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Abstract A capability

is crucial for MW-range beaThis capabilityBeam Transpodivert 80% of CW 162.5 MHprogrammed bone of the mosystem will be(PXIE) [2] faprototype of thwill be made kickers workinkickers are bstructure with 50 Ohm strucpaper will defunctional specelectromagnetipossible drivmechanical de

SCHEThe PXIE M

Two 50cm–loadvance and hduring passageRef.[3]) so tha

kic

Figure 1: Schenvelope. The envelope of thY envelope of

The kicker opposite polarbelow the beamσx,y≈2 mm, theto be 16 mm. Tlimited by pair_____________________________

# val@fnal.gov * Operated by FerAC02-07CH11359

PR

v#, A. Chen,

y to provide a lathe concept o

am to several y will be realort’s (MEBT)

f all bunches oHz beam to an bunch-by-bunchost challenging

e tested at the Pacility that wilhe Project X fro

by two idenng in sync. Prbeing investiga switching-ty

cture with a liescribe the chcifications for ic measureme

ver schemes, sign.

EME AND RMEBT choppinong kickers arhave opposite e of the same bat the kicks to th

ker 1 kic

heme of MEBthin lines are

he passing beamthe chopped-o

field is generrity to two setsm. With the tye vertical gap The aperture inrs (one at each_______________

mi Research Allia9 with the United S

ROGRES

R. PasquineFerm

T. Tan

arge variety ofof the Project

experiments sized by the M

chopping syf the initially 5absorber acco

h selection. Beg componentsProject X Injecll be built at ont end. The butical sets of tresently, two vgated: a helicype 500 V drivnear ±250 V

hopping systemthe kickers, pr

ents of the mand show

REQUIREMng scheme is sre separated bdirection of thbunch (similarhe bunch are s

cker2

BT optics [4] the central tra

m, and the thicout beam.

rated by applys of flat electroypical beam trabetween electrn the vicinity o

h end) of protec

ance, LLC, under CStates Department

S WITH P

elli, D. Petermilab*, Batang, SLAC, M

f bunch patternX [1] serving

simultaneouslyMedium Energyystem that wil5mA, 2.1 MeVording to a preeing considered, the chopping

ctor ExperimenFermilab as

unch deflectiontravelling-wavversions of thcal 200 Ohm

ver and a planaamplifier. Thi

m scheme andresent results o

models, discusa conceptua

MENTS shown in Fig.1by 180º phashe electric fieldr to the logic oummed.

and the beamajectory and 3σck lines are th

ying voltage oodes above andansverse size orodes is chosenof the kickers iction electrode

Contract No. DE-t of Energy

PXIE MEB

rson, G. Saewavia, IL 6051

Menlo Park, C

ns g y. y ll V e-d g

nt a n e e

m ar is d

of ss al

1. e d

of

m σ e

of d

of n is es

with the vbeam if th~10 µA toA voltag

of each buthe electrothe first k+250 V foduration, ±25V for chopped bkicker, anshould pr80% of bubetween pµs periovelocity smm/ns. assembly with a ful

Two veby their developed

The 50-which medeflected connectedprovidingLAMPF plates of 50mm withe electrexpected required tCooling oclamps, wthrough th

Figure 2:structure a

BT CHOP

wert, A. She10, USA CA 94025

vertical gap ofhe lost current o protect the kige is applied tounch. To proviode voltage, fokicker is -250or the bunches6σz≈1.3 ns, thpassing bunch

bunches. This nd for the prrovide ~10% hunches means pass/remove std, is 162.5/5should be maThe flange-tois 650 mm. T

l-power beam ersions of the

impedance, d.

50 OH-Ohm kicker cechanical desig

by voltage d in vacuum bg necessary del

[5]. The 50c14.6 mm len

idth and 1 mm rodes induced to be ~110 Wto withstand aof the Teflonwhich, in turnhe channels in

Mechanical and the cross s

PPER

emyakin, D.

f 13 mm. We pto any of these

ickers. o the kicker elide the separat

or example, at t0 V for the ps to be removehe voltage shohes and shouldvoltage is cal

resent kicker higher value. R

that the maxitates, averaged5=32.5MHz. atched to the o-flange lengThe vacuum inis expected to kicker and dr50 and 200

HM VERSIOconsists of two gn is shown in

applied to by coaxial cablays, similar tom-long struct

ngth (along ththickness. Theby the electr

W per structure, additional 40 W-insulated cabn, are cooledthe structure.

schematic of

section of the k

Sun, M. We

plan to interrue electrodes ex

lectrodes at pation shown in the top electroassing bunched. During the b

ould stay flat wd be ≥250 V flculated for an

designs the Removal of atmum switchin

d over the typicThe kicker beam speed

gth of the kn the kicker vibe 2·10-7 Torr.

river, referred b0 Ohm, are

ON identical struc

n Fig.2. The beplanar elect

bles with the lo the design uture has 25 che beam trajece total power lomagnetic sigand the struct

W of the beambles is provided by water flo

the 50-Ohm kkicker assembly

endt

upt the xceeds

assage Fig.1, des of

es and bunch within for the n ideal driver t least

ng rate cal ~1 phase of 20 kicker icinity . below being

ctures, eam is trodes length

used at copper ctory), loss in gnal is ture is

m loss. ed by owing

kicker y.

