120222;MAX Deliverable 2.1 CZipn · 0.05MeV and 3MeV to 0.03MeV and 1.5MeV, respectively. 4) The transition‐energy between the warm CH‐DTL part and the cold one has been accordingly

DELIVERABLE Number 2.1

352 MHz vs. 176 MHz

Injector Comparison & Choice

Authors:

Chuan Zhang, Horst Klein, Dominik Mäder, Holger Podlech,

Ulrich Ratzinger, Alwin Schempp, Rudolf Tiede, Markus Vossberg

First reporting period: 01/02/2011 – 31/07/2012

Date of issue of this report: 31/01/2012

Start date of project : 01/02/2011 Duration : 36 Months

MAX(Contract Number 269565)

[MAX] (D‐2.1) – 352 MHz vs. 176 MHz ‐ Injector Comparison & Choice Dissemination level: PU Date of issue of this report: 31/01/2012

DISTRIBUTION LIST

Name Comments

BAYLAC Maud, CNRS BIARROTTE Jean‐Luc, CNRS BOULY Frédéric, CNRS/TED BOUSSON Sébastien, CNRS BRUCKER Romain, EA DARGES Bernard, TED DE GERSEM Herbert, KUL ESSABAA Saïd, CNRS FERNANDEZ RAMOS Pedro, EA GARBIL Roger, EC GARDES Daniel, CNRS JUNQUERA Tomas, ACS KALININE Amélie, CNRS KLEIN Horst, IAP MARTIN‐SANCHEZ Juan, ADEX MASSCHAELE Bert, KUL NEVADO Antonio, ADEX PERROT Luc, CNRS PIERINI Paolo, INFN PIRES Rui, FE‐UCP PODLECH Holger, IAP ROGGEN Toon, KUL SAUGNAC Hervé, CNRS SIERRA Serge, TED SPYROU Smaragda, CNRS URIOT Didier, CEA VANDEPLASSCHE Dirk, SCK●CEN ZHANG Chuan, IAP

E‐copy of the document

[MAX] (D‐2.1) – 352 MHz vs. 176 MHz ‐ Injector Comparison & Choice

3

TABLE OF CONTENTS

1. INTRODUCTION ................................................................................................................... 4

2. FROM EUROTRANS TO MAX: NEW DESIGN CONCEPTS FOR THE INJECTOR …….................. 6

2.1. 352 MHz vs. 176 MHz .................................................................................................. 6

2.2. Other Major Changes ……………………………………............................................................ 8

3. THE RFQ ACCELERATOR ……………………………......................................................................... 9

3.1. Design and Simulation Results ..................................................................................... 9

3.2. Simulation Based on the LEBT Output Distributions ................................................. 12

3.3. Error Studies ………………………………………………………….................................................. 15

4. THE CH‐DTL PART ……………................................................................................................. 16

4.1. Design and Simulation Results ................................................................................. 16

4.2. Error Studies ………………………………………………………….................................................. 19

5. CONCLUSIONS …................................................................................................................. 21

6. REFERENCES ...................................................................................................................... 23


4

1. INTRODUCTION

Launched by the European Commission in 2005 and ended in 2010, EUROTRANS [1] was a

EUROpean research programme for the TRANSmutation of high level nuclear waste in an

accelerator driven system. As a successor of the EUROTRANS project, MAX [2], the so‐called

MYRRHA Accelerator eXperiment research and development programme, has been started in

2011 and will continue until 2014.

Different than EUROTRANS which was a pure research project, MAX is pursuing not only to

continue the R&D studies but also to deliver an updated consolidated design for the real

construction including prototyping and demonstration in Mol, Belgium.

Table 1: Specifications of the required proton beams for EUROTRANS & MAX.

