Small-thrust liquid-pulsed thrusters can achieve higher efficiency and more accurate control when operating in pulsed mode. However, the pulsed characteristic makes it challenging to measure the thrust. This paper describes a thrust stand for directly measuring the pulsed thrust from small-thrust liquid-pulsed thrusters. The proposed stand is based on a unique piezoelectric dynamometer on which the thruster is mounted through a connecting frame. A thrust experiment is conducted by applying a trapezoidal pulsed force, similar to the thrust generated by small-thrust liquid-pulsed thrusters, to the thrust stand. The experimental results show that the thrust stand can quickly trace the input trapezoidal force signal, although its output waveform exhibits obvious oscillations. Based on the experimental frequency response data, a thrust stand transfer function model is constructed, and this model is used to analyze the dynamic response performance of the thrust stand. The step response and trapezoidal pulse response of the thrust stand are obtained, and the influence of the damping ratio on the dynamic performance of the thrust stand is analyzed. A damping compensation transfer function is established to improve the dynamic measurement performance of the thrust stand. Compensated results are obtained by using the raw output from the thrust stand as the input to the damping compensation transfer function. The damping compensation method does not change the natural frequencies of the thrust stand, does not need any additional filtering process, effectively eliminates the waveform oscillations of the thrust stand output, and ensures good consistency between the input and output signals.

The influence caused by the temperature to the pulsed thrust test stand (PTTS) for the attitude control rocket engine is analyzed. It's evident that the primary cause of the temperature influence to PTTS leaded by the rocket engine is the thermal deformation located in the mechanical joint elements as well as the thermal stress generated from the deformation. And a series tests have been conducted to validate the accuracy of the theoretical analysis. A test bolt gluing a strain-gauge is developed to measure the thermal stress generated between the flange and the upper cover of the thrust dynamometer and compensate PTTS voltages shift in the temperature varying conditions. Tests results demonstrate that it is possible to implement temperature compensation to PTTS by the test bolts.

A piezoelectric thrust-measuring platform with high natural frequency is developed for measuring the pulsed thrust generated by attitude-control rocket engines. It consists of two shear mode piezoelectric quartz crystal sensors and an integral shell. The sensors are inserted into the grooves of the elastic rings with an interference fit. Shell stiffness is calculated by energy method (EM) and finite element method (FEM). The shell is optimized for obtaining a good compromise between the sensitivity and frequency response. The stiffness and natural frequency after optimization are verified by experiments. The results show that the stiffness calculated by FEM is more accurate than that calculated by EM. The sensitivity of the thrust-measuring platform is increased by 13.6% compared with before optimization. The natural frequency of the thrust measurement system is 1245 Hz.

Small thrust liquid pulsed rocket engines operating in pulsed mode have gained a good reputation in attitude control applications for their potential reliability and efficiency. However, the pulsed characteristic creates a difficult measurement problem. In this paper, a novel thrust dynamometer with high natural frequency is developed for accurately measuring the pulsed thrust. It consists of two shear mode piezoelectric quartz crystal sensors and an integral shell. The sensors are inserted into unique double-elastic-half-ring grooves with an interference fit. Stiffness equations of the shell which are used to estimate the amount of interference are derived. The thrust dynamometer is calibrated both statically and dynamically. Static calibration uncertainty is evaluated. A trapezoidal impulse force is used to simulate the pulsed thrust for further characterizing the dynamic measurement performance of the thrust dynamometer. An evaluation algorithm of dynamic error is presented and used to evaluate the results of the dynamic simulation. The results show the thrust dynamometer has high sensitivity and natural frequency, good linearity and repeatability, and excellent dynamic performance. It can accurately trace trapezoidal thrust signal of 50Hz without waveform distortion.

A thrust stand is developed for measuring the pulsed thrust generated by low-thrust liquid pulsed rocket engines. It mainly consists of a thrust dynamometer, a base frame, a connecting frame, and a data acquisition and processing system. The thrust dynamometer assembled with shear mode piezoelectric quartz sensors is developed as the core component of the thrust stand. It adopts integral shell structure. The sensors are inserted into unique double-elastic-half-ring grooves with an interference fit. The thrust is transferred to the sensors by means of static friction forces of fitting surfaces. The sensors could produce an amount of charges which are proportional to the thrust to be measured. The thrust stand is calibrated both statically and dynamically. The in situ static calibration is performed using a standard force sensor. The dynamic calibration is carried out using pendulum-typed steel ball impact technique. Typical thrust pulse is simulated by a trapezoidal impulse force. The results show that the thrust stand has a sensitivity of 25.832 mV/N, a linearity error of 0.24% FSO, and a repeatability error of 0.23% FSO. The first natural frequency of the thrust stand is 1245 Hz. The thrust stand can accurately measure thrust waveform of each firing, which is used for fine control of on-orbit vehicles in the thrust range of 5-20 N with pulse frequency of 50 Hz.

