A new experimental regime has recently been studied for achieving high fraction of the bootstrap current in the JT-60U hydrogen discharges.The high poloidal beta(βp~3.61)plasma was obtained by high-power neutral beam...A new experimental regime has recently been studied for achieving high fraction of the bootstrap current in the JT-60U hydrogen discharges.The high poloidal beta(βp~3.61)plasma was obtained by high-power neutral beam injection heating at very high edge safety factor(Ip=0.3 MA,Bt=3.65 T,qeff=25-35)region,and the bootstrap current fraction(fBS)was about 40%using the ACCOME code calculation.It was observed that there were no magnetohydrodynamics instabilities to retard the increase ofβp and fBS parameters in the new regime.展开更多
Results from stabilization of neoclassical tearing modes （NTMs） in JT-60U are described. NTM stabilization and confinement improvement have been demonstrated by employing a real-time NTM stabilization system, where ...Results from stabilization of neoclassical tearing modes （NTMs） in JT-60U are described. NTM stabilization and confinement improvement have been demonstrated by employing a real-time NTM stabilization system, where the identification of the location of an NTM and the optimization of the injection angle of the electron cyclotron wave are performed in real time. Also, a high-beta plasma with the normalized beta of 3 has been sustained by suppressing NTM by applying the electron cyclotron current drive （ECCD） before the onset （＇preemptive ECCD＇）. In addition, a simulation code for analysis of the NTM evolution has been developed by combining the modified Rutherford equation with the transport code TOPICS. It is found that the simulation well reproduces the NTM behavior in JT-60U. The simulation also shows that the ECCD width is also important for NTM stabilization, and that the EC wave power for complete stabilization can be reduced by narrowing the ECCD profile.展开更多
文摘A new experimental regime has recently been studied for achieving high fraction of the bootstrap current in the JT-60U hydrogen discharges.The high poloidal beta(βp~3.61)plasma was obtained by high-power neutral beam injection heating at very high edge safety factor(Ip=0.3 MA,Bt=3.65 T,qeff=25-35)region,and the bootstrap current fraction(fBS)was about 40%using the ACCOME code calculation.It was observed that there were no magnetohydrodynamics instabilities to retard the increase ofβp and fBS parameters in the new regime.
基金supported in part by the JSPS-CAS Core University Program in the field of Plasma and NucIear Fusionalso supported by the Grant-in-Aid for Young Scientists(B)of MEXT Japan
文摘Results from stabilization of neoclassical tearing modes （NTMs） in JT-60U are described. NTM stabilization and confinement improvement have been demonstrated by employing a real-time NTM stabilization system, where the identification of the location of an NTM and the optimization of the injection angle of the electron cyclotron wave are performed in real time. Also, a high-beta plasma with the normalized beta of 3 has been sustained by suppressing NTM by applying the electron cyclotron current drive （ECCD） before the onset （＇preemptive ECCD＇）. In addition, a simulation code for analysis of the NTM evolution has been developed by combining the modified Rutherford equation with the transport code TOPICS. It is found that the simulation well reproduces the NTM behavior in JT-60U. The simulation also shows that the ECCD width is also important for NTM stabilization, and that the EC wave power for complete stabilization can be reduced by narrowing the ECCD profile.
