L. P. Purohit

Numerical Simulation of Magnetron Injection Gun for 1mw 120 GHz Gyrotron

A 40A triode-type magnetron injection gun for a 1MW, 120GHz gyrotron has been designed. The preliminary design has been obtained by using some trade-ofi equations. Computer simulation has been performed by using the commercially available code EGUN and the in-house developed code MIGANS. The operating voltages of the modulating anode and the accelerating anode are 60kV and 80kV, respectively. The electron beam with a low transverse velocity spread (-fl?max = 3:3%) and velocity ratio, fi = 1:38 at beam current = 40A is obtained. The simulated results of the MIG obtained with the EGUN code have been validated with another trajectory code TRAK. The results on the design output parameters obtained by these two codes were found to be in close agreement. The sensitivity study has been carried out by changing the difierent gun parameters to decide the fabrication tolerance.

Three-Dimensional Simulation of MIG for 42-GHz 200-kW Gyrotron

This paper presents a three-dimensional (3-D) simulation of a triode-type magnetron injection gun (MIG) for a 42-GHz 200-kW gyrotron with a transverse-to-axial velocity ratio of the electron beam at 1.22 and a maximum transverse-velocity spread of 3.2%. The operating mode of the gyrotron is TE_03, and it is operated in the fundamental harmonic. The MIG has been designed by using some tradeoff equations and the 3-D particle-tracing code (computer simulation technology). The simulated results have been validated with the results obtained using the 3-D code OPERA Vector Fields and the two-dimensional trajectory codes EGUN and TRAK.

Design of Magnetically Tunable Magnetron Injection Guns for Gyrotrons at Multiple Frequencies

In this paper, the design of a triode-type magnetically tunable magnetron injection gun (MT-MIG) is presented for 1-MW 110-, 120-, and 127.5-GHz-frequency gyrotrons with the various operating modes. Some basic equations relevant to the problem available in the literature have been used to obtain the preliminary design. Computer simulation has been performed by using the commercially available code EGUN. The triode-type MT-MIG with the accelerating voltage of 80 kV, the beam current of 40 A, the average transverse-to-axial velocity ratio of the electron beam of 1.26-1.35, and the maximum transverse velocity spread of less than 5% has been designed. Tuning of the MT-MIG is performed by varying the magnetic field.

Synthesis of Cu doped ZnS nanostructures on flexible substrate using low cost chemical method

Flexible electronics is one of the emerging area of this era. In this paper we have reported synthesis of Cu doped Zinc sulphide nanostructures on filter paper flexible substrates. Zinc chloride and Thio urea were used as a precursor for Zinc and Sulphur. The structures were characterized by XRD, FE-SEM and UV visible spectrometer. All the peaks identified for cubic structure of ZnS. Appearance of small Cu peaks indicates incorporation of Cu into ZnS lattice. Zns nanostructures assembled as nanobelts and nanofibers as shown in FE-SEM micrographs. Compound Structures provide the reasonable electrical conductivity on filter paper. Absorption in UV region makes them suitable for flexible electronic devices.

Electron Beam Emission and Interaction in 0.3-THz Gyrotron for Second Harmonic, CW Operation

This paper describes the design of a 0.3-THz gyrotron at second harmonic operation. The interaction cavity design and the beam-wave interaction computation are carried out for TE0,6 mode by using the particle-in-cell electromagnetic simulation approach. The simulation results confirm > 6-kW output power with efficiency ~ 17% by using an electron beam with accelerating voltage 20 kV and current 2.0 A. To achieve the required electron beam parameters, a triode magnetron injection gun is designed. The transverse-to-axial velocity ratio (α), 1.27 and the transverse velocity spread <; 4% are realized. Considering the fabrication and operation of the device, the parametric analysis is also performed.

Improved conductivity of carbon-nano-fiber (CNF)/polytetrafluoroethylene (PTFE) composite

A series of CNF/PTFE composite loaded with different weight % of CNFs as 0.01, 0.02, 0.03, 0.05, 1, 2, 3, 4, 5 into PTFE is fabricated. In this work, the 5wt% heat-treated CNFs were used as filler in PTFE. Current-voltage (I-V) study of the samples confirmed the samples as conducting composite. In scanning electron microscope (SEM) study, the conducting CNFs channels were observed from upper surface to inside throughout the polymer matrix. A sintered composite of 5wt% loading of CNFs showed an improved conductivity and SEM image exhibited a good binding of CNFs into PTFE.

