvertent opening of a natural circulation valve, and loss-of-coolant accident considering breaks in the pump suction line and pump discharge line. It is demonstrated that fuel cooling is ensured and safety parameters are well within acceptable limits.

Specific features of focused electron beam transport through a narrow metal tube at negative potential in the forevacuum pressure range

We describe our investigations on the transport of a focused electron beam through a long and narrow metal tube, held at negative potential with respect to the vacuum chamber walls, in the elevated forevacuum pressure range. We have explored the effect of electron beam parameters and tube potential on beam transport. It is shown that the strength of this effect is connected to the initiation of a non-self-sustained glow discharge within the tube, as well as to the beam magnetic focusing parameters. We also show that increase in the fraction of electrons transported through the tube is conducive to uniformity of the distributions of the non-self-sustained discharge current and the discharge plasma density along the tube length.

Correlated 1–1000 Hz magnetic field fluctuations from lightning over Earth-scale distances and their impact on gravitational wave searches

We report Earth-scale distance magnetic correlations from lightning strokes in the frequency range 1-1000 Hz at several distances ranging from 1100 to 9000 km. Noise sources which are correlated on Earth-scale distances can affect future searches for gravitational-wave signals with ground-based gravitational-wave interferometric detectors. We consider the impact of correlations from magnetic field fluctuations on gravitational-wave searches due to Schumann resonances ($<$50 Hz) as well as higher frequencies ($>$100 Hz). We demonstrate that individual lightning strokes are a likely source for the observed correlations in the magnetic field fluctuations at gravitational-wave observatories and discuss some of their characteristics. Furthermore, we predict their impact on searches for an isotropic gravitational-wave background, as well as for searches looking for short-duration transient gravitational waves, both unmodeled signals (bursts) as well as modeled signals (compact binary coalescence). Whereas the recent third observing run by LIGO and Virgo was free of an impact from correlated magnetic field fluctuations, future runs could be affected. For example, at current magnetic coupling levels, neutron star inspirals in third generation detectors are likely to be contaminated by multiple correlated lightning glitches. We suggest that future detector design should consider reducing lightning coupling by, for example, reducing the lightning-induced beam tube currents that pass through sensitive magnetic coupling regions in current detectors. We also suggest that the diurnal and seasonal variation in lightning activity may be useful in discriminating between detector correlations that are produced by gravitational waves and those produced by lightning.

Numerical and theoretical studies on the tensile strength and stiffness of plate-to-CFST column connections reinforced with internal T-shaped diaphragms

The internal T-shaped diaphragm for steel beam to square concrete-filled steel tubular (CFST) column connections is an improvement over conventional internal diaphragms in terms of construction, cost, and mechanical property. The performance of steel beam to square CFST column connections reinforced with internal T-shaped diaphragms is evaluated by conducting static tensile load in this study. Finite element models (FEM) were established and verified, including 24 plate-to-square CFST column connections with internal T-shaped diaphragms in the weak direction (PTC-WD connections), 20 plate-to-square CFST column connections with internal T-shaped diaphragms in the strong direction (PTC-SD connections), and 16 plate-to-square CFST column connections with conventional internal diaphragms (PTC-CID connections) for comparative study. The effects of tube thickness, diaphragm thickness, anchor plate size, beam flange width, concrete filling, and tube width on the tensile behavior of the connections were studied numerically. Additionally, the stress distribution of the tube, the beam flange, the divided diaphragm, the anchor plate, and the infilled concrete are analyzed. The results showed that the tensile strength and stiffness of PTC-WD connections were improved tremendously due to the anchoring effect, and its strength and stiffness were superior to those of PTC-SD connections and PTC-CID connections under the same conditions. Based on the assumed failure mechanism of each component, the theoretical models and formulas for the tensile strength and stiffness of the connections were provided. It was found that the theoretical strength and stiffness coincide well with those of FEM results and test results.

Effects of support type and geometric shape of steel tube on concrete-encased concrete-filled steel tube beam under low velocity impact

Concrete-encased concrete-filled steel tube (CEFST) beams prepared by placing steel tube in RC beam is a beam type that has widespread use. The current study examines the effects of steel tube geometry and support conditions on the behavior of CEFST beams under low velocity impact loading. First, CEFST beam specimens with different lengths and different tube section geometries (circular and square) were produced in the laboratory. These four test specimens with two different support conditions were exposed to low velocity impact load tests. Finite element models of the test specimens were created using Abaqus\\Explicit software. In the next stage, 4 finite element models were verified by the experimentally obtained damage conditions, maximum displacements, and support reaction forces. In the final stage, as parametric study 12 finite element models were prepared in addition to 4 verified models and analyzed under low velocity impact loading. In addition to experimental values, Von Mises stresses, Equivalent plastic strain, Friction energy, and Damage energy values were also obtained by the numerical study and thus the effects of steel tube geometry and support conditions were comparatively examined. The obtained results showed that CEFST beams with a square tube section exhibited better performance under a sudden load such as impact compared to the beams with a circular tube section. Moreover, both numerical and experimental results pointed out that the beam length beyond support has a positive impact on the performance of beam under impact loading.

