The internal transport barrier (ITB) has been obtained in ELMy H-mode plasmas by neutron beam injection and lower hybrid wave heating on the Experimental Advanced Superconducting Tokamak (EAST). The ITB structure has been observed in profiles of ion temperature, electron temperature, and electron density within ρ<0.5. It was also observed that the ITB formation is stepwise. Due to the ITB formation, the confinement quality H 98y2 increases from 1 to 1.1 and the normalized beta, β N , increases from 1.5 to near 2. The fishbone activity observed during the ITB phase suggests the central safety factor q(0)∼1. Transport coefficients are calculated by particle balance and power balance analysis, showing an obvious reduction after the ITB formation.
Effective coupling for lower hybrid waves (LHWs) is achieved by adjusting the launcher position and optimizing the plasma configuration in L-mode in EAST. It is found that, compared with other divertor shapes, the plasma with double null shows better coupling performance at the same position of lower hybrid (LH) grill, especially in the case of a large safety factor near the separatrix (q 95 ) and a large edge recycling (D α ) intensity. The ion cyclotron range of frequency (ICRF) power has a significant impact on LH wave coupling when the ICRF antenna is magnetically connected to the LH grill. The asymmetry effects in the poloidal direction on reflection coefficients are obtained with a low edge density during ICRF power application. The origin of such a relevant asymmetry with ICRF is different from LHWs. Results not only suggest that ICRF power could modify the density in the local scrape-off layer (SOL), but also indicate that density convection in the SOL could be easily obtained with a low edge density. One promising alternative for eliminating the negative impact on LHW coupling induced by ICRF is gas (D2) injection both from the electronic side and ionic side in EAST.
Polysilicon thin-film semiconductor bridges (SCB) and Pb•BaTNR primary explosives are selected to prepare SCB/Pb•BaTNR samples, and their ignition performance is tested. The test results show that the SCB/Pb•BaTNR samples were ignited random when the ignition energy provided for SCB is insufficient but aroud critical value. Under different energy-storage capacitance, the voltages that lead to SCB completely gasifying into high-energy plasma are around 21V, indicating that charging voltage is the main factor affecting SCB elements to produce high-energy plasma. Ignition tests are performed on the SCB/Pb•BaTNR samples under the conditions of 47μF/21V, 64μF/21V, and 100μF/21V. The samples are found to ignite reliably, and the action time ranges from 0.17 ms to 0.4 ms, meeting the requirements for high instantaneity.
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