Key Parameters of Undulators Operated at PETRA III

At the 6 GeV storage ring PETRA III, DESY presently operates 19 independent insertion device (ID) beamlines. The straight sections of the ring can accommodate either one 5m long insertion device or two canted 2m devices. The standard undulators have a length of 2 m and their typical period length ranges from 29 mm to 33 mm. Several special IDs of up to 5 m length have been installed to meet the experimental requests for high energy X-rays (U21, U23), elliptically polarized light (UE65), and a higher degree of coherence. The key parameters of these devices are listed in the table below (I=100mA). Details on individual beamlines using these undulators can be found on the webpages of the PETRA III project and its extension.

 

U29

U32

U33

U23

UE65*

U29 5m

U36 10m

IVU21

minimum magnetic gap (mm)

9.5

9.5

9.5

9.5

11.0

9.5

12.5

7.0

period length λU (mm)

29.0

31.4

32.8

23.0

65.6

29.0

36.0

21.2

device length L (m)

2

2

2

2

5

5

2 x 5

4

number of full periods

67

61

58

84

72

168

2 x 137

185

peak field B0 (T)

0.81

0.91

0.88

0.61

1.03

0.81

0.72

0.76

deflection parameter Kmax

2.2

2.7

2.7

1.3

6.3

2.2

2.4

1.49

energy of 1st harmonic (keV)

3.5

2.4

2.3

8.0

0.3

3.5

2.5

7.8

total power Ptot (kW)

3.0

3.8

3.5

1.7

11.8

7.5

2 x 5.9

5.2

on-axis power dens. (kW/mrad²)

76

80

75

71

0.17

190

2 x 143

200

power in 1x1 mm² at 40 m (W)

47

49

46

44

0.1

119

2 x 88

122

*circularly polarized mode