Application of laser-induced breakdown spectroscopy in carbon sequestration research and development

The success of carbon capture and storage (CCS) programme relies on the long-term isolation of CO₂ from the atmosphere. Therefore, technologies concomitant to physical storage of CO₂ such as reliable measurement, monitoring, and verification (MMV) techniques are needed to ensure that the integrity of the storage site is maintained. We propose the use of laser-induced breakdown spectroscopy (LIBS) analytical technique to detect carbon dioxide leaks to aid in the successful application of CCS. LIBS has a real-time monitoring capability and can be reliably used for the elemental and isotopic analysis of solid, liquid, and gas samples. The flexibility of probe design and use of fibre optics make it a suitable technique for real time measurements in harsh conditions and at hard-to-reach places. Proposed monitoring with LIBS includes terrestrial soil samples, water samples from monitoring wells or from different formations, air samples from monitoring wells or suspected leakage areas. This work details the laboratory scale experiments to measure carbon contents in rock, soil, aqueous, and air samples. The potential of the technology for measurements in high pressure high-temperature conditions will also be discussed.     

The steady state of a particle in a vibrating box and possible application in short pulse generation of charged particles

In this paper the classical evolution of a particle is studied which bounces back and forth in a 1D vibrating cavity such that the reflection from the wall does not change the speed of the particle. A peculiar behaviour of the particle motion can be seen where the time evolution of the motion shows superposition of linear and oscillatory behaviour. In particular, the parameter range is found in which the particle oscillates between the walls in steady state as if the wall was static and it is showed that for these parameter ranges the particle settles to this steady state for all initial conditions. It is proposed that this phenomenon can be used to bunch charged particles in short pulses where the synchronization proposed in our model should work against the space charge effect in the charged particle bunch.     

Microwave power coupling with electron cyclotron resonance plasma using Langmuir probe

Electron cyclotron resonance (ECR) plasma was produced at 2.45 GHz using 200–750 W microwave power. The plasma was produced from argon gas at a pressure of 2 × 10^???4 mbar. Three water-cooled solenoid coils were used to satisfy the ECR resonant conditions inside the plasma chamber. The basic parameters of plasma, such as electron density, electron temperature, floating potential, and plasma potential, were evaluated using the current–voltage curve using a Langmuir probe. The effect of microwave power coupling to the plasma was studied by varying the microwave power. It was observed that the optimum coupling to the plasma was obtained for ~ 600 W microwave power with an average electron density of ~ 6 × 10¹¹ cm^???3 and average electron temperature of ~ 9 eV.     

STUDY OF HEAVY ION MODIFIED CR-39 (DIETHYLENEGLYCOL BISALLYL CARBONATE)

The commercially available solid state nuclear track detector CR-39 was bombarded with 100 MeV Si⁸⁺ ions. The Fourier transfonned infrared (FTIR) spectroscopic technique was employed for studying the changes in chemical properties whereas differential scanning calorimetry was used for studying the changes in thermal properties. It was observed that there were substantial chemical modifications in the sample, such as the breaking of C-0 single bonds and the formation of phenolic 0-H bonds. lt was further observed that CR-39 is amorphous and rigid and shows no glass transition temperature.     

Measurement of peak fluence of neutron beams using Bi-fission detectors

Fission fragments and other charged particles leave tracks of permanent damage in most of the insulating solids. Damage track detectors are useful for personal dosimeters and for flux/dose determination of high-energy particles from accelerators or cosmic rays. A detector that has its principal response at nucleon energy above 50 MeV is provided by the fission of Bi-209. Neutrons produce the largest percentage of hadron dose in most high-energy radiation fields. In these fields, the neutron spectrum is typically formed by low-energy neutrons (evaporation spectrum) and high-energy neutrons (knock-on spectrum). We used Bi-fission detectors to measure neutron peak fluence and compared the result with the calculated value of neutron peak fluence. For the exposure to 100 MeV we have used the iThemba Facility in South Africa.     

