High-power Electron Accelerators Research Articles

Conceptual design of hybrid target for molybdenum-99 production based on heavywater

Molybdenum-99 (99Mo) is used for preparing Technetium-99 m (99mTc), which is the most widely used isotope in nuclear medicine. In this work, a study for 99Mo production based on a high-power electron accelerator has been performed as an alternative approach to produce 99mTc. In this study, Monte Carlo MCNPX2.6 code has been used to examine a novel idea of simultaneous hybrid production of 99Mo via both photoneutron and neutron capture reactions using an electron accelerator in heavy water tank. It is expected that this conceptual design including an arrangement of metallic plates of 100Mo and 98Mo produces total activity of 97.5 Ci at the end of 20-h continuous e-beam irradiation (30 MeV, 10 mA).

High-power electron accelerator for the production of neutrons and radioisotopes

The purpose of the work is to study the possible use of existing high-power electron accelerators for neutron therapy and the production of radioisotopes. Calculations were performed for both applications and the results were normalized to the characteristics of the existing MEVEX accelerator (average electron current 4 mA at a monoenergetic electron beam of 35 MeV). A unifying problem for the applications is the task of cooling the target: at a beam energy of about 140 kW, almost half of this energy is released directly in the target. For this reason, a liquid heavy metal was chosen as a target in order to combine the high quality of thermohydraulics with the maximum performance of both bremsstrahlung radiation and photoneutrons. The targets were optimized using precision codes for radiation transfer and thermal-hydraulic applications. Optimization was also carried out on the installation as a whole: (1) on the composition of the material and the configuration of the photoneutron extraction unit for neutron capture therapy (NCT) and (2) on the bremsstrahlung generation scheme for producing radioisotopes. The photoneutron unit provides an acceptable beam quality for NCT with a large neutron flux density at the output: ~ 2·1010 cm–2s–1, which is an order of magnitude higher than the output values of existing and planned reactor beams. Such intensity at the beam output will make it possible in many cases to abandon fractionated irradiation. As for the production of radioisotopes, in the calculations for the (γ, n) reaction, 43 radionuclides in five groups were obtained. For example, using the Mo100(γ, n)99Mo reaction, it is possible to obtain the 99Mo precursor of the main diagnostic isotope 99mTc with a specific activity of ~ 6 Ci/g and a total target activity of 1.8 kCi after irradiation for 24 hours. The proposed schemes for generating and outputting photoneutrons and bremsstrahlung have a number of obvious advantages over traditional methods, including: (a) the use of electron accelerators for producing neutrons is much safer and cheaper than the use of reactor beams; (b) the accelerator with the target and the beam extraction unit with the necessary equipment and tooling can be easily placed in a clinical setting; and (c) the proposed liquid gallium target for NCT, which also serves as a coolant, is an “environmentally friendly” material: its activation is relatively small and drops quickly (after about four days) to the background level.

Industrial electron accelerators developed at the Budker Institute of Nuclear Physics, SB RAS

In the early 1960s, work on developing industrial high-power electron accelerators was initiated by Academician G I Budker, the founder and director of the Institute of Nuclear Physics (currently, Budker Institute of Nuclear Physics, BINP). This review describes the arrangements and principles of operation of high-power electron accelerators of the ELV and ILU series designed and constructed at the BINP. Since 1972, 170 ELV and more than 50 ILU machines have been shipped to many countries around the world, most of them still operational. International Atomic Energy Agency surveys rate the BINP as one of the few well-trusted global suppliers of reliable industrial accelerators.

Nuclear data for medical applications: An overview of present status and future needs

A brief overview of nuclear data required for medical applications is given. The major emphasis is on radionuclides for internal applications, both for diagnosis and therapy. The status of the presently available data is discussed and some of the emerging needs are outlined. Most of the needs are associated with the development of non-standard positron emitters and novel therapeutic radionuclides. Some new developments in application of radionuclides, e.g. theranostic approach, multimode imaging, radionanoparticles, etc. are described and the related nuclear data needs are discussed. The possible use of newer irradiation technologies for medical radionuclide production, e.g. intermediate energy charged-particle accelerators, high-power electron accelerators for photon production, and spallation neutron sources, will place heavy demands on nuclear data.

