High Energy Accelerator Research Organization Preliminary Study of Low SEE Coefficient Alumina for Coupler Window K. Iwamoto KYOCERA Corporation S. Michizono, A. Yamamoto High Energy Accelerator Research Organization I am Iwamoto, engineer of KYOCERA. First of all, I’d like to express my appreciation for this opportunity of presentation. I’d like to explain on the results of “Preliminary Study of Low SEE Coefficient Alumina for Coupler Window”.

Contents Introduction of KYOCERA Material Design Concept Introduction of AH100A Property for Sample Material S-band　RF Transmission Test Summary These are the contents of my presentation. 以下の内容について説明します。

Introduction of KYOCERA 1959 : Insulator for CRT E-Gun * 1st Product of Kyocera Scientific Analytical Equipment CRT U Shape Kelcima Industrial Components Semi-Conductor Processing Equipment Analytical Equipment Infrastructure/Communications Medical Equipment Kyocera Corporation started in 1959. Kyocera has produced a variety of unique products including very high voltage resistant materials for several key applications. 京セラは1959年に始まり、現在では様々な市場用途に対して、特色あるセラミック部品を製造しております。 絶縁碍子はあらゆる産業で使用されており、高電圧用途では高い耐電圧性能要求に対応しております。 Insulators are applied in various industries. High Voltage Application High Voltage Resistance Required (Surface Flashover Voltage/Dielectric Strength)

Material Design Concept Purpose Discharge Effecting Factor Material Approach High Resistance for Creeping Discharge Low Secondary Electron Emission Coefficient(SEEC) Electron Multiplication Charge Up Low Resistance Status for Material Low SEE 1014Ω・cm 99% Alumina KYOCERA A479 SEEC：11.2 New Alumina KYOCERA AH100A SEEC：4.6 1014Ω・cm On a commercial basis Low Resistance ・With this slide, I’d like to explain on the design concept of the newly developed material for high voltage applications. For the purpose of minimizing creeping discharge phenomenon, we’ve focused on the two factors: electron multiplication and charge-up on ceramic surface. In order to reduce electron multiplication, we focused “low secondary electron emission coefficient” as the material approach. And charge-up phenomenon can be reduced through the reduction of resistance of insulator. ・KYOCERA has so far developed “low surface resistivity material” and “Low SEE coefficient material”. During this session, I’d like to focus on the introduction of the “Low SEE coefficient material”. This material has the performance of SEEC 4.6. This means that Kyocera has succeeded in achieving the half level of SEEC 11.2 of the conventional 99% alumina. We have named this new Alumina material as AH100A. This material has just been released and commercially available now. Please let me present the key characteristic of this material in the following slides. 弊社の材料開発の方針について説明します。 セラミックの沿面放電抑制を目的として、２つの影響因子に着目しました。 ｾﾗﾐｯｸ表面のﾁｬｰｼﾞｱｯﾌﾟと電子増倍現象です。 材料アプローチとしてはﾁｬｰｼﾞｱｯﾌﾟを抑制するために、低抵抗化を。 電子増倍を抑制するために２次電子放出係数の低減が考えられます。 ・京セラでは標準的な99%アルミナに対して、表面抵抗率の低い材料や２次電子放出係数が小さい材料を開発してきました。 従来アルミナの２次電子放出係数が11.2に対して新材料は4.6と約1/2に低減できました。 この材料は現在AH100Aという材料コードで商用ベースで販売可能です。 次にこのAH100Aを紹介します。 Low Surface Resistivity Introduction of AH100A

