超伝導加速空洞の製作技術と計測技術（講義3/3）
OHO06 (KEK)佐伯 学行

空洞性能の計測技術

縦測定のクライオスタット

回収ライン

減圧ポンプ

縦測定スタンド

Pickup カプラー

Input カプラー

真空封じのためのメタルバルブ

縦測定用クライオスタット（保冷容器）

Pe

Ploss = 空洞壁で熱になる電力

Ploss = 空洞壁で熱になる電力
Pe =ポートから出て行く電力

(One-portでのPloss)

空洞から出て行く電力

QL = wU / (Ploss + Pe + Pt)= Q0 / (1+βin + βt)-1

Qt = Q0・Ploss / Pt

/ Ploss

Qt はアンテナの長さが固定なので、測定中に変わらない。

縦測定コントロール室
Power-meter (Pin, Pr, Pt)

Signal Generator (SG)Feed-back system (PLL)10 nΩ1 nΩRs = Γ/ Q0Qo vs Eacc
Eacc > 45 MV/m with new-shape at KEK

Eacc = Z sqrt(Qt・Pt) , Q0 = Qt ・ Pt / Ploss

Q0 vs Eacc （温度依存）
Temperature dependence (RE cavity)
10

10

RE-12th meas.

11

2005/09/21 Wed.

10

Qo

10

Eacc / Qo@Temp
47.14 / 1.04e10 @2K-1st
52.31 / 9.67e9 @2K-2nd
51.65 / 1.27e10 @1.91K
52.46 / 1.53e10 @1.73K
52.73 / 1.48e10 @1.64K

Qo(2K-1st)
Qo(2K-2nd)
Qo(1.8K)
Qo(1.7K)
Qo(1.5K)

9HPR(UPW)Nomura, 7MPa*1hr, with valve
1080102030

Eacc[MV/m]

405060Q0 vs Eacc（空洞性能評価）
ICHIRO Single cell 1st round

1011Quench
1010

Field Emission
With X-ray

Qo
109

IS#2-2nd

Q-dropAccidental

IS#3-1st
IS#4-1st
IS#5-1st
IS#6-1st
IS#7-1st

108
01020

Eacc[MV/m]

304050T-Mapping (1)T-mapping system: ~600 Allen-Bradley C-resistorsa)b)

Q0 = 6.0 109
Eacc = 20.6 MV/m

0.2
0.18
0.16
0.14
0.12
0.1

ΔT (K)

10.08
Large grain CEBAF Single cell cavity 25μm BCP 1:1:2
1E+11740.06

T=2.0 K

100.0413

T=1.7 K

BottomIi

Q0S13S11S9S7S5S3S134

3128

25

S15022Azimuth

19160.02

1E+10Equator

Top Iris
1E+09
010 20 30 40 50 60 70 80 90 100 110 120 130 140

Bp (mT)Q-dropとベーキング

Buffered Chemical Polished(1:1:1)

CEBAF Single cell cavity Nb/Ta 1162_33/1162_34
Q 0 v s. E acc,
1.0E+11after baking,120C,40 hrs
1250 C, 100micron,before
bakingTest#4, 300 micron bcp

1.0E+10Q0[B.Visentin,SRF2003]

electropolished

QuenchQuench
1.0E+0905101520

Eacc [MV/m]

25303540空洞性能が悪い原因と対処法
悪い空洞性能原因

高圧洗浄や空洞組み立て時に粒子が混入

電解研磨の時に硫黄が付着

ニオブ材の欠損

酸化膜が厚い電子ビーム用設備の研磨が不十分

改善方法

付着した粒子の除去

付着した硫黄の除去
酸化膜の除去

欠損の除去

処理内容

高圧洗浄と注意深い組み立て

新しいEP液で軽いEP
ベーキング

EPによる厚い除去
機械研磨（CBP）

除去厚み＝０除去厚み＝薄い除去厚み＝厚い10Re-cavity 5-2nd Meas.
CP(10um)+HPR(KEK)+Baking(57H@120oC)+
H-collection (26H@100k)
2005/06/18 Sat.

11

5-1st Meas. (06/16)
5-2nd Meas. (06/18)

水素Q病

10Qo

1010start processing

9Q dropped
sharply

X-ray increased
very sharply.
# 5-2nd meas. was done after the cavity temp. was maintained ~100K for 26hours.

1080

1020Eacc (MV/m)

304050Water quality R&D
Correlation between HPR water-quality and cavity performance was checked.
UPWPW (old)@Nomura @KEK
TOC (ppb)

10 - 20100 - 150

Bacteria(count / mL)

0-530 -60

HPR with Pure Water (PW) at KEK is
OK up to the cavity performance of ~35 MV/m.

PW is OK up to 36 MV/m

PW is OK up to 38 MV/m

14ICHIRO 9-cell 1st cavity (#0) w/o HOM
ICHIRO 9-cell 1st Cavity#0 w/o HOM
MP in cell

8th Vertical Test (V.T.)

Hard barrier around 29 MV/m.
This might be caused by MP atenlarged beam-pipe

No Q-disease was found.

15

Multi-pacting simulations by L. Ge at SLAC
Multi-pacting points
were found at the taper partof enlarged beam-pipefrom simulation.

 MP Particles Distribution(surviving 50 impacts)

 MP in end-group of ICHIRO
Cavity with enlarged beam-pipe

Eacc vs. time454035BCP
EP
10 per. Mov. Avg. (BCP)
10 per. Mov. Avg. (EP)E acc[MV/m]

30
2520
151050Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06

トピックスNb/Cu Clad Seamless Cavity (Necking Machine)
Status of 3-cell Necking Machine
RollerCollet Chuck

Cu Pipe3-cell Necking Machine was completed.
Tests with Cu pipes started.

Nb/Cu Clad Seamless Cavity
Necking of Cu pipes

Variation of thickness was checked.

3-cell necking test.

5-cell necking was also tested.

液圧成形機加工

液圧成形機 (KEK)３連シームレス空洞部の完成
左側：絞り加工後、中央：中間液圧成形、右側：液圧成形完成

Large Grain/Single Crystal Niobium
CBMMNinxiaWah Chang

Ingot “D”,800 ppm Ta

Heraeus
Ingot “A”, 800 ppm Ta

Ingot “C”, 1500 ppm Ta

Ingot “B”, 800 ppm Ta

Large Grain/Single Crystal Niobium
Discs from Ingot

CavityEpeak/Eacc = 1.674

Hpeak/Eacc = 4.286 mT/MV/m

Single Crystal Cavity (2)Single Crystal Cavity
1.86 K
1.0E+11

2.2 GHz Single Crystal

Qo

Scaled to 1.3 GHz

1.0E+101.0E+0905101520

Eacc [MV/m]

25303540