Parameter EUROTRANS

XT‐ADS

EUROTRANS

EFIT MAX

Operation (Design) intensity [mA] 2.5 – 4 ( 5 ) 20 ( 30 ) 2.5 – 4 ( 5 )

Output energy [MeV] 600 800 600

Beam trip number >1s: <5 per 3‐month operation cycle >1s: <3 per year >3s: <10 per 3‐month

operation cycle

Beam stability (on target) Energy: ± 1 %, Intensity: ± 2 %, Beam Size: ± 10 %

Beam time structure CW, with 200μs zero‐current holes at 1 Hz repetition frequency

The specifications of the required proton beams for EUROTRANS (including both XT‐ADS

and EFIT phases) & MAX are listed in Table 1, where the most demanding requirement is that

the beam trips (i.e. the beam interruptions on the target) with “long” duration periods (in

the order of second) have been restricted to very small amounts, because such beam trips

will cause serious thermal stress and fatal damages to the sub‐critical core. These beam‐trip

limits are two or three orders of magnitude lower than typical values found with existing


5

accelerators [3], so the primary concern for the design of the EUROTRANS or MAX driver

linac is how to ensure such extremely high reliability.

In the table it’s also seen that, except the slightly different beam‐trip limit all other beam

specifications for MAX are identical to those for XT‐ADS. Therefore, it has been decided that

the layout of the driver linac for MAX will follow the reference design made for the XT‐ADS

phase of the EUROTRANS project. Fig. 1 shows the schematic plots of the driver linacs for

both EUROTRANS and MAX. It can be seen that the required MAX accelerator is very similar

to that for the XT‐ADS phase of EUROTRANS, except the linac front end.

Figure 1: The driver‐linac layout for EUROTRANS and MAX.

During the EUROTRANS project, a 352MHz, 17MeV, and upgradeable 5‐30mA injector,

which consists of one RFQ accelerator, two RT (room‐temperature) CH (Cross‐bar H‐mode)‐

DTL (Drift‐Tube Linac) cavities, and four SC (superconducting) CH‐DTL cavities, was designed

and successfully accepted as the reference design by the project [4]. As shown in Fig. 1, the

MAX injector will use the basic layout design from the EUROTRANS one, but some new

design strategies and approaches, e.g. different resonant frequency and different type of the

RFQ structure, have been proposed and applied to reach a more reliable CW operation at

reduced costs [5].

In this deliverable, the 352MHz injector designed for EUROTRANS and the 176MHz one for

MAX are compared in detail.


6

2. FROM EUROTRANS TO MAX: NEW DESIGN CONCEPTS FOR THE INJECTOR

From EUROTRANS to MAX, some requirements have been changed. Cooled by liquid Pb‐Bi

eutectic, the MYRRHA reactor will have a thermal power of ~80MWth in the ADS mode. The

core geometry is optimized for an impinging proton beam energy of 600 MeV. Based on

these data, it is found that the required beam intensity varies between 2.5 and 4 mA,

depending on the burnup of the nuclear fuel [6]. Therefore, only 5mA will be taken as the

design beam intensity, and the higher design intensity, 30mA, is not an option any more.

Besides, the main differences for the linac front end are [5]: 1) The resonant frequency was

lowered by a factor of 2, i.e. from 352MHz to 176MHz. 2) The 4‐vane RFQ structure is now

replaced by the 4‐rod one. 3) The input and output energies of the RFQ were reduced from

0.05MeV and 3MeV to 0.03MeV and 1.5MeV, respectively. 4) The transition‐energy between

the warm CH‐DTL part and the cold one has been accordingly dropped to 3.5MeV.

2.1. 352 MHz vs. 176 MHz

The most important change in the injector design is that the resonant frequency is lowered

from 352MHz to 176MHz. The considerations for this change are as follows:

The main point is the fact, as indicated in Fig. 2, that the shunt impedance of an RFQ, Rp, is

roughly proportional to f ‐1.5. Therefore, a major advantage for adopting a half resonant

frequency is that the RF power consumption can be considably reduced.

