Recent Progress of 2MW 140GHz ECRH System on HL-2A

In order to provide more capability of physics study for high-performance plasma, such as current profile control, neoclassical tearing modes suppression, transport study and so on, a new 2MW/140GHz/3s second-harmonic ECRH system with X-mode injection is on schedule on HL-2A. The total power of this system is 2MW and the pulse duration is 3 sec, which is generated by two gyrotrons manufactured by GYCOM. Two evacuated Φ63.5mm transmission lines were used to propagate these two 1MW/3s wave beams. A fast steerable launcher has been designed and installed on the HL-2A tokamak to inject four beams with narrow beam width and enable continuous beam scanning in toroidal and poloidal directions independently

Recent Progress of 2MW 140GHz ECRH System on HL-2A

In order to provide more capability of physics study for high-performance plasma, such as current profile control, neoclassical tearing modes suppression, transport study and so on, a new 2MW/140GHz/3s second-harmonic ECRH system with X-mode injection is on schedule on HL-2A. The total power of this system is 2MW and the pulse duration is 3 sec, which is generated by two gyrotrons manufactured by GYCOM. Two evacuated Φ63.5mm transmission lines were used to propagate these two 1MW/3s wave beams. A fast steerable launcher has been designed and installed on the HL-2A tokamak to inject four beams with narrow beam width and enable continuous beam scanning in toroidal and poloidal directions independently

Measurement of the leptonic decay width of J/ψ using initial state radiation

Using a data set of 2.93 fb−1 taken at a center-of-mass energy of s=3.773 GeV with the BESIII detector at the BEPCII collider, we measure the process e+e−→J/ψγ→μ+μ−γ and determine the product of the branching fraction and the electronic width Bμμ⋅Γee=(333.4±2.5stat±4.4sys) eV. Using the earlier-published BESIII result for Bμμ=(5.973±0.007stat±0.037sys)%, we derive the J/ψ electronic width Γee=(5.58±0.05stat±0.08sys) keV

Measurement of the branching fractions of Ds+→η′X and Ds+→η′ρ+ in e+e−→Ds+Ds−

We study Ds+ decays to final states involving the η′ with a 482 pb−1 data sample collected at s=4.009 GeV with the BESIII detector at the BEPCII collider. We measure the branching fractions B(Ds+→η′X)=(8.8±1.8±0.5)% and B(Ds+→η′ρ+)=(5.8±1.4±0.4)% where the first uncertainty is statistical and the second is systematic. In addition, we estimate an upper limit on the non-resonant branching ratio B(Ds+→η′π+π0)<5.1% at the 90% confidence level. Our results are consistent with CLEO's recent measurements and help to resolve the disagreement between the theoretical prediction and CLEO's previous measurement of B(Ds+→η′ρ+)