• A K Sinha

      Articles written in Sadhana

    • Optimal design of a beam stop for Indus-2 using finite element heat transfer studies

      A K Sinha K J S Sawhney R V Nandedkar

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      This paper describes the design of an in-vacuum, water-cooled beam stop (X-ray shutter) for the materials science (X-ray diffraction) beamline proposed to be built on the wavelength shifter in the Indus-2 (2.5 GeV) synchrotron radiation source. The radiation source impinges ∼ 1 kW power on the beam stop and the heat transfer capabilities of the beam stop have been evaluated. Temperature distribution in the beam stop has been obtained under various cooling conditions using the finite element analysis calculations with ANSYS software. Design parameters of the beam stop have been optimised. It is also shown that radiation cooling alone is not sufficient for taking away the heat load. Water-cooling of the beam stop is essential.

    • Design, fabrication and testing of elliptical crystal bender for the EXAFS beam-line at INDUS-II synchrotron source

      N C Das S N Jha D Bhattacharyya A K Poswal A K Sinha V K Mishra

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      An extended X-ray absorption fine structure (EXAFS) beam-line for X-ray absorption studies using energy dispersive geometry and position sensitive detector is being developed for the INDUS-II synchrotron source. The optical design of the beam-line has been completed based on the working principle that a single crystal bent in the shape of an ellipse by a crystal bender would act as a dispersing as well as focusing element. The heart of the beam-line is the crystal bender which has been designed on the basis of the principle of four-point bending and has been fabricated indigenously. The crystal bender is capable of producing pre-defined elliptical curvature on a crystal surface by applying different couples at the two-ends of the crystal which has variable width along its length. The focusing property of the crystal bender has been tested using a laser source and has been compared with the theoretically simulated results.

    • Heat transfer studies for a crystal in a synchrotron radiation beamline

      A K Sinha

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      Heat load studies have been performed for the first crystal of a double crystal monochromator to be installed in a beamline of the 2·5 GeV synchrotron radiation source Indus-2. Finite element analysis (FEA) has been used to calculate the temperature distribution and the mechanical distortions on these crystals. Several cases of cooling schemes and heat loads have been studied. Based on these FEA results, the analytical relationships available in the literature have been modified. It is shown that modified analytical results compare well with the empirical results obtained from FEA. The optimisation of the cooling conditions can be achieved by doing FEA calculations for only one case. All other cases can then be calculated by using analytical relations proposed here. The proposed analytical equations are generic in nature and can be applied for any source—crystal combination and therefore would be useful for performance prediction of any new monochromator on a new synchrotron source without taking recourse to time consuming, computation-intensive FEA.

    • Cold test of cylindrical open resonator for 42 GHz, 200 kW gyrotron

      Vivek Yadav Sudeep Sharan Hasina Khatun Nitin Kumar M K Alaria B Jha S C Deorani A K Sinha P K Jain

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      This paper presents experimental results for cold testing of a gyrotron open resonator. Experiments were carried out to measure resonant frequency and their particular quality factor for TE mode at the frequency 42 GHz. The perturbation technique was used to determine the axial, radial and azimuthal electric field profile for identification of TE031 mode at operating frequency 42 GHz. The good agreement between experimental results and theoretical studies was found. The results verify the design and fabrication of the specific gyrotron cavity.

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