The lower frequency also enables the use of the 4‐rod RFQ structure instead of the

originally proposed 4‐vane one. Fig. 3 compares these two kinds of mainstream RFQ

resonant structures. The 4‐vane structure works in the TE‐mode and its RF properties are

determined not only by the vanes but also by the cavity wall, while the 4‐rod one is actually a

chain of λ/4 resonators and its inner structure is almost independent to the cavity wall. The

pros and cons of the 4‐vane RFQ are that it has relatively even RF power density and could be

easily cooled, but it will have a large radial size at frequencies ≤200MHz and the construction

and tuning are relatively complicated and expensive due to very tight tolerances. In case of

the 4‐rod RFQ, it could always have a compact radial size and an easy construction, tuning,


7

and even repair, but its local RF power density is typically ~2 times higher. At frequencies

higher than 300MHz, the 4‐vane structure is certainly the best choice for CW operation, but

at 176MHz, the 4‐rod structure is more attractive.

Figure 2: A survey of Rp values for RFQ accelerators (the original plot with the data marked in

black is from [7]; in [8], the data marked in blue was added; the data marked in green are

newly added, where the value for the IFMIF‐EVEDA RFQ was kindly provided by Dr. A. Pisent).

Figure 3: RFQ resonant structures.


8

2.2. Other Major Changes

As the test facility in Mol will be operated with beam intensities up to 4 mA, only 5mA will

be taken as the design intensity. Consequently, the inter‐vane voltage could have a drop from

65kV to 40kV in order to further reduce the RF power per length by ~40%.

The length of the RFQ could be kept constant by lowering the input and output energies by

40% and 50%, respectively. The 4m long structure which allows to use only one tank is in

principle similar to the SARAF RFQ [9] which can be operated in CW mode with much higher

power (more than 180kW) than we need for the MAX RFQ.

For the CH‐DTL, the input energy is now lowered from 3MeV to 1.5MeV. Though it brings

some difficulties to the beam dynamics design, it is favorable from the cavity design point of

view: 1) The effective shunt impedance Zeff which is roughly proportional to ß‐1 (see Fig. 4) is

increased by ~30%, which saves RF power as well as makes the cooling easier. 2) It could

compensate the cell length growth caused by the lowered frequency. Actually, the new

frequency is also helpful for the CH‐cavity design. For example, the first cell of the first RT‐CH

was lengthened from 3.4cm to 4.8cm, which provides more space for the field flatness

tuning.

Figure 4: RF power efficiency of multi‐cell structures [10, 11].


9

As in the EUROTRANS case, the two RT‐CHs will also cover an energy gain of 2MeV, but

both at 34% lower accelerating gradients Ea for further reducing RF power. In the new design,

the triplets have been moved further into the cavities (85mm instead of 35mm), which will

not only lead to a better field flatness but also save the drift space. In total, this part will be

still maintained compact.

The four SC‐CHs have been decided to keep working at Ea≈4MV/m. They will take over

some additional energy gain which was cut in the RFQ, so the total length will be somewhat

longer. However, only a 5mA beam will be fed into the MAX injector, so some focusing

elements from the previous design e.g. the 2nd rebuncher cavity and two solenoids could be

removed. Totally, the whole CH‐DTL part is even shorter. Moreover, the new SC‐CHs have

much less gaps, which makes the construction work (e.g. welding) easier and cheaper.

3. THE RFQ ACCELERATOR

Same to the EUROTRANS case, the beam dynamics design of the MAX RFQ was based on

the New Four‐Section Procedure (NFSP) [12, 13], an efficient design method for modern

RFQs, while the beam transport simulation was also performed with the PARMTEQM code

[14] using 105 input macro‐particles.

