In cold pulse experiments in J-TEXT, not only are rapid electron temperature increases in core observed, but also steep rises of inner density are found. Moreover, some evidence of acceleration of the core toroidal rotation is also observed during the non-local transport process of electron temperature. These new findings of cold pulse experiments in J-TEXT suggest that turbulence spreading is possible mechanism for the non-local transport dynamics.

The first plasma has been achieved successfully in the Experimental Advanced Superconducting Tokamak (EAST). Boronization by the glow discharge (GDC) method was studied in experiments. The plasma performance was obviously improved by GDC boronization. Extension of the operational region and improvement in the plasma performance were obtained. Sawtooth discharges were observed by means of soft x-ray signals, electron cyclotron emission signals and line averaged electron density after boronization. Lower qa and more stable operation were also achieved following GDC boronization. The plasma current ramp-up rate was also improved as a result of decreased impurity content and low averaged loop voltage due to boronization. PLEASE NOTE: THERE HAS BEEN A RETRACTION PUBLISHED FOR THIS ARTICLE.

Evolution of electron temperature, electron density and its fluctuation with high spatial and temporal resolutions are presented for the cold pulse propagation induced by supersonic molecular beam injection (SMBI) in ohmic plasmas in the EAST tokamak. The non-local heat transport occurs for discharges with plasma current Ip=450 kA (q 95 ∼ 5.55), and electron density n e0 below a critical value of (1.35 ± 0.25) × 10 19 m −3 . In contrary to the response of core electron temperature and electron density (roughly 10 ms after SMBI), the electron density fluctuation in the plasma core increases promptly after SMBI and reaches its maximum around 15 ms after SMBI. The electron density fluctuation in the plasma core begins to decrease before the core electron temperature reaches its maximum (roughly 30 ms). It was also observed that the turbulence perpendicular velocity close to the inversion point of the temperature perturbation changes sign after SMBI.

A high-frequency magnetic probe is designed and developed on the XuanLong-50 (EXL-50) spherical torus to measure high-frequency magnetic field fluctuation. The magnetic loop, radio filters, radio-frequency (RF) limiter, and data acquisition system of the probe are comprehensively examined. The fluctuation data from the EXL-50 plasma are analyzed in the time–frequency domain using fast Fourier transforms. Moreover, distinct high-frequency instabilities are detected using this diagnostic system. In particular, significant frequency chirping is observed, which is consistent with the bump-on-tail drive instability predicted using the Berk–Breizman model.

We examine the theoretical conditions in which the Lawson ignition criterion for p-11B fusion in a magnetized toroidal plasma can be reduced substantially. It is determined that a velocity differential between the protons and the boron ions of the order of the plasma sound speed (Mach number of 1 or 2 at a plasma temperature of ~102 keV) could raise the p-11B fusion reaction rate to ~2x10-22 m3/s or ~6x10-22 m^3/s, respectively, from the ~1x10-22 m3/s level in a static plasma. The Lawson triple product (ni τE Ti) required for ignition can thereby be reduced to as low as ~1023 m-3 s keV, which is one order of magnitude above the ITER requirement for D-T burn. Since order-unity Mach numbers in velocity differentials between deuterons and impurity carbon ions have been maintained in tokamak plasmas under excellent confinement conditions, similar levels of velocity differentials between protons and minority boron-11 ions could in principle be maintained also. A theoretical possibility of achieving p-11B fusion ignition in a toroidal plasma of ~102 keV in ion temperature is hereby presented. Similar p-13C plasmas, for example, will introduce a possibility of measuring the CNO fusion chain reaction rates in a laboratory.