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RSS2002 Vol. 14, No. 01
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2002,
14.
Abstract:
Through the descretization of the Maxwell's equations, the general finite integration theory has been introduced. This theory makes direct use of the electric and magnetic field as unknowns, thus yielding uniquely defined vectors in combination with a suitable grid definition. Finially through its reliability on the SFC (Injector Accelerator of HIRFL) resonate cavity, its reliability on cavity simulation has been discussed al so.
Through the descretization of the Maxwell's equations, the general finite integration theory has been introduced. This theory makes direct use of the electric and magnetic field as unknowns, thus yielding uniquely defined vectors in combination with a suitable grid definition. Finially through its reliability on the SFC (Injector Accelerator of HIRFL) resonate cavity, its reliability on cavity simulation has been discussed al so.
2002,
14.
Abstract:
In this paper, radiation of the space charge in a magnetically insulated transmission line oscillator (MILO) is studied. The results are as follows; the gain formula in the linear regime is derived in which the gain function is symmetric with respect to the mismatch of synchronism; the radiation field formula in the stauration regime is also derived, it shows that the radiation power at saturation is approximately proportional to the harmonic current squared. The theoretic results above are partially examined by numerical simulations.
In this paper, radiation of the space charge in a magnetically insulated transmission line oscillator (MILO) is studied. The results are as follows; the gain formula in the linear regime is derived in which the gain function is symmetric with respect to the mismatch of synchronism; the radiation field formula in the stauration regime is also derived, it shows that the radiation power at saturation is approximately proportional to the harmonic current squared. The theoretic results above are partially examined by numerical simulations.
2002,
14.
Abstract:
In this paper, the space-charge weight functions of 1D and 2D finite-size macro particles for cylindrical system are derived using Green's function. The difference between space-charge field weight functions using the model of finite-size macro particles and those using the model of disk or ring[1] is compared, and the more reasonable computing results are acquired. The output power of beam-wave interaction in helix TWT has been computed and compared with these two kinds of functions. The calculated results show that the output power of the finite-size macro particle model saturated sooner with a higher value than the other model.
In this paper, the space-charge weight functions of 1D and 2D finite-size macro particles for cylindrical system are derived using Green's function. The difference between space-charge field weight functions using the model of finite-size macro particles and those using the model of disk or ring[1] is compared, and the more reasonable computing results are acquired. The output power of beam-wave interaction in helix TWT has been computed and compared with these two kinds of functions. The calculated results show that the output power of the finite-size macro particle model saturated sooner with a higher value than the other model.
2002,
14.
Abstract:
A CRRFA30 L band linac is described in this paper. An electron beam of 2MeV is obtained from a thermionic cathode 1+1/2 RFGun, followed by an a -magnet with the beam current of 300mA. Then the beam is accelerated through three linac tanks. The first linac tank with 5 cells is driven by a KL-28 klystron RF system which can produce up to 3.5MW of peak output power, and accelerate the electron to 8MeV. The second and third linac tanks consist of 11 cells separately, each tank is powered by a KL-54 klystron RF system which can produce up to 10MW of peak output power, and accelerate the electron to 17.6MeV and 28MeV, respectively. The linac outputs electron beams of 290mA with energy spread of ≤1.4%, emittance of 9p mm-mrad, and brightness of 1.5×1010A/(m× rad)2. The accelerating structu
A CRRFA30 L band linac is described in this paper. An electron beam of 2MeV is obtained from a thermionic cathode 1+1/2 RFGun, followed by an a -magnet with the beam current of 300mA. Then the beam is accelerated through three linac tanks. The first linac tank with 5 cells is driven by a KL-28 klystron RF system which can produce up to 3.5MW of peak output power, and accelerate the electron to 8MeV. The second and third linac tanks consist of 11 cells separately, each tank is powered by a KL-54 klystron RF system which can produce up to 10MW of peak output power, and accelerate the electron to 17.6MeV and 28MeV, respectively. The linac outputs electron beams of 290mA with energy spread of ≤1.4%, emittance of 9p mm-mrad, and brightness of 1.5×1010A/(m× rad)2. The accelerating structu
2002,
14.
Abstract:
The electric field distribution of the dielectric surface was computed by a numerical simulation method. The physical mechanism of influencing dielectric surface flashove was analyzed. Four models of the radically dielectric structures were given and the comparison of the electric field strengths at the triple compination point and dielectric surface among the four kinds of structured was made. In addition the effects of an applied guide magnetic field, the emission of electrons and return electron flow on the surface flashover were also considered. Some istructive results for designing the dielectric structures with optimized parameters were obtained.
