Muons, Inc, Batavia
Fermilab, Batavia
A Superconducting RF (SRF) Linac can be used for an accelerator-driven subcritical (ADS) nuclear power station to produce more than 5 GW electrical power in an inherently safe region below criticality, generating no greenhouse gases, producing minimal nuclear waste and no byproducts that are useful to rogue nations or terrorists, incinerating waste from conventional nuclear reactors, and efficiently using abundant thorium fuel that does not need enrichment. First, the feasibility of the accelerator technology must be demonstrated. We describe the Linac parameters that can enable this vision of an almost inexhaustible source of power and we discuss how the corresponding reactor technology can be matched to these parameters.
Muons, Inc, Batavia
JLAB, Newport News, Virginia
ODU, Norfolk, Virginia
Parametric-resonance Ionization Cooling (PIC) is envisioned as the final 6D cooling stage of a high-luminosity muon collider. Implementing PIC imposes stringent constraints on the cooling channel's magnetic optics design. This paper presents a linear optics solution compatible with PIC. Our solution consists of a superposition of two opposite-helicity equal-period and equal-strength helical dipole harmonics and a straight normal quadrupole. We demonstrate that such a system can be adjusted to meet all of the PIC linear optics requirements while retaining large acceptance.
Muons, Inc, Batavia
Fermilab, Batavia
We study electron-positron in-flight annihilation as a potential source of quasi-monoenergetic photon (or gamma-ray) beams. A high-intensity tunable-energy (1.5 MeV to 15 MeV) gamma source has many potential uses in medical, industrial and security applications. Several electron-positron collision geometries are considered: a) head-on; b) collinear; and c) positron beam incident on a fixed electron target. We analyze advantages of each of the geometries in order to optimize parameters of the generated gamma-ray beams.
Fermilab, Batavia
Muons, Inc, Batavia
The Helical Cooling Channel (HCC) is a technique proposed for six-dimensional (6D) cooling of muon beams. The HCC for muon collider and some other applications is usually divided into several sections each with progressively stronger fields, smaller aperture, and shorter helix period to achieve the optimal muon cooling rate. Novel magnet design concepts based on simple coils arranged in a helical solenoid configuration have been developed to provide HCC magnet systems with the desired parameters. The level of magnetic field in the HCC high-field sections suggests using a hybrid coil structure with High Temperature Superconductors (HTS) in the innermost coil layers and Nb3Sn superconductor in the outer coil layers. The development of the concepts and engineering designs of hybrid helical solenoids based on advanced superconductor technologies, with special emphasis on the use of HTS for high fields at low temperature is the key step towards a practical HCC. This paper describes the conceptual designs and parameters of a short HTS model of a hybrid helical solenoid, and discusses the structural materials choices, fabrication techniques, and first test results.
Muons, Inc, Batavia
North Carolina State University, Raleigh, North Carolina
YBCO superconductors originally developed for high temperature operation carry significant critical current even in the presence of extremely high magnetic field when operated at low temperature. The final stage of phase space cooling for a muon collider uses a solenoid magnet with fields approaching 50 T. As part of an R&D effort we present measurements of mechanical and electromechanical properties of the YBCO conductor. We examine the critical current verses magnet field angle at 4.2 K in a magnetic field. Quench properties of the conductor such as minimum quench energy threshold and quench propagation velocity will be measured to establish safe operational conductions for the muon cooling magnets. In this paper we describe a conceptual picture for a high field solenoid to be used for muon phase space cooling that incorporates these low temperature properties of YBCO.
Muons, Inc, Batavia
North Carolina State University, Raleigh, North Carolina
NHMFL, Tallahassee, Florida
High field accelerator magnets are needed for high energy physics applications. Superconducting materials able to reach these fields with low losses are required, and YBCO Roebel cable is being developed to address this issue. Characterization of commercially available Roebel cables for high field low temperature superconducting magnets is needed. YBCO Roebel cable with low AC losses is being developed and has limited commercial availability. Its behavior is not fully understood, however, especially in liquid helium and at high magnetic fields. YBCO Roebel cable will be acquired from a commercial vendor and characterized at cryogenic temperatures, in varying magnetic fields, and different strain configurations. A comprehensive behavior analysis will be performed, including operational and fatigue limits. Characterization of YBCO Roebel cable at low temperatures will be performed, including determination of the current flow path in steady-state and during quench using magneto-optical imaging, investigation of the effects of strand insulation, and examination of the mechanical and quench behavior at 4.2 K, 77 K, and varying magnetic fields.
