Runaway electrons on HT-7 Tokamak with low hybrid current drive

Runaway electron detection system composed of CdTe, BGO and NaI was used to measure the hard X-ray (HXR) emission in the energy range 0.3～15 MeV when the runaways hit the first wall. With electron cyclotron emission and neutron detect systems,the runaway electrons on HT-7 Tokamak with low hybrid current drive (LHCD) were investigated. It was found that in LHCD discharges with high loop voltage as well as the termination of high low hybrid power can accelerate the fast electrons into runaways. The results also indicate that the reduction of the electric field accomplished by LHCD produces a suppression of the existing runaway population.