The electric field distribution of the dielectric surface was computed by a numerical simulation method. The physical mechanism of influencing dielectric surface flashove was analyzed. Four models of the radically dielectric structures were given and the comparison of the electric field strengths at the triple compination point and dielectric surface among the four kinds of structured was made. In addition the effects of an applied guide magnetic field, the emission of electrons and return electron flow on the surface flashover were also considered. Some istructive results for designing the dielectric structures with optimized parameters were obtained.
2002,
14.
Abstract:
The DNA microarray plates in quartz glass substrates are fabricated using a multiple-process, including photolithography, heat treatment, and ion beam etching. Both the scanning electron microscope and surface style measurement are carried out to determine the dimension and the surface morphology of the devices. The reason of the shape distortion of DNA microarray plate in quartz glass substrate is analyzed. The coupling method of the quartz glass plate and the DNA sample is discussed. The techniques utilized can be applied to fabricate the DNA microarray plate of larger.
The DNA microarray plates in quartz glass substrates are fabricated using a multiple-process, including photolithography, heat treatment, and ion beam etching. Both the scanning electron microscope and surface style measurement are carried out to determine the dimension and the surface morphology of the devices. The reason of the shape distortion of DNA microarray plate in quartz glass substrate is analyzed. The coupling method of the quartz glass plate and the DNA sample is discussed. The techniques utilized can be applied to fabricate the DNA microarray plate of larger.
2002,
14.
Abstract:
Scan uniformity of electron beam is an important technological index of industrial irradiation LINAC, especially to semi-conductor device, which has pretty high requirements for scan uniformity. Standard triangle wave current generator cannot get good scan uniformity, because the beam shape at the ends of scan region has significant difference compared to that in the middle. Thus, in order to obtain ideal scan uniformity, corrected scan current wave shape has to be adopted. Error back propagation method in artificial neural network is used in the calibration system in this paper. It conquers the change of electron beam shape caused by scan magnetic field and t he change of electron beam position which result in the nonuniformity of electron beam distribution, and the normalized RMS of sc
Scan uniformity of electron beam is an important technological index of industrial irradiation LINAC, especially to semi-conductor device, which has pretty high requirements for scan uniformity. Standard triangle wave current generator cannot get good scan uniformity, because the beam shape at the ends of scan region has significant difference compared to that in the middle. Thus, in order to obtain ideal scan uniformity, corrected scan current wave shape has to be adopted. Error back propagation method in artificial neural network is used in the calibration system in this paper. It conquers the change of electron beam shape caused by scan magnetic field and t he change of electron beam position which result in the nonuniformity of electron beam distribution, and the normalized RMS of sc
2002,
14.
Abstract:
The setup of the collinear fast ion-beam-laser spectroscopy (CFIBLS) with the Fabry-Prot interferometer is described and the method of analyzing the experimental data is given. The hyperfine structures of the transitions from metastable 4f95d7H08 to excited states 4f96p3/2(15/2, 3/2) for 159TbII was measured by CFIBLS. For the high spectral (sub-Doppler) resolution of CFIBLS, the HFS constants A and B of the involved levels were obtained with small errors.
The setup of the collinear fast ion-beam-laser spectroscopy (CFIBLS) with the Fabry-Prot interferometer is described and the method of analyzing the experimental data is given. The hyperfine structures of the transitions from metastable 4f95d7H08 to excited states 4f96p3/2(15/2, 3/2) for 159TbII was measured by CFIBLS. For the high spectral (sub-Doppler) resolution of CFIBLS, the HFS constants A and B of the involved levels were obtained with small errors.
2002,
14.
Abstract:
Experimental methods are emphatic ally described for Single Event Effects (SEE) experiments on semiconductor devices using accelerators. The particle beam from the accelerator can be scattered and reduced by several orders of magnitude with an Au foil. A novel system is designed for measuring the very low proton beam and a method is founded for measuring the uniformity of the proton flux. The proton Single Event Upset (SEU) cross section is of the order of 10- 14cm2·bit- 1 for Static Random Access Memories (SRAMs). The SEU heavy ion LET thresholds are 4～8MeV·cm2·mg- 1 and the saturation SEU cross sections are of the order of 10- 7cm2·bit- 1. Hard error in single bit and functional error in SRAMs and Single Event Latch-up in 80C86 are observed in proton experiments.
Experimental methods are emphatic ally described for Single Event Effects (SEE) experiments on semiconductor devices using accelerators. The particle beam from the accelerator can be scattered and reduced by several orders of magnitude with an Au foil. A novel system is designed for measuring the very low proton beam and a method is founded for measuring the uniformity of the proton flux. The proton Single Event Upset (SEU) cross section is of the order of 10- 14cm2·bit- 1 for Static Random Access Memories (SRAMs). The SEU heavy ion LET thresholds are 4～8MeV·cm2·mg- 1 and the saturation SEU cross sections are of the order of 10- 7cm2·bit- 1. Hard error in single bit and functional error in SRAMs and Single Event Latch-up in 80C86 are observed in proton experiments.
