Frontier Project Research Articles

Deriving the DEA frontier for two-stage processes

Data envelopment analysis (DEA) is a method for measuring the efficiency of peer decision making units (DMUs). Recently DEA has been extended to examine the efficiency of two-stage processes, where all the outputs from the first stage are intermediate measures that make up the inputs to the second stage. The resulting two-stage DEA model provides not only an overall efficiency score for the entire process, but as well yields an efficiency score for each of the individual stages. Due to the existence of intermediate measures, the usual procedure of adjusting the inputs or outputs by the efficiency scores, as in the standard DEA approach, does not necessarily yield a frontier projection. The current paper develops an approach for determining the frontier points for inefficient DMUs within the framework of two-stage DEA.

Archaeologies of Landscape

This article interrogates the materiality of Hadrian’s Wall beyond its widespread perception as a monument of/to Ancient Rome. Encounters with this monument have generated multitudinous materialities: hegemonic, conflicting and ambiguous. These trajectories have their own material circulations in both solid and narrative forms. Here, we consider materiality through the cultures inspired by/of the Wall. Through the formulation of an interdisciplinary methodology and praxis, we contribute to landscape studies generally and Romano—British frontier studies in particular. Firstly, we consider the genealogies of thought through which the Wall has been created, including its definition as a contested border and its use to inform discourses of nation and empire. Secondly, the material landscapes of the Wall are considered through phenomenon and encounter informed by contemporary debates in anthropology, archaeology and cultural geography. As part of the Arts and Humanities Research Council funded Tales of the Frontier project (http:// www.dur.ac.uk/roman.centre/ hadrianswall/), the authors aim to provide an enriched account of the materialities of the Wall beyond traditional narratives generated by fieldwork and ancient historical texts.

Biology thinks big to stay cuts

Intercontinental programme sets vision for frontier projects.

Design and construction of a compact microwave proton source for a proton linac

A 100 MeV, 20 mA proton linear accelerator is being developed by the Proton Engineering Frontier Project at the Korea Atomic Energy Research Institute. 20 MeV acceleration system using radio frequency quadrupole and drift tube linac was already developed and has been tested. To operate this acceleration system with a long time, more reliable proton source is needed. A compact microwave proton source was proposed and has been designed and constructed as a prototype ion source for the 100 MeV proton linear accelerator. The design of microwave power injection system is based on the microwave proton injector at LANL and CEA. The wave power from a 2.45 GHz, 2 kW magnetron source is introduced into a compact plasma chamber with 7 cm diameter and 5 cm length through a standard tapered, double-ridged waveguide (WRD250) and a quartz window. The microwave power supply is installed on high voltage platform. Axial magnetic fields up to 1 kG can be provided with a water-cooled solenoid coil. A single-hole three electrode extraction system is designed for an extraction current up to 30 mA at a 50 kV extraction voltage. The design and initial operations of the proton source are presented.

Evaluation of Skyshine Dose for the Proton Accelerator Facility of the Proton Engineering Frontier Project in Korea

Evaluation of the skyshine dose for the proton linac facility of the Proton Engineering Frontier Project in Korea was performed in this study. To predict the skyshine dose level outside of the facility, a Monte Carlo method (MCNPX code), analytical method using an estimation formula, and SKYSHINE-KSU codes using an integral line-beam method were considered in the evaluations. The neutron spectrum at the outer surface of the roof of the facility was considered as the radiation source term. The results from each method were in good agreement for the distance from 200 to 1000 m. The neutron dose of 1.65 × 10-4 μSv/h is expected at the fence of the facility, which is 400 m from the accelerator room.

Design and evaluation of proton accelerator beam window cooling configuration

A 100 MeV, 20 mA proton linear accelerator is being constructed as a part of the Proton Engineering Frontier Project (PEFP) funded by the Korean Ministry of Education, Science and Technology’s (MEST). To irradiate a target with proton beam for multiple applications, a beam window with a sound structure is essential, which successfully divides the accelerator compartment from the target. This paper presents how the cooling method for beam window was designed while considering various factors. Multiple cooling configurations were considered during the beam window design phase and each cooling configuration was tested to determine if the configuration successfully minimizes average temperature of the window during irradiation and also minimizes hot spot area. The heat transfer analysis was followed by a structure analysis to determine if the beam window can satisfy the design requirements. Through this investigation, the requirements for beam window cooling configuration and fabricated material were identified and these newly found requirements will be iterated to improve the final design.

