D bb ll F b i ti d T iDumbbell Fabrication and TuningDumbbell Fabrication and TuningDumbbell Fabrication and TuninggJ Gao Y L Chi J Y Zhai J Yu Z Q Li T X Zhao J RJ. Gao, Y. L. Chi, J. Y. Zhai, J. Yu, Z. Q. Li, T. X. Zhao, J. R

J Z Ch J Q Qi B iji H ji li S i d TJ. Z. Chen, J. Q. Qiao, Beijing Hejieli Science and TJ. Z. Chen, J. Q. Qiao, Beijing Hejieli Science and TH Yuan H Yu J X Wang Beijing InstituH. Yuan, H. Yu, J. X. Wang, Beijing Institu, , g, j g

W P Xie Ningxia Orient Tantalum InTHPPO067 W. P. Xie, Ningxia Orient Tantalum InTHPPO067

As the key component of the “IHEP 1 3 GHz SCRF Accelerating Unit and These problems were due to the differAs the key component of the IHEP 1.3 GHz SCRF Accelerating Unit and These problems were due to the differHorizontal Test Stand Project” a low-loss shape bare tube 9-cell cavity

pgrains with different crystal orientationHorizontal Test Stand Project , a low-loss shape bare tube 9-cell cavity grains with different crystal orientation

using Ningxia large grain niobium is being fabricated at IHEP This paper supposed to be eliminated by CBP on thusing Ningxia large grain niobium is being fabricated at IHEP. This paper supposed to be eliminated by CBP on thpresents the fabrication procedure and frequency tuning method of the adjusted the roundness of the half cellspresents the fabrication procedure and frequency tuning method of thed bb ll f thi it D t th i l ti f th l i

adjusted the roundness of the half cellsTh fi l d l th 0 2dumbbells of this cavity. Due to the special properties of the large grain The final roundness was less than 0.2 my p p p g g

material se eral mechanical and RF problems ere fo nd and s ccessf llThe final roundness was less than 0.2 m

material, several mechanical and RF problems were found and successfully, p ysolved After equator welding this cavity will be surface treated late this yearsolved. After equator welding, this cavity will be surface treated late this yearand tested early next yearand tested early next year.

L L L G i 9 ll C itL L L G i 9 ll C itLow Loss Large Grain 9-cell CavityLow Loss Large Grain 9-cell CavityLow Loss Large Grain 9-cell CavityLow Loss Large Grain 9-cell Cavityg yg yThe combination of the low-loss shape and large grain niobium material isThe combination of the low loss shape and large grain niobium material isexpected to be the possible way to achieve higher gradient and lower costexpected to be the possible way to achieve higher gradient and lower costf ILC 9 ll iti Th t d ti f th l i i bi iti D bbD bbfor ILC 9-cell cavities. The cost reduction of the large grain niobium cavities DumbbeDumbbeg glies in eliminating electro polishing process and the ne l de eloped m lti DumbbeDumbbelies in eliminating electro-polishing process, and the newly developed multi-g p g p , y pwire slicing technique on large grain niobium ingots at KEK

We chose two half cells with similar iriswire slicing technique on large grain niobium ingots at KEK.

We chose two half cells with similar irisoutside EBW were performed on the irisA low-loss 9-cell cavity with full end groups is also under development. outside EBW were performed on the irisA low loss 9 cell cavity with full end groups is also under development.

Th d ll h th HOM l d th d l t ill b ti i d t problems in spite of the large iris wall thThe end cell shape, the HOM couplers and the end plate will be optimized to problems in spite of the large iris wall thp , p p pdamp higher order modes and red ce high field Lorent force det ning dumbbell length after iris and stiffening ridamp higher order modes and reduce high field Lorentz force detuning dumbbell length after iris and stiffening rip g g gaccording to ILC requirements This cavity will be installed into the futureaccording to ILC requirements. This cavity will be installed into the futureshort cryomodule (HTS) for the horizontal test at IHEPshort cryomodule (HTS) for the horizontal test at IHEP .y ( )

Dumbbell FrequeDumbbell FrequeDumbbell FrequeDumbbell FrequeDumbbell FrequeDumbbell FrequeThe contact surface between the old dThe contact surface between the old d

Ni bi I tiNi bi I ti and the equator surface was a 3 mm thiNiobium InspectionNiobium Inspection and the equator surface was a 3 mm thiNiobium InspectionNiobium Inspection cells and dumbbells were below 1000pp cells and dumbbells were below 1000,l i d h d d hplain and hard contact need much moreUltrasonic and eddy current scanning were both performed on some of the plain and hard contact need much more

th fi t ith di l l tUltrasonic and eddy current scanning were both performed on some of the

thus a new fixture with radial slots onlarge grain niobium disks provided by OTIC Ningxia Some initial results offabricated for good RF contact With the

large grain niobium disks provided by OTIC, Ningxia. Some initial results ofth lt i i d t h t d f t f th t i l fabricated for good RF contact. With thethe ultrasonic scanning seemed to show no apparent defects of the material, g

values of the half cells and dumbbellsthe ultrasonic scanning seemed to show no apparent defects of the material,

hil f th i ti ti d i t f th i ti th d values of the half cells and dumbbellswhile further investigation and improvement of the inspection methods arestable at kHz

g p pneeded The measured RRR value of the large grain niobium is 430 stable at kHz.needed. The measured RRR value of the large grain niobium is 430.g g