Design and construction of tetrode tube modulator for high power electron accelerator

RFموج پیوسته پرداخته می‌‌شود. این مدولاتور به منظور راه اندازی بخشی از سیستم 200kWبا توان TH781 در این مقاله به تشریح مراحل طراحی و ساخت مدولاتور یکTH781 پروژه ساخت اولین شتاب‌دهنده پرقدرت الکترون ایران مشابه شتاب‌دهنده رودترون مورد استفاده قرار گرفته است. با توجه به حساسیت لامپ تتروددقت در طراحی ساخت قسمت‌های مختلف مدولاتور آن و همچنین ترتیب راه اندازی بسیار با اهمیت بود. لذا علاوه بر طراحی منابع تغذیه، مدارهای کنترلی نیز جهت حفاظت اجزای مختلف لامپ لحاظ شده است. نتایج حاصل از آزمون و بهره برداری این سامانه که برای اولین بار در کشور طراحی و ساخته شده است بسیار رضایت بخش می‌باشد

Design of photon converter and photoneutron target for High power electron accelerator based BNCT

An electron accelerator, ILU-14, with current of 10mA and 100kW in power has been considered as one of the options for neutron source in Boron Neutron Capture Therapy (BNCT). The final design of neutron target has been obtained using MCNPX to optimize the neutron production. Tungsten in strip shape and D2O in cylindrical form have been proposed as the photon converter and the photoneutron target, respectively. In addition calculation of heat deposition in the photon target design has been considered to ensure mechanical stability of target. The results show that about 8.37×1012photoneutron/s with average energy of 615keV can be produced by this neutron source design. In addition, using an appropriate beam shaping assembly an epithermal neutron flux of the order of 1.24×108cm−2s−1 can be obtained for BNCT applications.

LINAC-BASED PHOTONUCLEAR APPLICATIONS AT THE IDAHO ACCELERATOR CENTER

In this paper, current Idaho Accelerator Center (IAC) activities based on the exploitation of high energy bremsstrahlung photons generated by linear electron accelerators will be reviewed. These beams are used to induce photonuclear interactions for a wide variety of applications in materials science, activation analysis, medical research, and nuclear technology. Most of the exploited phenomena are governed by the familiar giant dipole resonance cross section in nuclei. By proper target and converter design, optimization of photon and photoneutron production can be achieved, allowing radiation fields produced with both photons and neutrons to be used for medical isotope production and for fission product transmutation. The latter provides a specific application example that supports long-term fission product waste management. Using high-energy, highpower electron accelerators, we can demonstrate transmutation of radio-toxic, long-lived fission products (LLFP) such as 99Tc and 129I into short lived species. The latest experimental and simulation results will be presented.

Development and Applications of High-Energy X-ray Sources Coupled with High-Power Laser and Electron Accelerator

Development and Applications of High-Energy X-ray Sources Coupled with High-Power Laser and Electron Accelerator

Pulse generators based on air-insulated linear-transformer-driver stages

In this paper we present the design and test results of pulse generators based on air-insulated linear-transformer-driver stages that drive a vacuum transmission line. A custom designed unit, referred to as a capacitor block, was developed for use as a main structural element of the transformer stages. It incorporates two capacitors GA 35426 (40 nF, 100 kV) and a multichannel multigap gas switch. Two types of stages were developed: (1) stage LTD-20 with four modules in parallel and five capacitor blocks in each module (in tests of this stage current amplitude up to 850 kA with $\ensuremath{\sim}140\text{ }\text{ }\mathrm{ns}$ rise time was obtained on a $0.05\text{ }\ensuremath{\Omega}$ load at 100 kV charging voltage); (2) stage LTD-4 with two modules in parallel and two capacitor blocks in each module. Several installations were built on the base of these stages, including a linear transformer, consisting of two identical LTD-20 stages in series, and a high power electron accelerator on the base of LTD-4 stages. The design, tests results, and main problems are presented and discussed in this paper for these installations.

A comparison of rat SPECT images obtained using 99mTc derived from 99Mo produced by an electron accelerator with that from a reactor

Recent shortages of molybdenum-99 (99Mo) have led to an examination of alternate production methods that could contribute to a more robust supply. An electron accelerator and the photoneutron reaction were used to produce 99Mo from which technetium-99m (99mTc) is extracted. SPECT images of rat anatomy obtained using the accelerator-produced 99mTc with those obtained using 99mTc from a commercial generator were compared. Disks of 100Mo were irradiated with x-rays produced by a 35 MeV electron beam to generate about 1110 MBq (30 mCi) of 99Mo per disk. After target dissolution, a NorthStar ARSII unit was used to separate the 99mTc, which was subsequently used to tag pharmaceuticals suitable for cardiac and bone imaging. SPECT images were acquired for three rats and compared to images for the same three rats obtained using 99mTc from a standard reactor 99Mo generator. The efficiency of 99Mo–99mTc separation was typically greater than 90%. This study demonstrated the delivery of 99mTc from the end of beam to the end user of approximately 30 h. Images obtained using the heart and bone scanning agents using reactor and linac-produced 99mTc were comparable. High-power electron accelerators are an attractive option for producing 99Mo on a national scale.