Muons, Inc, Batavia
North Carolina State University, Raleigh, North Carolina
Magnet applications for high energy physics has long been an important driver for the development of superconducting technology. New high temperature superconductors (HTS), which have very high values of the upper critical field Hc2, show promise for magnets generating fields greater than 25 T, such as those required for muon cooling [1]. (Rare Earth)Ba2Cu3Oy (REBCO) coated conductor is an HTS material which is well suited to these needs; however it requires characterization in the low temperature (4.2 K), high magnetic field regime. We are proposing to measure electro-mechanical and magnetic properties, including angular field dependence of commercially available REBCO conductor. Here we present results of initial testing to characterize commercially available REBCO coated conductors at 77 K, including critical current and quench testing to calculate minimum the quench energy (MQE) and normal zone propagation velocity (NZPV).
Fermilab, Batavia
JLAB, Newport News, Virginia
Muons, Inc, Batavia
Fast muon beam six dimensional (6D) phase space cooling is essential for muon colliders. The Helical Cooling Channel (HCC) uses hydrogen-pressurized RF cavities imbedded in a magnet system with solenoid, helical dipole, and helical quadrupole components that provide the continuous dispersion needed for emittance exchange and effective 6d beam cooling. A series of HCC segments, each with sequentially smaller aperture, higher magnetic field, and higher RF frequency to match the beam size as it is cooled, has been optimized by numerical simulation to achieve a factor of 105 emittance reduction in a 300 m long channel with only a 40% loss of beam. Conceptual designs of the hardware required for this HCC system and the status of the RF studies and HTS helical solenoid magnet prototypes are described.
Muons, Inc, Batavia
To achieve the high luminosity required for a muon collider strong quadrupole magnets will be needed for the final focus in the interaction region. These magnets will be located in regions with space constraints imposed both by the lattice and the collider detector. There are significant beam related backgrounds from muon decays and synchrotron radiation which create unwanted particles which can deposit significant energy in the magnets of the final focus region of the collider. This energy deposition results in the heating of the magnet which can cause it to quench. To mitigate the effects of heating from the energy deposition shielding will need to be included within the magnet forcing the aperture to be larger than desired and consequently reducing the gradient. We propose to use exotic high magnetization materials for pole tips to increase the quadrupole gradient.
Fermilab, Batavia
Muons, Inc, Batavia
IIT, Chicago, Illinois
ANL, Argonne
University of Chicago, Chicago, Illinois
Voss Scientific, Albuquerque, New Mexico
A high pressurizing hydrogen gas filled RF cavity has a great potential to apply for muon colliders. It generates high electric field gradients in strong magnetic fields with various conditions. As the remaining demonstration, it must work under high radiation conditions. A high intensity muon beam will generate a beam-induced electron swarm via the ionization process in the cavity. A large amount of RF power will be consumed into the swarm. We show the recent non-beam test and discuss the electron swarm dynamics which plays a key role to develop a high pressure RF cavity.
Muons, Inc, Batavia
Fermilab, Batavia
A helical cooling channel (HCC) consisting of a pressurized gas absorber imbedded in a magnetic channel that provides solenoidal, helical dipole and helical quadrupole fields has shown considerable promise in providing six-dimensional cooling for muon beams. The energy lost by muons traversing the gas absorber needs to be replaced by inserting RF cavities into the HCC lattice. Replacing the substantial muon energy losses using RF cavities with reasonable gradients will require a significant fraction of the channel length be devoted to RF. However to provide the maximum phase space cooling and minimum muon losses, the HCC should have a short period and length. In this paper we examine an approach where each HCC cell has an RF cavity imbedded in the aperture with the magnetic coils are split allowing for half of the cell length to be available for the RF coupler and other services.
JLAB, Newport News, Virginia
Muons, Inc, Batavia
Neutrino Factories and Muon Colliders require rapid acceleration of short-lived muons to multi-GeV and TeV energies. A Recirculating Linear Accelerator (RLA) that uses superconducting RF structures can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each muon to pass several times through each high-gradient cavity. A new concept of rapidly changing the strength of the RLA focusing quadrupoles as the muons gain energy is being developed to increase the number of passes that each muon will make in the RF cavities, leading to greater cost effectiveness. We discuss the optics and technical requirements for RLA designs, using RF cavities capable of simultaneous acceleration of both μ+ and μ- species, with pulsed Linac quadrupoles and arc magnets to allow the maximum number of passes. The design will include the optics for the multi-pass linac and droplet-shaped return arcs.
