MYRRHA Injector Design

(1)

MYRRHA Injector Design

Horst Klein

Dominik Mäder, Holger Podlech, Ulrich Ratzinger,

Alwin Schempp, Rudolf Tiede, Markus Vossberg, Chuan Zhang

(2)

(3)

Injector Part

(4)

ECR Ion Source

•

Pantechnik Monogan M-1000

•

20 mA capable

•

45 kV capable

•

emittance measurement

(Allison scanner) included

•

delivery and installation I-2013

ε

_rms

: 0.1 - 0.15 π mm mrad

(requested)

(5)

LEBT Design & Space-Charge Compensation

0.12 T

0.15 T

L

total

=2.3m

Courtesy of J.-L. Biarrotte

(6)

LEBT Beam Dynamics

(7)

Injector Part

300kW 41kW 47kW ∑=388kW

94kW 16kW 20kW ∑=130kW

ε=0.2 0.22 0.27π mm mrad

(8)

4-Vane Structure vs. 4-Rod Structure

(9)

RFQ Rp Values vs. Frequency

R

p

~

f

-1.5

Plot source: MAX_Deliverable_2.1.

(10)

CH-DTL Shunt Impedance

(11)

Why change the frequency from 352MHz

(EUROTRANS) to 176MHz (MAX)?

For all RFQs: the value of Rp=U

2

/P is increasing by a factor of ~2.5.

Nevertheless the best choice for f≥300MHz is the 4-vane RFQ. The

low frequencies allow the use of the simple 4-rod RFQ, which has

some advantages: the chain of



/4 resonators are strongly coupled,

resulting in a stable longitudinal field, so for example only 2 plungers

are needed for a 4m long RFQ. The outer conductor plays a small

role, so it can have a lid, which allows a direct access to the

electrodes for mounting and repair, increasing the reliability and

availability. It has a compact size, low weight, is relatively easy to

manufacture at low cost. And it can be built in a rather short time. Its

application allows to reduce the injection energy into the CH-linac to

1.5MeV, which reduces the overall power consumption considerably.

(12)

Parameter

EUROTRANS

MAX

SARAF (H+)

f [MHz]

352

176

I [mA]

5

Win / Wout [MeV]

0,05 / 3

0,03 / 1.5

0,02 / 1.5

U [kV]

65

40

32,5

Es, max / Ek

1,1

1

0,8

amin [mm]

2,3

2,9

2,7

mmax

1,8

2,3

2,7

gmin [mm]

2,6

3,6

3,7

ε

_int., n., rms

[π mm‐mrad]

0,2

0,175

ε

_outt., n., rms

[π mm‐mrad]

0,21 / 0,20

0,22 / 0,22

0,19 / 0,19

ε

_outl., rms

[π keV‐deg]

109

64,6

36

L [m]

4,3

4

3,8

T [%]

~100

95,5

T

_10mA

[%]

~100

92,3

Rp [kΩm]

61 (MWS)

67 (after

SARAF)

67 (meas.)

Pc [kW]

300 (MWS, +20%)

94

60

RFQ parameters for EUROTRANS & MAX

See Chuan Zhang’s

talk for more details

Exp.: 85% @1mA

65% @4mA

(13)

Several improvements of the RFQ were necessary to

fulfill the MYRRHA requirements (CW operation,

high reliability and availability)

Complete new design of the RFQ structure (e.g. outer conductor,

stems inserted from bottom) by A. Schempp, Lit.: Overview of Recent

RFQ Projects, Proc. LINAC08, MO302, p.41-43. Together with A.

Bechtold (NTG): New methods for production of stems and

electrodes, higher precision (~15



m), an improved cooling system,

new techniques for production of cooling channels (milling and

galvanic copper plating, new rf contacts at the tuning plates, better

alignment).

(14)

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RFQ Test Section

Length [mm]

532 (432)

Stem distance [mm]

97

Electrodelength [mm]

342

Beam axis [mm]

145

Frequency [MHz]

176

Quality factor

4900

Tuner (diameter) [mm]

40

45 mm 40 mm

30 mm

(17)

Surface Current

Power: 25 kW/m (design)

Power Test RFQ: 12 kW

Thermal losses: 8 kW

(simulated)

(18)

Stems with the new coolingsystem design (NTG)

Because of the thermal

losses, a very good

water cooling system is

required to hold the

frequency steady during

cw-operation.The new

cooling system of the

stem is split into two

paths. Booth sides of

the stems are well

cooled. In addition the

stems have a channel

for

the

electrode

(19)

(20)

(21)

Flow rate measurement (stems)

y = -0.0025x2_{+ 0.055x + 0.0344} 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0 2 4 6 8 F low r ate [l/s ec ] Pressure [bar]

Flow rate [l/sec] Poly. (Flow rate [l/sec])

Reynolds Number

4700

8100

11400

16100

18800

19400

20800

Pressure[bar] Flow rate [l/sec] Water speed [m/s]