WEPPD078 Proceedings of IPAC2012, New Orleans, Louisiana, USA

ISBN 978-3-95450-115-1

2708Cop

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htc ○

2012

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07 Accelerator Technology and Main Systems

T31 Subsystems, Technology and Components, Other

ei(dp

F

(cte(

dt

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Results of electromagnetiin Fig. 3. Th(50cm) structudistortion is parameters.

Figure 3: The 50-Ohm kicke(top right). Thclose to the inthe simulated electrode stru(blue).

The kicker decrease the lothe 6.15ns pushown in Fig.4

Figure 4: Testdistortion. (a) signal and (c)pulse; (d) outremoval of foubunch passage

After testinperformance o150W, 0.05-1 [6] was fousignificant lowprocedure was1. The amplifi

single 250 generator (Athe amplifie

simulations ic model conta

he expected ature is ~0.5 dlow enough

six-electrode eer structure andhe shape of thenput (reddish). distortion of th

ucture after in

will be driveower frequencyulse affecting a4c.

t of the CBA scheme of the

) correspondintput for a CWur consecutive

e.

ng amplifiers of a commerciaGHz amplifier

und satisfactorw frequency phs proposed and ier impulse res

ps pulse froAWG), and ther was calculat

and measureaining 6 electrottenuation in

dB, and the pto provide

electromagnetid results of itsoutput signal The bottom rihe output signnjecting a rec

en by a lineary content of thea single bunch

1G-150 ample test; (b) pre-

ng output signW pattern, coe bunches follo

from severally available Cr from Teseq Ary. To comphase distortiontested:

sponse was meom the arbitrhe complex gaed.

ements of thodes are shownthe full-lengthredicted signathe specified

ic model of ths measurement(violet) is very

ight plot shownal (red) in a 8ctangular puls

r amplifier. Toe output signalh is formed a

lifier with pre-distorted inpu

nal for a singlrresponding to

owed by a one

ral companiesCBA 1G-150,

AG, Switzerlandpensate for n, the following

easured using rary waveformain function o

e n h al d

e ts y

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2. The deindividcorrespexpecte

3. The wabe insid

4. The drobtainewavefoobtainewavefoThe tes

shape wawhen the of the amdistortion generationshape sati

Accordavailable should prchopper.

The 20(Figure 5(with a sioscilloscoa 28.6 mreturn. Tfour ceramthe 8.5mmimpedanc5.6x20x0.helix.

Figure 5:kicker and

While heaW), the sby beam ceramic sp

Figure 6:the prototare time s

esired wavefodual pulses ponding polaried to be repeataveform was cde of the amplriving signal ed as inverse Form spectrum ed waveformorm generator st results are

as very good faverage power

mplifier. In thn using iterativn. The maximisfying the spec

ding to the c1 kW amplifierovide the vo

200 OH0 Ohm kicker). A helical dignificantly sl

ope 7104. Thismm OD coppeThe wire is suspmic spacers. Tm helix pitch ce. The deflect.5 mm electro

: Mechanical d photo of a sin

ating from pulstructure is ratetails. The heapacers contacti

Simulation retype response (shifted.

orm is presenshaped as

ity. Note that tted at 1µs interchosen so that lifier bandwidth

for the ampFourier transfoto the amplif

m was fed [7]. shown in Fig

for single pulsr was approach

he future we pve algorithm mum signal acification was ompany, it her with similar

oltage amplitud

HM VERSIr consists of twdeflector was ulower rise times helix is a flat er tube that spended 4.8 mmThe combinatioresults in 200ting field is fo

odes soldered

drawing of 2ngle 200 Ohm

lsing is estimaed for removaat is removed ing the water-c

esults of the he(right). The tra

nted as a suin Fig.4c

the bunch pattrvals.

its spectrum wh.

plifier (Fig.4a)orm for ratio fier gain. Theninto the arb

g.4b,c,d. The ses and deteriohing the powerplan to correcfor the input amplitude wit240 V peak to

has a commerr characteristicde required fo

ION wo helical struused at LAMPe) and in Tekwire wound a

erves as the m above the tuon of this spac Ohm charact

ormed by flat cto each turn o

200 Ohm dualhelix prototyp

ated to be low al of 40W depmainly throug

cooled central t

elix kicker (lefaces at the righ

um of with

tern is

would

) was of the n, the bitrary

pulse orated r limit ct this

pulse th the peak.

rcially cs that or the

uctures PF [8] ktronix around signal

ube by ce and eristic

copper of the

l-helix pe.

