Heavy ion beam probe design study for TCABR

The Heavy Ion Beam Probe (HIBP) diagnostic is known as a unique tool for the direct plasma electric potential measurements. It gives also information on plasma density, temperature and current profile. The method is based on the injection of single charged ion beam into the plasma and the registration of the double charged particles born due to collisions with the plasma electrons. The area of the ionization in plasma is the sample volume of the plasma potential measurements. The position and the size of the sample volume are determined by the calculation of the trajectories of the probing particles. Three schemes have been analysed: Cs⁺, Tl⁺ ion and neutral injection for TCABR parameters: B0 = 1.5 T, Ipl = 135 kA. The calculations show that ion probing allows getting radial profiles of TCABR plasma parameters with the injection angle fast scan system. In all cases of ion beam injection we must use a curved beam line for ion beam transportation from last steering plates towards upper port. The primary ion beam injector must be situated out of high magnetic field area and its length is about 1.5m. The energy range (less than 100 keV for Cs⁺, or Tl⁺) allows using compact and cheap ion gun equipmenСистема зондування плазми пучком важких іонів відома як унікальний інструмент для прямих вимірювань потенціалу плазми. Вона також дозволяє одержувати інформацію про густину плазми, температуру і профіль току. Метод заснований на інжекції пучка однозарядних іонів у плазму та реєстрації двозарядних часток, утворених у результаті зіткнень з електронами плазми. Область іонізації у плазмі визначає елементарний об’єм, у якому здійснюється вимірювання потенціалу плазми. Положення і розмір елементарного об’єму визначається за допомогою розрахунків траєкторій зондуючих часток. Проаналізовано три варіанти: інжекція іонів Cs⁺, Tl⁺ та нейтральних атомів для параметрів TCABR: B0 = 1.5 T, Ipl = 135 кA. Розрахунки показують можливість одержання профілів параметрів плазми TCABR за допомогою системи швидкого сканування по кутам інжекції іонного пучка. У всіх випадках інжекції іонного пучка необхідно застосування вигнутого іонопроводу для транспортування іонного пучка від вихідних відхиляючих пластин до порту токамака. Інжектор первинного іонного пучка повинен бути розташований поза областю сильного магнітного поля , а його довжина буде біля 1,5 м. Енергія іонного пучка (біля 100 кеВ для Cs⁺ або Tl⁺) дозволяє застосувати компактний и дешевий іонний інжектор.Система зондирования плазмы пучком тяжелых ионов известна как уникальный инструмент для прямых измерений потенциала плазмы. Она так же позволяет получать информацию о плотности плазмы, температуре и профиле тока. Метод основан на инжекции пучка однозарядных ионов в плазму и регистрации двухзарядных частиц, образующихся в результате столкновений с электронами плазмы. Область ионизации в плазме определяет элементарный объем, в котором происходит измерение потенциала плазмы. Положение и размер элементарного объема определяются с помощью расчета траекторий зондирующих частиц. Проанализировано три варианта: инжекция ионов Cs⁺, Tl⁺ и нейтральных атомов для параметров TCABR: B0 = 1.5 T, Ipl = 135 kA. Расчеты показывают возможность получения профилей параметров плазмы TCABR с помощью системы быстрого сканирования по углу инжекции ионного пучка. Во всех случаях инжекции ионного пучка необходимо использование изогнутого ионопровода для транспортировки ионного пучка от выходных отклоняющих пластин до порта токамака. Инжектор первичного ионного пучка должен быть расположен вне области сильного магнитного поля , а его длина составит около 1,5 м. Энергия ионного пучка (около 100 кэВ для Cs⁺ или Tl⁺) позволяет использовать компактный и дешевый ионный инжектор

Reconstruction Activities And First Results From The Thomson Scattering Diagnostic On The Tcabr Tokamak