2002,
14.
Abstract:
In linear induction accelerator t he resistive wall monitors kown as “beam bugs” have been used as essential diagnostics of beam current and location. This paper presents a new method that can improve the accuracy of these beam bugs used for beam position measurements. With a fine beam simulation set, this method locates the beam position with an accuracy of 0.02mm and thus can scale the beam bugs very well. Experiment results prove that the precision of beam position measurements can reach submillimeter degree.
In linear induction accelerator t he resistive wall monitors kown as “beam bugs” have been used as essential diagnostics of beam current and location. This paper presents a new method that can improve the accuracy of these beam bugs used for beam position measurements. With a fine beam simulation set, this method locates the beam position with an accuracy of 0.02mm and thus can scale the beam bugs very well. Experiment results prove that the precision of beam position measurements can reach submillimeter degree.
2002,
14.
Abstract:
With the low-frequency phase aberration caused by optics simulated by random phase plate and quantified with RMS phase gradient, the propagation of the beam is simulated. Something new is found with the rule of low-frequency phase aberration superimposition, so that the formula for the rule is modified, which is the theoretical foundation of phase aberration correction; the relationship between the focal spot size and RMS phase gradients is evident after simulating some focusing process. As a result, a kind of new method of controlling the beam quality is obtained.
With the low-frequency phase aberration caused by optics simulated by random phase plate and quantified with RMS phase gradient, the propagation of the beam is simulated. Something new is found with the rule of low-frequency phase aberration superimposition, so that the formula for the rule is modified, which is the theoretical foundation of phase aberration correction; the relationship between the focal spot size and RMS phase gradients is evident after simulating some focusing process. As a result, a kind of new method of controlling the beam quality is obtained.
2002,
14.
Abstract:
The combined process of low temperature plasma nitriding and TiN film deposition was realized on the plasma-assisted vacuum arc plating set. The process of plasma nitriding can be done below 2 00℃. The low temperature plasma nitriding and TiN film deposition was realized on the same device. By the SEM analysis of the plating structure, low hardness grads from the substrate to the film was obtained, and it was found that the mixed nitride plating formed at the interface between the substrate and the film. The quantitative measurement of substrate-film adherence showed that the adherence was improved notably by using the process. The adherence between film and substrate can reach to 59.6MPa without the bias voltage supplying.
The combined process of low temperature plasma nitriding and TiN film deposition was realized on the plasma-assisted vacuum arc plating set. The process of plasma nitriding can be done below 2 00℃. The low temperature plasma nitriding and TiN film deposition was realized on the same device. By the SEM analysis of the plating structure, low hardness grads from the substrate to the film was obtained, and it was found that the mixed nitride plating formed at the interface between the substrate and the film. The quantitative measurement of substrate-film adherence showed that the adherence was improved notably by using the process. The adherence between film and substrate can reach to 59.6MPa without the bias voltage supplying.
2002,
14.
Abstract:
A fully relativistic multiconfiguration Dirac-Fock method with Breit and QED corrections is used to calculate the 3s2S—3d2D(Z=14～103) transition energy level separations, transition probabilities and oscillator strengths for the Na-like ions. In calculation, this paper considered significant Breit and QED corrections，the results are in good agreement with recent experimental data and other theoretical values. The results show that the electric quadruple transition probabilities are in correspondence with those of E1 transitions and can not be ignored in high temperature laser plasma in ICF and MCF Fusion.
A fully relativistic multiconfiguration Dirac-Fock method with Breit and QED corrections is used to calculate the 3s2S—3d2D(Z=14～103) transition energy level separations, transition probabilities and oscillator strengths for the Na-like ions. In calculation, this paper considered significant Breit and QED corrections，the results are in good agreement with recent experimental data and other theoretical values. The results show that the electric quadruple transition probabilities are in correspondence with those of E1 transitions and can not be ignored in high temperature laser plasma in ICF and MCF Fusion.
2002,
14.
Abstract:
Numeric Study of relativistic BWO with resonant reflector is present. SWS and a resonant reflector of the BWO are designed by use of linear theory of RBWO and code SUPERFISH respectively. Particle simulation of the device has been done in electromagnetic code KARAT ，in which structure of the BWO has been optimized and the dependence of microwave efficiency on applied magnetic field has been investigated. Simulation results show that a resonant reflector is able not only to reflect wave but also to pre-modulate electron beam and the BWO will generate relatively high power wave at low applied magnetic field.
