Ion cyclotron wall conditioning experiments on Tore Supra in presence of the toroidal magnetic field

Wall conditioning techniques applicable in the presence of the high toroidal magnetic field will be required for the operation of ITER for tritium removal, isotopic ratio control and recovery to normal operation after disruptions. Recently ion cyclotron wall conditioning (ICWC) experiments have been carried out on Tore Supra in order to assess the efficiency of this technique in ITER relevant conditions. The ICRF discharges were operated in He/H-2 Mixtures at the Tore Supra nominal field (3.8 T) and a RF frequency of 48 MHz, i.e. within the ITER operational space. RF pulses of 60 s (max.) were applied using a standard Tore Supra two-strap resonant double loop antenna in ICWC mode, operated either in pi or 0-phasing with a noticeable improvement of the RF coupling in the latter case. In order to assess the efficiency of the technique for the control of isotopic ratio the wall was first preloaded using a D-2 glow discharge. After 15 minutes of ICWC in He/H-2 gas mixtures the isotopic ratio was altered from 4% to 50% at the price of an important H implantation into the walls. An overall analysis comparing plasma production and the conditioning efficiency as a function of discharge parameters is given

Total Synthesis of Halichondrin C

The first total synthesis of halichondrin C has been completed, highlighted by development of the synthetic method to construct the C8–C14 polycycle. Cr-mediated coupling reactions are used seven times to form a new C–C bond. The acid stability of halichondrin C is studied, demonstrating that the macrolactone stabilizes the C8–C14 polycycle, relative to the one present in the C1–C16 model

Total Synthesis of Halichondrin C

The first total synthesis of halichondrin C has been completed, highlighted by development of the synthetic method to construct the C8–C14 polycycle. Cr-mediated coupling reactions are used seven times to form a new C–C bond. The acid stability of halichondrin C is studied, demonstrating that the macrolactone stabilizes the C8–C14 polycycle, relative to the one present in the C1–C16 model