0,8 0,07 1,04 1,6 0,12 1,73 2,9 0,17 2,48 4,9 0,24 3,45 6,2 0,28 3,96 6,9 0,29 4,20 7,6 0,31 4,40

(22)

Expansion measurement

accuracy 10



m

T [°C] x [mm]} y [mm] z [mm] T ΔT x1 x2 Δx Δy1 Δy2 z1 z2 Δz 20,7 0 95,54 205,52 109,98 - - 181,11 156,17 24,94 30 9,3 95,52 205,52 0,02 0,01 0,01 181,11 156,16 0,01 40 19,3 95,52 205,54 0,04 0,02 0,02 181,13 156,18 0,01 50 29,3 95,52 205,55 0,05 0,04 0,03 181,15 156,19 0,02 Expansioncoefficient [mm/°C*m] 1,7*10-5 _0,5*10-5 _3,0*10-5 Lit: 1,6*10-5

(23)

Pressure [bar] Coolingwater in [°C] Coolingwater out [°C] Copper Temperature [°C] Thermal bath [°C] 1,7 19 21,5 27,6 70 3 19 20,65 26 70 5,2 19 20,2 24,5 70 6,5 19 20 23,8 70 7,6 18,7 19,65 23,5 70

Thermal measurement

dm/dt [l/sec]] c [J/(kg*K]] DT [°C] P [W] 0,12 4182 2,5 1261 0,17 4182 1,65 1220 0,25 4182 1,2 1268 0,28 4182 1 1197 0,30 4182 0,95 1223

Power losses for a single Stem: 1350 W

→

D

T

_K

= 1,05 °C (for 7,6 bar)

(24)

Thermal measurements on a single stem

Different temperatures during the measurement. The stem was cooled down to nearly

water temperature after 30 seconds with a water flow rate of only 0.08 l/s at a water

pressure of 1 bar.

(25)

Thermal simulation with cooling

(26)

(27)

(28)

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(30)

(31)

(32)

(33)

Injector Part

300kW 41kW 47kW ∑=388kW

94kW 16kW 20kW ∑=130kW

ε=0.2 0.22 0.27π mm mrad

(34)

CH-DTL parameters for EUROTRANS & MAX

EUROTRANS

MAX

V

_eff

L

_cell

ß

_avg

E

_a

V

_eff

L

_cell

ß

_avg

E

_a

[MV]

[m]

[MV/m]

[MV]

[m]

[MV/m]

RB1

0.19

0.07

0.08

2.79

0.15

0.10

0.06

1.56

RT1

1.16

0.40

0.09

2.91

1.03

0.54

0.06

1.92

RT2

1.30

0.50

0.10

2.59

1.14

0.66

0.08

1.74

RB2

0.47

0.09

0.10

5.23

0.53

0.36

0.09

1.44

SC1

2.54

0.63

0.11

4.00

3.50

0.86

0.10

4.06

SC2

3.22

0.81

0.14

3.99

3.98

0.99

0.13

4.00

SC3

3.74

0.94

0.16

3.99

4.18

1.07

0.16

3.91

SC4

3.76

1.05

0.18

3.57

4.09

1.07

0.18

3.83

(35)

Transverse Beam Envelopes along the CH-DTL

See Chuan Zhang’s

talk for more details

(36)

Prototype cavity presently under

construction

RF test up to 40 kW/m

Parameter

CH-1

CH-2

Unit

Frequency

176

MHz

Duty factor

100

%

Z

_eff

113

100

M

W

/m

U

_eff

1.03

1.14

MV

P

_c

16.5

18.5

kW

CH-1

(37)

Test Results SC CH-Prototype

(38)

CH3

CH4

CH5

CH6

Parameter

Unit

SC-CH-1

SC-CH-2

SC-CH-3

SC-CH-4

Frequency

MHz

176.1

Gap number

---

10

9

8

7

Aperture Diam.

mm

30

40

Average

b

---

0.102

0.131

0.157

0.178

L

_tot

mm

916

1060

1129

1127

E

a

MV/m

3.88

3.71

3.59

3.47

U

_a

MV

3.55

3.93

4.05

3.91

(39)

Bellow Tuner

Static Tuners

Helium Vessel

Coupler Flanges

(40)

Parameter Unit CH-1 Beta 0.059 Frequency MHz 216.816 Gap number 15 Total length mm 687 Cavity diameter mm 409 Cell length mm 40.82 Aperture mm 20 Ua MV 3.369

Energy gain MeV 2.97 Accelerating gradient MV/ m 5.1

Ep/ Ea 6.4

B_p/ E_a mT/ (MV/m) 5.4

R/ Q Ω 3320

Static tuner 9

Dynamic bellow tuner 3

Main parameters of the 217 MHz CH-structure

Construction has started

3D-view of the 217 MHz cavity with helium vessel, without tuners

Helium vessel

Coupler flange

Pickup flange

Inclined

end stem

Tuner flange

Preparation

flange

217 MHz CH-Cavity