Papers by Rajdeep Singh Rawat
Physics Letters A, 1997
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Physical Review B, 1993
... 4 488 1993 The American Physical Society PHYSICAL REVIEW B I MARCH 1993-I 47 4858 CRYSTALLIZA... more ... 4 488 1993 The American Physical Society PHYSICAL REVIEW B I MARCH 1993-I 47 4858 CRYSTALLIZATION OF AN ... tallized to the rhombohedral phase and its reasonably good surface quality indicates that one can achieve a crystalline ferroelectric PZT thin film by DPF ...
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Physics Letters A, 1996
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Centre of Plasma Physics, Sonapur, Kamrup-782 402, Assam, India 1Applied Physics Section, Bhabha ... more Centre of Plasma Physics, Sonapur, Kamrup-782 402, Assam, India 1Applied Physics Section, Bhabha Atomic Research Centre, Mumbai-400 085, India 2National Institute of Education, Nanyang Technological University, 637616 Singapore (Received September ...
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Japanese Journal of Applied Physics, 2007
A comparative study on the ion emission characteristics such as flux and energy, and their variat... more A comparative study on the ion emission characteristics such as flux and energy, and their variation in angular positions and operating gas pressures has been carried out in a nitrogen-filling plasma focus device. Three different designs of cylindrical anode (central electrode) having hollow, solid and hemispherical tip have been tested for this study. The ion emission characteristics were investigated by employing three Faraday cups at various angular positions. The ion flux depends on the operating gas pressure irrespective of the anode designs and the maximum ion flux is found to be in the pressure range 0.3 to 0.5 Torr for all the anode designs. The hemispherical anode yields highest ion flux while the hollow anode emits lowest ion flux. The angular variation of ion flux is seen to be anisotropic irrespective of the anode designs with an ion dip at 0° (axis of the device) and maximal at 5° angular positions. The anisotropic character of ion emission is less in the case of the hemispherical anode than the hollow anode. The ion energy, measured by the time of flight method, shows its dependence on the anode designs. The maximum ion energy is found to be around 830 keV at an angular position 5° in the case of the hemispherical anode design. The most probable ions are found to be with energy less than 100 keV irrespective of the anode designs and the angular positions. This study indicates that the plasma focus device could be optimized to a great extent for optimal ions yield by using an appropriate anode design.
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Surface & Coatings Technology, 2001
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Surface & Coatings Technology, 2003
A 3.3 kJ pulsed plasma focus device was used to deposit thin films of titanium nitride (TiN) at r... more A 3.3 kJ pulsed plasma focus device was used to deposit thin films of titanium nitride (TiN) at room temperature onto the stainless steel—AISI 304 substrates. The small plasma focus device, fitted with solid titanium anode instead of the usual hollow copper anode, was operated with nitrogen as the filling gas for deposition of TiN thin films. Films were deposited with different numbers of focus shots, at different distances from the top of the anode, and at different angular positions with respect to the anode axis. Deposited films have been characterized for their structure by X-ray diffractometry (XRD), surface morphology by scanning electron microscopy (SEM), elemental composition and distribution mapping by energy dispersive X-ray (EDX) analysis and hardness using a nanoindenter. XRD patterns show the growth of as-deposited polycrystalline TiN thin film. Diffraction patterns for films deposited along the anode axis show induction of a phase corresponding to iron chromium nickel on the film–substrate interface. SEM pictures confirm uniformly distributed TiN grains with hardly any crack over the film surface. Conglomeration of smaller TiN grains, to form bigger size grains, is seen to occur at the films deposited with higher total ion flux. The EDX spectra show the presence of expected constituent elements. EDX mapping confirms the uniform distribution of TiN on the film surface. The variation in structure, morphology, thickness and hardness of the deposited films with the variation of film deposition parameters is explained, qualitatively, on the basis of ion emission characteristics of the focus device. Polycrystalline, smooth and hard thin films of TiN are successfully deposited at room temperature stainless steel—AISI 304 substrates using the plasma focus device.
