Yue Hao CAD For the eRHIC Team eRHIC linacring EIC LinacERL or the luminosity is negligible The first proposed linacring collider 250GeV p 159 e 15e33 cm2 s1 Why linacring ID: 159387
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Slide1
Accelerator R&D towards eRHIC
Yue Hao, C-AD
For the eRHIC TeamSlide2
eRHIC, linac-ring EIC
Linac=ERL, or the luminosity is negligible
The first proposed linac-ring collider
250GeV (p) *15.9 (e) @1.5e33 cm-2 s-1Why linac-ringLuminosity, remove the limitation of b-b parameter of e-beamHigh spin polarization (e-beam)Easy to upgradeEasier synchronization with various ion energy.
I. Ben-
Zvi
, J.
Kewisch
, J. Murphy and S.
Peggs
, Accelerator Physics Issues in eRHIC, NIM A463, 94 (2001), C-A/AP/14 (2000).Slide3
eRHIC LayoutSlide4
Luminosity
Defined by
P
SR
= 12 MW
Defined by
x
p
= 0.015
Defined by
D
Q
sp
= 0.035Slide5
Beam Synchronization, Detail
Ion at sub-
TeV
energies is not ultra-relativistic, Change in energy velocity
frequency
Linac-ring scheme enable a trick to adjust the frequency of RF to
sychronize
electron and ion at discrete ion energies
Reduces the need of path lengthening.
Ring-ring scheme can not take the trick. Slide6
eRHIC R&D efforts
IR design, crab cavity and
d
ynamic apertureBeam cooling – major R&D efforts, high priority R&DPolarization and Polarimetry (including electron polarimetry
)
Polarized
3
He production and acceleratio
n
Polarized electron source
Superconducting RF system
Multipass
ERL and related beam dynamics
FFAG energy recovery pass
Linac-ring beam-beam interaction......Slide7
NS-FFAG Layout of the eRHIC
Arc #2
#1 7.944 GeV
#2 9.266 GeV
#
3
10.588 GeV
#
4
11.910 GeV
#5 13.232 GeV
#6 14.554 GeV
#7 15.876 GeV
#8 17.198 GeV
#9 18.520 GeV
#10 19.842 GeV
#11 21.164 GeV
Injector 0.012 GeV
Linac 1.322 GeV
Arc #1
#
1
1.334 GeV
#2 2.565 GeV
#3 3.978 GeV
#4 5.300 GeV
#5 6.622 GeV
7.944 – 15.876 GeV
* 21GeV
Design,
Jan'14Slide8
Trajectory in FFAG
2.5819 m
0.90805
m
Half
of
1.09855 m
21.164 GeV
19.824 GeV
18.520 GeV
17.198
GeV
15.876
GeV
14.554
GeV
13.232
GeV
11.910
GeV
10.588
GeV
9.266
GeV
7.944
GeV
θ
D
=3.057567mrad
B
D
=0.1932 T, G
d
=-49.515 T/m
ρD=296.985 m
x(mm)θF=3.699017 mrad
ρF=296.984m
Bf= 0.1932 T, Gf=49.515 T/m
5.02
-7.5
Bmax[-0.178, 0.442 T]
Bmax[-0.013, 0.4215 T]
Other half of QF magnet
28.764 cm-4.61
4.17
28.764 cmHalf of
1.09855 m
QF
BDSlide9
Magnet for FFAG arcsSlide10
Two
alternative
magnets
Permanent
Magnet
Iron
(steel)Slide11
Bunch-by-Bunch BPM
With fewer BPMs than magnets, the space between some FFAG magnets could be used entirely by a BPM; this design produces “stretched” output pulses (from 13 ps rms bunches) intrinsically in the BPM in-vacuum hardware
1.0 ns
1.18
ns = ½
422
MHz
rf
wavelength
= minimum FFAG bunch spacing
long sampling platforms
signal processing: use pair of 2 GSPS ADCs
triggered ~ 200
ps
apartSlide12
Multi-pass FFAG Prototype
There is on-going plan to build a multi-pass FFAG Energy Recovery Linac prototype to prove the principle and the method of detecting and correcting the beam.
