Loss-cone instabilities for compact fusion reactor and field-reversed configuration

Loss-cone instabilities are studied for linear fusion devices. The gyro-kinetic equation for such a configuration is rigorously constructed in terms of action-angle variables by making use of canonical transformation. The dispersion relation, including for the first time, finite bounce frequency is obtained and numerically solved. The loss-cone modes are found near ion-cyclotron frequency. The growth rates are greatly reduced and approaching zero with increasing beta value. The results suggest that loss-cone instabilities are unlikely to be threatening to linear fusion devices since a new longitudinal invariant is found and gives a constraint which helps confinement.

Association between soft drink consumption types and risk of lung cancer and all-cancer: A prospective study of PLCO data

Diet/sugar-free soft drinks are considered to be healthier than regular soft drinks.However,few studies have examined the relationship between the types of soft drinks(regular and diet/sugar-free)and lung cancer(LC)/all-cancer(AC)risk.In this study,we comprehensively assessed the influence of the type of soft drink consumption on LC/AC risk based on the Prostate,Lung,Colorectal,and Ovarian(PLCO)Cancer Screening Trial.Multivariable Cox proportional hazards and competing risks Fine-Gray regression models adjusted for relevant confounders were used to estimate hazard ratios(HRs)and subdistribution HRs for different types of soft drink consumption.In the PLCO population,female subgroup,and the ever/current smoker subgroup,consumption of both regular and diet soft drinks was associated with a significantly reduced risk of LC compared with no soft drinks at all.For the non-lung cancer(NLC)risk,consumption of only diet soft drinks had a significant positive association for the total population and female subgroup.Based on our findings,it was suggested that partial replacement of regular soft drinks with diet soft drinks might be beneficial to LC prevention,especially for females and ever/current smokers.Additionally,completely replacing regular soft drinks with diet soft drinks might be detrimental to NLC prevention,especially for females.

Mitigation of ELMs by Electrostatic Field in Tokamaks

Mitigation of ELMs by electrostatic field is studied. The perpendicular heating in cyclotron waves tends to pile up the resonant particles toward the low magnetic field side in which a electrostatic field may result [J. Y. Hsu, V. S. Chan, R. W. Harvey, R. Prater, and S. K. Wong, Phys. Rev. Lett. 53, 564 (1984)]. The electrostatic field can make circulating particles trapped or make trapped particles circulating depending on the field direction. The trapped- particle population and bootstrap current change accordantly. Modulating bootstrap current, mitigation of type-1 ELM by the electrostatic field is possible. The electrostatic potential needed for the mitigation is quantitatively estimated. Experiments by either ECRH or biasing are being prepared to verify the theory.