The free-electron laser FLASH is currently in shutdown for an upgrade after which the FLASH1 line shall be fully externally seeded with the full repetition rate that FLASH can provide in burst mode.
After the re-start in August 2025, the superconducting linear accelerator of the FLASH facilities will simultaneously provides electron bunches with up to 1.35 GeV energy for the two independently operating undulator lines.
FLASH1
The new undulator chain of FLASH1 will consist of two modulator and at least six radiator undulators. The former are planar devices with a long period of 84mm, while the latter are based on the APPLE- III design with 35mm period. In order to increase the pulse energy at short wavelengths, three refurbished U32 devices from the former sFLASH experiment will be installed between modulators and radiators. They have a variable gap and are are identical to the U32 undulators used at PETRA III.
The parameters of the FLASH1 undulators are listed below:
|
U32 |
U33 |
|
|---|---|---|
|
minimum magnetic gap (mm) |
9.0 |
9.8 |
|
period length λU (mm) |
31.4 |
33.0 |
|
device length L (m) |
2.0 |
4.0 |
|
number of full periods |
61 |
120 |
|
deflection parameter Kmax |
2.72 |
3.03 |
|
number of devices |
||
|
peak field Bmax (T) |
||
|
max. maganetic load F (kN) |
FLASH2
The second branch FLASH2 contains 12 planar U32 variable gap undulators with a maximum deflection parameter Kmax = 2.81 and 2.5 m length each. In addition, FLASH2 is equipped with a Laserheater and an APPLE3 type afterburner.
The parameters for the FLASH 2 undulators are listed in the table below.
|
ID parameters |
FLASH 1 |
FLASH 2 |
|---|---|---|
|
minimum magnetic gap (mm) |
12.0 |
9.0 |
|
period length λU (mm) |
27.3 |
31.4 |
|
device length L (m) |
4.5 |
2.5 |
|
number of devices |
6 |
12 |
|
peak field B0 (T) |
0.47 |
0.98 |
|
deflection parameter Kmax |
1.17 |
2.81 |
|
max. magnetic load Fmag (kN) |
15 |
