1. Calibration simulation for 14N5+ ion acceleration regime
7 November 2008
Calibration simulation for 14N5+ ion acceleration regime
E.E. Perepelkin and S.B. Vorozhtsov
JINR, Dubna

2. Field in the axial channel
GL I38
I = 252A, Nturn = 130
Bzmax =3.16 kGs
GL I37
I = 115A, Nturn = 130
Bzmax = kGs
Distribution along OZ axis ( R = 0 m )

3. Beam before buncher Emittance εx = εy = 150 π.mm.mrad
Case 1: β = 5 mm/mrad => Beam radius = 25 mm
Case 2: β = 1 mm/mrad => Beam radius = 12 mm

4. Beam radius 25 mm

5. Emittance before buncher
βx = βy = 5 mm/mrad
1000 particles in 3 period super-bunch

6. Transverse focusing GL I37 GL I38 One period selection 320 particles
Focus point Z = 150 mm

7. Longitudinal focusing
Buncher voltage U = 160 Volt (adjusted to get longitudinal focus at the 1st accelerating gap)
At the inflector entrance
Z = 26.5 mm
At the middle of the 1st acceleration gap
(cyclotron electric field is switched OFF)

8. Central region acceleration
At the 1st gap φRF = - 30°
UDEE1 = 41.2 kV
Uinf = 3.6 kV
fRF = MHz
UDEE2 = 49 kV
Losses 61 % from the buncher to the 4th turn

9. Centering and RF phase Wk = 7 MeV/u
“Spiral structure” is a result of the poor centering due to the asymmetry of the Dee voltages
Wk = 7 MeV/u

10. For geometry courtesy of A. Vorozhtsov
ESD
For geometry courtesy of A. Vorozhtsov
8.2 mm
Wk = 7 MeV/u
Potential electrode
Septum
1 mm
Central trajectory
5.1 mm
4.9 mm
3.7 mm
2 mm

11. For geometry courtesy of A. Vorozhtsov
ESD
Potential electrode
Septum
Central trajectory
For geometry courtesy of A. Vorozhtsov

12. Beam radius 12 mm

13. Emittance before buncher
βx = βy = 1 mm/mrad
1000 particles in 3 period super-bunch

14. Transverse focusing GL I37 GL I38 One period selection 325 particles
Focus point Z = 100 mm

15. Longitudinal focusing
Buncher voltage U = 160 Volt (adjusted to get longitudinal focus at the 1st accelerating gap)
At the inflector entrance
Z = 26.5 mm
At the middle of the 1st acceleration gap
(cyclotron electric field is switched OFF)

16. Central region acceleration
At the 1st gap φRF = - 30°
UDEE1 = 41.2 kV
Uinf = 3.6 kV
fRF = MHz
UDEE2 = 49 kV
Losses 54 % from the buncher to the 4th turn

17. Extraction

18. ESD central trajectory
UESD = 37.6 kV
14N5+
Wk = MeV/u Angle, Pr = 1°
R = mm
Azimuth, φ = 0°

19. Conclusions
Asymmetric dee voltages permit the beam to get through the channel at the 1st turn.
=>Precession of the beam center as a side effect.
There is clear visible the reserve for increasing the beam transmission by additional adjustment of the GLs setting.
Extraction study will be upgraded by introduction of the effects of the harmonic coil and EMC field in the simulations

20. Discussion and question
Inflector voltage 3.6 kV

21. Backup slides
Previous visit

22. Goto-san central trajectory calibration
Goto-san’s
Central trajectory
Theoretical inflector trajectory rotated at -3°
Theoretical inflector trajectory used in CBDA
Goto-san’s
trajectory
CBDA trajectory
Strange

23. Reference particle initial parameters
Case W
MeV/u X mm Y Px
MeV/c Py R Ɵ
deg Pr
degree
Vesd kV
Goto-san
7.02
728
−11
563
1603
−0.866
Word
−11.63
−0.915
18.468
Excel
7.022
727
−0.51 −
727.84
−0.040
2.186
CBDA
Analytical ESD field 1 47 3D
ESD field
37.6

24. Goto-san’s parameters
W = 7.02 MeV/u from Word file
W = MeV/u from Excel file
X = 728 mm, Y = -11 mm from Word file
X = 727 mm, Y = mm from Excel file
PX = 563 MeV/c, PY = 1603 MeV/c from Word file. Arctan(PY/PX) = deg, ( Pr = deg )
From Excel file Arctan(ΔY/ΔX) = 89.2 deg, where ΔX = X1-X0, ΔY = Y1-Y0, ( Pr = deg )

25. CBDA parameters UESD = 47 kV ( obtained )
W = keV ( MeV/u, Excel )
R = mm ( Excel )
Θ = deg ( Excel )
Pr = 1 deg ( obtained )
Mass A = 14
Integration step τ = sec ( ~ 0.78 mm )
Angle between the analytical ESD field and the particle velocity is 90 deg.

26. ΔR(φ) = RCBDA(φ) – RGoto-san(φ)
Comparison
ΔR(φ) = RCBDA(φ) – RGoto-san(φ)
ESD mouth
ESD exit