AH100A Material Characteristic Introduction of AH100A AH100A Material Characteristic <Ref. Data> 99% Alumina (KYOCERA A479) AH100A Electrical Property SEE　Coefficient - 11.2 4.6 Ultimate Surface Flashover Field Gradient*1 MV/m 8.4 (Ave.) 14.1 (Ave.) Dielectric Strength*2 19 24 Volume Resistivity ohm･cm min. 1 X 1014 Dielectric Constant(1MHz) 9.9 10.2 Dielectric Loss Angle(1MHz) 2 X 10-4 1 X 10-4 Mechanical Ave. Flexural Strength(RT) ASTM D2442 TYPE3 MPa 310 330 Young’s Modulus GPa 360 380 Poisson Ratio 0.23 0.25 Fracture Toughness MPa･m1/2 3-4 5 Thermal Thermal Conductivity (RT) W/mK 29 Coeff. Thermal Expansion RT-400deg.C ppm/K 7.2 7.4 RT-800deg.C 8.0 8.2 This is the material property of AH100A in comparison with conventional A479. SEE coefficient of AH100A is the half of that of the conventional alumina. Surface flashover resistance is 1.6 times higher than conventional alumina. Dielectric strength is improved by 20%. AH100Aの材料特性を示します。 従来アルミナの代表として京セラA479と比較しました。 ２次電子放出係数が従来アルミナの約1/2になっています。 沿面耐電圧性能は1.6倍、絶縁耐力は1.2倍に向上しています。 *1 : Measurement Method : KYOCERA Internal, *2 : Measurement Method : According to JIS C 2141

Applied Flashover Field Gradient Joint Research about High Voltage Resistance Alumina with KEK Emeritus Prof. Yoshioka, Emeritus Prof. Matsumoto, Dr. Kurihara Oscilloscope Measurement Equipment Finemet Core Anode Attenuator 1k ohm Anode Photomultiplier Cathode SMA Cable Cathode HV Power Supply Max. 100kV 10M ohm Test Piece Dia. 20 X 5mm Insulator Measurement Procedure Applied Flashover Field Gradient (MV/m) ○ : Surface Flashover Occurs X : No Surface Flashover +1kV/5mm (0.2MV/m) × ○ -1 ～ -2 -3 -4 Run Number 1 2 N ・ ・This is the surface flashover test results through the joint research with KEK. We used High Voltage Test Facility of KEK. Shape of the Test Piece was the disc of 20mm diameter x 5mm thickness and set with metal electrodes on both sides. We recorded discharge current and so on. ・We applied 1kV step increase of voltage. We counted the number of the discharges. After discharge, we went back to 0 volt for next run number. We repeated the same methods. この材料はKEKと共同研究させて頂いた成果の一つです。 試験結果の一部を紹介します。 試験体形状はφ20×5mmの円板形状で、先ほどと同様に両端面に金属電極を設置します。 チャンバー内圧力は10-9Paと、極めて高真空条件下で測定しました。 放電電流を記録しました。 試験方法について説明します。 試験は１分1kVでステップ昇圧します。 放電回数を記録します。 放電後、０Vに戻し、次のRUN　NUMBERへ移ります。 この作業を繰り返します。 Vacuum Level:10-9 (Pa) Definition of Surface Flashover Voltage Number of Flashover : Times of Flashover during 5min.

Effect of AH100A in HV Product Measurement Result Flashover # Drastic Decrease from Conventional Alumina 99.7% Alumina (KYOCERA A480S) AH100A Flashover # :Approx.120 times Flashover # :Approx.10 times Flashover Number Flashover Number Field Gradient (MV/m) ・This is the test result. Left side is conventional alumina of 99.7% KYOCERA　A480S. Right side is AH100A. X-axis is Run Number, Y-axis is field intensity and Z-axis is the number of discharge. Conventional alumina had the discharge number of 120 times at high voltage area. However,　AH100A had only 10 times discharges at high voltage area. The number of discharges for AH100A is drastically decreased. ・These are the evaluation results of AH100A for other applications. ・放電実験の結果について説明します。 左側に従来アルミナとして弊社99.7%アルミナのA480Sを右側に今回の開発材の開発当初のコンセプト材の測定結果です。 このグラフはX軸がRun Number、Y軸が電界強度、Z軸が放電回数を示します。 従来アルミナでは初期放電電界強度が-2.2MV/mで放電回数は高電圧領域で１２０回と非常に多くなっています。 これに対して、コンセプト材は初期放電電界強度が-4.8MV/mで放電回数も１０回程度と少なくなっています。 従来アルミナと比較しますと初期放電電界強度が２倍に向上し、放電回数も大幅に低減できました。 ・これらはAH100Aの評価事例です。 Field Gradient (MV/m) Evaluation Results for AH100A Products Example Application Effect of AH100A in HV Product A TEM Reduced conditioning time to 1/10 of conventional alumina B X-ray tube for analysis Low leak current on ceramic part Reduced rate of numbers of discharge C Photomultiplier Tube AH100A can keep high voltage to be stable

