• Nuclear Engineering and Technology
• /
• v.38 no.8
• /
• pp.785-792
• /
• 2006

The microwave heating system of KSTAR consists of ECH and LHCD. ECH and LHCD offer the benefits ofa reliable operation at the start of plasma formation and a non-inductive current drive durable steady state operation, respectively. LHCD uses a C-band microwave system with a frequency of 5 GHz. A pulsed power modulator with a power of 3.6 MW, $4{\mu}S$, 200 pps is required to drive the high-powered magnetron. The development of a pulse modulator with 1:4 pulse transformers is the focus of the research in this study. The peak power handling capability is 3.6 MW (45 kV, 90 A at load side with a pulse width of $4{\mu}S$). This paper describes the system overview and test results of the pulsed modulator. In particular, a simulated waveform is compared with the tested waveform.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.3
• /
• pp.120-126
• /
• 2005

The Korean Superconducting Tokamak Advanced Research (KSTAR) tokamak device is being constructed to perform long-pulse, high-beta, advanced tokamak fusion physics experiments. The long-pulse operation requires the non-inductive current drive system such as the Lower-Hybrid Current Drive (LHCD) system. The LHCD system drives the non-inductive plasma current by means of C-band RF with 2-MW CW power and 5-GHz frequency. For the LHCD test experiments, an RF test system is developed. It is composed of a 5-GHz, 1.5-MW pulsed magnetron and a compact pulse modulator with $4\;{\mu}s$ of pulse width. The pulse modulator provides the maximum output voltage of 45 kV and the maximum current of 90 A. It is composed of 7 stages of Pulse Forming Network (PFN), a thyratron tube (E2V, CX1191D), and a pulse transformer with 1:4 step-up ratio. In this paper, the detailed design and the performance test of the pulse modulator are presented.

• Nuclear Engineering and Technology
• /
• v.55 no.9
• /
• pp.3126-3132
• /
• 2023

To meet the increasing heating needs of the China Fusion Experimental Tokamak Reactor (CFETR), the output power in each Lower Hybrid Current Drive (LHCD) transmission line should be increased from 250 kW to 500 kW. Therefore, a new high-power water load must be developed for the 4.6 GHz 500 kW LHCD system. This paper aims to report the most recent research progress of the water load: aluminum nitride (AlN) ceramic is used as the media material to isolate the water and vacuum, and the radio frequency (RF) simulation results show that the return loss of the water load is less than -25dB at 4.6 GHz over a wide temperature range. Under 500 kW continuous wave (CW) operation, the maximum temperatures of the ceramic and water are separately 67 ℃ and 62 ℃, resulting in thermal deformation of the ceramic of approximately 0.003 mm. Moreover, the AlN water load was tested on the 4.6 GHz 250 kW high-power test bench and found to work well with low reflected power.

• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.1778-1780
• /
• 2004

Microwave heating system of KSTAR consists of ECH and LHCD. ECH and LHCD offer the reliability of operation in the beginning of plasma formation and non-inductive current drive for long time steady state operation with maintaining MHD stability, respectively. LHCD demands 5 GHz of frequency and consists of c-band waveguide, 4-port circuitor, dry dummy load, dual directional coupler, E-bend, arc detector. Our system is a lineup type pulse modulator that has 45 kV of output pulse voltage, 90 A of pulse current, 4 us of pulse width. 1:4 step-up pulse transformer, 7 stages of PFN and thyratron tube (E2V, CX1191D) are used in this modulator. The purpose of this paper is to show the modulator design and experimental result.