(< 10 posited gh the tube.

ft) and ht plot

Proceedings of IPAC2012, New Orleans, Louisiana, USA WEPPD078

07 Accelerator Technology and Main Systems

T31 Subsystems, Technology and Components, Other

ISBN 978-3-95450-115-1

2709 Cop

yrig

htc ○

2012

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Simulations of the kicker structure compare well with prototype measurements (Fig. 6). Distortion during the propagation through the 200 Ohm helix is within specifications.

The 200 Ohm kickers are intended to be driven by broadband, DC coupled switches in push-pull configuration. The switching waveform pattern will be made to vary depending on the timing requirements of the experiments receiving beam. This design reduces the operating switching rates resulting in lower driver circuit switching losses as well as lower power dissipated in the helical structure.

The switch-driver is being developed in two versions. The first version is based on GaN multi-FET cascode scheme where five 200 V rated FETs [9] turn on together and share the voltage. Fig. 7a shows the circuit topology used for this switch, and Fig. 7b presents scope traces of preliminary tests of the individual transistors sharing voltage while switching. The rise time of the output signal, 3 ns (10-90%), is close to the requirement.

Figure 7: Simplified schematic of a multi-FET cascode switch and scope traces of the five FET drain voltages.

The second version is based on a 500V ultra-fast hybrid MOSFET/Driver switching module (HSM) [9], which is being developed at SLAC. The HSM consists of a pair of complementary MOSFETs arranged in totem pole configuration. The MOSFETs are acquired in bare die form and are attached to the circuit board using low-inductance assembly method to achieve ultra fast switching. A switching time of less than 1ns is observed in the simulation, which will be experimentally verified once the HSMs are fully fabricated and assembled.

Figure 8: Schematic of HSM switch and simulation results.

DISCUSSION AMD PLANS Presently the schemes of the kicker and driver

described above are being pursued in parallel. On one hand, the 50-Ohm version employs a proven kicker technology, commercially available feedthroughs, cables,

and loads, as well as is capable of using off-the-shelf amplifiers (with a special procedure of pre-distortion). On the other hand, the 200 Ohm scheme has a potential to be of a lower cost, and its DC coupling may be beneficial for forming the bunch patterns with long periods. So far, development of both versions does not show any clear showstoppers, and the final technology choice will be made later.

Both kicker structures are at the stage of mechanical design of vacuum-compatible prototypes. Manufacturing and following tests (electromagnetic, vacuum, and thermal) are scheduled for CY 2012.

ACKNOWLEDGMENT The authors acknowledge the insightful suggestion by

B. Chase (Fermilab) for the helical traveling wave structure concept; the engineering assistance of D. Frolov, an intern from Kuban State University, Russia, for his work on the cascode driver, and the proposal for protection electrodes from A. Aleksandrov.

REFERENCES [1] S. Holmes et al., Proc. of IPAC’12, New Orleans,

USA, May 20 - 25, 2012, THPPP090; [2] V. Lebedev et al., Proc. of IPAC’12, New Orleans,

USA, May 20 - 25, 2012, THPPP058, see also PXIE web page at http://www-bdnew.fnal.gov/PXIE/index.htm

[3] A. Aleksandrov, Proc. of EPAC08, Genoa, Italy, June 23-27, 2008, THPP074

[4] V. Lebedev et al., Proc. of IPAC’12, New Orleans, USA, May 20 - 25, 2012, THPPP057

[5] J.S.Lunsford and R.A.Hardekopf, IEEE Trans.on Nucl.Sci., NS-30, 4, 1983, p.2830

[6] http://www.teseq.us/com/en/products_solutions/emc_radio_frequency/power_amplifiers/CBA_1G-150_e.pdf

[7] www.chase2000.com/da14000.shtml [8] J.S.Lunsford et al., IEEE Trans.on Nucl.Sci., NS-26,

3, 1979, p.3433 [9] GaN FET’s from Polyfet RF Devices [10] T. Tang, C. Burkhart, “Hybrid MOSFET/Driver for

ultra-fast switching”, IEEE Trans. on Dielectrics and Electrical Insulation, Aug. 2009.

NMOS

500V

50 Driv er

1 2Charge Trigger

50

Discharge Trigger

Driv er

1 2Def lector200 ohm

FQPF2N60C

PMOSFQB1P50

14ns 16ns 18ns 20ns 22ns

0V

200V

400V

0.80nsFallTime:

0.86nsRiseTime:

WEPPD078 Proceedings of IPAC2012, New Orleans, Louisiana, USA

ISBN 978-3-95450-115-1

2710Cop

yrig

htc ○

2012

byIE

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Cre

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3.0)

07 Accelerator Technology and Main Systems

T31 Subsystems, Technology and Components, Other