Simple FEL Power Limit in an ERL

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(Simple) FEL Power Limit in an ERL

• Hywel Owen
• Accelerator Science and Technology Centre

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Energy Spread from an FEL
Before
After
FEL
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Energy Spread at the Dump
Before
After
FEL
Deceleration
Dump
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Illustration 4GLS VUV-FEL Power Limit from
Power Limit at Dump
Power limit probably from power hitting crotch in
first dipole
This is very high! But its the direct power
limit from the dump, does not care about the
bunch repetition rate
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Illustration 4GLS ERL Section (HACL) - Parameters
100mA, 550 MeV, 2 mm-mrad normalised
emittance 4.33 MHz, 77 pC, CW
10 MeV
550 MeV
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Illustration 4GLS FEL Power Limit from Energy
Spread Limit at Dump
About 10?
10 MeV
4.33 MHz (longest realistic cavity)
Power limit probably from power hitting crotch in
first dipole
77 pC
This is all linear but is it true?
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FEL Without Compression/Decompression
FEL
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FEL With Compression/Decompression
FEL
(e.g. David Douglas notes)
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HACL v1.1

• No lasing
• (0 FEL)
• (1D Model)

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HACL v1.1

• Lasing
• 0.5 rms
• (1D Model)

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HACL v1.1

• Lasing
• 0.7 rms
• (1D Model)

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HACL v1.1

• Lasing
• 0.8 rms
• (1D Model)