Pulsed Septum Magnet Research Articles

Magnetic Field Analysis and Measurement of Pulsed Septum Magnet

Traditional off-axis injection becomes inadequate in diffraction limited storage ring (DLSR) for its small dynamic aperture (DA). On-axis injection with thin septum could solve the problem. This paper focuses on the theoretical calculation, field simulation, and measurement of thin septum magnets. The scheme of eddy-current type thin septum magnets (the thinnest portion is with the thickness of 0.9 mm) was adopted with laminated silicon steel sheets as the magnet core. The simulation of main field, stray field along the beam trajectory, the leakage field decayed over 1 millisecond time was carried out within Opera 2D/3D. Field measurement and analysis of thin septum magnets also has been conducted comprehensively. The results meet requirements, and the work laid a foundation for injection technology of an advanced light source.

Toward transparent injection with a multipole injection kicker in a storage ring

Achieving transparent Top-Up injection, characterized by stored beam position perturbations lower than 10% of the root mean square (rms) size of the stored beam, is very challenging for third-generation storage ring-based synchrotron light sources. The standard bump-based injection scheme used at SOLEIL 2.75-GeV storage ring for daily operation relies on two pulsed septum magnets and four pulsed dipole kickers installed in a 12-m-long straight section. Perfect tuning of the kickers to meet the perturbation tolerances is impossible since it would require at least four identical magnets, Ti-coated ceramic chambers, and electronics. On the way toward transparent injection, the four kickers can be replaced by a single pulsed magnet, benefiting from a field-free region in the stored beam path. This Multipole Injection Kicker (MIK), developed in the frame of a collaboration between SOLEIL and MAX IV, and currently installed in the MAX IV 3-GeV storage ring, has proven to meet the transparency specifications. A copy of the MIK has been installed in a short straight section of the SOLEIL storage ring in January 2021. Perturbations of less than 2% of the rms size of the stored beam were measured using the newly installed high-performance diagnostics. In this article, a start-to-end model of the MIK-based injection is presented as well as major challenges inherent in designing such an innovative magnet. Then, the results of the MIK commissioning are presented in depth along with the high-performance diagnostics, which are essential when such levels of beam stability are to be achieved.

Beam-based mapping of pulsed septum stray field at VEPP-2000 collider

Various beam-based methods are widely used for machine study and accurate tuning. Beam closed orbit (CO) responses are routinely used worldwide for magnetic elements alignment and lattice correction. The paper presents the beam-based field mapping technique, applied for measurement of pulsed septum magnet stray field at VEPP-2000 electron-positron collider. Relatively slow pulse of weak leakage field disturbs the CO allowing detecting field longitudinal integral. While scanning with transverse coordinate in wide range one can measure the field map of the localized perturbation at machine in situ.

Pulsed ironfree inflectors for particle injection and extraction in cyclic accelerators

The layout of beam extraction from a cyclic accelerator using a pulsed septum magnet is presented. The magnetic field pulse duration is about 10 μs; the amplitude is about 1 T. The conceptual design of the septum and the power-supply circuit are described. The power-supply pulse generator provides a current of about 100 kA in the current loop with an inductance of 1 μH.

Design and fabrication of the vacuum systems for TPS pulsed septum magnets

Three in-air pulsed septum magnets were developed to inject and extract electron beams for the 3GeV synchrotron facility, the Taiwan Photon Source (TPS). The vacuum chamber is a novel combined aluminium-stainless steel design, using a bimetallic flange to connect the two material types. To evaluate the vacuum performances of these vacuum chambers, we set up a test bench at which we simultaneously measure the rates of thermal outgassing of the aluminium chamber and the septum tube with a throughput method. The test result indicates that the rate q72 of thermal outgassing measured after 1 day from baking at 150°C was 1×10−13mbarLs−1cm−2. The magnetic leakage measurements show the combination of conductor slitting, magnetic shielding and the aluminium vacuum chamber reduce the peak value of the leakage field integral to ~10Gcm along the trajectory of the stored beam.

New Septum Magnet at the SAGA Light Source

The SAGA Light Source is a middle-scale synchrotron radiation facility, and the accelerator consists of a 255-MeV linac and a 1.4-GeV electron storage ring. Electron beams are injected into the storage ring through a 20-degree pulsed septum magnet at a repetition rate of 1 Hz. We have replaced the original in-vacuum pulsed septum magnet with a new out-of-vacuum pulsed magnet to improve the vacuum condition in the injection section and the injection efficiency. The peak leakage field on the bump orbit from the septum magnet is less than 1.5 mT at nominal excitation current of 3700 A. With the new septum magnet, an ultrahigh vacuum (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> Pa) is maintained in the injection section with a stored current of 300 mA at the energy of 1.4-GeV.

