Compact Four Mirror Laser Wire System for Quick Measurement of Electron Beam Profile (original) (raw)
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Development of Four Mirror Pulsed Laser Wire System
2011
We are developing a four mirror Laser Wire beam profile monitor at KEK-ATF to measure a low-emittance electron beam in the damping ring. At present, CW Laser Wire has been used to measure the small emittance beam. If we replace it to pulsed laser wire, more efficient laser-beam collision can be realized. Four mirror resonator reduces the sensitivity to the misalignment of mirrors comparing to two mirror resonator. The aim of this project is to make a compact and stable pulsed laser wire system which achieves beam size less than =5 m in tangential plane. We report the development and performance studies of such type of compact four mirror laser wire system in this paper.
Development on Pulsed Laser Wire for Measurement of Beam Profile
2014
Production and handling of low emittance beam is important technology for linear colliders. For the view point of high energy experiments, luminosity and energy of collider is very important. So damping ring generates low emittance beam by radiation damping process. The advent of laser based beam profile monitor has increased the scope of studying low emittance beam dynamics. An Accelerator Test Facility (ATF) was built at KEK in hope of developing techniques for the low emittance beam. It consists of an electron linac, a damping ring in which beam emittance is reduced and an extraction line. The damping ring has two arc sections and two straight sections. 4 pm –rad vertical emittance was already confirmed by CW laser wire monitor at the ATF damping ring. The main goal of ATF damping ring was production of 10 pm-rad emittance beam stably with multibunch beam of 210 mA. In the damping ring at ATF, vertical beam size is less than 10 μm. For emittance measurement we are developing a ne...
2013
The Accelerator Test Facility (ATF) was constructed at KEK to study low emittance beam physics and to develop the technologies associated with it. In ATF damping ring, electron beam size is measured with laser wire system based on Compton scattering. A new four mirror laser wire system is developed for this purpose. This system has many advantages over two mirror laser wire system. Four mirror resonator reduces the sensitivity towards misalignment as compare to two mirror resonator. Measured Finesse of resonator is more than 4000. Optical cavity has enhancement factor of 1900. Inside ATF damping ring, electron beam has very small size of 10 in vertical direction. To measure electron beam profile, very thin laser beam size is needed. Laser waist size, around 6 in sagittal plane is achieved in between two concave mirrors. Special type of mirror alignment scheme is used to make a compact four mirror optical cavity. Laser resonator is designed to work in vacuum environment with a comple...
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2013
The aspect ratio is important when constructing a compact resonator with a very small beam waist of less than 5 mm. The total cavity length of a four-mirror resonator is matched according to the pulse repetition of mode-locked laser oscillator. Minimum beam waist is obtained in the sagittal plane using an IR pulsed laser. The advantage of such types of compact four-mirror-resonators is the total scanning time for measurement of the beam profile is much shorter in comparison to a CW laser wire system. By using a pulsed green laser that has been converted to the second harmonics from an IR pulsed laser, a minimum beam waist that has half the beam waist when using an IR laser oscillator can be obtained. Therefore, it is possible to obtain the beam waist of less than 5 mm (s value) that is required for effective photon-electron collision. We report on the development and performance studies for such types of compact fourmirror laser wire systems.
Measurement of an electron beam size with a laser wire beam profile monitor
Physical Review Special Topics - Accelerators and Beams, 2001
We describe the first measurement of an electron beam size in the accelerator test facility damping ring at KEK with a laser wire beam profile monitor. This monitor is based upon the Compton scattering process of electrons with a laser light target, which is produced by injecting a cw laser beam into a Fabry-Pérot optical cavity. We have observed clear signals of the Compton scattered photons and confirmed that the observed energy spectrum as well as the count rate agree with the expected ones. From the measurement, we have deduced the vertical beam size s b to be 9.8 6 1.1 6 0.4 mm, where the first (second) error represents statistical (systematic) uncertainty. Various improvements are in progress to enhance the signal-to-noise ratio, which is essential for the detailed study of the beam dynamics.
Development of a Laser Wire Beam Profile Monitor (I)
1999
A conceptual design work and a basic experimental study of a new beam profile monitor have been performed. The monitor will be used to measure emittance of an electron beam in the ATF damping ring at KEK, in which the transverse beam size of about 10 micron is expected. It utilizes a CW laser and an optical cavity, instead of
Characterization of Laser-plasma Accelerated Electron Beam for a Compact Storage Ring
2015
A compact radiation source can be utilized by an electron beam from a Laser-plasma acceleration combined with localized shielding in a small laboratory. The stability of synchrotron radiation in wavelength and power depends on the shot-to-shot jitters of the energy and charge of an electron beam, which is strongly influenced by the plasma density of target and the jitters of a laser beam. With the 30 TW fs laser in KAERI, the optimization for generating the electron beam have done using the different shape of gas nozzle. We also present the pointing stability of the laser-accelerated electron beams.
Measurement of a small vertical emittance with a laser wire beam profile monitor
Physical Review Special Topics - Accelerators and Beams, 2002
We describe in this paper a measurement of vertical emittance in the Accelerator Test Facility (ATF) damping ring at KEK with a laser wire beam profile monitor. This monitor is based on the Compton scattering process of electrons with a laser light target which is produced by injecting a cw laser beam into a Fabry-Perot optical cavity. We installed the monitor at a straight section of the damping ring and measured the vertical emittance with three different ring conditions. In all cases, the ATF ring was operated at 1.28 GeV in a single bunch mode. When the ring was tuned for ultralow emittance, the vertical emittance of " y 1:18 0:08 10 ÿ11 mrad was achieved. This shows that the ATF damping ring has realized its target value also vertically.
Physical Review Special Topics - Accelerators and Beams, 2003
We present the measurement results of electron beam emittance in the Accelerator Test Facility damping ring operated in multibunch modes. The measurements were carried out with an upgraded laser wire beam profile monitor. The monitor has now a vertical wire as well as a horizontal one and is able to make much faster measurements thanks to an increased effective laser power inside the cavity. The measured emittance shows no large bunch-to-bunch dependence in either the horizontal or vertical directions. The values of the vertical emittance are similar to those obtained in the single-bunch operation. The present results are an important step toward the realization of a high-energy linear collider.