Kazuo Huke

Development of Microwave Undulator

A microwave undulator which uses transverse fields of standing microwaves the been operated successfully at the Photon Factory electron linac. The undulator consists of a long rectangular cavity with two ridges. Using a pulsed S-band microwave of 300 kW and a pulsed electron beam, the undulator radiation was observed in the visible region, and the spectral intensities were measured. The equivalent magnetic field and the period are 430 Gauss and 5.5 cm, respectively.

Design of a vertical wiggler with superconducting coils

Abstract A vertical wiggler has been designed, which will be installed in the 2.5 GeV electron storage ring under construction at KEK-PF. The wiggler magnet with superconducting coils produces magnetic fields of 6 T and wiggles electron beams in a vertical plane. Synchrotronn radiation generated by the wiggler has a critical wavelength of 0.5 A and has an electric field-vector in the vertical direction, which is very important for precise experiments in various fields of the material sciences. The wiggler consists of three pairs of superconducting coils, an iron magnetic shield, a beam pipe and a liquid helium cryogenic system and is contained in a vacuum vessel which can move up and down together with the wiggler. During the injection time, the vessel is pushed up, so that electron beams with a large spatial spread go through the lower part of the beam pipe, where the aperture of the beam pipe is large enough. After the beam size becomes small due to radiation damping, the vessel is pushed down so that the electron beams go through the narrow gap of the wiggler magnet. Using the iron magnetic shield with iron pole pieces, the ratio between the magnetic field in the gap and the maximum field on the superconductor coils is reduced to 1.1.

Correlation between the Movement of the Light Source Building and the Vibration of the Synchrotron Radiation Axis

The vertical movement of the tunnel floor on which the magnets of the 2.5-GeV electron storage ring are installed was measured at twelve locations. The data were analyzed regarding frequency components in the range between 0.7 and 50 Hz. All of the frequency components were compared with those of the measured vibration of the synchrotron-radiation axis. It was found that the vibration of the synchrotron-radiation axis had frequency components ranging between 14.5 and 50 Hz, caused by tunnel-floor vibration which was excited by the severn air-conditioners installed in the light-source building as well as a refrigerator and an evacuation system, both of which were being used for the superconducting wiggler.

One-Third Resonance Extraction from INS AG Electron Synchrotron

Slow beam extraction from the INS-AG electron synchrotron was done by using a one-third resonance of the betatron oscillation. A current strip was used to change the number of the radial betatron oscillation per revolution from 2.25 to 7/3 and to enlarge the amplitude of the oscillation. The extracting beam orbit was analysed using an approximate Hamiltonian which has a separatrix represented by three straight lines and the result was in good agreement with that pursued by a computer. The properties of the extracted beam were as follows; The efficiency was 50% for electrons of 300 MeV up to 1 GeV. The maximum beam intensity was 4×1011 electrons per second. The maximum duty cycle was 3%. Phase volumes for the horizontal and the vertical motions were 10-3 rad cm and 0.75×10-3 rad cm, respectively. The beam transport system and the radiation shielding system are also described.

2.5 GeV electron storage ring construction at KEK-PF

Abstract A 2.5 GeV electron storage ring fully dedicated to synchrotron radiation researches is being constructed at KEK-PF, Synchrotron Radiation Center (Photon Factory), National Laboratory for High Energy Physics (KEK). The storage ring has an ellipse shape, the diameter of which is 68 m (long) and 50 m (short). The critical wavelength of synchrotron radiations generated from bending magnets is 2.98 A. The storage ring has eight medium straight sections and two long straight sections. In the first stage of the Photon Factory Project, a vertical wiggler magnet with superconducting coils was set in one of the medium straight sections. The wiggler magnet produces 6 t fields and generates intense synchrotron radiations with the critical wavelength of 0.5 A. As a whole, users take advantage of intense synchrotron radiations whose wavelength ranges from 0.1–1000 A. This means that studies of matters at the atomic and molecular level can be done in many scientific fields. The accumulating electron beam is expected to be 500 mA and the total radiation power 260 kW. In the second stage of the project, two long straight sections and four medium straight sections will be used for new devices in the synchrotron radiation facility.

Voltage Programming of Radio Frequency Accelerations in an Alternating Gradient Proton Synchrotron

The condition that RF buckets of radio frequency accelerations in synchrotrons have always no empty space by virtue of the adiabatic damping of phase oscillations, is obtained by calculating the action integral of phase oscillations. This analysis is applied to make an RF voltage programming which minimizes the maximum RF voltage and RF powers for the 12 Bev AG proton synchrotron of a high repetition rate. The behaviors of phase oscillations in the neighbourhood of the transition energy in this scheme of RF accelerations are also analysed and discussed.

Photon factory: status in 1986

The Photon Factory (PF) consists of a 2.5 GeV electron storage ring, a full energy injector linac and experimental facilities, and has been operated steadily in the third fiscal year 1985 since it was opened as a national synchroton light source in June 1983. The linac has served as the injector of the Photon Factory Ring and the 6 GeV Accumulation Ring of TRISTAN. The light source, 2.5 GeV-electron storage-ring has been running steadily after overcoming various types of instabilities and a lifetime more than 8 hr was achieved for a storage current of 200 mA and 300 mA with and without the vertical wiggler, respectively. The users experiments started with 8 beam lines (25 experimental stations) in 1983. In addition to commissioning two beam lines in 1985, now, two new beam lines are under construction and two are under design. In collaboration with outer organizations, five beam lines are in operation or under construction.

Electron Beam Extraction from INS AG Synchrotron. Part I. Theory

The theoretical basis for the electron beam extraction from the INS 0.75 GeV AG synchrotron is given. The method is essentially a Piccioni scheme in which the beryllium absorber target and two cascade kicker magnets are used. The extraction efficiency is calculated from the properties of the accelerated beam of the accelerator, the energy and angular distribution of the particles after passing through the absorber and the characteristics of betatron oscillations of the electrons in the guide field containing two pulse magnetic fields and the fringing field of the synchrotron magnet. The efficiency is found to be about 40% at most.

Electron Beam Extraction from INS AG Synchrotron. Part II. Experiment

The electron beam has been extracted from the INS 750 MeV AG synchrotron. A Piccioni scheme was applied and the extraction efficiency obtained was 10% at the electron energy of 540 MeV and 5% at 700 MeV. The behaviour of the beam inside and outside of the synchrotron was studied in comparison with the theoretical analysis. The pulse duration of the extracted beam could be extended to the order of 700 µs without any difficulty for the 21.5 cps operation of the synchrotron.

POLE FACE WINDINGS IN THE TODAI AG ELECTRON SYNCHROTRON

Pole face windings were applied to the Todai AG electron synchrotron to avoid an integral resonance line of betatron oscillations and increase the energy of accelerated electrons which would be lost at 98 MeV. Magnetic fields produced by the pole face windings were calculated by the use of a linear transformation and of an image method, and wee compared with the value measured to give good agreements. The locus of the frequency of the betatron oscillations in the stability pattern was also analysed when the pole face windings were applied, and was compared with experiments. With a rather small power supply, the electron energy of 135 MeV has been obtained.