托卡马克混合运行模式下电子回旋波杂散辐射数值模拟

Numerical investigation on electron cyclotron stray radiation under hybrid operation scenarios of tokamak

电子回旋波(EC波)在等离子体加热与电流驱动过程中未被等离子体完全吸收时将会产生杂散辐射。在HL-2M托卡马克三种混合运行模式参数条件下,利用TORAY-GA程序扫描105GHz EC波中平面发射时的环向和极向发射角,以EC波功率吸收份额η>η_(c)(η_(c)=95%)作为判断能有效避免杂散辐射的标准,开展EC波功率吸收数值模拟。研究发现发射角是影响EC波不完全吸收造成杂散辐射的关键因素之一。在n_(e1)=4.6×10^(19)m^(−3)、T_(e1)=7.41keV、I_(p1)=1MA和n_(e2)=5×10^(19)m^(−3)、T_(e2)=6.95keV、I_(p2)=1MA的参数条件下,能够有效避免杂散辐射的EC波发射角超过设计范围,在设计发射角范围内调节EC波发射角进行加热和电流驱动时可以忽略杂散辐射的影响。当参数为n_(e3)=6.5×10^(19)m^(−3)、T_(e3)=6.62keV、I_(p3)=0.95MA,设计发射角度范围中有一大部分会使得EC波有非常低的波功率吸收份额,需要特别注意杂散辐射。除发射角度外,电子密度是影响杂散辐射的另一个关键因素,电子温度影响非常小,可以忽略不计。

Imperfect absorption of electron cyclotron(EC)wave power in plasma results in stray radiation during plasma heating and current drive.Numerical investigations on EC stray radiation are performed under three hybrid operation scenarios of HL-2M tokamak.Scanning the toroidal and poloidal incident angles of 105GHz EC wave launched from low field side of mid-plane,the simulation is conducted by using TORAY-GA code.The standard to effective avoidance of stray radiation,as the absorption fraction of EC power satisfyingη>η_(c),is adopted.It is found that incident angle is one of the key factors that affect stray radiation caused by incomplete absorption of EC power.For two scenarios with n_(e1)=4.6×10^(19)m^(−3)、T_(e1)=7.41keV、I_(p1)=1MA and n_(e2)=5×10^(19)m^(−3)、T_(e2)=6.95keV、I_(p2)=1MA,the range of EC incident angle that can effectively avoid stray radiation exceeds the design.In these cases,the stray radiation can be ignored during heating and current drive.For the scenario with n_(e3)=6.5×10^(19)m^(−3)、T_(e3)=6.62keV、I_(p3)=0.95MA,a large part of the designed incident angle will make EC wave have a very low wave power absorption fraction,special attention should be paid to the stray radiation.Electron density is another key factor.The influence of electron temperature is very small and can be ignored.