금속이온 주입기에서의 Co 이온의 인출 특성 연구

양성자기반공학기술개발사업단에서는 설치된 금속이온주입기를 이용하여 금속이온의 인출 시험 중에 있으며 120keV의 금속 이온주입이 가능하다. 현재 코발트 이온 주입의 타당성 확인을 위한 특성시험을 수행하고 있다. 이온원에 알루미나 도가니를 설치하여 분말 코발트 염화물을 고온(<TEX>$648^{\circ}C$</TEX>) 가열에 의한 증기화로 인하여 플라즈마 방전이 되도록 하였다. 아크전압 120V, EHC 출력 250W에서 코발트 이온을 인출하기 위한 플라즈마를 발생하고 유지할 수 있었다. 코발트 이온 빔 전류는 플라즈마 내 아크전류에 의존하였으며 0.18A일 때 최대 빔전류 <TEX>$100{\mu}A$</TEX>를 얻을 수 있었다. 질량분리전자석에 의해서 <TEX>$Co^+$</TEX>와 <TEX>$CoCl^+$</TEX>, <TEX>$Cl^+$</TEX> 이온의 첨두 빔 전류 비율을 확인하였고 전체 이온 대비 <TEX>$Co^+$</TEX> 이온의 비율이 70% 수준을 유지함을 알 수 있었다. <TEX>$Co^+$</TEX> 이온을 알루미늄 시료에 빔전류 <TEX>$10{\mu}A$</TEX>, 90분 동안 이온주입 하여 RBS(Rutherford Backscattering Spectrometry)분석법으로 <TEX>$1.74{\times}10^{17}#/cm^2$</TEX>의 이온량을 확인하였다. Proton Engineering Frontier Project (PEFP) has supplied the metal ions to users by using an installed metal ion implanter of 120 keV. At present a feasibility study is being performed for a cobalt ion implantation. For a cobalt ion extraction we studied to sustain the high temperature(<TEX>$648^{\circ}C$</TEX>) for metal ions vaporization from a cobalt chloride powder by using an alumina crucible in the ion source. The temperature condition of the crucible was satisfied with the plasma generation at the arc current of 120V and EHC power of 250W. The extracted beam current of <TEX>$Co^+$</TEX> ions was dependent on the arc current in the plasma. The maximum beam current was <TEX>$100{\mu}A$</TEX> at 0.18A of the arc current. The 3 peak currents of the extracted ions such as <TEX>$Co^+$</TEX>, <TEX>$CoCl^+$</TEX> and <TEX>$Cl^+$</TEX> were obtained by adjusting a mass analyzing magnet and the <TEX>$Co^+$</TEX> ion beam peak current fraction as around 70% in the sum of the peak currents. The fluence of the implanted cobalt ions at the <TEX>$10{\mu}A$</TEX> of the beam current and 90 minutes of the implantation time into an aluminum sample as measured around <TEX>$1.74{\times}10^{17}#/cm^2$</TEX> by a quantitative analysis method of RBS (Rutherford Backscattering Spectrometry).

Development of the Resonant-Frequency Monitoring System for the PEFP DTL

Development of the Resonant-Frequency Monitoring System for the PEFP DTL Young-Gi Song, Han-Sung Kim, Hyeok-Jung Kwon and Yong-Sub Cho Proton Engineering Frontier Project, Korea Atomic Energy Research Institute, Daejeon 305-353 (Received 4 September 2008) A 20-MeV, 20-mA proton linac, which is comprised of a 50-keV proton injector, a 3-MeV radio frequency quadrupole (RFQ) and 20-MeV drift tube linac (DTL), has been developed in the Proton Engineering Frontier Project (PEFP). For a stable and e cient acceleration of a proton beam, the resonant frequency of the DTL cavities should be matched to the high power RF driving frequency. In PEFP DTL, a resonant control cooling system (RCCS) will be used to control the resonant frequency. The main objective of this study is to measure and transfer the resonance frequency error to the RCCS by measuring the RF eld pro le in the cavity. The algorithm derived by using a state-space model is used to represent the resonant frequency error. The control application program was developed with a VME-based PCI mezzanine card (PMC) extended board and a multitasking method based on the VxWorks. We tested the algorithm, the control board and the application program by using a dummy cavity. In this paper, the algorithm, the system con guration and the test results are presented. PACS numbers: 29.17.+w

Multipacting Behavior Research in a PEFP Low-Beta Superconducting RF Cavity and in a PEFP Fundamental Power Coupler

A low-beta superconducting radio-frequency (RF) cavity has been designed to accelerate a proton beam at an energy above 100 MeV at 700 MHz in the linac of the Proton Engineering Frontier Project (PEFP) and its extended project. Each low-beta superconducting cavity is composed of 5 cells and has a fundamental power coupler (FPC) to transfer the RF power from the klystron to the proton beam. The performance of the superconducting cavity and the FPC may be limited due to electron multipacting on the walls of the cavity, in the coaxial line, or in the RF window. In order to predict and prevent multipacting harm to a PEFP low-beta cavity and a FPC, we used MultiPac 2.1 for Windows to research the multipacting behaviors in those RF structures. By calculating the multipacting electron trajectories, the threshold values for the occurring multipacting and the nal energy of the secondary electron, we identi ed the location of multipacting occurrence and the power threshold. A reasonable design was obtained to prevent multipacting in the FPC.