Based on the piezoelectric quartz force-measuring platform,a suit of static calibration apparatus of small-power rocket motor thrust measurement is established.The problem of hydraulic load is solved.The static parameters of the force-measuring platform are acquired by experiments.The uncertainty of the static calibrating system is evaluated.The experimental results indicate that the piezoelectric quartz force-measuring platform has good performance.The parameters of linearity and repeatability are all less than 1%,and the uncertainty of the measuring results of the static calibrating system is far less than 5%,which means the system has high measuring accuracy.Therefore,the static parameters of the force-measuring platform all can satisfy the need of small-power rocket motor thrust measurement.

The 13N+p elastic resonance scattering has been studied at the secondary radioactive beam facility of CIAE in inverse kinematics via a thick-target method. The excitation function for the 13N(p,p) scattering was obtained in the energy interval of Ecm ≈ 0.5–3.2 MeV with a 13N secondary beam of (47.8±1.5) MeV. Careful analysis of the secondary beam components and extensive Monte–Carlo simulations enable the resolution of the experimental proton spectra. The resonance parameters for five low-lying levels in 14O were deduced by R-matrix fitting calculations with MULTI7 and SAMMY-M6-BETA. The present results show general agreement with those from a recent similar work, and thus confirm the observation of a new 0− level at 5.7 MeV in 14O with an improved width of 400(45) keV.

The 8Li(p, d)7Li reaction plays an important role in the inhomogeneous Big Bang nucleosynthesis and in the seed-nuclide production phase for the r-process. For the first time, its angular distribution at backward angles was measured in inverse kinematics at Ec.m. = 4.0 MeV by using an 8Li secondary beam. The result of measurement includes the contributions of 8Li(p, d0)7Li and 8Li(p, d1)7Li*. The 8Li(p, d0)7Li component is estimated to be 40%∼58% in the mixture angular distribution by analysing the measured result.

The elastic resonance scattering of 12C+p has been studied in inverse kinematics via a novel thick target method at GIRAFFE facility of HI-13 tandem accelerator laboratory, Beijing. The recoil protons were measured by a ΔE-E counter telescope based on a large area double-sided silicon strip detector at laboratory angles around θ0 = 15°. The excitation function for 12C(p,p) elastic scattering has been obtained over a wide energy range of Ec.m.=0.31–3.45 MeV, which was explained quite well by the R-matrix calculation with known resonance parameters of the first three levels in 13N nucleus. Thus it is demonstrated that the present setup can be directly applied to the study of elastic resonance scattering with secondary radioactive beams.

This paper described the nuclear astrophysical studies using the unstable ion beam facility GIRAFFE in CIAE, by indirect measurements. We measured the angular distributions for some single proton or neutron transfer reactions, such as Be-7(d,n)B-8, C-11(d,n)N-12, Li-8(d,p)Li-9 and N-13(d,n)O-14 in inverse kinematics, and derived the astrophysical S-factors or reaction rates of Be-7(p,gamma)B-8, (11)(P,gamma)N-12, Li-8(n,gamma)Li-9, N-13(p, gamma)O-14 by asymptotic normalization coefficient, spectroscopic factor, and R-matrix approach at astrophysically relevant energies. Some most recent progress of nuclear astrophyiscal work in CIAE axe also summarized.

Temperature dependence of nuclear decays in metallic environments is a controversial issue. We measured the temperature dependence of the β+-decay half-life of22Na implanted into the metal host of palladium. It is found that the β+ -decay half-life of22Na in the metal Pd cooled to T = 15 K is shorter by 0.46(14)% than that at room temperature. The result is consistent in sign with, but clearly smaller than, the estimated one by the Debye model.

Modification techniques of the tapered roller bearings used the convex rollers can avoid or reduce the border contact stress concentration occurred between rollers and inner, outer ring raceways. Analysis is carried in the stress condition of different tapered rollers convexity with the ANSYS.The results show that the border contact stress concentration occurred between rollers and inner, outer ring raceways of tapered roller bearings with the convexity can be reduced maximumly under certain conditions.

The elastic resonance scattering of C-12+p has been studied in inverse kinematics via a novel thick target method at GIRAFFE facility of HI-13 tandem accelerator laboratory, Beijing. The recoil protons were measured by a Delta E-E counter telescope based on a large area double-sided silicon strip detector at laboratory angles around theta(0)=15 degrees. The excitation function for C-12(p,p) elastic scattering has been obtained over a wide energy range of E-c.m.=0.31-3.45 MeV, which was explained quite well by the R-matrix calculation with known resonance parameters of the first three levels in N-13 nucleus. Thus it is demonstrated that the present setup can be directly applied to the study of elastic resonance scattering with secondary radioactive beams.

<正>放射性核束的出现为核物理及核天体物理前沿领域的实验研究注入了新的活力。为有效利用流强相当较弱的放射性核束,不少新方法、新技术应运而生,弹性共振散射的厚靶实验方法就是一例。该方法使用较厚的固体或气体反应靶,使次级束的能量全部或部分地损失在靶中,在反应靶的下游,通过测量出射的较轻的粒子,可以1次得到较大能量范围的激发函数。