Energy of linac ~100MeV
# of passes: ~4Slide13
IR design
Crab-cavities
p
e
Forward detector components
SC magnets
Slide14
IR and DA
10
mrad
crossing angle and crab-crossing
90 degree lattice and beta-beat in adjacent arcs (ATS) to reach beta* of 5 cm
Combined
function triplet with large aperture for forward collision products and with field-free passage for electron beam
Only soft bends of electron beam within 60 m upstream of
IPSlide15
Beam cooling, CEC PoP
Traditional stochastic cooling does not have enough bandwidth to cool intense proton beams (~ 3×10
11
/
nsec
). Efficiency of traditional electron cooling falls as a high power of hadron’s energy. Coherent Electron Cooling has a potential for high intensity beams including heavy ions.
Research Goals:
Develop complete package of computer simulation tools for the coherent electron cooling
Demonstrate cooling of the ion beam
Validate developed model
Develop experimental experience with
CeC
systemSlide16
Gun
Beam
Dump
FEL Section
Helical Wigglers
Low Power
Beam Dump
Flag
ICT
ICT
Flag
Flag
Flag
Linac
Bunching
Cavities
Pepper
Pot
Modulator
Section
Kicker
Section
Parameter
Units
Value
Electron Energy
MeV
21.9
R.M.S. normalized emittance
mm
mrad
5
Peak current in FEL
A
60-100
R.M.S. momentum spread
1.0×10
-3
Charge per bunch
nC
1-5
Parameter
Units
Value
Ion’s Energy
GeV
/u
40
R.M.S. normalized emittance
mm
mrad
2
R.M.S bunch length
ns
1.5
R.M.S. momentum spread
3.5×10
-4
Repetition rate
kHz
78.3
CEC
PoP
, cont’dSlide17
CEC
PoP
, anticipated results
Ion bunch – 2 nsec
Electron bunch – 10
psec
After 60 sec
After 250 sec
After 650 sec
r.m.s. length of the cooled part 80-120 ps. The cooling effects can be observed with oscilloscope 2 GHz or more bandwidth or spectrum analyzer with similar upper frequency
Modeling of cooling is performed
with betacool by A. FedotovSlide18
CEC timeline
CEC
PoP RHIC ramp is developedInjection system
(112
MHz
gun,
500
MHz
buncher)
were installed.Main cavity
(704MHz) is fabricated.Commission injector system
in July 2014
Experiment starts 2015Slide19
Polarized e-source
We
are aiming at a high-current (50 mA), high-polarization electron gun for eRHIC.
The
principle we are aiming to prove is funneling multiple independent beams from 20 cathodes.
External
review was carried out in 2012
.
Next week, first HV conditioning and possibly first beam!Slide20
eRHIC will utilize
five-cell
422
MHz cavities, scaled versions of the BNL3 704 MHz cavity developed for high current linac applications.Stability considerations require cavities with highly damped HOMs.The HOM power is estimated at 12 kW per cavity at a beam current of 50 mA and 12 ERL passes.Apply funding to build prototype.
5-cell SRF cavity
HOM ports
FPC port
HOM high-pass filterSlide21
Crab Cavity
Development of a highly compact Double Quarter Wave Crab Cavity at 400
MHz.
Prototype to be tested in the CERN
SPS in 2016-
2017.
Helium vessel
Cavity
FPC
Input power waveguides
Tuning system
Cryo
jumper
Thermal shielding
(80K – nitrogen)
M
agnetic
shieldingSlide22
ERL test facility
The
BNL
ERL objectives 20 MeV at >100 mA (500 mA capability). Experiment in progress, will see first photo-emission soon.Loop in Oct, 2014, project completes in 2016.
All hardware in house, most installedSlide23
Electron beam disruption
Ion Beam
eSlide24
Summary
There are many on-going simulation and experiment aiming on the challenge port of
eRHIC
.The design now is based on extensive simulations.R&D experiments are on-going, need few years to finish.Slide25
Thank you for your attention!