Query: fast scanning magnet power supply

title: Design and Test of the Power Supply for a Fast Kicker Magnet
abstract: To perform fast beam switch during spot scanning and energy modulation procedure, a fast kicker magnet system is adopted in HUST PTF (Huazhong University of Science and Technology Proton Therapy Facility) The rising/falling time is expected to be less than 100 ms, and the maximum repetition rate should be up to 500 Hz. To meet the specifications on dynamic response of the power supply, a solution with two separate DC link scheme is present in this paper. Since the Kicker is closed to other sensitive equipment, an output filter is installed to prevent electromagnetic disturbances from propagating along the cables. The optimized design of the output filter and comparison measurement results of the power supply are introduced as well. Here, a trade off between the voltage oscillation, dynamic performance and engineering implementation has been made.

title: Development of Fast Scanning Magnets and Their Power Supply for Particle Therapy
abstract: At the Heavy Ion Medical Accelerator in Chiba (HIMAC) more than 8000 patients have been successfully treated by carbon ion beams since 1994. The successful results of treatments have led us to construct a new treatment facility equipped with a 3 D pencil beam scanning irradiation system. For the implementation of this irradiation technique, we developed a fast scanning magnet and its power supply, which are required to have field ramp rate of more than 250 T/s. The scanning magnets set at the entrance of the irradiation system are two dipole magnets to scan the beam in both horizontal and vertical directions and used to form the irradiation field to be tumor shape. Before the installation, performance test including both static and dynamic field measurement was carried out. Severe delay of the field and temperature rise were not observed as expected. Measured field ramp rate reached up to 300 T/s. After the installation, we verified the accuracy and stability of the scanned ion beam through the commissioning with the beam. As a successful result of the commissioning, treatment using the new scanning system was started in 2011.

title: Development and measurement of a fast kicker magnet applied to a proton therapy facility
abstract: A proton therapy facility based on spot scanning technique requires a fast ON/OFF beam switch during beam spots and energy modulation procedures. At HUST, a proton therapy facility (HUST PTF) with multiple treatment rooms is under development. For HUST PTF, this beam switch function is implemented by a fast kicker magnet and downstream beam dump. This paper introduces the development and measurement of this kicker magnet system, with main topics: (1) the development and measurement of the fast kicker magnet; (2) the corresponding pulsed power supply to implement the kicker function; (3) the dynamic magnetic field measurement system based on printed circuit board (PCB) technique.

title: DEVELOPMENT OF MAGNET POWER SUPPLY SYSTEM FOR FAST PATTERN EXCITATION
abstract: A power supply system for a fast pattern excitation has been required for bump magnets for the injection into a synchrotron, scanning magnets for the particle therapy and industrial use and etc. It is necessary that the excitation time to the target current value is short and the current fluctuation is low enough. We developed a new power supply system in order to make the pattern excitation faster and to make a deviation from the target current value smaller. The power supply is composed of two circuits; one is a forcing circuit and the other is a constant current circuit. Two circuits of power supply are connected in series with the magnet. IGBT (Insulated Gate Bipolar Transistor) is applied as the switching device of each circuit. The forcing voltage is set from 200V to 200V and the output current is set from 450A to 450A. The current is increased linearly with 1A per 0.1ms as the rate of the current excitation. The deviation of the target current is also suppressed within 0.1%

title: Performance of the NIRS fast scanning system for heavy ion radiotherapy.
abstract: A project to construct a new treatment facility, as an extension of the existing HIMAC facility, has been initiated for the further development of carbon ion therapy at NIRS. This new treatment facility is equipped with a 3D irradiation system with pencil beam scanning. The challenge of this project is to realize treatment of a moving target by scanning irradiation. To achieve fast rescanning within an acceptable irradiation time, the authors developed a fast scanning system.  In order to verify the validity of the design and to demonstrate the performance of the fast scanning prior to use in the new treatment facility, a new scanning irradiation system was developed and installed into the existing HIMAC physics experiment course. The authors made strong efforts to develop (1) the fast scanning magnet and its power supply, (2) the high speed control system, and (3) the beam monitoring. The performance of the system including 3D dose conformation was tested by using the carbon beam from the HIMAC accelerator.  The performance of the fast scanning system was verified by beam tests. Precision of the scanned beam position was less than 0.5 mm. By cooperating with the planning software, the authors verified the homogeneity of the delivered field within 3% for the 3D delivery. This system took only 20 s to deliver the physical dose of 1 Gy to a spherical target having a diameter of 60 mm with eight rescans. In this test, the average of the spot staying time was considerably reduced to 154 micros, while the minimum staying time was 30 micros.  As a result of this study, the authors verified that the new scanning delivery system can produce an accurate 3D dose distribution for the target volume in combination with the planning software.

