• Aditya Team

      Articles written in Pramana – Journal of Physics

    • Mirnov coil data analysis for tokamak ADITYA

      D Raju R Jha P K Kaw S K Mattoo Y C Saxena Aditya Team

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      The spatial and temporal structures of magnetic signal in the tokamak ADITYA is analysed using recently developed singular value decomposition (SVD) technique. The analysis technique is first tested with simulated data and then applied to the ADITYA Mirnov coil data to determine the structure of current peturbation as the discharge progresses. It is observed that during the current rise phase, current perturbation undergoes transition from m=5 poloidal structure to m=4 and then to m=3. At the time of current termination, m=2 perturbation is observed. It is observed that the mode frequency remains nearly constant (≈10 kHz) when poloidal mode structure changes from m=4 to m=2. This may be either an indication of mode coupling or a consequences of changes in the plasma electron temperature and density scale length.

    • Electron temperature (Te) measurements by Thomson scattering system

      R Rajesh B Ramesh Kumar S K Varshney Manoj Kumar Chhaya Chavda Aruna Thakkar N C Patel Ajai Kumar Aditya Team

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      Thomson scattering technique based on high power laser has already proved its superoirity in measuring the electron temperature (Te and density (ne) in fusion plasma devices like tokamaks. The method is a direct and unambiguous one, widely used for the localised and simultaneous measurements of the above parameters. In Thomson scattering experiment, the light scattered by the plasma electrons is used for the measurements. The plasma electron temperature is measured from the Doppler shifted scattered spectrum and density from the total scattered intensity. A single point Thomson scattering system involving a Q-switched ruby laser and PMTs as the detector is deployed in ADITYA tokamak to give the plasma electron parameters. The system is capable of providing the parameters Te from 30 eV to 1 keV and ne from 5 × 1012cm−3−5 × 1013cm−3. The system is also able to give the parameter profile from the plasma center (Z=0 cm) to a vertical position of Z=+22 cm to Z=−14 cm, with a spatial resolution of 1 cm on shot to shot basis. This paper discusses the initial measurements of the plasma temperature from ADITYA.

    • Second-harmonic ion cyclotron resonance heating scenarios of Aditya tokamak plasma

      Asim Kumar Chattopadhyay S V Kulkarni R Srinivasan Aditya Team

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      Plasma heating with the fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) is one of the auxiliary heating schemes of Aditya tokamak. Numerical simulation of second-harmonic resonance heating scenarios in low-temperature, low-density Aditya plasma has been carried out for fast magnetosonic wave absorption in ICRF range, using full-wave ion cyclotron heating code TORIC combined with Fokker–Planck quasilinear solver SSFPQL and the results are explained. In such low-temperature, low-density plasma, ion absorption for second-harmonic resonance heating is less but significant amount of direct electron heating is observed.

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