Simple multijunction launcher with oversized waveguides for lower hybrid current drive on JT-60U

Ikeda, Yoshitaka; Naito, O.; Seki, M.; Kondoh, T.; Ide, S.; Anno, K.; Fukuda, H.; Kitai, Takato; Kiyono, K.; Sawahata, M.; Shinozaki, S.; Suganuma, K.; Suzuki, Norio; Ushigusa, K.

doi:10.1016/0920-3796(94)90027-2

Cited by 23 publications

(9 citation statements)

References 7 publications

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“…The other one is installed in a horizontal port and consist of four rows of four MJ modules which have 12 sub-waveguides [9,10]. However, the lower two rows of the launcher has been no more used since the end of 1997.…”

Section: Setup Of Experimentsmentioning

confidence: 99%

LHCD current profile control experiments towards steady state improved confinement on JT-60U

Ide¹,

Naito²,

Oikawa³

et al. 2000

Nucl. Fusion

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In JT-60U lower hybrid current drive (LHCD) experiments, a reversed magnetic shear configuration that was accompanied by the internal transport barriers was successfully maintained by means of LHCD almost in the full current drive quasi-steady state for 4.7 s. The normalized beta was kept near 1 and the neutron emission rate was almost steady as well indicating no accumulation of impurities into the plasma. Diagnostics data showed that all the profiles of the electron and ion temperatures, the electron density and the current profile were almost unchanged during the LHCD phase. Moreover, capability of LHCD in H-mode plasmas has been also investigated. It was found that the lower hybrid waves can be coupled to an H-mode edge plasma even with the plasma wall distance of about 14 cm. The maximum coupling distance was found to depend on the edge recycling.

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Section: Setup Of Experimentsmentioning

confidence: 99%

LHCD current profile control experiments towards steady state improved confinement on JT-60U

Ide¹,

Naito²,

Oikawa³

et al. 2000

Nucl. Fusion

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“…A negative ion based NB (N-NB) system [23][24][25] has been developed for central heating and current drive. The LHRF system has two multijunction launchers at 1.74-2.23 GHz with N peak = 1.3-2.3 and an injection power of ∼3.5 MW [26,27]. The ICRF system for second harmonic hydrogen minority heating consists of two antennas and has the function of real time impedance matching by frequency feedback control [28].…”

Section: Introductionmentioning

confidence: 99%

High performance and prospects for steady state operation on JT-60U

Oikawa¹,

Team²

2000

Nucl. Fusion

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Recent experimental results for steady state high performance plasma on JT-60U are described, emphasizing plasma control, especially active control of profiles. In reversed shear (RS) plasma, a DT equivalent fusion gain of 0.5 was sustained for 0.8 s (∼ the energy confinement time) by controlling plasma β with a newly developed stored energy feedback control technique. An internal transport barrier (ITB) with an RS configuration was successfully maintained by means of LHCD in full current drive quasi-steady state for 4.7 s. The viability of a steady state RS configuration sustained by a large bootstrap current fraction has been demonstrated in ELMy H mode edge RS plasmas for the first time. In high-βp ELMy H mode plasmas, an integrated core plasma performance with H factor of 2.56, βN = 2.4, and bootstrap current fraction and non-inductively driven current fraction close to the ITER requirements was achieved at Ip = 1.5 MA in a near full current drive state by negative ion based NB (N-NB) injection. A rudimentary simulation of a reactor operation with simultaneous feedback control of both the core and divertor plasmas has been demonstrated in ELMy H mode plasma. Aiming at active control of the pressure gradient at the ITB in RS plasmas, a feedback control system of the electron temperature gradient has been developed and optimization of the discharge scenario using this system has recently started.

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“…A similar design is used in high power LHCD experiments in other tokamaks, e.g. Tore Supra [5,6] and JT60-U [7]. The full LHCD system in JET (Figure 1), which was brought into operation in early 1994, operates at 3.70 GHz and has a generator capability of 12 MW for 20 s, supplied by 24 klystrons.…”

Section: Description Of the Jet Lhcd Systemmentioning

confidence: 98%

Conditioning and high power operation of the lower hybrid current drive launcher in JET

Dobbing

Finburg

Fischer

et al. 1998

Plasma Devices and Operations

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The full lower hybrid current drive (LHCD) system on the Joint European Torus (JET) has been operational since the start of the pumped divertor phase of JET in 1994. By a campaign of vacuum conditioning in the beginning of operation, the power transmission and conditioning of the full launcher was speeded up, as compared with the prototype launcher used in 1990/91. After vents of the tokamak, the conditioning can be recovered by -300 vacuum pulses over 3-4 days. Even after extensive conditioning and with efficient pumping, the power handling of the full LHCD system on plasma is limited by the maximum electric field in the waveguides, the limit being 400-500 kVfm.

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Simple multijunction launcher with oversized waveguides for lower hybrid current drive on JT-60U

Cited by 23 publications

References 7 publications

LHCD current profile control experiments towards steady state improved confinement on JT-60U

LHCD current profile control experiments towards steady state improved confinement on JT-60U

High performance and prospects for steady state operation on JT-60U

Conditioning and high power operation of the lower hybrid current drive launcher in JET

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