title: PRACTICAL EXPERIENCE WITH SELF OPTIMIZING HIGH DYNAMIC CONTROL OF ACCELERATOR MAGNET POWER SUPPLIES
abstract: In 1999, the first fully digitally controlled magnet power supplies were commissioned at PSI (Paul Scherrer Institute, Switzerland) Today, approximately 1000 of them are in use at PSI and a multiple of that worldwide. An extended PI structure is used for control. PI control is very effective and simple to use but the attainable dynamic performance is usually limited by the higher order characteristics of the output filter and the load. For the future we expect increasing requirements from highly dynamic applications, such as beam orbit feedback systems and fast scanning magnets for proton irradiation of tumours. Therefore, a self optimizing power supply control system was developed in collaboration with the University of Applied Sciences Northwestern Switzerland. It is based on the second generation of PSI digital power electronics controller, which allows more complex control algorithms and higher sampling rates. This paper presents the achieved dynamic performance of the new control structure for various types of power supplies and magnets and compares them with the dynamic performance obtained using standard PI control.

title: A RASTER SCANNING POWER SUPPLY SYSTEM FOR CONTROLLING RELATIVISTIC HEAVY ION BEAMS AT THE BEVALAC BIOMEDICAL FACILITY
abstract: A power supply system is currently being designed and constructed to sweep an 8.0 Tesla meter relativistic heavy ion beam in a raster scanning mode for radiotherapy use. Two colinear dipole magnets with orthogonally oriented magnetic fields are driven by the system to produce a rectangular field (40 x 40 cm max. with a uniform dose 2.5% to a target volume 6 meters away. The 'fast' horizontal scanning magnet is driven by a single power supply which in conjunction with a triac bridge network and a current regulated linear actuator will produce a 1200 cm/sec max. sweep rate. The 'slow' (40 cm/sec) vertical scanning magnet will be controlled by dual current regulated linear actuators in a push pull configuration. The scanner system can provide off axis treatment profiles with large aspect ratios and unusual dimensions.

title: Design considerations of a fast kicker system applied in a proton therapy beamline
abstract: In a proton therapy system based on cyclotrons, a kicker magnet is an essential equipment to perform fast beam switch within 100 m s level during energy modulation and spot scanning procedures. This paper gives a systematic view related to the design and technical considerations of a fast kicker applied to HUST PTF. From the layout and physical requirement of the kicker, a comparative study on the static/dynamic magnetic field with two type of core materials is performed, and a MnZn ferrite core is chosen finally. Technical considerations including the structure design, the topology design of the power supply, and the method for dynamic field measurement are introduced as well.

title: Performances of the scanning system for the CNAO center of oncological hadron therapy
abstract: In hadron therapy one of the most advanced methods for beam delivery is the active scanning technique which uses fast scanning magnets to drive a narrow particle beam across the target. The Centro Nazionale di Adroterapia Oncologica (CNAO) will treat tumours with this technique. The CNAO scanning system includes two identical dipole magnets for horizontal and vertical beam deflection, each one connected to a fast power supply. The dose delivery system exploits a set of monitor chambers to measure the fluence and position of the beam and drives the beam during the treatment by controlling the sequence of currents set by the power supplies. A test of the dynamic performance of the scanning system has been performed using a Hall probe to measure the field inside the magnet and the results are presented in this paper.

title: Research of current closed loop control program on scan magnet
abstract: In this paper, a program to improve the scan magnet power supply was introduced. This program was based on the traditional non linear approximation system and adopted a closed loop PWM based control program, which could control the output current of scan magnet power supply with peak peak at 0 8 A, and scanning frequency with continuous triangular wave at 5 8 Hz. The output electric current linearity is better than traditional system. As a fast closed loop system, the robustness is also superior to the traditional programs.