PROPOSAL 2006 - G.I.A.F. (HYBRID GUN AT HIGH FREQUENCY) · 1 hybrid structure 61.0 KEuro 2...
Transcript of PROPOSAL 2006 - G.I.A.F. (HYBRID GUN AT HIGH FREQUENCY) · 1 hybrid structure 61.0 KEuro 2...
PROPOSAL 2006 - G.I.A.F.(HYBRID GUN AT HIGH FREQUENCY)
INFN-LNF – UNIVERSITY OF ROME “LA SAPIENZA”- UCLA
• D. Alesini (T), M. Ferrario (R), A. Gallo (T), F. Marcellini (T), V.Fusco (art. 23), B. Spataro (T) (Resp. Naz.)
• LNF Full Time Equivalent 1.5 (1.3 tecnologist – 0.2 researcher)
• L. Ficcadenti (D), M. Esposito (AU), M. Migliorati (R), A.Mostacci (consultant), L. Palumbo (PO)
• University of Rome Full Time Equivalent 1.2 (0.6 tecnologist –0.6 researcher)
• J. Rosenzweig(PO)• UCLA Dept. of Physics and Astronomy Full Time Equivalent
1.0 (R)TOTAL FTE 3.7
HYBRID GUNELECTROMAGNETIC DESIGN
AND RF MEASUREMENTS
2) DESIGNED STRUCTURES:
a) Integrated accelerating structure;
b) Integrated velocity bunching (acceleration+longitudinalbunch compression);
3) POSSIBLE MEASUREMENTS ON PROTOTYPES
1) THE HYBRID STRUCTURE: ADVANTAGES
SW 1.6 Cell Gun
Input Cell
Emittance-CompensatingSolenoids
Cathode
TW structure
Input Port
1) THE HYBRID STRUCTURE
1) Eliminate transient reflection associated with SWstructures (especially needed for X-band);
2) Compactness:-simplicity (RF distribution system, etc.)
-energy efficiency from TW section
3) Promising good beam dynamics in term of beamemittance and reachable bunch length (velocitybunching)
1) THE HYBRID STRUCTURE: ADVANTAGES
2) DESIGNED STRUCTURES: GENERAL CONSIDERATIONS
The steps to design the structure are the following:
a) “Separate” tuning of the SW and TW sections in order to achieve a uniform fieldflatness of the E field in the SW gun and a zero reflection coefficient at the waveguideinput port of the TW section at the working frequency of the whole system;b) Final tuning of the whole structure to put the SW section perfectly on resonancewith a uniform field flatness of the E field in the first two cells;
1) the phase of the E field betweenthe SW gun and the TW sectiondoes not depend on the geometry ofthe input coupler cell, irisdimensions,… and is about 90 deg.This results has been found by 3Delectromagnetic simulations and hasbeen justified with an equivalentcircuit model;
2) the coupling iris aperturebetween the input coupler cell andthe SW structure allows adjustingthe ratio beween the amplitude ofthe fields in the SW cells and in theTW section: in particular if weincrease the radius we increase thisratio;
RESULTS (S-Band Case)
E.M. field characteristics @ gun resonance
Input coupler cell
∼90 deg
Ez(z,t)=E0(z)cos(ph(z)+ωt)
π Mode of the gun
4) Since the phase between the SWstructure and the TW one is fixed, thesynchronism between the acceleratingfield and the bunch passage can beadjusted by properly chosing thelenght of the input coupler cells.It is therefore possible to design twodifferent structure:-the first one obtainded choosing Dc=2/3λ in which the beam is accelerated inboth structures SW gun and and TWsection;-the second one obtained by choosingDc=5/12λ in which the bunch isaccelerated in the SW section andlongitudinally compressed (velocitybunching technique) in the TW one;
Dc
3) for reasonable values of thecoupling iris (that gives a ratiobetween the amplitude of the fields upto 5) the perturbation on thematching of the input couplerwaveguide is completely negligible.
