5-9 September 2016
Prague Congress Centre
Europe/Prague timezone

P2.031 Design of high power traveling wave antenna for KSTAR helicon wave current drive

6 Sep 2016, 14:20
1h 40m
Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Foyer 2A (2nd floor), 3A (3rd floor)

Prague Congress Centre

5. května 65, Prague, Czech Republic
Board: 31
Poster B. Plasma Heating and Current Drive P2 Poster session

Speaker

Hyunho Wi (KSTAR Research center)

Description

Steady-state operation of a DEMO-like tokamak requires substantial off-axis current be driven by external current drive systems. Non-inductive current drive is needed to complement the bootstrap current to support the plasma current in steady state. Recently, helicon wave current drive at frequencies of 500~700 MHz is gained much attention to achieve off-axis current drive with high efficiency. Helicon wave current drive has been shown computationally to have higher efficiency in the mid-radius region than other current drive techniques under reactor-like conditions. KSTAR can be a good test-stand to validate and to use off-axis current drive capability of helicon wave because it has adequate machine parameters and it will have high electron beta plasmas in near future with additional ECH power. To test the feasibility of helicon wave current drive, low power mock-up travelling wave antenna (TWA) has been fabricated and tested in KSTAR plasmas. The TWA has advantage, its insensitivity to the density profile at the plasma edge. Among the various TWA types, combline filter based TWA was chosen to test in KSTAR plasmas. It already had shown good load resilient and efficient coupling properties in JFT-2M tokamak. In order to investigate the effectiveness of off-axis current drive high power TWA with a launched n|| spectrum peaked at 3.0 will be installed and tested during 2016 KSTAR plasma experiments. The prototype TWA is composed of ten current straps, 8° tilted faraday shield, and 5 inches RF coaxial feeder for high power handling. The total length of the prototype TWA is 600 mm. The operation frequency of prototype antenna is 500 MHz and its bandwidth is about 40 MHz. Detailed design parameters and electrical properties of high power TWA for KSTAR helicon wave current drive will be presented.

Co-authors

Haejin Kim (KSTAR Research center, NATIONAL FUSION RESEARCH INSTITUTE, 169-148 GWAHAK-RO, YUSEONG-GU, DAEJEON 34133, South Korea) Hyunho Wi (KSTAR Research center, NATIONAL FUSION RESEARCH INSTITUTE, 169-148 GWAHAK-RO, YUSEONG-GU, DAEJEON 34133, South Korea) Jong gu Kwak (KSTAR Research center, NATIONAL FUSION RESEARCH INSTITUTE, 169-148 GWAHAK-RO, YUSEONG-GU, DAEJEON 34133, South Korea) Sonjong Wang (KSTAR Research center, NATIONAL FUSION RESEARCH INSTITUTE, 169-148 GWAHAK-RO, YUSEONG-GU, DAEJEON 34133, South Korea)

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