Power Balance Estimation in Long Duration Discharges on QUEST

Fully non-inductive plasma start-up was successfully achieved by using a well- controlled microwave source on the spherical tokamak, QUEST. Non-inductive plasmas were maintained for approximately 3-5 min, during which time power balance estimates could be achieved by monitoring wall and cooling-water temperatures. Approximately 70%-90% of the injected power could be accounted for by calorimetric measurements and approximately half of the injected power was found to be deposited on the vessel wall, which is slightly dependent on the magnetic configuration. The power distribution to water-cooled limiters, which are expected to be exposed to local heat loads, depends significantly on the magnetic configuration, however some of the deposited power is due to energetic electrons, which have large poloidal orbits and are likely to be deposited on the plasma facing components.

Magnetic Sensorless Control of Plasma Position and Shape in a Tokamak

Magnetic sensorless sensing and control experiments with the plasma horizontal position have been carried out in the superconducting tokamak HT-7. The sensing is made to focus on the ripple frequency component of the power supply with thyristor and directly from them without time integration. There is no drift problem with the integrator of wagnetic sensors. Two kinds of control experiments have been carried out： to keep the position constant and swing the position in a triangular waveform, And magnetic sensorless sensing of plasma shape is discussed.

Two Dimensional Density FlUCtuation Measurements During the Non-Inductive Current Ramp-up Phase in the Compact Plasma Wall Interaction Experimental Device CPD

Two-dimensional structure of density fluctuations is examined during the current jump phase, indicating a change from the open magnetic fields to the closed ones. During the smooth current ramp-up phase the two-dimensional contour of the LiI intensity shows vertically alignment, consistent with the magnetic surfaces. At the inflection point in Ip ramp-up the LiI intensity contour becomes flat in the observation regime and then suddenly a steep gradient and higher intensity regime are formed in the vertical direction. This higher intensity corresponds to a burst of LiI waveform. According to these changes in the contour, it is found that, within ~1 ms around the burst of LiI, a low frequency coherent wave with a long wavelength rapidly grows. The relations with other signals （magnetic flux and microwave stray power） are discussed with respect to the topological change in the magnetic configuration and mode conversion of the incident electromagnetic waves.

Magnetic Sensorless Sensing of Plasma Position in the Superconducting Tokamak HT-7

Magnetic sensorless sensing experiments of the plasma horizontal positionhave been carried out in the superconducting tokamak HT-7. The horizontal position is calculatedfrom the vertical field coil current and voltage without using signals of magnetic probes placednearby a plasma. The calculations are focused on the ripple frequency component of the power supply.There is no drift problem with the time integration of magnetic probe signals. The error of thederived plasma position is lower than 2% of the plasma minor radius.

Algorithm Validation of the Current Profile Reconstruction of EAST Based on Polarimeter/Interferometer

The method of plasma current profile reconstruction using the polarimeter/interferometer（POINT） data from a simulated equilibrium is explored and validated.It is shown that the safety factor（q） profile can be generally reconstructed from the external magnetic and POINT data.The reconstructed q profile is found to reasonably agree with the initial equilibriums.Comparisons of reconstructed q and density profiles using the magnetic data and the POINT data with 3%,5%and 10%random errors are investigated.The result shows that the POINT data could be used to a reasonably accurate determination of the q profile.