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£à¬³­ÈéBµ½ªÁÄCdqo`ÌCSR ÍOûÉúo³êé½ßC©ª©gÌdqo`ÉÕË³¹é±ÆÍ¢ïÅé BCSR ðp¢½ ICS ÅÔÌhç¬ªo`·æèàå«¢êÉÍCCSR ªWõ·
é^C~OÆ¸êª¶¶CÕËø¦ªºªé°êªÍC~[ÈÇÌõwnÉæÁÄ CSR ð±«CãÉ±¢

éB±êÍ´`±Á¬ó´ÈÇÌÀèxÉå«­Ë¶µCÄ­édqo`ÆÕË³¹éBFig. 6 É¦µ½õwnÌ

RpNg ERL ÅÍo`³k[hÅÅå400 fs öx

ICS Æ[U[ðp¢½êÆärµ½BÍ®}ÅCCSR_

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éªCRpNg ERL ÅÍJèÔµª1.3 GHz Æ± Ì¼É C³ ç Éå« Èt b NX ð¾ é½ ßÉ C

å«¢½ßC±ÌVvÈõwnÉ¨¢Äàå«ÈtCSR ðIveBJLreBÉ~Ï·éû@Â¢Äà

bNXâPxªúÒÅ«éB{eÅÍ}WbN~[ÆI¢µ½BFig. 6 Æ¯lÉCO[U[ðp¢½êÆvªveBJJreBðp¢½õwnÉÂ¢Äà¾·éBÊíÌ`àµ­ÍÈ~Ì`óðÂ~[ÌêCÎärµ½Í®}ð Fig. 7 ÉÚ¹éBÇ¿çàCÑæÌÀç
ê½½Ë¦Ì~[Å\¬³ê½LreBÌÉõðüd¥ÎÌO¹ãÌÙÈé_©çúËµ½ CSR ðê_É~ÏµÄ ICS Égp·éBî{IÈl¦ûÍ¯¶ÅWõ³¹é±Æª¢ïÅª C ÙÈ é _ª 3 ÂéB»±ÅCO¹ÉÁÄúËéé Bê Â ÍC ­ õ_ Ì ê Å·é CSR ªêÂÌ_ÉWõ·éæ¤ÉÝv³ê½ÁêÈ

éBO[U[ÍLreBÌO¤É~[C}WbN~[ªñÄ³êCewcÌr[Ìá¢~[ðÊµÄLreBàÉüêéKvªé½ßC§ß¦éB

úËõ Nov. 2011 Vol.24 No.6  325

Fig. 6

Schematic drawing of the simple optics of inverse Compton scattering. (a): conventional ICS (b): CSR_
ICS.

Fig. 7

Schematic drawing of an optical cavity of inverse Compton scattering. (a): conventional ICS (b): CSR_ICS.

µ©µCCSR ÍLreBÌÌÎüd¥ÎàÅúË³
êé½ßC¼ÚLreBàÉ~Ï·é±ÆªÂ\Å éB
2 ÂÚÍ~Ï³ê½õÌRq[g«ÅéB\¢IÉO[U[ÍÊª¸êé±ÆÈ­­U·é½ßCLreBÌ~[ÌÊuÔuªg·æè\ª¬³¢¸xÅÀèµÄ¢êÎCLreBÉ~Ï³êéõÌÊÍíÉ»ë¤Bµ©µ CSR_ICS ÅÍCæÉq×½æ¤Édqo`ÌÔÌhç¬ªg·Éä×Ä\ªÉ¬³¢ÆÍ¢¦È¢½ßCCRq[gÉ~Ï·éÆ¼èµ½B3ÂÚÌá_Í~[ÌÅÍ 2 Ì~[Å\ªÅFig. 8

Schematic of an orbit of an electron bunch in a bending mag­net equipped with an optical cavity.