Numeric Study of relativistic BWO with resonant reflector is present. SWS and a resonant reflector of the BWO are designed by use of linear theory of RBWO and code SUPERFISH respectively. Particle simulation of the device has been done in electromagnetic code KARAT ，in which structure of the BWO has been optimized and the dependence of microwave efficiency on applied magnetic field has been investigated. Simulation results show that a resonant reflector is able not only to reflect wave but also to pre-modulate electron beam and the BWO will generate relatively high power wave at low applied magnetic field.
2002,
14.
Abstract:
The driving power for a Multiple-beam klystron amplifier is critical. By using a Programmable Controller (PLC), a self-adapting control system or equalizer have been designed, which can automatically control the driving power of the amplifier. Based on the output peak power of the klystron, the system automatically controls the driving power of the klystron by adjusting an electric adjusted attenuator. By using this system, the influence caused by variations of signal level, travelling wave tube (TWT) gain, circuit attenuation and klystron characteristics can be dramatically reduced, resulting in that the klystron always works in the best driving state and the biggest output power can be abstained.
The driving power for a Multiple-beam klystron amplifier is critical. By using a Programmable Controller (PLC), a self-adapting control system or equalizer have been designed, which can automatically control the driving power of the amplifier. Based on the output peak power of the klystron, the system automatically controls the driving power of the klystron by adjusting an electric adjusted attenuator. By using this system, the influence caused by variations of signal level, travelling wave tube (TWT) gain, circuit attenuation and klystron characteristics can be dramatically reduced, resulting in that the klystron always works in the best driving state and the biggest output power can be abstained.
2002,
14.
Abstract:
According to Maxwell theory, the RF field in the RF cavity can be expressed by the modes of the cavity. And the characterizes of the cavity is determined by these modes, such as the frequencies and the fields. Because of sophisticated shapes of cavities, it's very difficult to calculate the modes of an actual cavity by using the usual methods. In this paper, an actual RF cavity is divided into two parts: the normal part (such as normal cylindrical cavity) and the abnormal parts. According Maxwell theory, there exists a coupling equation between the modes of the normal part and the modes of the cavity. In another words, the modes of the cavity can be expressed by the modes of the normal part. And by solving the coupling equation, frequencies and fields of the cavity's modes can be calculate
According to Maxwell theory, the RF field in the RF cavity can be expressed by the modes of the cavity. And the characterizes of the cavity is determined by these modes, such as the frequencies and the fields. Because of sophisticated shapes of cavities, it's very difficult to calculate the modes of an actual cavity by using the usual methods. In this paper, an actual RF cavity is divided into two parts: the normal part (such as normal cylindrical cavity) and the abnormal parts. According Maxwell theory, there exists a coupling equation between the modes of the normal part and the modes of the cavity. In another words, the modes of the cavity can be expressed by the modes of the normal part. And by solving the coupling equation, frequencies and fields of the cavity's modes can be calculate
2002,
14.
Abstract:
Employing a 2.5-D PIC code, radial transittime oscillator, is simulated numerically and the details are presented. The relations between output power and extractor size, radial cavity span and different modes are obtained. The results indicate that with the extractor size decreasing from 1cm to 2mm, the output power increases, and the relation between radial cavity span and output power coincides with that derived from linear theory. Comparison of different modes shows that TEM1 is the most suitable mod e to generate high power microwave. With a 200kV and 8kA electron beam, A 500MW, 5GHz peak output power microwave with mode TEM1 is generated by simulation. The starting time to oscillate is less than 15ns. The peak efficiency is over 30% .
Employing a 2.5-D PIC code, radial transittime oscillator, is simulated numerically and the details are presented. The relations between output power and extractor size, radial cavity span and different modes are obtained. The results indicate that with the extractor size decreasing from 1cm to 2mm, the output power increases, and the relation between radial cavity span and output power coincides with that derived from linear theory. Comparison of different modes shows that TEM1 is the most suitable mod e to generate high power microwave. With a 200kV and 8kA electron beam, A 500MW, 5GHz peak output power microwave with mode TEM1 is generated by simulation. The starting time to oscillate is less than 15ns. The peak efficiency is over 30% .
2002,
14.
Abstract:
A cold and uniform plasma-filled traveling wave tube with sinusoidally corrugated slow wave structure is driven by a finite thick annular intense relativistic electron beam and the entire system is immersed in a strong longitudinal magnetic field. By means of the linear field theory, the dispersion relation for the traveling wave tube RTWT is derived. The dispersion characteristic of the RTWT is analyzed by numerical computation. The trend of the change for gain, bandwidth and center frequency of the RTWT is discussed in detail in different kinds case which include density of plasma, transmission place of electron beam, voltages as well as current. Some useful results are obtained on the base of the discussion.