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This paper reports the results of characterization and optimization experiments carried out on a ... more This paper reports the results of characterization and optimization experiments carried out on a newly developed NX-3 dense plasma focus device (20 kJ at 20 kV, a quarter time period of ~ 3 μs, and 10 kJ/600 kA at 14 kV) at the Plasma Radiation Source Laboratory, NIE, Nanyang Technological University, Singapore. Initial experiments were conducted with an electrode assembly configuration having anode radius and length of 20 and 160 mm, respectively, for detailed neutron emission characterization of NX-3 device followed by further optimization of neutron yield using various other electrode configurations designed using the Lee Code. At ≥10-kJ operation, the average neutron yield on the order of 109 neutrons/pulse in 4πsr was obtained for the deuterium filling gas pressure range of 6-8 mbar. The neutron yield of ~ 4.6 ×109 neutrons/pulse at 10 kJ/6 mbar is the highest ever reported for a device with the same stored energy. The neutron anisotropy measurements point to the beam-target mechanism as the dominant neutron production mechanism for NX-3 plasma focus device. Further optimization of neutron yield in NX-3 was achieved with the peak average neutron yield being enhanced from ~ (2.38 ±0.31) ×109 neutrons/shot for the initial electrode configuration to about ~ (3.40 ±0.43) ×109 neutrons/shot for the electrode configuration with anode radius and length of 26 and 140 mm, respectively. The analysis of neutron yield results for various electrode assembly configurations demonstrates the speed factor as a key optimization tool for maximization of neutron yield.
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Optics and Lasers in Engineering, 2008
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... Correlation Analysis of Intense and High-Energy Deuteron Beam, Pinch Images, and Neutron Yiel... more ... Correlation Analysis of Intense and High-Energy Deuteron Beam, Pinch Images, and Neutron Yield Mahmud Vahdat Roshan, Paul Lee, Zhenying Pan, Rishi Verma, Rajdeep Singh Rawat, and Stuart Victor Springham ... Rajdeep Singh Rawat received the B.Sc. ...
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Page 1. IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 32, NO. 6, DECEMBER 2004 2227 Soft X-ray Optimi... more Page 1. IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 32, NO. 6, DECEMBER 2004 2227 Soft X-ray Optimization Studies on a Dense Plasma Focus Device Operated in Neon and Argon in Repetitive Mode D. Wong, A. Patran, TL Tan, RS Rawat, and P. Lee ...
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As a first step toward the development of a compact and portable, quasi-continuous pulsed neutron... more As a first step toward the development of a compact and portable, quasi-continuous pulsed neutron source, we have demonstrated a 'fast miniature plasma focus (PF) device' as a compact nuclear fusion apparatus. The system operates with deuterium gas and produces an average neutron yield (Y90°) of (1 ± 0.27) × 104 neutrons/shot at ~70 kA peak discharge current. In the range of 1.5-4 mbar, a distinct and sharp dip in the current derivative signal indicates a strong pinching action with subsequent emission of hard x-rays followed by a neutron pulse. The yield and the time history of the neutrons were measured by both active and passive detection techniques (such as a 3He proportional counter, NE102A plastic scintillator and CR-39 SSNTDs). The overall dimensions of the apparatus, which includes a capacitor bank, sparkgap switch and the focus chamber, are 0.2 m × 0.2 m × 0.5 m and the total mass of the system is ~25 kg. The scope of this paper is to evaluate/demonstrate the potential of such a fast miniature PF device as a compact and portable fusion apparatus producing neutrons while operating at relatively low energy.
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Magnetic spectrometry using polymer nuclear track detectors is used for high-resolution measureme... more Magnetic spectrometry using polymer nuclear track detectors is used for high-resolution measurement of the energy spectrum of deuterons emitted from the pinch-column of the NX2 plasma focus (PF). The spectrum is measured for single PF shots. A 25 μm pinhole images the deuteron source on the spectrometer. Deuteron tracks are measured with an automated scanning system. The recognized and counted tracks are accumulated in a histogram of track displacement in bins representing equal energy stripes on the detector. A very distinct neutrals spot is clearly visible for each spectrum, resulting from uncharged deuterons passing through the spectrometer in straight-line paths and producing a densely tracked zone. The deuteron trajectory in the magnetic field is calculated in order to obtain the deuteron energy as a function of the distance from the neutrals spot on the detector. The deuteron spectrum d^2N/dEdφ is derived from the track displacement histogram. The deuteron spectrum is used to estimate the beam-target contribution for fusion neutron production. The number of Nitrogen-13 nuclides in the activation of graphite through ^12C(d,n)^13N is estimated using the deuteron spectra and the thick target yield.
