International Journal of Applied Electromagnetics and Mechanics - Volume 14, issue 1-4

Authors: Ishigohka, Takeshi | Ninomiya, Akira | Hayakawa, Kihachiro | Mitsuhashi, Tsukasa

Article Type: Research Article

Abstract: In order to examine the fundamental availability of a homopolar machine with laminated armature rotor disks, the authors fabricated and tested a small superconducting experimental homopolar machine with two rotor disks. The machine was tested as a generator. The obtained experimental data show that the output voltage of the 2-disk machine is about 2 times larger than that of the 1-disk machine. From this experimental result, we can conclude that the output voltage of a homopolar …generator with axially laminated rotor disks is proportional to the number of the disks. Show more

DOI: 10.3233/JAE-2002-390

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 115-120, 2002

Authors: Vajda, I. | Györe, A. | Porjesz, T. | Sokolovsky, V. | Meerovich, V.

Article Type: Research Article

Abstract: The concept of an all-superconducting (AS) mini power plant (MPP) model is presented. An experimental HTS fault current limiter (FCL) for the protection of the generator unit of the AS MPP model was designed. During its lifetime the HTS FCL can be activated thousands of times. Duration tests were performed on the HTS FCL to determine the dependence of the value of the limited current and the voltage of the FCL on the number of activations of the …device. The experiments have shown that the parameters of the HTS FCL are approximately constant after three thousand activations. This result indicates that the relevant parameters of the HTS ring used in the device are approximately constant, and that the FCL can be designed and used in the network with predictable parameters. Show more

Keywords: high temperature superconductor, fault current limiter, mini power plant

DOI: 10.3233/JAE-2002-493

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 121-126, 2002

Authors: Demachi, Kazuyuki | Miura, Akira | Sawada, Akihiko | Miya, Kenzo | Higasa, Hiromasa | Takahata, Ryoichi | Kameno, Hiroo

Article Type: Research Article

Abstract: The degradation of rotation speed is one of the most significant problems for the practical use of superconducting magnetic bearing (SMB) for flywheel energy storage system. This is called the rotation loss. This phenomena is caused by the AC magnetic field due to the inhomogeneous distribution of magnetic flux density on the permanent magnet (PM) rotor. In this research, our simulation method was improved so that the 3-dimensional rotational dynamics was taken into account.

DOI: 10.3233/JAE-2002-391

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 127-132, 2002

Authors: Weiland, Thomas | Schuhmann, Rolf

Article Type: Research Article

Abstract: The quality of particle beams depends strongly on the quality of the accelerator. The major components of particle accelerators are beam optics elements such as quadrupole magnets, bending magnets and accelerating structures such as RF-cavities. The numerical field analysis of magnetic elements is well advanced and has become a standard tool in virtually any accelerator design. In this area there is only little progress to report as only in very specialized areas remains some need for …new research. This is however not the case for the design procedures of accelerating structures. With the ever increasing demands for higher energy and very high quality beams the demands for electromagnetic design tools is drastically increasing. In this paper we focus on the latest developments in the area of high precision field computation and discuss new developments for the analysis of parasitic trapped modes. Show more

DOI: 10.3233/JAE-2002-368

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 133-142, 2002

Authors: Kobayashi, T. | Muroya, Y. | Watanabe, T. | Ueda, T. | Yoshii, K. | Uesaka, M. | Katsumura, Y. | Nakajima, K. | Zhu, X.

Article Type: Research Article

Abstract: For a sub-picosecond pump-and-probe-type radiation chemistry work, a new synchronized electron linac and laser system was installed in Nuclear Engineering Research Laboratory (NERL) of University of Tokyo. The new 0.3 TW laser system with a Ti:Sapphire oscillator (795 nm) and amplifiers generate 300 ps pulses at 10 Hz at first. The laser is splitted into the two beams. The first is compressed to 4 ∼ 11 ps so as to drive the RF-Gun and generate a …pump-electron-beam. The second is compressed to 100 fs and used for the probe-light. The drive laser is converted to the third harmonics (265 nm, < 250 μJ). Moreover, a new 15 MW klystron was installed for the linac RF system. The RF power is divided to the gun and the accelerating section. Finally the time jitter between the pump-electron-beam and the probe-laser is designed to be 320 fs (rms). By using the new drive laser system, the charge of 7 nC per bunch was observed at the exit of the gun. Improvement of the vacuum in the gun < 10^{-9} Torr) is most effective to obtain such a high charge beam. After two and a half years operation of the gun, no degradation of QE has been found for the Cu photo-cathode. Show more