A cold and uniform plasma-filled traveling wave tube with sinusoidally corrugated slow wave structure is driven by a finite thick annular intense relativistic electron beam and the entire system is immersed in a strong longitudinal magnetic field. By means of the linear field theory, the dispersion relation for the traveling wave tube RTWT is derived. The dispersion characteristic of the RTWT is analyzed by numerical computation. The trend of the change for gain, bandwidth and center frequency of the RTWT is discussed in detail in different kinds case which include density of plasma, transmission place of electron beam, voltages as well as current. Some useful results are obtained on the base of the discussion.
2002,
14.
Abstract:
According to the numerical study of the mode converters in smooth bent, circular waveguides on highpower millimeter waves TM01—TE11, the geometrical dimensions of the bent waveguides are optimized in this paper. On the basis of mode conversion theory, this paper further optimized a better dimension and obtained the regulation about the radius of the circular waveguides, curvature and frequency of bent circular wave guides and the bandwidth. The mode converter designed in this way owns high conversion efficiencies of 99% with its bandwidth exceeding 29.8%.
According to the numerical study of the mode converters in smooth bent, circular waveguides on highpower millimeter waves TM01—TE11, the geometrical dimensions of the bent waveguides are optimized in this paper. On the basis of mode conversion theory, this paper further optimized a better dimension and obtained the regulation about the radius of the circular waveguides, curvature and frequency of bent circular wave guides and the bandwidth. The mode converter designed in this way owns high conversion efficiencies of 99% with its bandwidth exceeding 29.8%.
2002,
14.
Abstract:
The symplectic algorithm of Hamiltonian system is extended to the complex symplectic space. The numerical solutions of the 1-dimensional model of strong field are calculated by means of both symplectic and Runge-Kutta algorithms. The results show that the symplectical gorithm preserves the Wronskian, which is in good agreement with theoretical analyses, but the Wronskian calculated by using the Runge-Kutta algorithm increases rapidly after a long distance of computation. Therefore the symplectic algorit hm is a better algorithm for the calculations of the 1-dimensional model of strong field.
The symplectic algorithm of Hamiltonian system is extended to the complex symplectic space. The numerical solutions of the 1-dimensional model of strong field are calculated by means of both symplectic and Runge-Kutta algorithms. The results show that the symplectical gorithm preserves the Wronskian, which is in good agreement with theoretical analyses, but the Wronskian calculated by using the Runge-Kutta algorithm increases rapidly after a long distance of computation. Therefore the symplectic algorit hm is a better algorithm for the calculations of the 1-dimensional model of strong field.
2002,
14.
Abstract:
p-t of singlet oxygen generator (SOG) was experimentally proved to be a key parameter for the chemical efficiency of the chemical oxygen-iodine laser (COIL). In our small scale COIL device with square pipe-array jet-type SOG and chlorine flowrate of 94mmol/s, experiments revealed the strong dependences of O2(1D ) absolute yield on the p-t of SOG. Here, the O2(1D ) absolute yield is defined as the convertin g efficiency from chlorine. It was shown that the increasing of each unit of p-t led to nearly 10% absolute decreasing of O2(1D ) absolute yield. In our 5# COIL device with stable cavity, it was found the chemical efficiency increased significantly as the p-t decreased. So, for a given COIL device, it is essential to minimize the p-t of SOG as possible. The dependences of the p-t on some
p-t of singlet oxygen generator (SOG) was experimentally proved to be a key parameter for the chemical efficiency of the chemical oxygen-iodine laser (COIL). In our small scale COIL device with square pipe-array jet-type SOG and chlorine flowrate of 94mmol/s, experiments revealed the strong dependences of O2(1D ) absolute yield on the p-t of SOG. Here, the O2(1D ) absolute yield is defined as the convertin g efficiency from chlorine. It was shown that the increasing of each unit of p-t led to nearly 10% absolute decreasing of O2(1D ) absolute yield. In our 5# COIL device with stable cavity, it was found the chemical efficiency increased significantly as the p-t decreased. So, for a given COIL device, it is essential to minimize the p-t of SOG as possible. The dependences of the p-t on some
2002,
14.
Abstract:
In optics polishing process, the active lap can reshape the profile for fitting the surface of large optical component with different local position and rotating angle in real time. In this paper, the working process of active lap is modeled, and the possibility of active lap for optical polishing is also discussed. The deforming capability of the active lap is simulated by finite element method (FEM) to reform a parabolic mirror with diameter 1.5m, f1/2. The results show that the active 1ap enable reshaping fine quadratic curved face symmetrically or dissymmetrically.
