Recent beam transport experiments conducted on the linac driving the FERMI@Elettra free electron laser (FEL) have provided new insights concerning the transverse emittance degradation due to both coherent synchrotron radiation (CSR) and geometric transverse wakefield (GTW), together with methods to counteract such degradation. For beam charges of several 100's of pC, optics control in a magnetic compressor helps to minimize the CSR effect by manipulating the H-function. We successfully extended this approach to the case of a modified double bend achromatic system, opening the door to relatively large bending angles and compact transfer lines. At the same time, the GTWs excited in few mm diameter iris collimators and accelerating structures have been characterized in terms of the induced emittance growth. A model integrating both CSR and GTW effects suggests that there is a limit on the maximum obtainable electron beam brightness in the presence of such collective effects. Copyright © 2013 CC-BY-3.0 and by the respective authors.
Emittance control in the presence of collective effects in the fermi@elettra free electron laser linac driver
Giannessi, L.
2013-01-01
Abstract
Recent beam transport experiments conducted on the linac driving the FERMI@Elettra free electron laser (FEL) have provided new insights concerning the transverse emittance degradation due to both coherent synchrotron radiation (CSR) and geometric transverse wakefield (GTW), together with methods to counteract such degradation. For beam charges of several 100's of pC, optics control in a magnetic compressor helps to minimize the CSR effect by manipulating the H-function. We successfully extended this approach to the case of a modified double bend achromatic system, opening the door to relatively large bending angles and compact transfer lines. At the same time, the GTWs excited in few mm diameter iris collimators and accelerating structures have been characterized in terms of the induced emittance growth. A model integrating both CSR and GTW effects suggests that there is a limit on the maximum obtainable electron beam brightness in the presence of such collective effects. Copyright © 2013 CC-BY-3.0 and by the respective authors.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