Error Analysis of PEFP Beam Lines

This work is related to the error analysis of the proton engineering frontier project (PEFP) beam lines. In order to evaluate the error e ects on the trajectory of the beam center, we used an error analysis code that included a rst-order perturbation of the translational and the rotational errors of the dipole and the quadrupole magnets in the beam lines. The distorted beam trajectory can be corrected by using corrector magnets. The speci cations of the correction dipoles are obtained by using an error correction algorithm that is included in the code.

Mechanical Properties of the External Beam Window for the PEFP

There are 6 external beam lines among the Proton Engineering Frontier Project's (PEFP's) user facilities. The beam window size for large-area irradiation was determined to have a 300 mm diameter and a 0.5 mm in thickness and an aluminum-beryllium alloy (AlBeMet) was adopted as the basic material due to not only its good radiation damage resistance but also its good thermal characteristics. In this work, numerical simulations were conducted to nd the proper supporting method for the thin beam window and an O-ring seal was introduced to relieve the concentrated stress. The AlBeMet sheet used in the plastic-forming process for the concave shape was also simulated with the AUTOFORM code. With these results, a pilot beam window was made and tested.

Radiation Shielding Design for 300keV Ion Implanter

PEFP(Proton Engineering Frontier Project) developed the 300 keV ion implanter for basic experiments. This facility, sponsored by ARTI (Advanced Radiation Technology Institute), was designed and manufactured for studies on a surface modification by an ion beam. Generally, in developing an ion implanter whose energy is around 300 keV or more, a shielding provision should be considered to prevent an unexpected exposure. During the development of PEFP’s 300 keV ion implanter, its shielding issue was a localization of the shielding effect and the prevention of an acceleration of the secondary electrons by using a magnetic field, because it was needed to reduce X-ray more efficiently and the weight of the shielding material as well. In this paper, localization shielding concept was adopted and also a magnetic field was placed in the middle of an accelerator tube. Consequently, through this work, we reduced not only 30% of the X-ray intensity but also the weight of the shielding materials.

Insulation Design and Experimental Results for Transmission Class HTS Transformer With Composite Winding

In the response to the demand for electrical energy, much effort aimed to develop and commercialize high temperature superconducting (HTS) power equipments has been made around the world. In Korea, companies and universities are developing a power distribution and transmission class HTS transformer that is one of the 21st century superconducting frontier projects. The composite winding of transmission class HTS transformer is concentrically arranged primary winding (High)-Secondary winding (Low)-tertiary winding (High) from center. Primary winding is continuous disk type, Secondary winding is layer type and tertiary winding is Double pancake type. For the development of transmission HTS transformer with composite winding, the cryogenic insulation technology should be established. We have been analyzed insulation composition and investigated electrical characteristics such as breakdown of , barrier, kapton films and surface flashover on Fiber Reinforced Plastic (FRP) in Liquid nitrogen . We are going to compare with measured each value and apply the value to most suitable insulating design of the HTS transformer.

Off-gas Ventilation System Design for the Shielding Structure of the 100MeV Proton Accelerator of PEFP

In this paper, we describe a design of a ventilation system to limit the total doses given to workers by satisfying the regulatory limits. We suggest a radiation shielding design scheme to reduce the Ar-41 production rate in each target room of the Beam Application Research Area (BARA).Analyses were performed for the ventilation system design of Proton Engineering Frontier Project (PEFP). According to the analyses results, the radioactivity production rate in the accelerator tunnel is saturated at 5.57×10−3 Bq/cm3 in 16 h without a ventilation system operation, which satisfies the regulatory limits. In the target rooms of the BARA, the radioactivity production rate is reduced within the range from 329Bq/cm3 to 5.19 Bq/cm3 by the proposed ventilation system for the PEFP radiation shielding scheme.