Thermal neutrons effect on improvement of electrical properties at CIGS thin film derived by sol-gel dip coating technique

The thermal neutron effect on the copper indium gallium (di)selenide thin film synthesized by the sol-gel dip-coating technique has explained the novel use of this film under extreme conditions (such as neutron irradiation fields). The thin film samples were treated by using the reactor neutrons to obtain the optimum neutron treatment for the determination of the variations in the structural characteristics. The gamma filter system has provided the evaluation of the high thermal neutron flux effect on the thin film samples by using the tangential beam tube of ITU TRIGA Mark–II reactor. The influence of the neutron effect on the electrical and optical features was explained by the rise of selenium amount in the thin film. The neutron-treated thin film samples (at 50 at. % Se) had a significant effect on the lowest electrical resistivity depending on the increase of the film density. The equivalent gamma dose of the neutron-treated thin film was determined as a 0.024 Gy dose level for neutron irradiation. The neutron treatment was significant to evaluate the decrease in the sheet resistivity of the thin film at this dose level. The neutron dose has led to a slight decrease in the optical band gap as the result of the thermal and epithermal neutrons' effects on the thin film.

Research on a Spontaneous Combustion Prevention System in Deep Mine: A Case Study of Dongtan Coal Mine

ABSTRACT Due to the influence of high ground stress, high ground temperature, high water inflow and other problems in deep mines, coal spontaneous combustion (CSC) is seriously harmful. This paper studied the variation law of three kinds of indicator gases in the process of coal heating in deep mines, and established a multi-parameter gas indicator prediction system for CSC. Secondly, in view of the shortcomings of the negative pressure bundle tube. A positive pressure beam tube monitoring system for early warning of CSC was developed, the accuracy of sampling data was verified on site, and the high temperature area in the well was further identified by isotope radon measurement. Combined with the positive pressure beam tube monitoring system, to realize the joint detection of uphole and downhole. Finally, according to the detection results of the fire area, the fire prevention methods for small space fire area, multi-coal seam and multi-source air leakage complex fire area and large-area concealed fire area are determined. The above-mentioned CSC early warning and prevention system was applied in Dongtan (DT) Coal Mine, and a good fire prevention effect was achieved. In this paper, the CSC prevention and extinguishing system established has important significance in the prevention and control of mine fires.

Evaluation of computed tomography dose profiler probe for computed tomography dose index and geometric efficiency measurements

The purpose of this study was to evaluate the performance of solid-state sensor based computed tomography dose profiler (CTDP) probe for measurement of standard computed tomography dose metric CTDI100 and free in air geometric efficiency for various beam widths available in a 128-slice CT scanner and also to estimate the efficiency of CTDI100 metric. The response accuracy of CTDP probe was verified using a standard 100 mm long ionization chamber. The geometric efficiency measurements performed by the CTDP probe were validated using XR-QA2 radiochromic film measurements. The efficiency of CTDI100 metric was assessed by calculating the ratio of CTDI100 measured in the center hole position to CTDI∞ measured in the same position of both head and body phantoms. The weighted CTDI values derived from CTDI100 measured by the CTDP probe showed an average difference of 8% from ionization chamber measured values. The efficiency of CTDI100 metric estimated using CTDP probe and 150 mm long phantoms was in the range of 82% to 86% and 76% to 80% for head and body phantom measurements respectively. The differences in the geometric efficiency values for various beam settings and tube voltages measured by the CTDP probe and films were within 7%. Taken together, the results of this study proved that unlike the 100 mm long ionization chamber, the CTDP probe can be efficiently used to determine CTDI for any length over which dose integration is desired and also measure geometric efficiency of MDCT scanners for various beam widths in helical mode of operation.

Proof-of-Principle Design of a High-Field Overpass/Underpass Nb3Sn Dipole

A block coil geometry is appealing in the body of particle accelerator dipole or quadrupole magnets, but less so in the ends of conventional designs, because conductors near the midplane of the beam tube must be bent in the hard direction to cross over to the other side of the tube. To avoid damage to brittle conductors such as Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn or HTS, the bend must be very gradual, resulting in undesirably long magnet ends. An alternative design - “overpass/underpass” or “cloverleaf” - can ramp the conductor within a short length with bending only in the easy direction. Described here is a proof-of-principle design and analysis of an “overpass/underpass” coil geometry for a block coil dipole of 11 T or more.

