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feasibility study presented at EPAC08, 23-27 June 08. A single bunch properly tuned can generate THz radiation power via CTR. An optimized set of parameters has been found for the generation of THz radiation downstream the SPARC dogleg and magnetic compressor. A THz radiation source at SPARC.
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feasibility study presented at EPAC08, 23-27 June 08 A single bunch properly tuned can generate THz radiation power via CTR. An optimized set of parameters has been found for the generation of THz radiation downstream the SPARC dogleg and magnetic compressor. A THz radiation source at SPARC A train of micro-bunches produced by the comb beam feature can enhance the THz emitted power with respect to the one bunch case. The work done on the sub-ps high charge disks by the space charge force produces a negative linear energy chirp can be exploited to restore the initial density profile with a magnetic compressor with R56<0 (~ -100 mm).
THz emitted power by a single bunch compared to a train of bunches Power spectrum emitted by a bunch N(1- f(w)) + N2 f(w) incoherent coherent N total number of particles g(x) longitudinal profile f(w) form factor related to the bunch geometry properly spaced bunches enhance the emitted power in the THz range! f(w) for different comb beams N2f(w) for different comb beams
Q=300 pC L= 200 fs R = 1mm Q=120 pC/peak L= 200 fs R = 1mm Single bunch 5 micro-bunches train cathode exit of linac (12 m) exit of compressor longitudinal profile DE vs length longitudinal profile DE vs length Example of comb beam simulation result compared to single bunch The quality of the coherent spectrum emitted by a comb beam is tightly connected both to the electron micro-bunches lengths and to micro-pulses inter-distance The quality of the coherent spectrum emitted by a singlebunch depends on how short we can make it There is still margin of improvement and work is in progress to further optimize all the electron beam parameters to maximize the THz emitted power.
Other exploited cases of comb beam simulations 2 micro-bunches train 3 micro-bunches train Q=300 pC/peak L= 200 fs R = 1mm Q=300 pC/peak L= 200 fs R = 1mm cathode exit of linac (12 m) exit of compressor longitudinal profile DE vs length longitudinal profile DE vs length