D bb ll R hD bb ll R hHalf Cell Fabrication and ReshapingHalf Cell Fabrication and Reshaping Dumbbell ReshapDumbbell ReshapHalf Cell Fabrication and ReshapingHalf Cell Fabrication and Reshaping Dumbbell ReshapDumbbell ReshapHalf Cell Fabrication and ReshapingHalf Cell Fabrication and Reshaping ppS l bl f d d i th f b i ti f h lf ll f l With a special jig we reshaped the dumSeveral problems were found during the fabrication of half cells from large With a special jig, we reshaped the dump g ggrain material Earrings and steps were found in the equator area Large

p j g pthe parallelism to be less than 0 2 mmgrain material. Earrings and steps were found in the equator area, Large the parallelism to be less than 0.2 mmg g p q g

cracks and unsmooth were found between adjacent grains in the iris area sum of the two half cells length before wcracks and unsmooth were found between adjacent grains in the iris area. sum of the two half cells length before wIris wall thickness was not uniform after trimming (the largest thickness the perturbation method [1] we meaIris wall thickness was not uniform after trimming (the largest thickness the perturbation method [1], we mea

i di id l f f h h lf lldifference is nearly 1 mm) The spring back after deep drawing of the half individual frequency of the half cells odifference is nearly 1 mm). The spring back after deep drawing of the half individual frequency of the half cells o50 kHcell was large according to 3D measurement and the equator became oval was 50 kHz.cell was large according to 3D measurement and the equator became oval

d t i t l tdue to internal stress.

f th IHEP L G i 9 ll C itg of the IHEP Large Grain 9 cell Cavityg of the IHEP Large Grain 9-cell Cavityg of the IHEP Large Grain 9 cell Cavityg g yR Zhang J Gu M Hou J P Dai IHEP Beijing 100049 ChinaR. Zhang, J. Gu, M. Hou, J. P. Dai, IHEP, Beijing 100049, ChinaT h l D l t C Ltd B iji 100026 ChiTechnology Development Co. Ltd., Beijing 100026, ChinaTechnology Development Co. Ltd., Beijing 100026, Chinaute of Aviation Materials Beijing 100095 Chinaute of Aviation Materials, Beijing 100095, China, j g ,ndustry Co Ltd Shizuishan 753000 Chinandustry Co. Ltd., Shizuishan 753000, China

rent mechanical properties of the large Then according to the DESY cavity tuning method [2] and the estimatedrent mechanical properties of the large Then, according to the DESY cavity tuning method [2] and the estimatedp p gn The steps and unsmooth area are

g y g [ ]9 cell cavity frequency and length evolution we calculated the trimmingn. The steps and unsmooth area are 9-cell cavity frequency and length evolution, we calculated the trimming

he 9-cell cavity For the oval shape We length for each half cell of the dumbbell The tuning target frequency of thehe 9-cell cavity. For the oval shape, We length for each half cell of the dumbbell. The tuning target frequency of theby reshaping the equator with a fixture dumbbell π mode was 1298 277 MHz and the target length was 57 96 mmby reshaping the equator with a fixture. dumbbell π mode was 1298.277 MHz, and the target length was 57.96 mm.

D t th l ti l bi tt i f th h lf ll l th d fmm. Due to the relatively big scattering of the half cell length and frequency, wemm. Due to the relatively big scattering of the half cell length and frequency, weill k d bb ll t hi f t EBW di t b th th twill make dumbbell matching for equator EBW according to both the equatorg q g q

diameter and the tuning requirementdiameter and the tuning requirement.g q

Dumbbell Tuning ExampleDumbbell Tuning Example1.5 mm

Dumbbell Half cell Trimming PretuningDumbbell # Length Half cell # frequency

glength

gLengthDumbbell # Length

/ mmHalf cell # frequency

/ MHzlength/ mm

Length/ mm/ mm / MHz / mm / mm

#7 1298 721 0 45 0 29#7 1298.721 0.45 0.29

ll EBWll EBW#7-14 117.95

ell EBWell EBW #14 1298.072 0.88 0.41ell EBWell EBW #14 1298.072 0.88 0.41

diameter to form a dumbbell Inside anddiameter to form a dumbbell. Inside ands The EBW of the iris did not meet big Cavity Frequency Change and Controls. The EBW of the iris did not meet big

f / MHFinal Frequency Target

ickness difference The shrinkage of the f / MHz Key Frequency Point ickness difference. The shrinkage of the Measurable Frequency Point

ng EBW is about 2 mm Unmeasurable Frequecy Point Horizontal Test Tuner Tuning Range, typically Slow tuner 500 kHz, Piezo 1 kHz ng EBW is about 2 mm.Controllable Frequecy Change