Design of optically pumped cesium beam tube with hexapole magnetic system for longer lifetime and better SNR

In order to get a better tradeoff between the long lifetime and high performances of cesium beam atomic clocks, we proposed a design scheme of compact optically pumped cesium beam tube (OPCBT) based on hexapole magnetic focusing (HMF) system for the confinement of cesium. A practical optically pumped cesium beam tube without HMF system has been implemented and tested with high-stability laser by modulation transfer spectroscopy (MTS), and a signal-to-noise ratio (SNR) of 18,000 in 1 Hz bandwidth and Allan deviation of 2×10−12/τ were obtained. Based on this test, the simulation analysis results of the newly designed tube with HMF show that the predicted lifetime can reach over 20 years without degradation of the performances, and the expected frequency stability of the clock can be 6.5×10−13/τ with a lifetime of 10 years.

Neutron Beam Characterization on the Beam Tubes of 30 MW G.A. Siwabessy Reactor Using Monte Carlo

The neutron beam characterization had been conducted on six tubes of RSG-GAS reactor for BNCT application in a simulation using Monte Carlo method with MCNP computer code. The simulation was conducted by modeling the geometry and material of RSG-GAS reactor with a model of radiation source from 235U fission reaction in 40 fuel bundles type U3Si2Al with 235U levels of 19.75%. The distribution of neutron and gamma fluxes was simulated from the reactor core to the edge of beam tube of S1, S2, S3, S4, S5, and S6 with a tube length of 400 cm and a diameter of 30 cm. The highest neutron flux produced by the beam tube of S5 was 4.3×1010 cm−2s−1 with the highest gamma dose was 1362 Sv/j. The lowest neutron flux produced by the beam tube of S6 was 5.9×109 cm−2s−1 with a gamma dose was 51 Sv/j. Based on the characterization result, it was shown that the output neutron beam of each RSG-GAS beam tube had the potential to be used for many application.

Risk identification of coal spontaneous combustion in goaf based on variable weight grey target model

ABSTRACT Accurately determining the risk level of coal spontaneous combustion (CSC) in goaf is very important for coal mine safety production. In this paper, bituminous coal in Shanjiaoshu Coal Mine (SJS) was used as the research object to conduct a simulated spontaneous combustion experiment of coal with programmed heating. The results show that according to the characteristic temperature of CSC combined with the Graham R2 coefficient and the degree of spontaneous combustion and oxidation, the risk level of CSC in SJS Coal Mine is classified into four risk levels: low risk, general risk, greater risk, and major risk. Based on the grey target theory and grey entropy correlation analysis method, the equilibrium function is introduced to determine the variable weight of evaluation indexes and the risk grade judgment method of CSC in goaf. Based on the variable weight grey target model is established. The bull’s-eye distance corresponding to each risk level were 0 ~ 0.0052, 0.0052 ~ 0.1455, 0.1455 ~ 0.9554, and >0.9554, respectively. The verification results of the model based on the data of 6 groups of 12 measuring points of the beam tube monitoring system in SJS are consistent with the actual risk level.

Dynamic distribution and prevention of spontaneous combustion of coal in gob-side entry retaining goaf.

The 11101 working face of Qipanjing Mine was taken as the research object to explore the dynamic change law of the spontaneous combustion of the remaining coal in the gob-side entry retaining goaf area. A sealed oxygen consumption experiment was conducted to determine the (critical) oxygen volume fraction in the suffocation zone and continuous oxygen consumption rate of coal samples. The parameters of the working face were measured on site, and the air volume fraction in the goaf was monitored using a beam tube. Considering upward ventilation and the effect of gravity, a UDF control program for the falling medium in the gob-side entry retaining goaf was written. Based on the experimental results, a control program for the continuous oxygen consumption rate of the remnant coal was compiled, the dynamic distribution of the flow field in the gob-side entry retaining goaf was simulated with different advancing positions and air leakage at the working face, and a prediction model for the spontaneous combustion danger area was established. Finally, fire prevention measures via grouting in the return air lane side and nitrogen injection in the retaining lane side were put forward. The results showed that with the variation in the advancing position of the working face or in the air leakage of the air intake lane, the range of the natural hazardous area of the gob-side entry retaining goaf presents a distribution with a power function SF = xn+b (0 < n < 1). The theoretically proposed fire-fighting measures can effectively reduce the risk of spontaneous combustion of coal.

Short review on cryostats with superconducting magnets

Modern accelerators typically include many components working at cryogenic temperatures, like superconducting (sc) magnets, sc cavities, cooled beam tube, sc undulators. In most of the cases, sc magnets or cavities are used. Sc magnets were intensively developed over the last 50 years, and it is possible to say that for some sc materials, like NbTi or Nb3Sn, the technology reached a maturity. The sc magnets could be installed either in liquid helium reservoirs or be mounted on metallic structures and passively cooled by the thermal conduction. Though there is a large variety of different types of cryostats, some general requirements posted on them by sc magnets, bus-bars or current leads could be seen. In the present paper a short review on cryostats with superconducting magnets is done as well as general design requirements on bus-bars and safety diodes are shortly mentioned. Two typical cryostat types used for scientific needs or industry applications are discussed. Cryostats with high-Tc current leads or magnets are also shortly mentioned.