Characteristics of the joint mini-model high temperature superconducting cable

To obtain realistic data on the high temperature superconducting (HTS) power cable, 3-phase 100 m long, 22.9 kV class HTS power transmission cable system have been developed by Korea Electrotechnology Research Institute (KERI) and LS cable Ltd. that is one of 21st Century Frontier Project in Korea. This cable was installed at Go-chang testing site of Korea Electric Power Corporation (KEPCO). For the application of the HTS power cable joint is very important to ensure the performance. Therefore, this paper gives some investigation of AC loss, critical current and joint resistance in jointed HTS tape. We experimentally showed that the influence of joint resistance on AC loss by using several joint methods. Finally, we are measured critical current, AC loss and jointed resistance for the manufactured mini-model cable.

Design of a Fundamental Power Coupler for the PEFP Superconducting RF Cavities

Elliptical superconducting RF cavities are being considered to accelerate a proton beam from 80 MeV at 700 MHz in the linac of the Proton Engineering Frontier Project. Each PEFP SRF cavity has one fundamental power coupler to transfer RF power from the klystron to the beam. A coaxial-type fundamental power coupler is designed for the PEFP SRF cavities. The doorknob transition has been designed to match the impedance of a WR-1150 waveguide to that of a 50coaxial guide. A coaxial window has been optimally designed after calculating its stress distribution and RF elds and simulating its multipacting behavior. The dimensions of the coaxial guides have been determined after calculating the electromagnetic eld distribution near the ceramic window when the standing wave arises and after considering a cryomodule assembly.

Amplitude and Phase Stability of Analog Components for the LLRF System of the PEFP Accelerator

The Proton Engineering Frontier Project (PEFP) low-level radio frequency (LLRF) system for the 3-MeV radio frequency quadrupole accelerator (RFQ) and the 20-MeV drift tube linear accelerator (DTL) has been developed. A stability of 1 % in the amplitude and 1 degree in the phase is required. Therefore, the drift of the analog components should be low enough to satisfy these requirements. An analog chassis, as a prototype of the LLRF system, was con gured and tested. RF components, including an IQ modulator, an RF switch, a mixer, RF splitters, RF lters, a circuit for measuring tank phase and a trip circuit for high voltage standing wave ratio (VSWR), have been installed in this chassis. The analog chassis performs an error compensation of the RF amplitude and phase from the IQ signal, a down-conversion to the 10 MHz IF signal, an interlock for the arc and the high VSWR and a distribution for the RF and the clock signals. The amplitude and the phase stability of each component were measured to check the e ect on the whole system's performance. In the test with dummy cavities, a uctuation of 5 degrees was measured in the 340 MHz LO signal, but the relative phase between the two cavities was maintained within 0.2 degrees because of the e ect being the same for the LO signals of the two cavities.

Beam Steering of the PEFP 100-MeV Linac

Beam Steering of the PEFP 100-MeV Linac Ji-Ho Jang, Kui Young Kim, Byung Chul Chung, Hyeok Jung Kwon and Yong Sub Cho Proton Engineering Frontier Project, Korea Atomic Energy Research Institute, Daejeon 305-353 (Received 21 September 2007) This work focuses on the beam steering of the PEFP (Proton Engineering Frontier Project) DTL (drift tube linac) in order to control the beam uctuation generated by displacement and rotation errors of the quadrupole magnets in the drift tubes. We evaluated the e ects of the errors on the beam motion and studied the beam-steering algorithm. Based on this work, we determined the position of the steering magnets and their speci cations. PACS numbers: 29.17.+w, 29.27.-a

A CW K-Klystron of 700 MHz and 1 MW for PEFPfootnoteSupported by Proton Engineering Frontier Project (PEFP)

A CW K-Klystron of 700 MHz and 1 MW for PEFPfootnoteSupported by Proton Engineering Frontier Project (PEFP)

Test results of the proton injector of the Proton Engineering Frontier Project accelerator

One of the goals of the Proton Engineering Frontier Project (PEFP) is to develop a 100 MeV proton accelerator. As a low energy part, a 20 MeV proton linac has been developed and tested. The 20 MeV accelerator consists of a 50 keV proton injector, a 3 MeV radio frequency quadrupole, and a 20 MeV drift tube linac. The proton injector includes a duoplasmatron type ion source and a low energy beam transport. After a preliminary test with 1 mA peak current of the 20 MeV accelerator, the proton injector was modified with the goal of increasing the 20 MeV beam current up to 20 mA peak value. The modifications include the reduction of the proton injector length, installation of a beam current monitor, and electron trap and supplement of the solenoid and steering magnets. In this paper, the modifications of the PEFP proton injector are described and initial test results are presented.