0.5deg/kHz
Integrated velocity bunching (1/2)
Amplitude of the E fieldalong the structure (E0(z))
Phase (ph(z)) of theelectric field along thestructure: the sensitivity ofthe phase with respect tothe resonant frequency ofthe SW structure requiresvery good stabilization ofthe temperature or an RFfeedback
Ez(z,t)=E0(z)cos(ph(z)+ωt)
Eacc
z z
Inputcoupler
Outputcoupler
Traveling wave structure
zbunch
Integrated velocity bunching (2/2)
EaccEacc
Integrated velocity bunching dimensions
ac
bc
dc
t
ab
d
aw bw/2
w/2
hbf
bh
df
dh
tg
tc
ag
35.2w
12.5ag
41.67bh
31.49dh
41.7bf
52.48df
19.05tg
72.14bw
30.21aw
2h
34.99d
42.89b
16a
8t
43.74dc
40.93bc
19.05tc
9[mm]
ac
Integrated accelerating structure dimensions
ac
bc
dc
t
ab
d
aw bw/2
w/2
hbf
bh
df
dh
tg
tc ag
33.3w
12.5ag
41.67bh
31.49dh
41.7bf
52.48df
19.05tg
72.14bw
36.09aw
2h
34.99d
42.89b
16a
8t
69.98dc
40.53bc
19.05tc
9[mm]
ac
3) RF MEASUREMENTS
Steele method (C.W. Steele, IEEEtrans. on micr th. and tech., 1965)is applicable to SW and to TWstructures separately;
Difference between the reflection atthe input port with and without theperturbing object at z longitudinalposition
Pertubing objects
Hybrid gun NA
( ) ( ) ( )zph22
011
j
e ezEKzS!="
z
( )zS11
PARMELA simulationsInput Beam Parameters:
Q=1 nCLTW=3 m
T0 =10 psecRb=1.57 mmφ0=40 deg
Magnetic field
Energy gain and Momentumspread evolution
Bunch length and Transversebeam size evolution
Emittance evolution
<4<2<2<2Rms norm. emittance [µm]400100800100Peak Current [A]1.50.31.00.1Energy Spread [%]2250180220Energy [MeV]331212Total Length [m]
RFCompr.
NormalRFCompr.
NormalModeHYBRID (S Band)SPARC (S Band)
Work planning
20071 Design of the hybrid structure at 3 GHz (velocity bunching);2 Construction of a prototype at 3 GHz with no cooling and brazing for the
measurements at room temperature; beam dynamic simulation ;3 Some tests for brazing on some cells.20081 Design of the hybrid structure at 11 GHz (velocity bunching);2 Construction of a prototype at 11 GHz with no cooling and brazing for the
measurements at room temperature; beam dynamic simulation ;3 Tests for brazing on some cells.20091 Design of a hybrid structure at 11 GHz included the cooling system;2 Construction of a brazed hybrid structure and measurements at room
temperature;3 High power tests for structures at 3 GHz and 11 GHz
Estimates costs2007 Costs ( 3 GHz)1 hybrid structure 61.0 KEuro2 waveguide tapers 10.0 KEuroBrazing tests 5.0 KEuroConsumable 3.0 KEuroDurable equipment 8.0 KEuro2008 Costs (11 GHz)1 hybrid structure 37.0 KEuro2 waveguide tapers 8.0 KEuroBrazing tests 5.0 KEuroConsumable 3.0 KEuroDurable equipment 8.0 KEuro2009 Costs (11 GHz)1 hybrid structure 90.0 KEuro2 waveguide tapers 10.0 KEuroBrazing tests 5.0 KEuroConsumable 13.0 KEuroDurable equipment 8.0 KEuroDomestic travel/year 2.0 KEuroAbroad travel/year 5.0 KEuro
SUMMARY COSTS
201.024.029.030.06.0Total
90.08.013.010.02.02009
40.08.08.010.02.02008
71.08.08.010.02.02007
Equipmentconstructions(KEuro)
Durableequipment(KEuro)
Consumable(KEuro)
Abroadtravel(KEuro)
Domestictravel (KEuro)
Consumable : attenuator, connectors, cables, vacuum components (flanges,gaskets, valves), ceramic transitions, brazing alloys etc.
Durable equipments : guide transitions, loads, directional coupler, powersupplyEquipment constructions : hybrid structure included 2 waveguide tapers