117,468 research outputs found
Machine Protection
The protection of accelerator equipment is as old as accelerator technology
and was for many years related to high-power equipment. Examples are the
protection of powering equipment from overheating (magnets, power converters,
high-current cables), of superconducting magnets from damage after a quench and
of klystrons. The protection of equipment from beam accidents is more recent.
It is related to the increasing beam power of high-power proton accelerators
such as ISIS, SNS, ESS and the PSI cyclotron, to the emission of synchrotron
light by electron-positron accelerators and FELs, and to the increase of energy
stored in the beam (in particular for hadron colliders such as LHC). Designing
a machine protection system requires an excellent understanding of accelerator
physics and operation to anticipate possible failures that could lead to
damage. Machine protection includes beam and equipment monitoring, a system to
safely stop beam operation (e.g. dumping the beam or stopping the beam at low
energy) and an interlock system providing the glue between these systems. The
most recent accelerator, the LHC, will operate with about 3x10 14 protons per
beam, corresponding to an energy stored in each beam of 360 MJ. This energy can
cause massive damage to accelerator equipment in case of uncontrolled beam
loss, and a single accident damaging vital parts of the accelerator could
interrupt operation for years. This article provides an overview of the
requirements for protection of accelerator equipment and introduces the various
protection systems. Examples are mainly from LHC, SNS and ESS.Comment: 23 pages, contribution to the CAS - CERN Accelerator School: Advanced
Accelerator Physics Course, Trondheim, Norway, 18-29 Aug 201
Machine Protection and Interlock Systems for Circular Machines - Example for LHC
This paper introduces the protection of circular particle accelerators from
accidental beam losses. Already the energy stored in the beams for accelerators
such as the TEVATRON at Fermilab and Super Proton Synchrotron (SPS) at CERN
could cause serious damage in case of uncontrolled beam loss. With the CERN
Large Hadron Collider (LHC), the energy stored in particle beams has reached a
value two orders of magnitude above previous accelerators and poses new threats
with respect to hazards from the energy stored in the particle beams. A single
accident damaging vital parts of the accelerator could interrupt operation for
years. Protection of equipment from beam accidents is mandatory. Designing a
machine protection system requires an excellent understanding of accelerator
physics and operation to anticipate possible failures that could lead to
damage. Machine protection includes beam and equipment monitoring, a system to
safely stop beam operation (e.g. extraction of the beam towards a dedicated
beam dump block or stopping the beam at low energy) and an interlock system
providing the glue between these systems. This lecture will provide an overview
of the design of protection systems for accelerators and introduce various
protection systems. The principles are illustrated with examples from LHC.Comment: 23 pages, contribution to the 2014 Joint International Accelerator
School: Beam Loss and Accelerator Protection, Newport Beach, CA, USA , 5-14
Nov 201
Introduction to Machine Protection
Protection of accelerator equipment is as old as accelerator technology and
was for many years related to high-power equipment. Examples are the protection
of powering equipment from overheating (magnets, power converters, high-current
cables), of superconducting magnets from damage after a quench and of
klystrons. The protection of equipment from beam accidents is more recent,
although there was one paper that discussed beam-induced damage for the SLAC
linac (Stanford Linear Accelerator Center) as early as in 1967. It is related
to the increasing beam power of high-power proton accelerators, to the emission
of synchrotron light by electron-positron accelerators and to the increase of
energy stored in the beam. Designing a machine protection system requires an
excellent understanding of accelerator physics and operation to anticipate
possible failures that could lead to damage. Machine protection includes beam
and equipment monitoring, a system to safely stop beam operation (e.g. dumping
the beam or stopping the beam at low energy) and an interlock system providing
the glue between these systems. The most recent accelerator, LHC, will operate
with about 3 x 10 protons per beam, corresponding to an energy stored in
each beam of 360 MJ. This energy can cause massive damage to accelerator
equipment in case of uncontrolled beam loss, and a single accident damaging
vital parts of the accelerator could interrupt operation for years. This
lecture will provide an overview of the requirements for protection of
accelerator equipment and introduces various protection systems. Examples are
mainly from LHC and ESS.Comment: 20 pages, contribution to the 2014 Joint International Accelerator
School: Beam Loss and Accelerator Protection, Newport Beach, CA, USA , 5-14
Nov 2014. arXiv admin note: text overlap with arXiv:1601.0520
Variable-beamwidth antennas
Two effective designs have been developed for Cassegrain and Gregorian antenna configurations. Each provides for both high-gain and low-gain operations. Cassegrain system sacrifices some efficiency due to small amount of increased spillover loss. Gregorian system provides for independent spillover control with two feeds
Bidirectional zoom antenna
Antenna comprises two parabolic cylinders placed orthogoanlly to each other. One cylinder serves as main reflector, and the other as subreflector. Cylinders have telescoping sections to vary antenna beamwidth. Beamwidth can be adjusted in elevation, azimuth, or both. Design has no restriction as to choice of polarization
An improvement in blackbody cavity design
Setting the axis of the conical cavity at an angle to the axis of observation removes the imperfection at the apex of the cone from the direct observation area of the radiometer. Fillet no longer behaves as a nonuniformity in the blackbody
Electronic scanning of 2-channel monopulse patterns
Scanning method involves separation of scanning capability into two independent degrees of freedom. One degree of freedom corresponds to azimuthal scanning and other to elevation scanning on spiral coordinate axes. Scanning of both prime-feed and mirrored patterns is accomplished with reduction of mechanical vibration damage to large antennas
Electronic scanning of 2-channel monopulse patterns Patent
Monopulse scanning network for scanning volumetric antenna patter
Focal axis resolver for offset reflector antennas
Method and apparatus for determining the focal axis of an asymmetrical antenna such as an offset paraboloid reflector whose physical rim is not coincident with the boundary of the electrical aperture but whose focal point is known is provided. A transmitting feed horn array consisting of at least two feed horn elements is positioned asymmetrically on either side of an estimated focal axis which is generally inclined with respect to the boresight axis of the antenna. The feed horn array is aligned with the estimated focal axis so that the phase centers (CP sub 1, CP sub 2) of the two feed horn elements are located on a common line running through the focal point (F) orthogonally with respect to the estimated focal axis
Dish antenna having switchable beamwidth
A switchable beamwidth antenna includes a concave parabolic main reflecting dish which has a central circular region and a surrounding coaxial annular region. A feed means selectively excites only the central region of the main dish via a truncated subreflector for wide beamwidth or substantially the entire main dish for narrow beamwidth. In one embodiment, the feed means comprises a truncated concave ellipsoid subreflector and separate feed terminations located at two foci of the ellipsoid. One feed termination directly views all of the main dish while the other feed termination, exciting the main dish via the subreflector, excites only the central region because of the subreflector truncation. In the another embodiment, the feed means comprises one feed termination and a convex hyperboloid subreflector via which the feed excites the main dish
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