Beam-Based Design of a Correction Coil for the Stray Field of a Pulse Septum Magnet

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A direct-drive pulse septum magnet has been in operation for injection of a 1 GeV electron beam at synchrotron light source ring NewSUBARU. Its nominal field is 0.35 T with waveform of 0.92 ms half-sine. Its stray field was measured using the stored electron beam and found to be different from the original design, probably because of an alignment error of the septum current sheet. In the data analysis, the stray field was separated in two components. One component had the expected normal field symmetry, and the other had an unexpected opposite field symmetry. As reported here, a correction coil system for the stray field was designed on the basis of measurements using the stored electron beam. The magnetic field produced by the correction coil was calculated with the field calculation code OPERA-3d. With this correction system, the stray field with the opposite symmetry was reduced from 213 <formula formulatype="inline"> <tex>$\mu{\rm Tm}$</tex></formula> (Tesla meter) maximum to 8 <formula formulatype="inline"> <tex>$\mu{\rm Tm}$</tex></formula> maximum. </para>

A pulse septum magnet with low outgassing rate

A novel pulse septum magnet for the injection system of NSRL storage ring which is a dedicated synchrotron radiation facility is described in this paper. The main parameters and measured results of the septum including its magnetic field distribution and its vacuum characteristic are also given. After making a shim the stray field near current strip-to-gap magnetic field was reduced to 0.1%, and the pressure of the vacuum chamber, in which the septum magnet was installed, is less than 5 × 10 −10 mbar after baking. Now the septum magnet is playing an important part in getting a high injection efficiency and high accumulating current in the NSRL storage ring during the machine running.

Magnetic pulsed septa for the synchrotron "Pakhra"

Slow extraction system of the Synchrotron Pakhra contains two pulsed septum magnets. They are located inside the synchrotron vacuum chamber. Both the soft and the hard septum magnets have similar mechanical construction. They consist of four magnetic blocks split by three copper brackets. The dimensions of the magnetic gap are 1.2 cm height and 3.6 cm width. The soft septum thickness is 0.1 cm. The septum is cooled indirectly by the copper brackets. The fringing field is less than 2% of the field in the core gap. To generate the maximum field of 0.08 T in an one-turn winding 800 A current is required. The second septum is water cooled and it is 0.5 cm thick. The field strength of this magnet can be raised up to 0.4 T at 4000 A. The septa are fed by current pulsers. The leading edge of the pulses is 1 msec and their flat peaks range from 2 msec to 3 msec. Repetition rate is 50 Hz. >

The injection septum magnets of the SPring-8 storage ring

Three DC septum magnets and a pulsed septum magnet are used for the injection of the SRing-8 storage ring. This paper describes the design principle of these injection septum magnets and the electromagnetic performances of a prototype pulsed magnet. The peak strength of the magnetic stray field of the pulsed septum magnet is 1.3 gauss on the bump orbit, and is lower than the limit of sensitivity of the measurement on the reference orbit when the field strength in the magnet gap is 5600 gauss and the pulse width is 65 /spl mu/sec. >

High Power Septum Magnet with a Conductive Septum Coil Holder.

A pulse septum magnet is designed and fabricated to have a high magnetic field intensity with thin septum width. The magnetic field is 1.75 T with a septum width of 2.3 mm. The applied current waveform is one cycle sinusoidal wave and the peak current is 13, 500 A.In our magnet, a conductive (made of copper) septum coil holder is used to overcome the difficulties of high power septum magnet, such as the heat loss at the thin septum coil, the degradation of the field uniformity in the magnet and the leakage flux outside the magnet.The heat loss at the septum coil is effectively removed by tightening up the septum coil to the coil holder with thin stainless steel bands. The temperature rise of the septum coil is only 20 centigrade at normal operation.The degradation of the field uniformity and the leakage flux are suppressed by an eddy current, which is induced in the coil holder.The pulse magnetic field distribution of the septum magnet is measured by a pick-up loop and the results show that the good field region, where the field homogeneity is less than ±0.1%, is 7.5 mm which is twice as large as the septum magnet without the eddy current in the coil holder. As for a leakage flux, the field intensity is only 14 G at 10 mm outside the magnet which is also reduced to 1/10 by the eddy current in the coil holder.The high energy beam extraction experiments are also perfomed and the beam monitors, which are placed down stream of the beam transport line, show that the beam can be stably extracted by the septum magnet.