éBO[U[ÌêéªCCSR_ICS ÌêÍC

CSR ÌúË_ÆÕË_Ì 2 ©ÅX|bgTCYÈÇð

ãÅ zR ¨æÑ w0 ðÝèµ½B}WbN~[ÌP[XÉä×ÄCdqo`ÌÔÌhç¬Ìe¿Í¬³¢B

é½ßCÅá 4 Ì~[ªKvÉUõÌõqÍ CSR ÌæèÝpxâÕËÊÏÉå

ÈéBÇ¿çÌP[XàC½Ë¦99.97`99.98÷Ì~[«­¶E³êéB±êçðIveBJLreBÉ~ÏÅK»·éKvª·é[hÉÎµÄÅK»µ½B{eÅÍCCSR Ìg·

Å1000{öxÌ~Ïª©ÜêéB±±ÅCewcÌæÅ½Ë¦ðL·é~[ªKÉÎµÄñÜÀEÌKEVA[hð~Ï·éÆzè·¨æÑ»Ì­Up½ûüÌLªè sCSR
xvÆÈéBâðã\Æ·éà®ÍewcÌæÅ¢½

éBCSR õ¹ÌË¦ðL·éàÌÌC98÷öxÉÆÇÜéBg·ªTuxÌLªè sCSRx ðp¢éÆCñÜÀEÌðÍÈºÌ®

mm ©ç10 mm ÅÍC99÷ÈãÌ½Ë¦ðÂ~[ÆµÅ\·±ÆªÅ«éBÄUdÌ½w~[ªp¢çêé±Æª½¢ªCewcÌæÅÍJ­ª¢ïÆ³êÄ¢éBµ©µßNCõw

sCSR
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x
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»Æ^ówð10 mm ÌÔuÅÏÝdËé±ÆÉæÁ

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é½ßC

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éªCIveBJLreBÌ~[ÉæÁÄÑæª§À³êéB·éÆCt[GÀEÉæè CSR ÌÑæ Dl/l ÆpX· st ÌÏÍêèÅ

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U
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x k

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Du2c{

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2

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éB{eÅÍC~[ÌÑæª10÷ÌÆ«É CSR ÌgÌ
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326  úËõ Nov. 2011 Vol.24 No.6±±Å U ÍÎüpxÅ

èC®(18)ð½·ÅåÌ U ð

gsbNX ¡ Rq[gVNgõÉæétRvgU

Fig. 9Spectra of scattered photons of CSR_ICS in the scheme of the magic mirror. Parameters of the electron bunchfollow as; electron energy 200 MeV, electron charge 77 pC, bunch length 100 fs. Horizontal acceptance angle is
300 mrad. The transverse beam size over the orbit in the bending magnet is assumed to be 70~30 mm2.

Table 1

Number of X­ray photons expected in the optical cavity schemeElectron energy[MeV]

Charge
[pC]

sz/c
[ps]

K

X­ray energy
[keV]

NX
[phs./pulse]

NX[phs./s]

60

77

0.1

0.013

0.4

1~104

2~1013

60

500

1

0.009

0.04

4~104

0.7~1013

200

200

0.1

0.034

4

2~105

1~1014

200

1000

1

0.017

0.4

3~105

3~1013ÒÅ«éBæèÝpxÆ·éB

Optical cavity Å ú Ò ³ êé X ü Ì õ q  ð Table 1 É

5. cERL ÅúÒ³êéî X ü

Ú¹éBdqÌGlM[Í60 MeV ¨æÑ200 MeVCo`·Í100 fs ¨æÑ 1 psC¹Ä 4 ÂÌP[XÉÂ¢Ä

Fig. 9 É}WbN~[ÅúÒ³êé CSR ¨æÑUèµ½Bo`·ª0.1 ps ÌêCCSR Ìg·Í¨æõÌXyNgðÚ¹éBÎüd¥ÎÍRpNg ERL»190 mmCæèÝpx U ¨æÑX|bgTCY w0 ÍÆ¯¶È¦¼a 1 m ¨æÑÈ°p45xÆµC}WbN~»ê¼ê50 mrad ¨æÑ 0.3~0.3 mm2 ÆÈéB1 ps Ìê[ÌæèÝpxÍ300 mrad ÆÝèµ½Bdqo`ÍCCSR Ìg·ª¨æ»1900 mmCæèÝpx U ¨éÆæÑX|bgTCY w0 Í»ê¼ê110 mrad ¨æÑ 3~3¼èµ½B±ÌTCYÍÊíÌ[U[tRvgU