P3-14: Effect of beam tunnel geometry on electron beam parameters for 42 GHz Gyrotron

A triode type Magnetron Injection Gun (MIG) for a 200kW, 42GHz Gyrotron has been designed by using commercially available code EGUN. The design optimization of the beam tunnel has been done with the help of 3-D simulation software CST-Microwave Studio. This paper presents the effect of beam tunnel geometry on the electron beam parameters for 42 GHz gyrotron.

Comparative EGUN and TRAK simulation studies on the design of the magnetron injection gun of a 200kW, 42GHz gyrotron

A triode-type magnetron injection gun (MIG) for a 42 GHz, 200 kW gyrotron was designed by two commercial codes: EGUN and TRAK. An in-house code MIGANS was used as the p ost-processor of the EGUN. Some basic equations relevant to the problem available in literature were used while using the EGUN code for the purpose. The results on the design output parameters obtained by these two codes were found to be in close agreement. The gyrotron is a device to generate high powers at high frequencies. In this device, the source of electrons is a magnetron injection gun (MIG) which forms a beam of electrons in which the electrons execute the small cyclotron orbits at a frequency required for the cyclotron resonance interaction with RF waves in the device (1,2). The MIG is placed in an axially symmetrical magnetic field at the magnetic field strength determined by the magnetic compression ratio . The initial electron motion occurs in the crossed electric and magnetic fields so that the electron s follow the helical trajectories around the magnetic field lines. The gun anode accelerates the beam to th e final beam energy. Downstream from the gun, the magnetic field increases smoothly in the magneti c compression region to the required peak value at the interaction region. The magnetic field compress ion reduces the radius of the beam and results in an increase of the velocity component perpendicular to the magnetic field. Since the total energy is constant, the drift velocity is correspondingly reduced. In India, an activity related to the design and development of 42GHz, 200kW gyrotron has been started. The operating mode has been selected as TE03 with the second maximum of the transverse-plane field pattern of the cylindrical interaction cavity as the be am launching position for the fundamental beam-mode operation. For the better performances of the gyrotron and the gyro-devices, an electron beam of good quality is required (1-6). The triode-type MIG has been designed having the beam voltage V0 = 65kV, the beam current I0 = 10A and the transverse-to-axial beam velocity ratio � = 1.26. The

Synthesis, structural and optical characterization of undoped, N-doped ZnO and co-doped ZnO thin films

ZnO, N-doped ZnO and Al-N co-doped ZnO thin films were deposited on ITO coated corning glass by spin coater using sol-gel method. The films were annealed in air at 450°C for one hour. The crystallographic structure and morphology of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The X-ray diffraction results confirm that the thin films are of wurtzite hexagonal with a very small distortion. The optical properties were investigated by transmission spectra of different films using spectrophotometer (Shimadzu UV-VIS-NIR 3600). The results indicate that the N doped ZnO thin films have obviously enhanced transmittance in visible region. Moreover, the thickness of the films has strong influences on the optical constants.

Growth of Green and Blue Luminescent Cu Doped CdS Nanorods and Their Optical Structural Characterization

Highly luminescent Copper doped CdS nanorods were prepared by modified sol-gel method. The sol was prepared by continuous stirring of mixture of ethylene glycol, ethanol and acetic acid with Cadmium chloride (CdCl2) and thiourea as the precursors of Cd and S respectively at 50 °C temperature for 3 h. For Cu doping cuprous chloride was added slowly. Fine green and blue colored particles were obtained. The samples were analyzed by XRD, SEM, optical transmission and photoluminescence studies. Broad peak of (101) is observed in X-ray diffractograms for undoped CdS. Intensity of this peak increases with increase in copper (Cu) doping. In SEM, large number of islands is observed in undoped CdS. On doping with copper these islands grow as more and more particles bind together. Undoped structures are generally spherical with uniform size and start to reassemble in ordered rodlike structure on increase in doping.