The design of multi-pulses, multi giga-watt, high voltage generators is of particular interest for electron beam induction accelerators. The major requirements for this type of pulsed power generators are a few percent flat top, a jitter in the range of 1 ns, high pulse reproducibility shot to shot and a drastic reliability. As an opportunity for future flash X-rays
machines, CEA is developing...
The Spallation Neutron Source (SNS) beam chopping system uses a segmented electrostatic lens in the Low Energy Beam Transport (LEBT) to deflect the beam out of the RFQ input aperture to create gaps in the 1ms beam macro-pulse for extraction from the Ring, or fully displace the beam. The lens is split azimuthally into four quadrants which are pulsed independently by four bipolar high voltage...
Two types of the high-voltage cells are developed for a 20 MeV, 2 kA linear induction accelerator and a 2 MeV injector. Each accelerator’s cell incorporates 16 inductors, it is supplied in an inductive voltage adder manner with a pulse voltage up to 336 kV and different flattop duration of 60-380 ns. At the first stage the cells were tested in a 60 ns pulse mode, the test results with an...
The Spallation Neutron Source (SNS) utilizes an electron scanner in the accumulator ring for non-destructive transverse profiling of the proton beam. The electron scanner consists of a high voltage pulse generator driving an electron gun, a medium voltage ramp generator, and a CCD camera. A new high voltage pulse generator that provides 100 kV pulses with rise times of less than 200 ns,...
Generally, the performances of high power electron beam diode, such as current levels, impedance collapse, and plasma expansion, have been attributed to the combination of the cathode and anode instead of just the cathode. The issues of anode have been paid more and more attention in research and practical applications. In this paper, five kinds of anode materials, stainless steel, titanium...
Regarding semiconductor-device production, ion-implant energy is decreasing since the junction depth becomes shallower along with the shrinkage of device size. The lowest energy level for practical use has been around several 100eV and will become lower than 100eV in a near future [1]. For realizing such low-energy beams, ions are decelerated before implantation. We reported in the past that...
The Saturn Accelerator at Sandia National Laboratories was originally designed as a short pulse, negative polarity machine with a power pulse width of approximately 28 ns feeding a three ring diode bremsstrahlung x-ray source supporting the machine’s primary function as a high dose-rate x-ray simulator. For upcoming x-ray source designs such as the reflex triode, the machine must be operated...
The new electron accelerator GESA-SOFIE for long pulse operation was specially designed for in-situ diagnostics and investigation of the beam characteristics and operation performance under different conditions. One of the new features is the possibility to tune the shape and position of the electrodes. The use of a planar cathode necessary to optimize the diagnostics, for instance, makes an...
At the EPURE facility, in France, a high power electron diode is used to generate an intense high quality pulsed electron beam in order to produce a bremsstrahlung radiation pulse for flash radiography. For this purpose, a cold cathode is driven by a 75 Ω graded transmission line, which delivers a 3.8 MV, 95 ns (FWHM) high power electrical pulse across a diode gap of 17.2 cm. The cathode is...
This work presents numerical modeling of interaction between intense electron beam and target plasma in LIA accelerator. Well-focused electron beam hit tantalum target that causes producing of high-density target plasma. This plasma consists of electrons and ions of tantalum and different contaminations adsorbed on the target surface [1]. Because of negative potential of the electron beam,...
A numerical model using both electromagnetic and Monte-Carlo simulations is used to investigate the performances of a 1 MV LTD pulsed high-power accelerator [1]. Particle-In-Cell calculations were employed to examine the beam dynamics throughout the Magnetically Insulated Transmission Line which governs the coupling between the generator and the electron diode. Based on the information...
Dynamics of beam spot on high Z target is key quality factor of LIA radiographic machines [1]. To obtain direct observation of beam spot evolution during the LIA shot the experimental procedure with time resolution of tens of nanoseconds was introduced [2]. It based on pinhole camera and scintillator with segmented structure. In this report the measurements of beam spot dynamics on the 2 MeV...
Electron beam (e-beam) generation in high power vacuum diodes results in anode and cathode plasma formation. It is well documented that expansion of these plasmas into the A-K gap can adversely affect diode performance during the main e-beam pulse. However, ionized gases may exist for many microseconds afterward and can contribute to localized breakdowns in the diode gap if transient voltage...
Pulsed plasma thrusters utilizing solid propellants have relatively low efficiency [1]. As alternative propellants, liquids are considered to be used in PPTs. However, using of liquid arises the problem of supplying it to the discharge area [2]. This work presents the results of the estimation of plasma formation efficiency of the discharge unit utilizing vacuum pump oil as a propellant. It...
*The Proton Power Upgrade(PPU)project at SNS is planned to accelerate 38mA of beam current to 1.3GV, effectively doubling the accelerator power capability to support the planned Second Target Station. This project required three additional modulators to power the 28 additional 700kW klystrons and associated high beta cavities. An alternate topology high voltage converter modulator (AT-HVCM)...
The pulse forming networks (PFN) were developed to provide a 2 kA, 20 MeV linear induction accelerator cells power supply. A PFN’s and high-voltage capacitors manufacturing is organized at BINP. The PFN is a LC-network with nonuniform impedance made of capacitive sections with a combined paper-film dielectric filled with a castor oil in a polypropylene case. A PFN’s isolation is rated at 50 kV...
Dielectric Wall Accelerator (DWA) is a new type of pulsed linear accelerator. Its working mechanism is regulating the discharge order of different power sources to keep the accelerating electric field present near the particles all the time, and it is really suitable for heavy ions acceleration. The Institute of Fluid Physics, China Academy of Engineering Physics (IFP, CAEP) began the research...
The natural rubber research is ongoing project at the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The project aims to use electron beam irradiation for high quality vulcanization process for natural rubber. The main accelerator system consists of a DC thermionic electron gun, 5-cell linear accelerator structure, control system, RF system and electron beam...
*NSTec product number: DOE/NV/25946--3117
After the 1992 moratorium on underground nuclear testing, the Subcritical Experiment (SCE) program was initiated to support stockpile stewardship. The SCE laboratory is located in a tunnel complex 1,000 feet below ground surface at the Nevada National Security Site (NNSS). Cygnus is a radiographic x-ray source which is a primary diagnostic for the SCE...
A pulsed system for a 2 kA, 20 MeV linear induction accelerator power supply was developed. On a first stage of operation it is capable of producing a 336 kV, 2 kA, 60 ns single pulse at the accelerating inductive cells. Each cell is supplied by 8 pulse modulators based on an inductive voltage adder principle. Each modulator is designed to produce pulses up to 21 kV, 10 kA with a different...
Linear induction accelerator LIA is designed and developed at the Budker Institute of Nuclear Physics in 2010 year as injector for fullscale radiographic machine. Now it is currently used as independent radiographic X-ray source for testing objects with an optical thickness up to 70 mm lead equivalent. In 2014 year the high-voltage power supply system was upgraded. Accelerator operates in one...
The energy deposition plays an important role in the study of the thermal mechanical effect of intense electron beam. A new method to obtain the time-dependent electron beam energy deposition at different anode target position was presented. First, the electron beam energy should be discretized according to diode working time(every 5ns), so that the electron beam in each time period is...
Recently, demands on high-coherent, ultra-bright, and ultra-fast X-ray photon beams are increased for an ultra-fast basic science applications. The pulse-to-pulse stability of RF linac klystron modulators is one of critical issues in 3rd generation synchrotron machine for the top-up operation of the PLS-II linac. This machine requires highly stable RF sources with a stability of 0.01% rms, to...