An incoherent and infrared Thomson scattering diagnostic (ITS) was transferred from ISTTOK (Lisboa) and reconstructed on TCABR (S. Paulo). In the first phase of this international collaboration, the diagnostic uses a Neodymium:Glass laser with up to 10 Joules per laser pulse and a first generation polychromator with three pairs of interference filters and avalanche photodiodes. It measures 90° scattered radiation in a single volume of observation with a single laser pulse to obtain the instant plasma electron temperature. This paper reports the reconstruction activities already carried out and presents the first experimental results. These activities include: new data model performance, laser refurbishing, new laser delivery system, stray-light reduction in the vacuum vessel, new collection lens and relative diagnostic calibration. A long run of experiments with this diagnostic shows consistency and coherence with the other TCABR diagnostics and gives indications to be able to contribute effectively to the Alfven heating program of this tokamak. © 2010 IOP Publishing Ltd.227Alonso, M.P., Wilcock, P.D., Varandas, C.A.F., (1999) Rev. Sci. Inst., 70 (1), p. 783Alonso, M.P., Berni, L., Severo, J.H., Borges, F.O., Elizondo, J.I., MacHida, M., Varandas, C.A.F., Galvo, R.M.O., (2008) Plasma Fusion. Sci., 996, p. 192Alonso, M.P., Figueiredo, A.C.A., Berni, L.A., Varandas, C.A.F., (2008) Plas. Sci. IEEE Trans. Plasma Sci., 36 (4), p. 11094Bellintani, J.V., Elfimov, A.G., Elizondo, J.I., Fagundes, A.N., Fonseca, A.M.M., Galvo, R.M.O., Guidolin, L., MacHida, M., (2006), 875, p. 350Berni, L.A., Alonso, M.P., Oliveira, R.M., (2004) Rev. Sci. Inst., 75 (10), p. 388

Resistive Instabilities In Reversed-field Confinement Configurations Without Shear

A resistive mode with azimuthal mode number m = 1 is shown to exist in reversed-field confinement configurations without shear. The mode has an almost constant radial profile from the magnetic axis to the radius where the magnetic field vanishes; its growth rate scales with the 1/3 power of the plasma resistivity, and the corresponding perturbed displacement parallel to the field lines is much larger than the perpendicular one in the resistive region. This mode may lead to the splitting of the plasma column into many rings, and may also be a triggering mechanism for the rotational m = 1 instability that is observed in θ-pinch discharges. ©1981 American Institute of Physics.24466166

Influence Of Diffusion On The Quasi-linear Growth Of Magnetic Islands

It is shown that the rate at which a magnetic island grows in the non-linear stage of a tearing mode is reduced by the equilibrium resistive flow. © 1983.946-7295297Furth, Killeen, Rosenbluth, Tearing mode in the cylindrical tokamak (1973) Physics of Fluids, 6, p. 1054White, Princeton University Plasma Physics Report PPPL - 1655 (1980) Resistive instabilities and field line reconnection, , PrincetonBiskamp, (1980) Physics of plasmas close to thermonuclear conditions, 1, p. 159. , B. Coppi, C.G. Leotta, D. Pfirsch, R. Pozzoli, E. Sindoni, Commission of the European Communities, BrusselsRutherford, (1973) Phys. Fluids, 16, p. 1903White, Monticello, Rosenbluth, Waddell, (1977) Phys. Fluids, 20, p. 800Robinson, (1975) Proc. of the seventh European Conf. on Controlled fusion and plasma physics, 1, p. 114. , Centre de Recherche in Physique des Plasmas, Lausanne, SwitzerlandDobrott, Prager, Taylor, (1977) Phys. Fluids, 20, p. 1850Killeen, Shestakov, (1978) Phys. Fluids, 21, p. 1746Pollard, Taylor, (1979) Phys. Fluids, 22, p. 126Galvão, Machado, Sakanaka, Influence of equilibrium flows on the resistive internal kink and reconnecting modes (1981) Physics of Fluids, 24, p. 365Furth, Rutherford, Selberg, (1973) Phys. Fluids, 16, p. 1054Carreras, Waddell, Hicks, (1979) Nucl. Fusion, 19, p. 1423Sauthoff, von Goeler, Stodiek, (1978) Nucl. Fusion, 18, p. 144