An air scintillator

A method for bremsstrahlung dosimetry by air luminescence at high-power pulsed electron accelerators is considered. Light emitted in an air scintillator is focused by the lens at the tip of a quartz optical fiber and transmitted to the photocathode of a photomultiplier tube. The sensitivity of the measuring channel is determined using a standard ribbon lamp. Bremsstrahlung pulses producing an exposure of 0.18 C/kg at the bremsstrahlung beam axis in a ∼20-ns time interval are detected at the ЛИУ-30 electron accelerator with a high accuracy. This exposure corresponds to an absorbed dose rate, integrated over the beam diameter, of 7.5 × 107 Gy m/s.

Degradation kinetics of electron beam irradiated poly(propylene-co-ethylene) heterophasic copolymer

This study considers the effects of electron beam radiation on degradation kinetics of a poly(propylene-co-ethylene) heterophasic copolymer. Polypropylene heterophasic copolymers are composed of ethylene–propylene rubbery phase dispersed in crystalline polypropylene homopolymer matrix. Electron beam radiation can affect both polypropylene homopolymer matrix and ethylene–propylene dispersed phases simultaneously. Both phases undergo degradation and crosslinking reactions, but degradation is more probable in the polypropylene homopolymer matrix. The aim of this work is to study kinetics of degradation in this material. A high power electron accelerator irradiated raw samples under nitrogen atmosphere. The samples are analyzed using TGA in non-isothermal mode, and the degradation kinetic parameters were determined using Kissinger, Flynn–Wall–Ozawa and Coats–Redfern methods. The kinetic parameters resulted from these methods are compared. Results of kinetics studies show that orders of degradation reactions occurring in nitrogen atmosphere are all less than one. It indicates degradation takes place due to thermal dissociation of the chemical bonds.

Precision modeling of the internal injection and beam dynamics for a high-power RF accelerator

A new high-power electron accelerator for industrial applications has been developed in Novosibirsk. The main parameters of the accelerator are: operating frequency of 178 MHz, electron energy of 5 MeV, and average beam power of up to 300 kW. The accelerator consists of a chain of accelerating cavities connected by on-axis coupling cavities with coupling slots in the walls. A triode RF gun on the base of a grid-cathode unit placed on the wall of the first accelerating cavity is used for internal injection of electrons. The paper presents the results of modeling and optimization of the accelerating structure, internal injection, and beam dynamics. A modification of the electrostatic computer code SAM designed for simulation of beam dynamics in linear RF accelerators by the long-wave approximation method is described.

The IBA rhodotron TT1000: a very high power E-beam accelerator

Due to the relatively low conversion efficiency of electrons into X-rays, the use of X-rays on an industrial basis requires high-power high-energy electron accelerators. Based on its experience acquired in the development of the Rhodotron (Nucl. Instrum. Methods B 40/41 (1989) 943; Nucl. Instrum. Methods B 79 (1993) 865), IBA has launched a few years ago a vigorous R&D program to develop such high-power electron accelerator devoted to X-ray industrial applications. This research program resulted in the TT1000 Rhodotron aimed at delivering 5 and 7 MeV electron beams with a current intensity of 100 mA. This project is now reaching its final phase with the qualification tests of the first prototype of this new machine.

