Electron beam profile measurements and emittance manipulation at the MAXlaboratory
(1997) Abstract
 The emittances of the electron beams at the MAXlaboratory accelerator system have been studied. Apart from the buildup of the diagnostic tools for precise determination of the beam spatial profiles, the objectives have been: a) to verify the accelerator design emittances at low currents and to try to determine the emittances also at high currents; b) to investigate possibilities to manipulate the emittances. The method for emittance determination was optical measurements of the electron beam profiles. Then, by different means the accelerator lattice functions were estimated at the observation point. From this knowledge and from measurements of the synchrotron frequency, the emittances in all three dimensions were determined.
... (More)  The emittances of the electron beams at the MAXlaboratory accelerator system have been studied. Apart from the buildup of the diagnostic tools for precise determination of the beam spatial profiles, the objectives have been: a) to verify the accelerator design emittances at low currents and to try to determine the emittances also at high currents; b) to investigate possibilities to manipulate the emittances. The method for emittance determination was optical measurements of the electron beam profiles. Then, by different means the accelerator lattice functions were estimated at the observation point. From this knowledge and from measurements of the synchrotron frequency, the emittances in all three dimensions were determined.
As a consequence of the desire to determine very low transverse emittances, a theoretical model for the emission and focusing of synchrotron radiation had to be employed. A model based on classical electrodynamics and waveoptics was chosen. The accuracy of this model was partly verified in the visible region, by measurements at low circulating currents in the MAXII storage ring at injection energy. Simultaneously, the measurements gave indications of a possibility to measure transverse emittances even below 20 pm rad.
Both the MAXI and MAXII storage rings were found to reach the expected natural horizontal emittances. The vertical emittance at low currents, which elucidates to which accuracy the ring magnetic elements are aligned, was in MAXI / MAXII measured to be 300 pm rad / 50 pm rad, respectively. At high currents, an increased energy spread was the main source of beam quality dilution in both rings if no countermeasures were taken. The introduction of a short period, narrow gap undulator into MAXI did not bring about any beam quality deterioration.
The MAXI lattice was tuned towards small momentum compaction values, and by controlled beam energy changes the emittances were manipulated such that an rms bunch length of less than 1 mm was reached at low currents. Second order theory accounted well for the observed horizontal and longitudinal beam profiles. The lattice of MAXII was chosen to give a finite dispersion in the long straight sections, which allowed the natural horizontal emittance to be decreased about a factor of two compared to the dispersionfree case. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/29536
 author
 Andersson, Åke ^{LU}
 opponent

 Dr Hofmann, Albert, CERN, CH1211 Geneva 23, Switzerland
 organization
 publishing date
 1997
 type
 Thesis
 publication status
 published
 subject
 keywords
 optics, quantum excitation, emittance, synchrotron radiation, electron beam, lattice, Accelerator, storage ring, diffraction, Physics, Fysik
 pages
 130 pages
 publisher
 MAXlab, Lund University
 defense location
 sal B Fysiska Institutionen
 defense date
 19971017 10:15
 external identifiers

 Other:ISRN: LUNTDX/NTMX1003SE
 ISBN
 9162826867
 language
 English
 LU publication?
 yes
 id
 ea20e921a4754dea91597ea4cbf8ad38 (old id 29536)
 date added to LUP
 20070613 09:09:03
 date last changed
 20160919 08:45:13
@misc{ea20e921a4754dea91597ea4cbf8ad38, abstract = {The emittances of the electron beams at the MAXlaboratory accelerator system have been studied. Apart from the buildup of the diagnostic tools for precise determination of the beam spatial profiles, the objectives have been: a) to verify the accelerator design emittances at low currents and to try to determine the emittances also at high currents; b) to investigate possibilities to manipulate the emittances. The method for emittance determination was optical measurements of the electron beam profiles. Then, by different means the accelerator lattice functions were estimated at the observation point. From this knowledge and from measurements of the synchrotron frequency, the emittances in all three dimensions were determined.<br/><br> <br/><br> As a consequence of the desire to determine very low transverse emittances, a theoretical model for the emission and focusing of synchrotron radiation had to be employed. A model based on classical electrodynamics and waveoptics was chosen. The accuracy of this model was partly verified in the visible region, by measurements at low circulating currents in the MAXII storage ring at injection energy. Simultaneously, the measurements gave indications of a possibility to measure transverse emittances even below 20 pm rad.<br/><br> <br/><br> Both the MAXI and MAXII storage rings were found to reach the expected natural horizontal emittances. The vertical emittance at low currents, which elucidates to which accuracy the ring magnetic elements are aligned, was in MAXI / MAXII measured to be 300 pm rad / 50 pm rad, respectively. At high currents, an increased energy spread was the main source of beam quality dilution in both rings if no countermeasures were taken. The introduction of a short period, narrow gap undulator into MAXI did not bring about any beam quality deterioration.<br/><br> <br/><br> The MAXI lattice was tuned towards small momentum compaction values, and by controlled beam energy changes the emittances were manipulated such that an rms bunch length of less than 1 mm was reached at low currents. Second order theory accounted well for the observed horizontal and longitudinal beam profiles. The lattice of MAXII was chosen to give a finite dispersion in the long straight sections, which allowed the natural horizontal emittance to be decreased about a factor of two compared to the dispersionfree case.}, author = {Andersson, Åke}, isbn = {9162826867}, keyword = {optics,quantum excitation,emittance,synchrotron radiation,electron beam,lattice,Accelerator,storage ring,diffraction,Physics,Fysik}, language = {eng}, pages = {130}, publisher = {ARRAY(0xb9697e0)}, title = {Electron beam profile measurements and emittance manipulation at the MAXlaboratory}, year = {1997}, }