Material Design Concept Purpose Discharge Effecting Factor Material Approach High Resistance for Creeping Discharge Low Secondary Electron Emission Coefficient(SEEC) Electron Multiplication Charge Up Low Resistance Status for Sample Material Low SEE 1014Ω・cm 99.9% Alumina SEEC：9.2 New Alumina KYOCERA AH100A SEEC：4.6 1014Ω・cm Low Resistance SEEC:3.2 Low Surface Resistivity 1014Ω/sq Sample Material Low Surface Resistivity With the understanding that it’s necessary to further reduce the SEE Coefficient as well as Surface Resistivity for RF Coupler application, Kyocera has also evaluated another sample material with lower SEE and Surface Resistivity, which is still under development. 京セラは今回、AH100Aより表面抵抗率を下げた材料について評価しました。 この材料はまだ開発中の評価用サンプルです。 この材料を用いてRFカプラー用窓材料としての可能性を評価しました。 Under investigation We evaluate the possibility of this material for coupler window application

SEE (Secondary Electron Emission) Coefficient Measurement Method Test Piece Detector Primary Electron Secondary Electron SEE Coefficient　Measurement Result AH100A has 1/2 smaller SEE Coefficient than that of 99% alumina. Sample material can make SEE coefficient less than AH100A, however still higher than TiN coated alumina surface. After Annealing at 1200 degree C This slide shows SEE coefficient measurement result. ①This figure shows Measurement method. ②The graph shows the measurement result of SEE coefficient. X axis shows irradiation electron energy, Y axis shows SEE Coefficient. We compared the SEE Coefficient of “Sample material” with AH100A. We added measurement value of 99% alumina and TiN coating on alumina for reference. ③AH100A has the half SEE Coefficient of that of 99% alumina. “Sample material” showed less SEE coefficient than AH100A, however still higher than TiN coated alumina surface. ①２次電子放出係数についての測定結果です。 ②このグラフの横軸は入射電子のエネルギー、縦軸は２次電子放出係数を示します。 ③AH100Aの２次電子放出係数は９９％アルミナよりも1/2小さい。 Sample materialの２次電子放出係数 はAH100Aよりも更に小さいが、TiNコート品よりは高い。

Comparison of Measurement Value for Evaluated Ceramic AH100A Sample <Ref. Data> 99.8% Alumina for RF Application (A479B) AH100A Sample Material Electrical Property Volume Resistivity ohm･cm min. 1 X 1014 - Surface Resistivity ohm/□ 8.9 X 1014 7.4 X 1015 1.2 X 1014 SEE　Coefficient 11.4 4.6 3.2 Dielectric Constant 1MHz 9.9 10.2 8GHz 10.0 Dielectric Loss Angle 1 X 10-4 *1 4 X 10-5 1 X 10-4 3 X 10-3 Mechanical Ave. Flexural Strength(RT) ASTM D2442 TYPE3 MPa 300 330 Young’s Modulus GPa 370 380 Poisson Ratio 0.23 0.25 Thermal Thermal Conductivity (RT) W/mK 29 24 Coeff. Thermal Expansion RT-400deg.C ppm/K 7.0 7.4 This is the summary of the properties of “Sample material” in comparison with AH100A and 99.8% alumina KYOCERA A479B for RF applications. A479B was selected as the comparison material in the following S-band RF Transmission test and its dielectric loss was the lowest among these 3 materials. The surface resistivity of “Sample material” is lower than those of other materials. SEE coefficient of “Sample material” is even lower than AH100A. However, dielectric loss of “Sample material” is larger than others. Sample materialの材料特性についてまとめます。 比較のためAH100Aの値も示します。 また、この後示しますS-band RF Transmission testにおいて比較試験体としてる弊社RF用途材料99.8%アルミナA479Bの特性も示します。 誘電損失が低いことが特徴のアルミナです。 Sample materialの表面抵抗率が他の材料と比較して低く、これにより２次電子放出係数がAH100Aよりも更に低くなっています。 反対に誘電損失は大きくなっています。 *1:Lower limitation of measurement method S-band　RF Transmission Test Sample

