Extraction Scenarios of CIS

Zhengzheng Liu Mar 12th, IUCF

Pulse from linac Extracted beam

Kicker 1

Lambertson septum

Kicker2

Shut down during extraction

Some Parameters in extraction

• • • • Extraction requirement estimation: (1) 13 turns injection scheme (horizontal tune 1.72) (2) 5 mm septum thickness (3) 60 MeV injection and extraction energy • Total energy delivered to the target in pulsed mode: • Assuming linac current 0.5 A, inject 40ns electron beam per turn. with 13 turn accumulation, we obtain

Q

 0 .

5

A

 40

ns

 13  260

nC Energy



QE

 260

nC

 60

MV

 15 .

6

J

Accumulated beam after injection

• After multi-turn injection, we will carry out single-turn extraction. Below is the accumulated beam at the septum right after the last injection turn.

0.015

0.01

0.005

-0.01

0.01

0.02

0.03

-0.005

-0.01

Electrostatic kicker for extraction

The injection and extraction share the same section in the ring. Beam size is about 50 mm . So we need to bump the closed orbit by 47 mm in order to kick the whole beam into the septum.

x’ 5mm 25mm 25mm x 8mm 

x co = 47mm



x co

(

s

)  2  sin (

s

)   2

i

  1 

i



i

cos     (

s

)  

i

 

k

 36

mrad

Closed orbit bumped for extraction

Kicker field and aperture requirement



k

 36 .

6

mrad

orbit bump. Using electrostatic kicker: 

k



c E

 

B L

 and

B

  0 .

2 [Tm] for 60 MeV extraction Thus we get E L=2.2 [MV/m] [m] for 60 MeV extraction. If assume 50mm kicker length, displacement within the kicker are: Kicked beam θ k beam 

x co



x co

  tan( 0 .

006 / 2 )  1 .

5 13th injection turn.



x co

turn).



L

 tan( 0 .

036 / 2 )  9

mm

at extraction (after 13th injection



x

 1 .

75

Aperture requirement for kicker 2 44

mm horizontal aperture is enough for the 2 nd kicker.

0.02

0.01

13th injection turn at the entrance of the second kicker.



x co = 1.5mm.

0.01

0.02

-0.01

-0.01

During extraction, kicker is shut down, so the phase space at the kicker location is like

Aperture requirement for kicker 1 After 12 th injection turn, we shut down kicker 2. Thus, the 13 th injection turn phase space at the kicker 1 entrance requires –x aperture to be at least 26mm

.

0.015



x co

 9

mm

at the exit 0.01

0.005

-0.025

-0.02

-0.015

-0.01

-0.005

-0.005

-0.01

-0.015

-0.02

0.005

0.01

Total horizontal aperture required : 52mm

Vertical Lambertson extraction magnet

The vertical Lambertson septum is used to extract beam vertically.

Injection Extraction

Septum

0.81m

35  35  35 

1.15m

1.15m

0.2m

We put the septum in the middle of the drift space where  (kick  sept.)   / 2 .



z

' 

B x B



l

we choose 

z

'  35  deflected by the septum to avoid the next element.

Septum strength and aperture

x 35   z z • For 60 MeV extraction,

B



B

   0 .

0834 [

Tm

] 0 .

2 [

Tm

]

B x B x

  0 .

25 [

T

] 0 .

61 [

T

] the 50mm horizontal beam size, we need 50mm and 1cm vertical aperture.

horizontal aperture