Septum-magnets for emergency beam extraction system of UNK first stage

The design of a pulse septum-magnet, containing a laminated C-shaped iron core and single-turn excitation coil with frontal conductor electrically connected on the iron core, is presented. The magnet is installed in the vacuum box with a residual pressure up to 2.7*10/sup -7/ Pa and has indirect natural coil cooling. Investigations on a full-scale model of the septum-magnet carried out on a vacuum testbed have confirmed the feasibility of the required vacuum in the septum-magnet boxes of the emergency beam extraction system of the UNK first stage. >

A new magnetic material with low outgassing rate for the electron storage ring of HESYRL

A novel pulse septum magnet with low outgassing rate, which was directly installed in the uhv chamber of the 800 MeV electron storage ring at HESYRL, is described in this paper. The septum magnet was manufactured from 0.6 mm thick steel sheet with the surface coated by pure ceramic powder using a special technology. After that, its outgassing rate was not only significantly reduced, but also the material has some absorption capacity after baking. The pressure of the vacuum chamber, in which the pulse septum magnet with the ceramic coating was installed, was less than 8 × 10 −10 mbar after baking and pumping for 48 hours.

Injection septum magnets for the Loma Linda medical accelerator

Experience obtained from operation of the pulsed septum magnets in the Fermilab Antiproton Source was used to design injection septum magnets in the proton accelerator of the Loma Linda University Proton Therapy Facility. A detailed description is given of the septum magnets, which produce a peak field of 3.4 kG at a current of 28 kA within a 0.1-ms long pulse. Each magnet has a single-turn copper coil bonded to a stainless-steel plate for reinforcement. This eliminates insulating material, which could be subject to radiation damage, at the septum. The stainless steel plate is welded to the magnet laminations. The current is confined to the septum by the insulation between the laminations, which are of a standard core material. The total septum thickness with shield is 1.27 cm. Pulsing the magnet eliminates the need for water cooling.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A Pulsed Septum Magnet for the Fermilab Antiproton Source

A 2 meter curved pulsed septum magnet for use in the Fermilab Antiproton Source is described. The magnet produces a peak field of 6 kGauss at a current of 20,000 Amperes within a 0.4 msec long pulse. The field uniformity obtained is AB/B<0.2% out to 3.8 cm from the copper septum. Power enters the magnet from the center resulting in very simple ends and the magnet incorporates a 0.5 cm steel guard which reduces the field to <1.4 Gauss in the zero-field region. The total septum thickness is 1.3 cm. The vacuum enclosure doubles as the stacking fixture for the magnet laminations allowing easy assembly of a magnet with a 50 m radius of curvature.

A Large Aperture Pulsed Septum Magnet for Antiproton Injection into the CERN AC Ring

A new collector ring (AC) is being built around the existing Antiproton Accumulator (AA) machine in order to increase the accumulation rate of antiprotons [1]. A much larger fraction of the particles produced at an improved target station will be transported to AC with a new 3.5 GeV/c beam line. This increased flux will be injected using a large aperture pulsed septum magnet capable of handling the 240 ?.mm.mrad transverse emittances. Because the antiproton beam traverses the septum gap in air no vacuum problems arise and consequently the magnet can be of simple, glued construction. The beam requirements together with some of the unusual engineering design features of the 1.6 m long, 1 Tesla curved septum magnet are discussed.

Magnet systems for the Daresbury synchrotron radiation source

The design, production and testing of the main dipole and quadrupole magnets for a 2 GeV electron storage ring are described, with particular emphasis on the integrated field performance including the optimisation of magnet ends. In addition fast pulsed kicker and septum magnets for control of injection and extraction processes in both the storage ring and its booster synchrotron injector are treated. All magnets are now installed and operating routinely in the new Synchrotron Radiation Source at Daresbury.

A shielded beam channel septum magnet

Design and performance data of a shielded beam channel, pulsed magnetic septum magnet are presented. Simple construction, good field quality, extremely low stray field are the advantages of this type of deflecting magnet.

Pulsed Septum Magnet and Power Supply for the 8 GeV Beam Transfer Line at the National Accelerator Laboratory

The construction of the pulsed septum magnets and their power supply used in the 8 GeV beam transfer line between the NAL booster and main ring is briefly described. The solid state power supply provides 20,000 A pulses at about 1500 V and a PRR of 15 per second.