3.1. Design and Simulation Results

In Table 2, the detailed design and simulation results at 5mA for both the EUROTRANS RFQ

and the MAX RFQ are presented. For a good comparison, the corresponding parameters of

the SARAF RFQ for accelerating protons are also listed in the table. Obviously, from

EUROTRANS to MAX, the transmission and transverse output emittances are still very similar,

but the longitudinal output emittance is decreased considerably. In addition, the Kilpatrick

factor is now only 1, well below 1.8, a safe value proven by the LEDA RFQ for CW operation

[15]. And the minimum gap between electrodes is enlarged by 1mm. Both results are

favorable for leading to a very reliable CW operation. Generally speaking, the MAX RFQ has

quite similar main RF and geometric parameters to the built SARAF RFQ, so the Rp value

measured from the latter, 67 kΩm, could be used as a reference and we could easily estimate


10

that the RF power of the former is 23.5kW/m. The SARAF experiments have shown that for

one 8‐hour CW operation at 40kW/m only two beam trips (in the order of ms) happened and

the reached power record for CW operation is 50kW/m [16]. Therefore, it’s clear that the

MAX RFQ design is very reliable.

Comparing the EUROTRANS 4‐vane RFQ with the MAX 4‐rod RFQ, it should be aware of

course that the lower frequency would also be a corresponding advantage for the 4‐vane

RFQ, but would require a very bulky, heavy, and expensive cavity.

Table 2: RFQ parameters for EUROTRANS & MAX.

Parameter EUROTRANS@5mA MAX SARAF (H+)

f [MHz] 352 176 176

I [mA] 5 5 5

Win / Wout [MeV] 0.05 / 3 0.03 / 1.5 0.02 / 1.5

U [kV] 65 40 32.5

Es, max / Ek 1.7 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

εint., n., rms [π mm‐mrad] 0.2 0.2 0.175

εoutt., n., rms [π mm‐mrad] 0.21 / 0.20 0.22 / 0.22 0.19* / 0.19*

εoutl., rms [π keV‐deg] 109 64.6 36*

L [m] 4.3 4.0 3.8

T [%] ~100 ~100 95.5*

T10mA [%] ~100 ~100 92.3*

Rp [kΩm] 61 (MWS) 67 (after SARAF) 67 (meas.)

Pc [kW] 300 (MWS, +20%) 94 60

* Simulated by A. Bechtold using the RFQSim code (no image effects or multipole effects).


11

At 5mA, the beam tranport plots for both the EUROTRANS RFQ and the MAX RFQ are

compared in Fig. 5.

Figure 5: Beam transport plots of the EUROTRANS (top) and MAX (bottom) RFQs.


12

3.2. Simulation Based on the LEBT Output Distributions

Fig. 6 shows two versions of the LEBT (Low Energy Beam Transport) section designed by

J.‐L. Biarrotte for the MAX project [17].

Figure 6: Schematic layouts of the MAX LEBT (top: short version, bottom: long version) [17].

For the design of the MAX RFQ, a 4D‐Waterbag distribution was used. By taking the

output particle distributions from both short and long LEBT versions as the input

distributions, new RFQ simulations were performed. Fig. 7 and Fig. 8 show that the input and

output distributions at the beginning and at the exit of the RFQ for the different cases,

respectively.


13

Figure 7: RFQ simulation results based on the short LEBT (top: transient, bottom: nominal).


14

Figure 8: RFQ simulation results based on the long LEBT (top: transient, bottom: nominal).


15

Table 3 summarizes the beam performance with different input distributions. It can be

seen that the beam‐loss situation and the transverse emittance growths are still very

satisfying in all cases. Induced by the wing‐form halo particles from both LEBT designs, all

output longitudinal emittances are somewhat bigger, but still acceptable.

Table 3: RFQ beam performance with different input distributions.