Measurement of the figure of merit of indigenously developed Nd-doped phosphate laser glass rods for use in high power lasers

High energy, high power (HEHP) Nd:glass laser systems are used for inertial confinement fusion and equation of state (EOS) studies of materials at high temperature and pressure. A program has been undertaken for the indigenous development of Nd-doped phosphate laser glass rods and discs for HEHP lasers. In this paper, we report the characterization of the Nd-doped phosphate laser glass rods produced under this program and compare the indigenously developed laser glass to LHG-8 laser glass of M/s Hoya, Japan. We experimentally measured the values of the stimulated emission cross-section (σ) and coefficient of intensity-dependent refractive index (n ₂) and hence the figure of merit F = σ / n₂ of the indigenous phosphate laser glass rods. This value is found comparable to the reported value of identically doped Nd:glass rods.     

Role of near threshold resonances in intermediate energy nuclear physics

The presence of a resonance close to the threshold strongly effects the dynamics of the interacting particles at low energies. Production of ¹²C, the element for life, in ⁴He burning in Sun is a classic example of such a situation. In intermediate energy nuclear physics, this situation arises in the interactions of a η-meson with a nucleon and that of a K ^?-meson with a proton at low energies, where, both these systems have a resonance or a bound state near their thresholds, resulting in a strong attractive interaction. If putting these mesons in nuclear environment produces a strong attraction, it is possible that, in nature there may exist η- and K ^?-nuclear bound states. Such a tantalizing possibility has led to experimental and theoretical programmes to search for them. These efforts have produced positive results. This paper gives a brief critical overview of these studies, emphasizing especially the efforts led by Bhabha Atomic Research Centre (BARC).     

Higher Order Difference Formulae for the Numerical Solution of the Heat Conduction Equation

In this note some new higher order stable difference formulaefor the numerical solution of the heat conduction equation aregiven. Stable methods up to order six are derived.     

NORMAL MODE LOCALIZATION FOR A TWO DEGREES-OF-FREEDOM SYSTEM WITH QUADRATIC AND CUBIC NON-LINEARITIES

The non-similar normal modes of free oscillations of a coupled non-linear oscillator are examined. So far, the study of non-linear vibrations has been based on the assumption that the system is admissible. This requirement is satisfied when the stiffness of the springs are odd functions of their displacement. In this work, a two-degrees-of-freedom tuned system is considered with stiffness elements having linear, quadratic and cubic non-linearities. The potential energy function of this system is not symmetric with respect to the origin (equilibrium point) of the configuration space due to the presence of the quadratic non-linearity. Hence, the system considered is no longer admissible. A study of the balancing diagrams is performed to determine the “degenerate” and “global” similar modes of the system. Manevich-Mikhlin asymptotic methodology is used for solving the singular differential equation describing the non-similar modes and approximate analytical expressions are derived. For this system, with weak coupling, localized non-similar modes are detected in a small neighborhood of degenerate similar modes of the tuned system. Numerical integration is used to verify theoretically predicted non-similar normal modes. It is found that these modes pass periodically through a non-zero point in the configuration space.     

多通道超声相控阵驱动控制系统设计

低强度经颅聚焦超声是一种利用脉冲聚焦超声调控脑神经元的治疗技术。为抑制人颅骨的非均质性和个体结构差异影响,须对多阵元相控阵聚焦换能器的各阵元进行参数调控实现经颅精准定位聚焦,各阵元参数调控需通过相位控制和驱动电路系统来实现。该文设计并搭建了一种基于直接数字式频率合成技术的多通道相位、幅值独立可调的相控驱动系统。实测结果表明,可实现正弦波和方波高精度相控输出,输出信号电压峰峰值在0~37.5 V可调,相位分辨率为0.1°,延时误差小于1 ns,可满足多阵元相控阵聚焦换能器驱动及其所需相位分辨率的需要。