DOI: 10.3233/JAE-2002-495

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 143-150, 2002

Authors: Takasago, Kazuya | Yada, Akira | Miura, Taisuke | Washio, Masakazu | Kannari, Fumihiko | Torizuka, Kenji | Endo, Akira

Article Type: Research Article

Abstract: Arbitrary shaping of a sub-milli joule femtosecond pulses has been demonstrated by manipulation of optical frequency phase components on the Fourier plane. The shaped pulses were pulse trains and picosecond square pulses for low emittance electron generation in a RF photocathode. Since the pulse shaping apparatus was placed between an oscillator and a pulse stretcher in order to avoid damage to the liquid crystal spatial light modulator, phase-only modulation was used for shaping to avoid damage …to optical elements in a regenerative amplifier. The phase modulation was designed by simulated annealing optimization method. Show more

DOI: 10.3233/JAE-2002-373

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 151-156, 2002

Authors: Kashiwagi, S. | Hama, Y. | Hara, S. | Ishikawa, H. | Kuroda, R. | Kobuki, T. | Oshima, T. | Sato, K. | Washio, M. | Yada, A. | Urakawa, J. | Hayano, H.

Article Type: Research Article

Abstract: At Waseda University, we have started a new research project named "High-Tech Research Center Project" which is supported by the Ministry of Education, Culture, Sports, Science and Technology. In this project, a laser photo-cathode rf-gun with 1.6 acceleration cells has been installed for production of low emittance and short bunched electron beam. The high quality electron beam is very powerful tool for the study on radiation physics, radiation chemistry, material science etc. Development of pulsed X-ray …generation by the inverse Compton scattering between high quality electron beam and laser pulse obtained from an all-solid-state Nd:YLF laser system will be started in 2001 fiscal year. The system will be applied to the pulse radiolysis experiments for the studies on radiation physics and chemistry. In this paper, we will describe the X-ray generation experiment at Waseda University. Show more

DOI: 10.3233/JAE-2002-388

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 157-162, 2002

Authors: Masuda, Kai | Kii, Toshiteru | Yamaguchi, Tomohiko | Toku, Hisayuki | Yoshikawa, Kiyoshi | Yamazaki, Tetsuo

Article Type: Research Article

Abstract: Aiming at production of high brightness electron beams with longer pulses than several μsec for applications to free electron lasers by use of an RF gun with a thermionic cathode, the adverse effect of back-streaming electrons onto the cathode surface were studied both experimentally and numerically. Temperature rises of the thermionic cathode surface due to the back-streaming electrons were observed directly by use of an infrared thermometer. From the measured temperature rises, powers of the …back-streaming electron beams were, then, evaluated by use of a 0-dimensional model taking into account heat transfer through thermal radiation and thermal contact to the gun body, and comparisons were made with numerical results by use of a 2-dimensional particle-in-cell simulation code we have developed. Both by the experimental evaluation and by the particle-in-cell simulation, the beam power onto the cathode surface was found to increase with the increasing RF input to the RF gun cavities, and reach a considerable power compared to the cathode heater power supply. Show more

DOI: 10.3233/JAE-2002-376

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 163-170, 2002

Authors: Hajima, Ryoichi | Nishimori, Nobuyuki | Nagai, Ryoji | Shizuma, Toshiyuki | Sawamura, Masaru | Kikuzawa, Nobuhiro | Minehara, Eisuke J.

Article Type: Research Article

Abstract: We present recent results and future plans of the JAERI free-electron laser driven by a superconducting linac. These are experimental results of high-power IR lasing, third harmonic lasing, design and construction of energy-recovery system, and future extension to shorter wavelength.

DOI: 10.3233/JAE-2002-375

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 171-175, 2002

Authors: Tanaka, Hirofumi | Pu, Yuehu | Kim, Tae Hyun | Makita, Yo | Tsukishima, Chihiro | Nakanishi, Tetsuya | Nakamura, Shiro

Article Type: Research Article

Abstract: A CW microtron with a 500~MHz RF cavity is proposed for industrial applications. The machine is of a racetrack type. The acceleration energy and the beam power of a prototype machine are 5 MeV and 30 kW, respectively. The RF cavity is a conventional normal-conducting 2-cell cavity with coupling slots. The injection energy is 80 keV, and a 500 MHz CW gun is used. The bending magnets are divided into two subsections to adjust the acceleration phases of …every turn. Beam tracking studies show that the longitudinal phase stable region is more than 20 degrees and the transverse beam stability can be obtained with fringe fields of the bending magnets and two QMs near the RF cavity. Show more

DOI: 10.3233/JAE-2002-380

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 177-184, 2002