In optics polishing process, the active lap can reshape the profile for fitting the surface of large optical component with different local position and rotating angle in real time. In this paper, the working process of active lap is modeled, and the possibility of active lap for optical polishing is also discussed. The deforming capability of the active lap is simulated by finite element method (FEM) to reform a parabolic mirror with diameter 1.5m, f1/2. The results show that the active 1ap enable reshaping fine quadratic curved face symmetrically or dissymmetrically.
2002,
14.
Abstract:
Under the conditions of known thermophysical properties of mediums and supposed some thermal contact resistances of interface between two layered infinite complex mediums, the inside temperature distribution of medium and the temperature raise curve at the two-concave-di sk target's back surface center is computed numerically when the front surface is irradiated by laser. And the temperature raise curve is also measured experiment ally. The thermal contact resistance of the interface is determined by comparing the experimental data with the computed results. Through numerical computation, it is found that the concave disks accord with the supposition of infinite slab and the effect of thermal expansion on the interface thermal contact resistance is very small.
Under the conditions of known thermophysical properties of mediums and supposed some thermal contact resistances of interface between two layered infinite complex mediums, the inside temperature distribution of medium and the temperature raise curve at the two-concave-di sk target's back surface center is computed numerically when the front surface is irradiated by laser. And the temperature raise curve is also measured experiment ally. The thermal contact resistance of the interface is determined by comparing the experimental data with the computed results. Through numerical computation, it is found that the concave disks accord with the supposition of infinite slab and the effect of thermal expansion on the interface thermal contact resistance is very small.
2002,
14.
Abstract:
The high-resolution absorption spectra of real atmosphere near the 1.315m m wavelength were recorded accurately using an experimental system. The system includes a tunable narrow-line-width pulsed OPO laser, a multipass absorption cell of the White-type with total optical length of 1097m, and a single time-division multiplexing fastresponse detector. The absorption cross-section of atmospheric absorption molecule at the 7 603.14cm- 1 wavelength of iodine laser was measured (1.05±0.09)×10- 24cm2 at the standard atmospheric condition. And the parameters of atmospheric absorption lines including the central position, strength and air-broadening halfwidth were also obtained around the wavelength of 1.315m m from the measured spectra of real atmosphere. It is found that the minimum absorp
The high-resolution absorption spectra of real atmosphere near the 1.315m m wavelength were recorded accurately using an experimental system. The system includes a tunable narrow-line-width pulsed OPO laser, a multipass absorption cell of the White-type with total optical length of 1097m, and a single time-division multiplexing fastresponse detector. The absorption cross-section of atmospheric absorption molecule at the 7 603.14cm- 1 wavelength of iodine laser was measured (1.05±0.09)×10- 24cm2 at the standard atmospheric condition. And the parameters of atmospheric absorption lines including the central position, strength and air-broadening halfwidth were also obtained around the wavelength of 1.315m m from the measured spectra of real atmosphere. It is found that the minimum absorp
2002,
14.
Abstract:
The influence of laser spatial coherence on illumination uniformity is studied in this paper. Partially coherent Gaussian beam is expanded into an independent superposition of Hermite-Gaussian modes. The coherence length of partially coherent Gaussian beam can be derived from its M2 factor. The larger the M2 factor, the shorter the coherence length. Propagation of laser beam through atmospheric turbulence is treated with phase screen approximation. The uniformity of illumination beam is expressed by s 2I . s 2I of partially coherent beams with different M2 factor is computed after propagation through atmospheric turbulence. Th e results of numerical simulation show that illumination uniformity is improved with the decrease of illumination laser spatial coherence.
The influence of laser spatial coherence on illumination uniformity is studied in this paper. Partially coherent Gaussian beam is expanded into an independent superposition of Hermite-Gaussian modes. The coherence length of partially coherent Gaussian beam can be derived from its M2 factor. The larger the M2 factor, the shorter the coherence length. Propagation of laser beam through atmospheric turbulence is treated with phase screen approximation. The uniformity of illumination beam is expressed by s 2I . s 2I of partially coherent beams with different M2 factor is computed after propagation through atmospheric turbulence. Th e results of numerical simulation show that illumination uniformity is improved with the decrease of illumination laser spatial coherence.
2002,
14.