(99.8% Alumina for RF Application) Purpose of RF Transmission Test Sample Material is evaluated for the possibility of usage as RF coupler window without TiN coating. S-band　RF Transmission Test Sample WINDOW A B Ceramic Material Sample Material (Low SEEC Alumina) KYOCERA A479B (99.8% Alumina for RF Application) Metallize Mo-Mn Brazing Au-Cu I’d like to explain on the S-band RF Transmission Test from this page. The purpose of the test is that “Sample material” is evaluated for the usage as RF coupler window without TiN coating. Test sample was RF window of S-band Pillbox type, “Sample Material” in Window A, and A479B in Window B. The photograph shows Window A as the example and we applied the same coating for Window B. We coated TiN in the upper half on the upper side of the ceramic window, and TiN coating in half right on the back side. ここからはS-band RF Transmission Testについて説明します。 Sample materialがTiNコーティング無しでRFカプラー用窓として使える可能性について初期評価することです。 試験体はS-band　Pillbox typeのRF窓とし、Window AにSample Materialを、Window BにA479Bを用いました。 写真はWindow Aです。。 いずれの窓にもセラミック窓の表側には上半分にTiNコーティングを裏側には右半分にTiNコーティングを行いました。 TiN Coating Thickness:10nm RF Wave Direction Ceramic Metal Flange Window A Sample Material Left side view Window A Sample Material right side view

∝ S-band RF Transmission Test Method Resonant Ring in KEK TiN Coating Item Condition RF Power 1MW-10MW Pulse Width 2ms Frequency 50Hz Pressure 10-6Pa Resonant Ring in KEK TiN Coating (Back side) TiN Coating (Front side) Rectangular waveguide Uncoated Camera This is the test method. We have used the resonant ring at KEK as the test stand. We set up the ceramic window. RF wave goes through from the left side of the window to the right side. We can observe the ceramic window surface during RF transmission from the both side. Input RF power is 1MW to 10MW, because the multipactor phenomenon occurs in this range based on the past experience. This is one example photograph of the luminescence on ceramic window from the right side during RF transmission. Luminescence from right half is low because of TiN coating on the right half of the ceramic window. Since this luminous phenomenon is supposed to be due to cathode luminescence by electron incident on the ceramic surface, the cathode luminescence intensity is related to the amount of multipactor. 測定方法について説明します。 実験装置はKEKのレゾナントリングです。 この部分にセラミック窓を設置します。 高周波はセラミック窓の左側から右側に透過します。 高周波透過時のセラミック窓表面を左右の窓から観察しました。 入力RFパワーはこれまでの経験からマルチパクター現象が起こる１MWから１０MWとしました。 RF透過時の右側から見たセラミック窓の発光の１例を示します。 セラミック窓手前側の右半分にTiNコーティングがされており、発光が少なくなっています。 この発光現象はセラミック表面への電子入射によるカソード発光と考えられるので、発光量はマルチパクターの発生量と関係しています。 Luminescence on ceramic surface during RF transmission ∝ Rectangular waveguide Cathode Luminescence from ceramic Multipactor Bombardment

Test Result of RF Transmission TiN Coating (Back side) Luminescence on ceramic surface of Window A 　　 is Less than Window B. TiN Coating (Front side) View area INPUT RF POWER (MW) Electric Field (MV/m) TE11-like mode Window A Sample material Low SEEC Alumina Window B KYOCERA A479B 99.8%　Alumina for RF Application Photo exposure time Luminescence on ceramic surface 1 0.6 30s 5 1.3 0.5s 10 1.8 15s This is the test result. From left side, Input RF Power, Electric Field, Luminescence photo for WINDOW A and WINDOW B. Each photo is taken by adjusting the exposure time, so we show exposure time for each photos. Luminescence for WINDOW A is less than Window B in all range of the input RF power. テスト結果です。 左からINPUT RF POWER,　電界強度、WINDOW AとWINDOW Bの発光の様子です。 各写真は露光時間を調整して撮影していますので、露光時間も示しました。 全てのRF出力においてWINDOW Aの方が発光強度がBと比較して少ない結果でした。

