FEL1

FEL1

Beam
Energy	12–25 MeV
Undulator
period (λu)	65 mm
no. periods	42
no. poles	84+2
gap (range)	22.6–110
KRMS (range)	0.4–2.08
undulator type	PPM
magnet type	SmCo

FELIX-1, or FEL1, is the far-infrared or long-wavelength beam line of FELIX operating from 30–140 µm.

Spectral Range vs. Beam Energy

Please complete whenever data is available

Beam Energy [MeV]	Min [µm]	Max [µm]	Min [cm-1]	Max [cm-1]	Max pulse width [µs]	Max power [mJ@µm]
16.9	80	150	65	260	12	20 @ 90
17.7	-	-	-	-	12
18	-	-	-	-	12
19	33	110	91	303	12	28 @ 42
19.6	28	111	90	360	12	45 @ 42
20.5	34	100	100	294	12	range needs verification
22	28	66	151	360	12	range needs verification
26	18	33	300	555	?	65 @ 24

Parameters

Cavity Mirrors

Upstream

The default upstream mirror is M5. For long wavelengths, one of the stronger focussing mirrors M2 or M3 may be selected.

Mirror	Range (µm)	Offset (µm)
M1 -	-	-
M2 R=2400	> 120	95
M3 R=2650	> 90	260
M4 -	-	-
M5 R1=R2	< 110	0

Downstream

Check the table for a proper downstream mirror. Mirrors with larger holes will have smaller gain (and therefore slower rise of the optical pulse), but will emit more light at larger wavelengths.

Mirror	Range (µm)	Offset (µm)
M1 4mm R=2250	> 90	310
M2 5mm R=2250	> 100	170
M3 2mm	20–40	150
M4 3mm	30–70	20
M5 4mm	50–110	0

The position of the cavity zero detuning length should be -840 µm from the positive limit for mirror combination M5/M5. N.B. on 2022/07/11 the cavity zero was +480 µm more than it should have been according to these values. To be checked on the next occasion.

Undulator

See feluc.

Pure Permanent Magnet (entirely made up of magnets, i.e. not hybrid)

Free-Electron Laser for Infrared eXperiments