Fermilab, Batavia
Muons, Inc, Batavia
Alternative RF cavity fabrication techniques for accelerator applications at low frequencies are needed to improve manufacturability, reliability and cost. RF cavities below 800 MHz are large, take a lot of transverse space, increase the cost of installation, are difficult to manufacture, require significant lead times, and are expensive. Novel RF cavities partially loaded with a ceramic for accelerator applications will allow smaller diameter cavities to be designed and built. The manufacturing techniques for partially loaded cavities will be explored. A new 200MHz cavity will be built for the Fermilab Proton Source to improve the longitudinal emittance and energy stability of the linac beam at injection to the Booster. A cavity designed for 400 MHz with a ceramic cylinder will be tested at low power at cryogenic temperatures to test the change in Qo due to the alumina ceramic. Techniques will be explored to determine if it is feasible to change the cavity frequency by replacing an annular ceramic insert without adversely effecting high power cavity performance.
Fermilab, Batavia
Muons, Inc, Batavia
Typically, high power sources for accelerator applications are multi-megawatt microwave tubes that may be combined together to form ultra-high-power localized power stations. The RF power is then distributed to multiple strings of cavities through high power waveguide systems which are problematic in terms of expense, efficiency, and reliability. Magnetrons are the lowest cost microwave source in dollars/kW, and they have the highest efficiency (typically greater than 85%). However, the frequency stability and phase stability of magnetrons are not adequate, when magnetrons are used as power sources for accelerators. Novel variable frequency cavity techniques have been developed which will be utilized to phase and frequency lock magnetrons, allowing their use for either individual cavities, or cavity strings. Ferrite or YIG (Yttrium Iron Garnet) materials will be attached in the regions of high magnetic field of radial-vaned, π−mode structures of a selected ordinary magnetron. A variable external magnetic field that is orthogonal to the magnetic RF field of the magnetron will surround the magnetron to vary the permeability of the ferrite or YIG material.
Muons, Inc, Batavia
JLAB, Newport News, Virginia
The operation of the RHIC facility at BNL and the Electron Ion Colliders (EIC) under development at Jefferson Laboratory and BNL need high brightness ion beams with the highest polarization. Charge exchange injection into a storage ring or synchrotron and Siberian snakes have the potential to handle the needed polarized beam currents, but first the ion sources must create beams with the highest possible polarization to maximize collider productivity, which is proportional to a high power of the polarization. We are developing one universal H-/D- ion source design which will synthesize the most advanced developments in the field of polarized ion sources to provide high current, high brightness, ion beams with greater than 90% polarization, good lifetime, high reliability, and good power efficiency. The new source will be an advanced version of an atomic beam polarized ion source (ABPIS) with resonant charge exchange ionization by negative ions. An integrated ABPIS design will be prepared based on new materials and an optimized magnetic focusing system. Polarized atomic and ion beam formation, extraction, and transport for the new source will be computer simulated.
Muons, Inc, Batavia
ORNL, Oak Ridge, Tennessee
Development of novel modifications of H- source designs is proposed. The new source will be an advanced version of a Penning DT SPS (Dudnikov-Type Penning Surface Plasma Source) which will generate brighter beam in noiseless discharge, deliver up to 20 mA average current with better electrode cooling using new materials, and have longer lifetime, fast beam chopping capability, and reduced cesium loss.
Muons, Inc, Batavia
UMD, College Park, Maryland
ORNL, Oak Ridge, Tennessee
In this project we are developing an RF H- surface plasma source which will synthesize the most important developments in the field of negative ion sources to provide high pulsed and average current, high brightness, good lifetime, high reliability, and higher power efficiency. We describe two planned modifications to the present SNS external antenna source in order to increase the plasma density near the output aperture: 1) replacing the present 2 MHz plasma-forming solenoid antenna with a 13 MHz saddle-type antenna and 2) replacing the permanent multicusp magnetic system with a weaker electro-magnet. Progress of this development will be presented.
Muons, Inc, Batavia
Fermilab, Batavia
The designs of accelerator systems that will be needed to transform Fermilab's Project X into a high-power proton driver for a muon collider and/or a neutrino factory are discussed. These applications require several megawatts of beam power delivered in tens or hundreds of short multi-GeV bunches per second, respectively. Project X may require a linac extension to higher energy for this purpose. Other major subsystems that are likely to be needed include storage rings to accumulate and shorten the proton bunches and an external beam combiner to deliver multiple bunches simultaneously to the pion production target.