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Page 1. Effect of insulator sleeve length on soft x-ray emission from a neon-filled plasma focus ... more Page 1. Effect of insulator sleeve length on soft x-ray emission from a neon-filled plasma focus device This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2004 Plasma Sources Sci. Technol. 13 569 ...
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The six-phase Lee model code is used to fit the computed current waveform to the measured current... more The six-phase Lee model code is used to fit the computed current waveform to the measured current waveform of INTI plasma focus (PF; 2.2 kJ at 12 kV), a T2 PF device, operated as a source of neon soft X-ray (SXR) with optimum yield around 2 torr of neon. The characteristic He-like and H-like neon line SXR pulse is measured using a pair of SXR detectors with selected filters that, by subtraction, has a photon energy window of 900 to 1550 eV covering the region of the characteristic neon SXR lines. From the analysis of the fitted current and the measured SXR pulses, the characteristic neon SXR pulses are correlated to the pinch dynamics, and the subsequent slightly harder SXR pulses are correlated to the anomalous resistance phase. The characteristic neon SXR yield is measured; the pulse has a duration of 25 ns. The characteristic neon SXR typically starts 10 ns before the pinch phase and continues through the end of the 10-ns pinch phase, tailing into the anomalous resistance phase. Harder SXR pulses, probably Bremsstrahlung, are correlated to the anomalous resistance phase, with the main pulse occurring nearly 200 ns after the characteristic neon SXR pulse.
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High-energy deuterons from a small (1.7 kJ) plasma focus device were studied by nuclear activatio... more High-energy deuterons from a small (1.7 kJ) plasma focus device were studied by nuclear activation of a boron-carbide target. The ratio of (10)B(d,n)(11)C and (12)C(d,n)(13)N yields indicates a deuteron spectrum decreasing rapidly between 400 keV and 1 MeV. This spectrum could take the form of dN(d)/dE alpha E(-n) with n approximate to 9. (C) 2009 Elsevier B.V. All rights reserved.
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The coded aperture imaging (CAI) technique has been applied to investigate the spatial distributi... more The coded aperture imaging (CAI) technique has been applied to investigate the spatial distribution of DD fusion in a deuterium filled 1.6 kJ plasma focus (PF) device operated in its neutron-optimized regime. The coded mask has been fabricated in Havar alloy with 20 × 20 pixels and 57 square holes (14% open area) using a Singer-set Cyclic Difference pattern. Five CAI cameras were employed simultaneously: one placed on-axis (0°) and four at 45° to the PF axis. CR-39 polymer nuclear track detectors were used to register proton tracks from D(d,p)T reactions. The detectors were covered by 75 μm Kapton film to stop all energetic charged particles (mostly deuterons) other than the 3 MeV fusion protons. A de-convolution algorithm was applied to the measured proton track coordinates to obtain images of the fusion source from the five directions. Typically (2–8) × 104 proton tracks were registered by each detector per shot. Also two beryllium fast-neutron detectors were employed simultaneously to measure the associated neutron yield and anisotropy. The CAI images show the fusion source is a cigar-shaped region around the pinch column with no indication of plasma column instabilities. The proton anisotropy is comparable to the measured neutron anisotropy.
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Japanese Journal of Applied Physics, 2005
This paper reports a study of the proton emission from a 3 kJ, 14 kV plasma focus device operated... more This paper reports a study of the proton emission from a 3 kJ, 14 kV plasma focus device operated with deuterium gas at 400 Pa. A filtered pinhole camera with a 1.8 mm diameter hole is placed axially downstream of the plasma focus, and images of the proton-emitting region are recorded using CR-39/PM-355 nuclear track detectors. The detector plates are scanned using an automated track measurement system and the spatial track density profile is acquired. The resulting density distribution is interpreted with the help of a simple pinhole imaging model that assumes the 2H(d, p)3H reaction protons are emitted from a conical region extending from the tip of the anode to a fixed distance downstream. Comparison of the experimental track density profile with the model calculations supports the view that the beam-target mechanism is the dominant fusion production mechanism in this small plasma focus device.
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Papers by Rajdeep Singh Rawat