Multichannel Spark Gaps with Control Bar Electrodes: Their Development and Application (A Review)

Multichannel low-inductance (∼1 nH) gas-filled spark gaps (MSGs)1 with several tens of channels each, bar control electrodes designed for an operating voltage of ≤100 kV, and a switched current of up to 400 kA are reviewed. The control electrodes, made in the form of narrow thin plates, have an intermediate potential, are positioned in the gap between two common main electrodes (high-voltage and low-voltage (grounded)), and are oriented uniformly along their length. Upon a near-simultaneous change in the bars' potential in a time of 0.1 MPa) of the MSG-filling gas. Electrical circuits for initiating the discharge development in the MSGs, the transients in such circuits, and the factors affecting the parameters of processes and the gap-breakdown delay and rate are considered. Particular MSG designs, multicable systems for parallel triggering of a large number of MSGs, and the use of 48 four-channel 50-kV MSGs in the first iron-free LIA-2 linear electron accelerator (2 MeV, 25 kA, and 60 ns) created in 1967 are described. The successful operation of MSGs stimulated further studies and the development of efficient trigatrons for operating voltages of 100 and 500 kV. Up to 3000 MSGs of this type are used in new high-power linear electron accelerators. A low-impedance (0.45 Ω) generator of high-voltage pulses (50–200 kV) with a multicable output has been developed to synchronously trigger such large numbers of trigatrons as these.

Wide-Range Inductive Sensors of Currents with Nanosecond Rise Times for Measuring Parameters of High-Current Pulses (Review)

The design and characteristics of inductive current sensors (modernized Rogovski coils) and inductive sensors on their basis (in the form of a part of a tore) with shielded coils for measuring the parameters of pulse currents in conductors with diameters of up to 1.7 m and electron beam currents of 10–2000 kA with durations of 10–100 ns in a self-integration mode. The Rogovski coils and sensors have current rise times of nanosecond duration and improved noise immunity and mechanical strength. Methods for the calibration of Rogovski coils for determining their transient response and amplitude sensitivity are presented. Specific features of the certification of large-diameter devices are pointed out, and a new method for certifying such sensors is expounded. The sensors are used in experimental investigations and the refinement of units of high-current linear induction accelerators as well is in the starting and adjustment work with a high-power LIA-30 electron accelerator with water-insulated radial lines in the inductors of accelerating modules and for monitoring its parameters (40 MeV, 100 kA, 20 ns). Such sensors are applicable for recording pulse current characteristics in other electrophysical facilities.

A Multichannel Automatized System for Measuring Current Pulses in the LIA-30 Electron Accelerator

In the LIA-30 high-power linear pulsed induction electron accelerator (40 MeV, 100 kA, 25 ns), the energy is stored, and pulses of the accelerating voltage are shaped by 288 water-insulated radial lines arranged in succession along a common air-free acceleration channel. The lines are simultaneously charged up to 500 kV from 72 shielded Marx generators. To measure the parameters (amplitude, pulse shape, pulse rise time, pulse fall time, and pulse duration) of the synchronized pulses of the charging current with amplitudes as high as 60 kA and duration of 0.85 μs in each of the 72 charging circuits, an automatized measuring system is used. The current pulse is sensed at the output of each generator by a self-integrating Rogovsky coil galvanically isolated from the generator. The signal from the coil is transmitted over a cable to an analog-to-digital converter, sampled with a period of 50 ns, and recorded in memory. Upon operating the accelerator, the signals are reproduced in succession or selectively on the display screen, and their shapes are compared to the shape of a standard pulse.

Current approach to design of high-power electron accelerators to match actual requirements of radiation technology in Poland

Existing and continuously emerging new applications of electron beam processing technologies evoke a constant interest in elaboration and design of accelerators’ solutions, matched to definite requirements of most-needed treatment procedures. In close collaboration with the Institute of Nuclear Chemistry and Technology, and the Andrzej Sołtan Institute for Nuclear Studies, the proposal for two types of technological accelerators has been formulated. In the present paper, basic features of these accelerators—10V, 10–20 kW and 10 MeV, 20–50 kW—are briefly described.

D.C. high power electron accelerators of ELV-series: status, development, applications

Abstract In the work presented here the parameters of powerful electron accelerators of continuous action are given and the main systems of the accelerator and a wide set of supplementary devices extending the application range of the accelerator are given and some directions of further development are noted.

High power electron accelerators for flue gas treatment

Over 1000 accelerators based on different principles have been constructed and used in the field of radiation chemistry and radiation processing. One of the radiation processes which was successfully demonstrated in many laboratories and pilot plant facilities is the reduction of SO2 and NOx pollutants from flue gases emitted during fuel combustion in boilers for electrical power and heat production. The full scale industrial implementation of an electron beam process for flue gases treatment would require accelerator modules with a beam power of over 500 kW and electron energy in the range 1–1.5 MeV. The 500 MW power plant may require 5–8 MW of electron beam power deposited in the flue gas.