Summary Kyocera has developed AH100A high voltage resistant Alumina. AH100A shows a high withstand voltage performance in some of the customer, it is already commercialized. Sample Material evaluated this time has surface resistivity of 1 to 2 orders of magnitude lower than AH100A, SEE Coefficient also is even smaller. But Tanδ is larger. Luminescence in RF window of “Sample Material” is smaller than one of the conventional Alumina in the transmission test. KYOCERA will continue to cooperate the evaluation of Sample Material with KEK for the RF coupler applications. As summary, Kyocera has developed AH100A high voltage resistant Alumina. AH100A shows a high withstand voltage performance in some of the customer, it is already commercialized. “Sample Material” evaluated this time has surface resistivity of 1 to 2 orders of magnitude lower than the AH100A, SEE Coefficient also is even smaller. But Tanδ is larger. Luminescence in RF window of “Sample Material” is smaller than one of the conventional Alumina in the transmission test. KYOCERA will continue to cooperate the evaluation of “Sample Material” with KEK for the RF coupler applications. 京セラはConventional Aluminaよりも耐電圧性能の高いAH100Aを開発した。 　　既にいくつかの顧客において高い耐電圧性能を示し、商品化されている。 今回評価したSample MaterialはAH100Aよりも表面抵抗率が１桁～２桁低く、SEE Coefficientも更に小さくなっている。 　　しかしTanδは大きくなっている。 RF窓のRF透過試験においてSample Materialの窓はConventional Aluminaよりも発光が小さい。 京セラは今後もSample MaterialがRFカプラー用途に使用頂けるかKEKの評価に協力していく。

Thank you for your attention

APPENDIX

Calculation Method for Surface Resistivity Surface Resistivity: ρs（Ω/□） Dm･π Rs ： Surface Resistance （Ω） Dm ： Mean Diameter (mm) g ：Gap length between Anode and Cathode (mm) D1 ： Diameter of Cathode (mm) D2 ： Diameter of Anode (mm) ρs = ･Rs g D1 + D2 Dm = 2 D2 –D1 ( - ) (+) Guard g = 2 Measurement for Surface Resistivity Result Item Condition Sample size φ16X1.5mm D1 6mm D2 10mm Measuring method 3-terminal method Measuring equipment Meg-ohm meter TAO DSM-8103 Voltage 500V Temperature 25℃ Humidity 30％ n=45 This slide shows the surface resistivity. It shows the calculation method of surface resistivity in the upper side. The left bottom table shows the measurement conditions. The right bottom graph shows the test result. Left side is AH100A and right side is the “Sample material” with lower surface resistivity. Surface resistivity for “Sample material” is 1 to 2 order magnitude smaller than that of AH100A. 表面抵抗率について説明します。 上段に表面抵抗率の計算方法を示します。 測定条件はこちらにまとめています。 測定結果です。 左側に比較のためAH100Aの結果をしめし、右側に今回のサンプル材料の結果を示します。 Sample materialの表面抵抗率はAH100Aより1-2桁小さくなりました。 1-2 order of magnitude decrease Surface Resistivity （Ω/□） n=12 AH100A Sample Material 17

Measurement Method for RF property Item Condition Sample size Φ17 X 8.5mm Measuring method Rod Resonance Measuring frequency 8GHz Temperature 25℃ Measurement Result for RF property Tand of Sample Material is higher than one of AH100A Dielectric Constant Dielectric Loss Angle AVE.3.1X10-3 This page shows RF property. Measurement method is Rod resonance method. Frequency is 8GHz. Dielectric constant for “Sample Material” is the same on average as that of AH100A. Dielectric loss for “Sample Material” is 1 order of magnitude larger than that of AH100A. RF特性についてです。 測定方法は円柱共振器法で８GHｚでの結果です。 誘電率においてはSample MaterialはAH100Aと平均値で同じでした。 誘電損失においてはSample MaterialはAH100Aよりも１桁大きくなりました。 AVE.1.4X10-4 1 order of magnitude larger