The status of the research on muon colliders is discussed and plans are outlined for future theoretical and experimental studies. Besides work on the parameters of a 3-4 and 0.5 TeV center-of-mass (COM) energy collider, many studies are now concentrating on a machine near 0.1 TeV (COM) that could be a factory for the s-channel production of Higgs particles. We discuss the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from 1098-4402͞99͞2(8)͞081001(73)$15.00 © 1999 The American Physical Society 081001-1 PRST-AB 2 CHARLES M. ANKENBRANDT et al. 081001 (1999) a heavy-Z target and proceeding through the phase rotation and decay (p ! m n m ) channel, muon cooling, acceleration, storage in a collider ring, and the collider detector. We also present theoretical and experimental R&D plans for the next several years that should lead to a better understanding of the design and feasibility issues for all of the components. This report is an update of the progress on the research and development since the feasibility study of muon colliders presented at the Snowmass '96
A code has been developed which calculates the cyclotron radiation spectrum emitted by a slab model tokamak plasma in a direction outward along a major radius. The calculation assumes both a thermal and a suprathermal electron component for the plasma, and includes the effects of self-absorption of the radiation by the thermal plasma. Various methods are described by which the cyclotron radiation spectrum can be unfolded to obtain parameters of the electron population. A procedure is described by which the electron temperature profile can be obtained from spectral measurements of the cyclotron emission at optically thin frequencies. No absolute calibration of the detection equipment is needed for this method. The code can be used to find parameters of the suprathermal distribution function from its synchrotron emission spectrum, and for the special case of suprathermal electrons at a constant major radius, analytical results are obtained. Finally, the code has been used to calculate cyclotron spectra for various tokamaks: CLEO, TFR, ATC, PLT, and Alcator.
National Laboratory is part of the U.S. program to explore heavy-ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density 0:2 C=m) over long pulse durations (4 s) in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo, and electron and gas cloud effects. We present the results for a coasting 1 MeV K ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius) for which the transverse phase space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor (80%) is achieved with acceptable emittance growth and beam loss, even though the initial beam distribution is not ideal (but the emittance is low) nor in thermal equilibrium. We achieved good envelope control, and rematching may only be needed every ten lattice periods (at 80% fill factor) in a longer lattice of similar design. We also show that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics.
We describe the next set of experiments proposed in the U.S. Heavy Ion Fusion Virtual National Laboratory, the so-called Integrated Beam Experiment (IBX). The purpose of IBX is to investigate in an integrated manner the processes and manipulations necessary for a heavy ion fusion induction accelerator. The IBX experiment will demonstrate injection, acceleration, compression, bending and final focus of a heavy ion beam at significant line charge density. Preliminary conceptual designs are presented and issues and tradeoffs are discussed. Plans are also described plans for the step after IBX, the Integrated Research Experiment (IRE), which will carry out significant target experiments.
The HIF-VNL High Current Experiment (HCX) [1] is exploring transport issues such as dynamic aperture, effects of quadrupole rotation, and the effects on the beam of non-ideal distribution function, mismatch, and electrons, using one driver-scale 0.2 microcoulomb/m, 2-10 microsecond coasting K + beam. 2D and 3D simulations are being done, using the particle-in-cell (PIC) code WARP to study these phenomena. We present results which predict that the dynamic aperture in the electrostatic focusing transport section will be set by particle loss.
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