Parameter 4D‐WaterbagShort LEBT

transient

Short LEBT

nominal

Long LEBT

transient

Long LEBT

nominal

εint., n., rms [π mm‐mrad] 0.20 0.18 0.16 0.14 0.14

εoutx., n., rms [π mm‐mrad] 0.22 0.20 0.17 0.17 0.15

εouty., n., rms [π mm‐mrad] 0.22 0.20 0.16 0.17 0.15

εoutl., rms [π keV‐deg] 64.6 92.4 92.7 108 80

T [%] 100 99 98.5 98.2 98.6

3.3. Error Studies

The error studies have been carried out for the MAX RFQ with respect to seven input

parameters: the intensity, emittance, inter‐vane voltage, Twiss parameters, energy spread,

and spatial displacement, respectively. Table 4 gives the error settings, while Fig. 9 shows the

lowest transmission is higher than 97% in all tested cases.

Table 4: Error study settings and results of the MAX RFQ.

Parameter Start value End value Design value Step length Tmin [%]

Iin [mA] 0.5 9.5 5 1.5 99.9

εint., un. [π cm‐rad] 0.006 0.024 0.015 0.003 99.6

U [%] 97 103 100 1 99.8

Twiss α 0.28 1.48 0.88 0.2 97.9

Twiss ß [cm/rad] 2.48 5.48 3.98 0.5 97.5

ΔW [%] 2 12 0.0 2 ~100

δx [mm] 0.1 0.6 0.0 0.1 99.5


16

Figure 9: Transmission as a function of test step for different input parameters.

4. THE CH‐DTL PART

Same to the EUROTRANS case, the beam dynamics design of the MAX CH‐DTL was based

on the KONUS method [18], while the beam transport simulation was also performed with

the LORASR code [19]. Besides, the RF structure design was made using the MWS software.

4.1. Design and Simulation Results

In Table 5, the detailed design and simulation results at 5mA for both the EUROTRANS

CH‐DTL and the MAX CH‐DTL are compared. And in Fig. 10, the first room‐temperature CH

cavities and the first superconducting CH cavities of the EUROTRANS CH‐DTL and the MAX

CH‐DTL are shown.


17

Table 5: CH‐DTL parameters for EUROTRANS & MAX.

EUROTRANS MAX

Veff Lcell ßavg Ea Veff Lcell ßavg Ea

[MV] [m] [MV/m] [MV] [m] [MV/m]

RB1 0.19 0.07 0.08 2.79 0.12 0.10 0.06 1.25

RT1 1.16 0.40 0.09 2.91 1.03 0.54 0.06 1.91

RT2 1.30 0.50 0.10 2.59 1.14 0.66 0.08 1.72

RB2 0.47 0.09 0.10 5.23 – – – –

SC1 2.54 0.63 0.11 4.00 3.50 0.87 0.10 4.02

SC2 3.22 0.81 0.14 3.99 3.98 1.01 0.13 3.94

SC3 3.74 0.94 0.16 3.99 4.18 1.07 0.16 3.89

SC4 3.76 1.05 0.18 3.57 4.09 1.07 0.18 3.82

Figure 10: 1st RT CH cavities (left) and 1st SC CH cavities (right)

for EUROTRANS (top) [20] and MAX (bottom) [21].


18

Figure 11: Beam transport plots of the EUROTRANS (top) and MAX (bottom) CH‐DTLs.


19

In Fig. 11, the maximum transverse beam sizes along the accelerating channel are plotted

for EUROTRANS and MAX, respectively. In both cases, a large safety margin is available. At

the exit of the MAX injector, the phase spread is ~15° (1.36cm) and the energy spread is

~300keV. In the acceptance plot of the 17MeV, 352MHz Spoke cavity provided by J.‐

L. Biarrotte [22], it can be seen maximally a ~0.6ns (3.44cm) long beam with an energy

spread of ±300keV can be accepted.

4.2. Error Studies

Error studies have been also performed for the MAX CH‐DTL. Randomly generated by the

LORASR code, the introduced lens and cavity errors are Gaussian distributed and truncated at

the 2σ‐width within the ranges given in Table 6, where QMIS, QROT, VERR, and PERR are

indicating transverse lens offset errors, lens rotation errors, tank / gap voltage errors, and

tank phase errors, respectively.