mm2 ÆÈéBÇ¿çÌg·àCCSR ÌX|bgTCYÍ

ÌTCYÍ½ûüÅ70 mmC¼ûüÅ30 mm Åæèàââå«¢ªC±êÍæèÝpxª300 mradC

dqo`ÌWõTCYÉä×Ä\ªå«¢Bdqo`ÂÜèòs£30 cm ÉnÁÄÏêÉr[ðiéKvªÌd×ÊÍ CSR wake ÈÇÌñü`øÊÈÇðl¶ÉüéBÎüd¥ÎÅÍGlM[ÉæÁÄ½êÄÝèµCJèÔµÍd¬ª100 mA ÉÈéæ¤ÉÝèûüÉO¹ª¸êé½ßC»Ìe¿àl¶µ½ÊC½µ½BX üÌg·Í0.04 keV ©ç 4 keV ðJo[·éBé½ßÅûüÌr[TCYª 2 {ÈãÉå«­ÈÁ½Bo`ÇÌP[XÉ¨¢Äà K lª¬³¢½ßC®(12)Å¦µ·100 fs Ìdqo`©çÍ190 mm ÈãÌg·Åå«È½æ¤ÈUõÌg·ÌÏ»Í³Å«éBXyNg

CSR ªúÒÅ«C3~1014 phs./pulse 10÷BWCJèÔµ10 ÷ Å p  X  ½ è Ì õ q  Í 104 © ç 105 phs. / pulse

4~1023 phs./s 10÷BW ÌtbNXÉÈéB

10÷BWCtbNXÍ1013 ©ç1014 phs./s 10÷BW ª

1.3 GHz ÅSÌÌõqÍ¾çêéUõÌXyNgÍ CSR É©ÜêéB}WbN~[ÌP[XÉä×ÄCCSR Ì½`óðÂFõªúÒ³êéBpXÍdqo`æèÝpxª¬³­CWõTCYªå«¢ÉàÖíçÆ¯¶öxÉÈéªCFõðªõ·éÆCt[GÀE¸C¯öx©»êÈãÌtbNXª¾çêé±ÆªúÒÉæèpX·ªLÑéBGlM[ 4 keV Ì X üÌõ³êéBPxÍdqÌG~b^XÉæÁÄÜé½ßC

qÍ 5~103 phs./pulse 10÷BWCJèÔµ1.3 GHz Å

CSR wake ÈÇªdqÉyÚ·ñü`Èr[_Ci~NtbNXÍ 6~1012 phs./s 10÷BW ÆÈéBXyNgXÌøÊàl¶µÄZo·éKvªSÌÅÍC4~105 phs./pulse ¨æÑ 5~1014 phs./s ªú

MeVC200 pC ÌP[XÅÍ­õ_ÌKi»G~b^XéBTable 1 Ì200

úËõ Nov. 2011 Vol.24 No.6  327

ð10 mm­mrad Æ¼èµ½êC¨æ»1016 phs./s mm2°Å·Mð·é±ÆªoÜµ½±Æð´ÓµÜ·B

mrad2b.w.0.1÷ªúÒÅ«éBQl¶£

6. ÜÆß

1)

RpNg ERL Í}` GeV NX ERL ÌeXg@2)

ÆµÄ¾¯ÅÈ­Cewcõâd X üÉg üÌõ¹

3)

pðvæµÄ¨èCCSR Ì­¶â[U[tRvg
UÌ¢ªißçêÄ¢éB{eÅÍCå­xÌewcõ¹ÆµÄúÒ³êÄ¢é CSR ðtRvgU
ÉpµCPF OÉpÒÌ½¢î X üÌ¶¬ÉÂ

4)5)¢ÄñÄµ½BO[U[ÆÌå«Èá¢ÍCCSR Í

6)dq©gªÎüd¥ÎÅúË·éÆ¢¤_Å7)Æèâ·¢Æ¢¤bgªèC¯úª

éBÜ½Cg·ª·¢½ßeÕÉLªÁÄµÜ¢CÕË_ÅWõTCYð¬³­·é±ÆªÅ«È¢Æ¢¤fbgª

éBRpNg ERL ÌdqGlM[60 MeV ¨æÑ200

8)
9)
10)