1300 000 C it i C d lUncontrollable Frequency ChangeVT Power Source Range

1300.000 Cavity in CryomoduleEquator Tuning Available Region0 1

1Cryomodule Vacuum ShrinkageTuning Available Region0 -1

1299.500 102LHe Pressure CBP11 13

Cavity Vertical Test1

13

9EP or CP

-1

2

8

9Dumbbell

Deform and Reform

EP or CP-2

3TemperaturePretuning7

8AnnealingTemperature

Pretuning TargetPretuning Target12

EP or CP DumbbellT i i

4 6Permittivity Trimming

Stiffening Ring Shrinkage5 to 2

5Pressure Iris Shrinkage14

0 Tuner Preload (HT)1297.350 & Deformation

150 Tuner Preload (HT)

ency Measurementency Measurement EP or CP limitency Measurementency Measurement Field Flatness Tuningency Measurementency MeasurementL /

HALF CELLS9-CELL CAVITY DUMBBELLS

L / mm

dumbbell frequency measurement fixturePretuning LengthTolerance Range Half cell Length

Dumbbell Reform Length Target

Dumbbell LengthTarget

Cavity Length Range(~ 2 mm)dumbbell frequency measurement fixture Tolerance Range gLength TargetTarget( 2 mm)

ck niobium plate The Q values of the halfck niobium plate. The Q values of the half

SSand the frequency was not stable The SummarySummaryand the frequency was not stable. Thed d f fl SummarySummarye press and good equator surface flatness, yye press and good equator surface flatness,

thi l t d l ti ha thinner plate and elastic washers waspe new fixture and about 10 kg press the Q Several problems have been solved during the fabrication EBW ande new fixture and about 10 kg press, the Q Several problems have been solved during the fabrication, EBW and

t i f 13 d bb ll f th IHEP l i l l h 9 llg p

s are above 5000 and the frequency is tuning of 13 dumbbells for the IHEP large grain low-loss shape 9-cells are above 5000, and the frequency is tuning of 13 dumbbells for the IHEP large grain low loss shape 9 cellit Th h l it ill b ld d d t t d i l t 2009 dcavity. The whole cavity will be welded and treated in late 2009, andy y ,

tested in KEK next springtested in KEK next spring.gLarge grain niobium cavity fabrication has many special issuesLarge grain niobium cavity fabrication has many special issues.

Dimension and frequency control related to material mechanicalDimension and frequency control related to material mechanicalproperties is important and needs more investigationproperties is important and needs more investigation.

[1] A S t l A th d t th f i f i di id l h lf ll i d bb ll it[1] A. Sun et al. A method to measure the frequencies of individual half cells in a dumbbell cavity.Review of Scientific Instruments 79 104701 2008Review of Scientific Instruments, 79, 104701, 2008[2] G Kreps et al Half cell and d mbbell freq enc testing for the correction of the TESLA ca it length[2] G. Kreps et al. Half-cell and dumbbell frequency testing for the correction of the TESLA cavity length.

i d T ii d T i 9th workshop on RF superconductivity, Santa Fe, New Mexico, U.S.A, 1999ping and Tuningping and Tuning 9th workshop on RF superconductivity, Santa Fe, New Mexico, U.S.A, 1999ping and Tuningping and Tuningp g gp g gAcknowledgementAcknowledgementmbbells to the target length and adjusted Acknowledgementmbbells to the target length and adjustedg g j

m The reshaping target length was the We would like to thank K. Yokoya and H. Hayano of KEK, B. Kephart and S.m. The reshaping target length was the We would like to thank K. Yokoya and H. Hayano of KEK, B. Kephart and S.Mi h f F il b d th k t K S it d F F t f KEK fwelding minus iris EBW shrinkage With Mishra of Fermilab, and many thanks to K. Saito and F. Furuta of KEK forwelding minus iris EBW shrinkage. With s a o e ab, a d a y a s o Sa o a d u u a o oi t t ti th 9 ll it f b i ti T Kh bib lli fasured six frequencies to calculate the important suggestions on the 9-cell cavity fabrication, T. Khabiboulline ofasured six frequencies to calculate the

f d bb ll Th b ip gg y ,

Fermilab for the information of the dumbbell frequency measurementof a dumbbell. The perturbation amount Fermilab for the information of the dumbbell frequency measurementof a dumbbell. The perturbation amountfixturefixture.