Dynamically self-optimized beam distributions at the UCLA Pegasus laboratory: Linearity of transverse and longitudinal phase spaces
✍ Scribed by P. Musumeci; J. Moody; R.J. England; J.B. Rosenzweig; T. Tran
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 441 KB
- Volume
- 593
- Category
- Article
- ISSN
- 0168-9002
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✦ Synopsis
In this paper we present preliminary experimental results of the recently proposed idea to generate ideal uniformly filled ellipsoidal beam distributions in an rf photoinjector by cathode illumination with a very short laser pulse (35 fs rms) and subsequent expansion under the beam's own space-charge forces. The great interest for uniformly filled ellipsoidal beam shapes derives from the electromagnetic fields associated with such charge distributions, which depend linearly on the bunch coordinates, thus allowing a perfectly linear, emittance-growth free transport. At the UCLA Pegasus laboratory, where the experiment was performed, we used an X-band deflecting cavity as an electron streak camera to visualize directly on a fluorescent screen the longitudinal beam profiles and verify the space-chargedominated beam expansion. The transverse quality of the bunch was then characterized by a pepper-pot technique, yielding emittance values close to the thermal limits. The measured phase spaces, both transverse (reconstructed from the emittance measurement) and longitudinal (directly measured using the deflecting cavity on a dispersion screen), are also presented.