Table 6: Error settings for the MAX CH‐DTL.

Error Type Error Settings

QMIS [mm] ΔX, ΔY =±0.1

QROT [mrad] Δφx, y=±1.5, φz=±2.5

VERR [%] ΔUgap=±5, ΔUtank=±1

PERR [°] ΔΦtank=±1

The common transverse beam envelopes for 100 non‐ideal CH‐DTLs and the additional rms

emittance growths caused by the above‐mentioned errors are plotted in Fig. 12 and Fig. 13,

respectively. Not only no beam loss has been observed, but also it’s clear that the beam

quality at the end of the injector is still kept good. The maximum additional rms emittance

growths for the x, y and z planes are only 8%, 12% and 15%, respectively.


20

Figure 12: Common transverse beam envelopes with (red) and without (green) errors for the

MAX CH‐DTL.

Figure 13: Additional emittance growths caused by errors for the MAX CH‐DTL.


21

5. CONCLUSIONS

Fig. 14 shows the schematic layouts of both the 352MHz EUROTRANS injector and the

176MHz MAX injector together (scaled in length). In the RFQ part, the 4‐vane structure is

now replaced by a shorter 4‐rod cavity. In the CH‐DTL part, now some focusing elements i.e.

the 2nd rebuncher cavity and two solenoids are removed, the triplets are inserted more

deeply into the room‐temperature CH cavities, and steerer and diagnostics are now included.

The beam properties at the end of the injector allow transfer into the 352MHz Spoke cavities

and further acceleration in the main linac. As a result of all above‐mentioned new design

concepts and changes, the new layout is even 0.8m shorter at half the frequency.

Figure 14: The 17MeV injectors for EUROTRANS (top) and MAX (bottom).

An overview of the RF power consumption of the main RT cavities for the EUROTRANS and

MAX injectors is given in Fig. 15, where the value for the 4‐vane RFQ was given by the MWS

software with a safety margin of 20%, that for the 4‐rod RFQ was estimated using the


22

measured shunt‐impedance of the SARAF RFQ, 67kΩm [16], and those for the RT‐CHs were

obtained from MWS with a safety margin of 15%. Clearly, the total power consumption for

the warm part is considerably reduced, and more important that all power losses for the

MAX injector are well below 30kW/m, much lower than 50kW/m, a safe value for reliable

CW operation proven by the SARAF RFQ [16].

0

50

100

150

200

250

300

350

400

450

RFQ RT-1 RT-2 Total

EUROTRANS, Copper Power [kW]

MAX, Copper Power [kW]

EUROTRANS, Copper Power per Length [kW/m]

MAX, Copper Power per Length [kW/m]

Figure 15: RF power consumption of the main RT cavities.

To sum up, the new injector will have:

• A safer CW operation

o Lower power density (<<50kW/m).

o Greatly reduced sparking risk in the RFQ by increasing the minimum gap

between electrodes from 2.6mm to 3.6mm and decreasing the inter‐vane

voltage from 65kV to 40kV.

o Less components, so less error sources.

• Still good beam performance

o No beam losses.

o Small emittance growths.

• Reduced costs

o 4‐rod RFQ structure (easy construction, installation, tuning …).


23

o Lower copper power (cheaper RF sources & operation, easy cooling).

o Less focusing elements.

o Less gaps in the cold part (easier and cheaper welding).

o Shorter layout.

All above‐mentioned results have shown that the new design concepts and approaches,

especially to use 176MHz as the resonant frequency, will lead to a not only cost‐saving but

also more reliable injector for CW operation while keeping the beam dynamics performance

satisfying.

6. REFERENCES

[1] http://nuklear‐server.ka.fzk.de/eurotrans/.

[2] http://ipnweb.in2p3.fr/MAX/.

[3] N. Pichoff, H. Safa, “Reliability of Superconducting Cavities in a High Power Proton Linac”,

Proceedings of the 7th European Particle Accelerator Conference, Vienna, Austria, pp.

