Development of high-power, long-pulse, multi-frequency ECH/CD system for JT-60SA

A gyrotron and a matching optics unit (MOU) for the multi-frequency electron cyclotron heating and current drive (ECH/CD) system in JT-60SA have been developed successfully. The gyrotron demonstrated stable operation at high powers of 1.5 MW for 5 s and 1.9 MW for 1 s at 110 GHz. To obtain high HE11 mode purity (> 90%) at the outlet of the waveguide in the ECH/CD launcher, a MOU for operating at three frequencies of 82 GHz, 110 GHz, and 138 GHz that includes three pairs of water-cooled phase correcting mirrors has been developed, which allows the mirrors to be changed without opening the evacuated MOU. The mode purity at the inlet of a dummy load in the transmission line was evaluated at high-power and an HE11 mode purity of > 90% was obtained at three frequencies.

TANTANGAN DALAM MENGAKTIFKAN PEMBANGKIT TENAGA AIR SKALA KECIL

Air adalah salah sumber tenaga listrik berdasarkan siklus alami. Air sebagai tenaga listrik telah lama dieksplorasi yang umumnya berskala besar karena lebih ekonomis. Akhir-akhir ini, pemanfaatan tenaga air berskala kecil mulai mendapat perhatian karena menipisnya sumber bahan bakar fosil. Secara teknis, pembangkit listrik tenaga air sekala kecil banyak yang menghadapi permasalahan, diantaranya adalah pemahaman tentang teknologi tenaga air dan pentingnya perawatan, dan kualitas listrik. Pengoptimalan tegangan sistem saluran dan dummy load diturunkan secara matematik secara jelas. Formulasi-formulasinya telah diterapkan di Pembangkit Listrik Tenaga Mikrohydro Suralaya, Jawa Barat, dengan memperbaiki tegangan sistem dari 220 V ke 1 kV untuk memenuhi tegangan dan rugi-rugi saluran. Sedangkan kapasitas dummy load optimalnya adalah 26 kW, ini lebih kecil dari kapasitas terpasang 50 kW.

A pulse current generator for dense plasma focus

A pulse current generator applied in a type of high-yield intense pulsed neutron source, the Dense Plasma Focus (DPF), is designed and developed in this paper. There are three key components in this generator. Each group of capacitors and switches is integrative to meet the DPF's requirements of low circuit inductance. A coaxial multi-channel switch is developed to solve the problems of the switch inductance, the jitter and the electrode erosion. A kind of sectorial plate transmission line is adopted to transfer the high pulse current from the capacitors to the DPF. The following technical parameters of the generator were achieved on dummy load: output current amplitude of ∼560 kA when primary capacitors are charged with 22 kV.

Vibration compensation using dummy load-cell in dynamic mass measurement

Checkweighers, that can measure the mass of a target object continuously while conveying the object on a belt conveyor, are affected by environmental vibration. As a result, accuracy of the mass measurement gets worse. To solve this problem, we have proposed a method that can eliminate the effect of the environmental vibration. This paper enhances the proposed method and improves the performance of the proposed method.

Extension of Castigliano’s method for isotropic beams

In the present contribution Castigliano’s theorem is extended to find more accurate results for the deflection curves of beam-type structures. The notion extension in the context of the second Castigliano’s theorem means that all stress components are included for the computation of the complementary strain energy, and not only the dominant axial stress and the shear stress. The derivation shows that the partial derivative of the complementary strain energy with respect to a scalar dummy parameter is equal to the displacement field multiplied by the normalized traction vector caused by the dummy load distribution. Knowing the Airy stress function of an isotropic beam as a function of the bending moment, the normal force, the shear force and the axial and vertical load distributions, higher-order formulae for the deflection curves and the cross section rotation are obtained. The analytical results for statically determinate and indeterminate beams for various load cases are validated by analytical and finite element results. Furthermore, the results of the extended Castigliano theory (ECT) are compared to Bernoulli–Euler and Timoshenko results, which are special cases of ECT, if only the energies caused by the bending moment and the shear force are considered. It is shown that lower-order terms for the vertical deflection exist that yield more accurate results than the Timoshenko theory. Additionally, it is shown that a distributed load is responsible for shrinking or elongation in the axial direction.