1 / 20

Technical Overview of VUV/IR Ring Operation and Design Parameters (1992-2004)

This document presents an intricate overview of the VUV/IR Ring's technical design and operational parameters at the National Synchrotron Light Source (NSLS) set from 1992 to 2004. Managed by Stephen Kramer, the VUV ring began operations in 1982, with X-ray capabilities in 1984, supporting over 2300 users annually. Key aspects include beam dynamics, thermal and microwave instabilities, and the development of far-infrared (FIR) ports and bolometers. Insights into the Collective Synchrotron Radiation (CSR), impedance measurements, and technical challenges faced in achieving stable emission highlight the ring's operational complexity.

cirila
Download Presentation

Technical Overview of VUV/IR Ring Operation and Design Parameters (1992-2004)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CSR Emission Studies in VUV/IR Ring NSLS Stephen Kramer, VUV Ring Manager 1992-2002

  2. Technical Design Parameters NSLS VUV and Xray Light Sources Proposed in 1970’s VUV ops 1982, Xray ops 1984 with >2300 Users/year using >65 beam lines from Far-IR to Hard Xrays VUV /IR Ring Parameters

  3. VUV Period for Achromatic Optics Peak x ~ 1.51 m,Doublet makes βx small in dispersion and large in ID making Touschek lifetime small due to septum edge

  4. IR Developed in 1989  6 in 2004 e bolometer(lHe) UHV Source point Mirror M3 cone chop window MirrorsM1 and M2 lamellargratinginterferometer

  5. FIR Port at end of Dipole U12IR extraction U11/U12/U12IR Two VUV ports ahead of FIR, at 7° and 22° into 45° dipole, ρ = 1.91 m dipole chamber shielding cut-off for CSR and ISR fc ~ 24 GHz or 0.8 cm-1

  6. ~1998 U12IR FIR Beam Saturated Detector

  7. Threshold Current Microwave Instability Bunch length data showed a threshold of 100-120mA for Microwave threshold at 745-800 MeV with Zbb/n ~ 1.8Ω and Spear scaling

  8. Energy Dependence Microwave Instability The microwave threshold based on the Keil-Schnell Criterion

  9. FIR Measurements of Spectra in 2-FIR Interference model for line structure in both ISR and CSR pattern with Δf ~ 1cm-1 spacing in two similar beamlines with different spectra ranges

  10. Reflection from Dipole Chamber Outer Wall Could give a Sin2(2π f Δt) modulation to broadband ISR and CSR spectra ΔL~1cm or frequency spacing ~ 30 GHz Slope =2*sin(/2) ~ 0.4 Zero at ~30 GHz due to 180 degree phase shift at metal boundary

  11. FIR Beam Coupler Has Cut Off ~30GHz Optical coupling to FIR port cuts off below ~30 GHz, 4” beam window available 90° Metal paddle to block FIR beam deflects microwaves down to window (ring VC limits) Dipole chamber cut-off waveguide frequency TE1,0 ~ 2GHz and TM1,1 ~ 4 GHz Microwave measurements confirm CSR peak ~42GHz ~1.4 cm-1 peak “C”, but see two more “A and B” Microwave horns for deflected light

  12. Time Dependence of Peak Signals • B and C are prompt signals from the bunch limited by RF diode ~1GHz BW Revolution time To=170nsec • A signal 60 -100ns wide delayed by ~30-50ns from bunch

  13. Power in Peaks versus Bunch Current • C &B signal linear for Io < Ith • C&B quadratic for Io > Ith • C&B Ey polarization • A signal always quadratic or higher beam impedance P~ I2 * R • A signal unpolarized

  14. A Peak - Wakefield Emission From Bellows Vacuum bellows shield with Cu convolutions 1cm gave calculated beam impedance  RF microwave and charge modulation shows 6.5GHz but ~4GHz at current below Threshold current

  15. Micro-bunching measured with SC Triggering the Streak Camera on the A peak signal yielded consistent micro-structure with 150 psec modulation or 6.5 GHz, no other micro-bunch was significant.

  16. Warnock & Venturini CSR Signal + Interferr. Adding a 0.8cm delay for reflection from outer dipole chamber wall

  17. Interference Pattern from Different Ports U10IR port has only 20° of bend ahead of port not > 23° for Interference pattern from dipole. However pattern from upstream dipole less clear.

  18. FIR Beam Port and Detectors Response

  19. Summary and Status • VUV ring CSR emission above Microwave Instability which scales with energy and α1 • CSR and ISR show interference pattern from outer wall broader than WG modes but related • Shielded ISR and CSR cut-off frequency appears to be ~ 24 GHz but sharp cutoff, allows the 6 GHz wakefield signal to be observed • Wakefield power growth proceeds CSR, shows clear micro-bunching above CSR threshold • FIR users not interested in stable CSR emission but maybe hard to achieve without RF upgrade

More Related