Influence Of Equilibrium Flows On The Resistive Internal Kink And Reconnecting Modes

The effect of a finite diffusion velocity on the stability of the resistive internal kink and reconnecting modes is investigated. It is shown that the diffusion velocity modifies the growth rate of only the second mode. © 1981 American Institute of Physics.24236536

Electron Temperature And Density Measurements By The Unicity Of Particle Confinement Time On The Tcabr Tokamak

The electron temperature Te and density ne at inner border side of plasma on TCABR tokamak are determined using the unicity of particle confinement time τp. In this method, the signals from hydrogen Balmer series emissions like H alfa, beta and gama are measured with an absolutely intensity calibrated spectrometer during the discharge and the particle confinement time then is evaluated using these three emissions for large range of electron temperature and density, until the unique value of τp is achieved. The results show that during the current plateau, the values of the edge electron density and temperature in high fill density discharge, present much strong variations compared to the low fill pressure because of larger edge turbulence activity. © 2006 American Institute of Physics.87513914

Multipoint Thomson Scattering Diagnostic For The Tcabr Tokamak With Centimeter Spatial Resolution

This paper describes a multiapoint Thomson scattering system that is being developed for the TCABR tokamak based on a signal delay technique, which allows the determination of the electron temperature and plasma density radial profiles, with approximately 1 cm spatial resolution, employing just one spectrometer. © 2008 American Institute of Physics.996192198Bellintani Jr., V., Overview of recent results of TCABR (2006) AIP Conference Proceedings, 875, p. 350Alonso, M.P., Wilcock, P.D., Varandas, C.A.F., (1999) Rev. Sci. Instrum., 70, p. 783Bemi, L.A., Alonso, M.P., Oliveira, R.M., (2004) Rev. Sci. Instrum., 75, p. 3884Desilva, W., The evolution of light scattering as a plasma diagnostic (2000) Contrib. Plasma Phys., 40, pp. 23-35Sheffield, J., (1975) Plasma Scattering of Electromagnetic Radiation", , Academic Press Londo

Spectral Line Profile Analysis Using Higher Diffraction Order In Vacuum Ultraviolet Region

Using a one meter VUV spectrometer and a MCP coupled to a CCD detector on TCABR tokamak, ion temperatures from impurity species have been measured and much better spectral resolution was obtained using higher order diffraction lines. Due to very small Doppler effect in the VUV region compared to large instrumental broadening, ion temperatures obtained from first order diffraction present large errors. The use of second, third and fourth order diffraction emissions increases the line broadening and results in lower error temperature measurements. © 2008 American Institute of Physics.996235240Daltrini, A.M., Machida, M., (2007) Rev. Sci. Instrum., 78, p. 066101Nascimento, I.C., Kuznetsov, Y.K., Severo, J.H.F., Machida, M., Galv, R.M.O., Sanada, E.K., Ferreira, A.A., (2005) Nucl. Fusion, 45, p. 796To be published at same proceedingKubo, H., (1993) Nucl. Fusion, 33, p. 427Isler, R.C., (1997) Fusion Enginnering and Design, 115, pp. 34-35Biel, W., Bertschinger, G., Textor team (2004) Rev. Sci. Instrum., 57, p. 2471Field, A.R., Fink, J., Fussmann, G., Wenzel, U., (1995) Rev. Sci. Instrum., 66, p. 543

Ballooning stability of JET discharges

SIGLEAvailable from British Library Document Supply Centre- DSC:4672.626(JET-P--89/34) / BLDSC - British Library Document Supply CentreGBUnited Kingdo