We evaluate the characteristics of global energy confinement in KSTAR (τE,KSTAR) quantitatively in three ways; firstly by comparing it with multi-machine scalings, secondly by deriving multiple regression equations for the L- and the H-mode plasmas, respectively, and lastly by comparing confinement enhancement of the H-mode phase with respect to the L-mode phase in each discharge defined as Hexp. The KSTAR database exhibits τE,KSTAR of ∼0.04 to ∼0.16 s and of ∼0.06 to ∼0.19 s in L-mode and in H-mode plasmas, respectively. The multiple regression equations derived by statistical analysis present the similar dependency on PL and higher dependency on Ip compared with the multi-machine scalings, however the dependency on κ in both L- and H-mode plasmas draw the negative power dependency of κ−0.68 and κ−0.76 for H-mode and for L-mode database, respectively on the contrary to the positive dependency in all multi-machine empirical scalings. It is found that the energy confinement of both L-mode and H-mode of the discharges with Hexp > 1.5 can be well-predicted by multi-machine scalings, τE,89L and τE,92H. Apart from this, the H-mode confinement with 1.5 < Hexp < 2.0 is well-predicted by using the multi-machine empirical L-mode scaling τE,89L.
h i g h l i g h t s• Recent achievements of the KSTAR plasma control system are described.• Requirements and results of the testbed system for the future upgrade of the KSTAR plasma control system are presented.• An overview of the upgrade layout based is given. a b s t r a c t The plasma control system (PCS) has been one of essential systems in annual KSTAR plasma campaigns: starting from a single-process version in 2008, extensive upgrades are done through the previous 7 years in order to achieve major goals of KSTAR performance enhancement. Major implementations are explained in this paper. In consequences of successive upgrades, the present KSTAR PCS is able to achieve ∼48 s of 500 kA plasma pulses with full real-time shaping controls and real-time NB power controls. It has become a huge system capable of dealing with 8 separate categories of algorithms, 26 actuators directly controllable during the shot, and real-time data communication units consisting of +180 analog channels and +600 digital input/outputs through the reflective memory (RFM) network. The next upgrade of the KSTAR PCS is planned in 2015 before the campaign. An overview of the upgrade layout will be given for this paper. The real-time system box is planned to use the CERN MRG-Realtime OS, an ITER-compatible standard operating system. New hardware is developed for faster real-time streaming system for future installations of actuators/diagnostics.
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