MeV ÌP[XÅÍCî X üÌGlM[Í0.04 keV ©ç
4 keV ðJo[µCpX·Í ps ©ç100 fs ÌI[_[éB»Ì CSR ÌtRvgUÌ½ßÌIveBÅ

NX Æ µÄ 2 ÂÌ Ä ðñ ¦ µ½ B êÂ Í C} W b N~
[ðp¢ ½àÌÅéB±êÍ L¢æè ÝpxÅCSR ðWßÄdqÆ¯¶TCYÉWõµÄÕË³¹éàÌÅéBZpXÌFõªúÒ³êéªCî X üÌÑæðÀè·éÆt[GÀEÉæÁÄpX·ªLÑÄµÜ¤Bà¤ÐÆÂÍIveBJLreBðp¢½à
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éB½Ë¦Ì~[Ì±üÉæè1000{Ì~Ïª©ÜêCärIÑæÌ·¢ X üð¢JèÔµÅ¾
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14)
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16)

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Í104 ©ç105 phs./pulse 10÷BWCtbNXÍ1013 ©

19)

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20)

Ó«{¤ðÜÆßéÉ

½èCGlM[Á¬í¤@

21)\iKEKjÌ¶oé³öC»w¤ÌFJ³FmÌ²ðÆT|[gª¾çê½±ÆðåÏ[­´ÓµÜ·BÜ½CGlM[Á¬í¤@\iKEKjÌ¬Ñ
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328  úËõ Nov. 2011 Vol.24 No.6

22)

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ERL ÌÝv¤v
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gsbNX ¡ Rq[gVNgõÉæétRvgU ÒÐî cü¿GlM[Á¬í¤@\Á¬í¤{Ý æ 7 ¤nÉ³
E­mail: miho.shimadakek.jpêåFÁ¬í¨
mªðn
2001N}gåwHw¤ÈmÛöC¹CmiHwjB2001N_2003Ns¸_ãw¤B2004N_2005N
GlM[Á¬í¤@\CÁ¬í¤
{ÝB2006N_2007Nªq»w¤
UVSORB2008N 4 æèGlM[
Á¬í¤@\CÁ¬í¤{Ýi¨¿\¢Èw¤jÌm¤õðo
ÄC2010N 4 æè»EBHÇê

ú{´qÍ¤J­@\Êqr[p¤åÉO[v[_[E­mail: hajima.ryoichijaea.go.jpêåFúËõ¹CdqÁ¬ímªðn
1989Nåwåw@Hwn¤ÈCmÛöC¹CmiHwjBåwèCutC³öðoÄC1999Næè
»EB©Rdq[U[CGlM[ñû^jAbNÌ¤J­É]B

Inverse Compton Scattering by Coherent
Synchrotron Radiation
Miho SHIMADA
Ryoichi HAJIMAHigh Energy Accelerator Research Organization (KEK)
1_1 Oho, Tsukuba, Ibaraki 305_0801, Japan
Japan Atomic Energy Agency
2_4 Shirane Shirakata, Tokai­mura, Naka­gun, Ibaraki 319_1195, Japan

Abstract Energy recovery linac (ERL), which recovers a beam energy of a circulated electron bunch to ac­celerate a new electron bunch derived from the electron gun, refreshes an quality of electron bunch perturbed
by some wakes and instabilities after one or a few circulations. The electron beam and its synchrotron radia­
tion have dierent characters from conventional storage rings. It is an advantage for high_brilliant light source
via the laser inverse Compton scattering (ICS) because after the energy recovery the energy spread caused by
the ICS can be reset and the low emittance beam can be recovered. Coherent synchrotron radiation (CSR)
from a short electron bunch is also expected for ERL as a high intense terahertz radiation. It is why ERL canrecover the beam quality deteriorated by a CSR wake, which is serious problem at a short electron bunch.
The laser ICS and CSR are considered as a light source in the compact ERL, which is under construction in
the KEK site as a test facility of multi­GeV ERL. In this article, the scheme of ICS induced by CSR is proposed toobtain a soft X­ray with a subpicosecond short pulse duration.

úËõ Nov. 2011 Vol.24 No.6  329