2049‐2051 (June 26‐30, 2000).

[4] C. Zhang, M. Busch, H. Klein, H. Podlech, U. Ratzinger, J.‐L. Biarrotte, “Reliability and

Current‐Adaptability Studies of a 352MHz, 17MeV, Continuous‐Wave Injector for an

Accelerator‐Driven System”, Phys. Rev. ST ‐ AB 13, 080101 (2011).

[5] C. Zhang, H. Klein, D. Mäder, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede, “From

EUROTRANS to MAX: New Strategies and Approaches for the Injector Development”,

IPAC’11, San Sebastian, Spain, pp.2583‐2585 (September 2011).

[6] Dirk Vandeplassche, Jean‐Luc Biarrotte, Horst Klein, Holger Podlech, “The MYRRHA

Linear Accelerator”, Proceedings of the 10th International Topical Meeting on Nuclear

Applications of Accelerators, Knoxville, USA (April 3‐7, 2011).

[7] A. Schempp, Habilitationsschrift, Frankfurt University (1990).

[8] T. Sieber, PhD Thesis, Frankfurt University (2001).

[9] P. Fischer, PhD Thesis, Frankfurt University (2007).

[10] U. Ratzinger, Habilitationsschrift, Frankfurt University (1998).

[11] H. Podlech, Habilitationsschrift, Frankfurt University (2008).


24

[12] C. Zhang, Z.Y. Guo, A. Schempp, R.A. Jameson, J.E. Chen, J.X. Fang, “Low‐Beam‐Loss

Design of a Compact, High‐Current Deuteron Radio Frequency Quadrupole Accelerator”,

Phys. Rev. ST ‐ AB 7, 100101 (2004).

[13] C. Zhang, A. Schempp, “Beam Dynamics Studies on a 200mA Proton Radio Frequency

Quadrupole Accelerator”, Nucl. Instrum. Methods Phys. Res., Sect., A, Volume 586, Issue

2, pp.153‐159 (2008).

[14] K.R. Crandall, LANL Internal Report, Nr. LA‐UR‐96‐1836 (Revised December 7, 2005).

[15] L.M. Young, “Simulations of the LEDA RFQ 6.7MeV Accelerator”, Proceedings of the

1997 Particle Accelerator Conference in Vancouver, B.C., Canada, pp. 2752‐2754 (May

12‐16, 1997).

[16] Discussions with Dr. A. Bechtold, NTG, Germany.

[17] J.‐L. Biarrotte, “MYRRHA LEBT Preliminary Design Report” (July 18, 2011).

[18] U. Ratzinger, R. Tiede, “Status of the HIIF RF Linac Study Based on H‐Mode Cavities”,

Nucl. Instrum. Methods Phys. Res., Sect., A, Volume 415, pp.229‐235 (1998).

[19] R. Tiede, G. Clemente, H. Podlech, U. Ratzinger, A. Sauer, S. Minaev, “LORASR Code

Development”, Proceedings of the 10th European Particle Accelerator Conference in

Edinburgh, Scotland, United Kingdom, pp. 2194‐2196 (June 26‐30, 2006).

[20] F. Dziuba, Diplom Thesis, Frankfurt University (2010).

[21] Dominik Mäder, Horst Klein, Holger Podlech, Ulrich Ratzinger, Markus Vossberg, Chuan

Zhang, “Development of CH‐Cavities for the 17 MeV MYRRHA‐Injector”, Proceedings of

the 2nd International Particle Accelerator Conference in San Sebastian, Spain, pp.2571‐

2573 (May 4‐9, 2011).

[22] J.‐L. Biarrotte, private communication.

Documents

120222;MAX Deliverable 2.1 CZipn · 0.05MeV and 3MeV to 0.03MeV and 1.5MeV, respectively. 4) The transition‐energy between the warm CH‐DTL part and the cold one has been accordingly