Abstract:
The principle of realtime modal reconstruction algorithms used for adaptive optics (AO) systems was introduced. A novel sensor-eigen modal reconstruction algorithm was proposednd analyzed. The sensor-eigen functions were deduced by orthogonalizing the correlation matrix between Hartmann-Shack wave-front sensor and deformable mirror. Compared to the normal direct-gradient reconstruction algorithm, the effect of measurement noise to AO system decreases more easily, the real-time system is more stable and the performances of the whole AO system improves through the modal algorithms. This novel algorithm was applied to a 61-element AO system and the theoretical results were verified by the experimental ones.
The principle of realtime modal reconstruction algorithms used for adaptive optics (AO) systems was introduced. A novel sensor-eigen modal reconstruction algorithm was proposednd analyzed. The sensor-eigen functions were deduced by orthogonalizing the correlation matrix between Hartmann-Shack wave-front sensor and deformable mirror. Compared to the normal direct-gradient reconstruction algorithm, the effect of measurement noise to AO system decreases more easily, the real-time system is more stable and the performances of the whole AO system improves through the modal algorithms. This novel algorithm was applied to a 61-element AO system and the theoretical results were verified by the experimental ones.
2002,
14.
Abstract:
The optimal pump and resonator configurations can be determined before the laser is built. A ray-tracing algorithm is used to determine the pump-absorption, and the mode-coupling efficiencies to specific transverse modes are calculated. The diode laser side-pumped CW Nd:YAG slab is studied as CW 40W pumped socurse. Over 11.8W single transverse mode power output is achieved. The optical-optical efficiency is about 30%. The instability of the output laser is less than 1.2%.
The optimal pump and resonator configurations can be determined before the laser is built. A ray-tracing algorithm is used to determine the pump-absorption, and the mode-coupling efficiencies to specific transverse modes are calculated. The diode laser side-pumped CW Nd:YAG slab is studied as CW 40W pumped socurse. Over 11.8W single transverse mode power output is achieved. The optical-optical efficiency is about 30%. The instability of the output laser is less than 1.2%.
2002,
14.
Abstract:
Based on the Principle of Maximum Shearing-Stress, a theoretical model is developed for the reverse-plugging of a thin plate under irradiation of long pulsed laser. The formula of the laser density threshold for the reverse-plugging is deduced. As an example, the reverse-plugging of a Cu thin plate irradiated by ms-degree long pulsed laser is calculated both analytically and numerically, and the laser density threshold and the temperature data are obtained. The analytical, numerical and experimental results are in good agreement with one another.
Based on the Principle of Maximum Shearing-Stress, a theoretical model is developed for the reverse-plugging of a thin plate under irradiation of long pulsed laser. The formula of the laser density threshold for the reverse-plugging is deduced. As an example, the reverse-plugging of a Cu thin plate irradiated by ms-degree long pulsed laser is calculated both analytically and numerically, and the laser density threshold and the temperature data are obtained. The analytical, numerical and experimental results are in good agreement with one another.
2002,
14.
Abstract:
Transient radiation response for microcircuit PN junctions with enhanced photocurrent models are calculated using two-dimensional numerical simulation. On the basis of Wirth-Rogers photocurrent models, the enhanced models include two additional effects as high injection effects on excess minority carrier lifetime and electric fields in the substrate (quasi-neutral regions). These effects are most pronounced in high resistivity material. An excellent evaluation approach is provided for accurate prediction of transient response of modern microcircuit pn junctions to ionizing radiation.
Transient radiation response for microcircuit PN junctions with enhanced photocurrent models are calculated using two-dimensional numerical simulation. On the basis of Wirth-Rogers photocurrent models, the enhanced models include two additional effects as high injection effects on excess minority carrier lifetime and electric fields in the substrate (quasi-neutral regions). These effects are most pronounced in high resistivity material. An excellent evaluation approach is provided for accurate prediction of transient response of modern microcircuit pn junctions to ionizing radiation.
2002,
14.
Abstract:
According to the calculating result on Ne-like Ar X-ray laser pumped by capillary discharge, with code XDCH(1D radiation magneto-hydrodynamics coupled to time-dependent rate equations), this paper presents the whole process of producing gain of 46.9nm laser line. It is shown that higher gain came from higher population of Ne-like ion and faster change of electron temperature and density, different from the lower gain in situation of static state. With the analysis on the viewpoint of atomic kinetics, some helpful advice to experiments are put foward.
According to the calculating result on Ne-like Ar X-ray laser pumped by capillary discharge, with code XDCH(1D radiation magneto-hydrodynamics coupled to time-dependent rate equations), this paper presents the whole process of producing gain of 46.9nm laser line. It is shown that higher gain came from higher population of Ne-like ion and faster change of electron temperature and density, different from the lower gain in situation of static state. With the analysis on the viewpoint of atomic kinetics, some helpful advice to experiments are put foward.
2002,
14.
Abstract:
This paper describes a new tracking algorithm for extended target moving in complex conditions. The moment invariants are chosen as the tracking feature since the size, shape and orientation of the extended target would change distinctly during the moving period. The moment invariants are calculated based on edge region of the local target, through which the computation quantity is reduced drastically. Utilizing these moment invariants, a new roughprecise stages correlation tracking algorithm is proposed, in which the multistage and subsample are adopted to reduce the matching time. In addition, the new creditability evaluation is given by the correlativity of the sequence images, according to that, the method of template correction is established. Experimental results indicate the valid
This paper describes a new tracking algorithm for extended target moving in complex conditions. The moment invariants are chosen as the tracking feature since the size, shape and orientation of the extended target would change distinctly during the moving period. The moment invariants are calculated based on edge region of the local target, through which the computation quantity is reduced drastically. Utilizing these moment invariants, a new roughprecise stages correlation tracking algorithm is proposed, in which the multistage and subsample are adopted to reduce the matching time. In addition, the new creditability evaluation is given by the correlativity of the sequence images, according to that, the method of template correction is established. Experimental results indicate the valid
2002,
14.
Abstract:
The transmission and reflectance of optical thin film were tested using the scan facility at 1.06m m. Scan lines were drawn from the experimental data. The scan lines of two kinds of thin film were analyzed. By using the method, the first kind of damage which is obvious by microscope could be detected accurately, some of the second kind of damage which is not obvious by microscope could also be found. The comparison between scan results and microscope observation shows that the scan method is of higher sensitivity. The reason why the scan method is more sensitive than microscope was discussed. As it is easy to establish the facility, it can be used for online test.
The transmission and reflectance of optical thin film were tested using the scan facility at 1.06m m. Scan lines were drawn from the experimental data. The scan lines of two kinds of thin film were analyzed. By using the method, the first kind of damage which is obvious by microscope could be detected accurately, some of the second kind of damage which is not obvious by microscope could also be found. The comparison between scan results and microscope observation shows that the scan method is of higher sensitivity. The reason why the scan method is more sensitive than microscope was discussed. As it is easy to establish the facility, it can be used for online test.
2002,
14.
Abstract:
Five gas components (CO2, N2, He, Xe and H2) in a CO2 laser are optimized by applying a genetic algorithm and taking the laser power as an objective function. With a resonator of 1.2ml ength and constant discharge voltage of 15kV, the laser power increases by 1.27 times after the optimization with the optimized gas pressures of 1. 15×133.3Pa for CO2, 7.32×133.3Pa for N2, 12.95×133.3Pa for He, 0.36×13 3.3Pa for Xe and 0.01×133.3Pa for H2 respeotively.
Five gas components (CO2, N2, He, Xe and H2) in a CO2 laser are optimized by applying a genetic algorithm and taking the laser power as an objective function. With a resonator of 1.2ml ength and constant discharge voltage of 15kV, the laser power increases by 1.27 times after the optimization with the optimized gas pressures of 1. 15×133.3Pa for CO2, 7.32×133.3Pa for N2, 12.95×133.3Pa for He, 0.36×13 3.3Pa for Xe and 0.01×133.3Pa for H2 respeotively.
2002,
14.
Abstract:
In this paper, the simulated annealing algorithm, the genetic and the gradient descent algorithm are retrospectively and successfully amalgamated to optimal design of pure phase element for uniform beams. The process of this method is divided into three steps, first the energy enhancement of the main lobe, then the process to make the top of the main lobe to be smooth and the fringe to be steep, at last the of the full optimization beam. After these three steps of optimization, the beam is good enough to be applied to ICF.
In this paper, the simulated annealing algorithm, the genetic and the gradient descent algorithm are retrospectively and successfully amalgamated to optimal design of pure phase element for uniform beams. The process of this method is divided into three steps, first the energy enhancement of the main lobe, then the process to make the top of the main lobe to be smooth and the fringe to be steep, at last the of the full optimization beam. After these three steps of optimization, the beam is good enough to be applied to ICF.
2002,
14.
Abstract:
Using numerical calculation the distribution of pump wave, Stokes wave and sound wave in optical fiber during the whole SBS process can be achieved, which is useful to analyze the transient SBS processing and the influence of SBS reflectivity and threshold from the fiber length, pump pulse width. Hereby a new type of fiber phase conjugator with adjust able core radius is shown in this paper.
Using numerical calculation the distribution of pump wave, Stokes wave and sound wave in optical fiber during the whole SBS process can be achieved, which is useful to analyze the transient SBS processing and the influence of SBS reflectivity and threshold from the fiber length, pump pulse width. Hereby a new type of fiber phase conjugator with adjust able core radius is shown in this paper.
