A. Soukas

Test modulator of AGS injection fast kicker

A test modulator of the Brookhaven AGS injection fast kicker is described. During the fourth batch transfer of the proton beam from the booster to AGS, the fall time of the AGS injection kicker has to be very fast (<140 ns), so that it does not appreciably deflect the first batch of injected protons that is circulating in the AGS. A test modulator was built, which consists of a PFN (pulse forming network), a tail-biting section, and two thyratron switches. One thyratron switches the current to the load magnet, and another bites down the current at the end of the pulse. The load and circuit stray inductance is about 1.95 mu H to 2.15 mu H, and the required peak current is about 1000 A. The current pulse waveform, tested at half current level (500 A), has a fast fall time as well as a fast rise time.<<ETX>>

The AGS accelerator complex with the new fast extraction system

The delivery of a beam with characteristics appropriate for the g-2 muon storage ring and the filling of the RHIC heavy ion collider from the AGS main ring requires a new fast extracted beam (FEB) system. The new FEB system will be capable of performing both one-turn fast extraction and single bunch multiple extraction of either a heavy ion beam or a high intensity proton beam at a rate of 30 Hz up to 12 times per AGS cycle. The new system consists of a fast multi-pulsing kicker and an ejector septum magnet with local extraction orbit bumps.

Observation and correction of resonance stopbands in the AGS Booster

At the design intensity of 1.5/spl times/10/sup 13/ ppp, the space charge tune shift in the AGS Booster at injection has been estimated to be about 0.35. Therefore, the beam is spread over many lower order resonance lines and the stopbands have to be corrected to minimize the amplitude growth by proper compensation of the driving harmonics resulting from random errors. The observation and correction of second and third order resonance stopbands in the AGS Booster, and the establishment of a favorable operating point at high intensity are discussed.<<ETX>>

Transient analysis of the AGS-booster ring dipole and quadrupole magnet system

A case study has been conducted for the quantitative analysis of the transmission line effects in the Brookhaven Alternating Gradient Synchrotron (AGS) booster ring dipole and quadrupole magnet string. The booster is a rapid cycling synchrotron (7.5Hz) which is excited by multiphase rectifier power supplies. A computer model and a simulation program were developed to study the transient current response of the magnet string due to an applied step voltage. To damp out the staircase noise caused by wave reflection during the current ramp, external resistors will be added in parallel with each half dipole magnet and each quadrupole magnet. The system model and simulation values are based on the actual magnet parameters, the magnet power supply bus system, and the proposed current ramping rate. The system simulation approach is discussed.<<ETX>>

Heavy ion acceleration strategies in the AGS accelerator complex-1994 status report

The strategies invoked to satisfy the injected beam specifications for the Brookhaven Relativistic Heavy ion Collider (RHIC) continue to evolve, in the context of the yearly AGS fixed target heavy ion physics runs. The primary challenge is simply producing the required intensity. The acceleration flexibility available particularly in the Booster main magnet power supply and RF accelerating systems, together with variations in the charge state delivered from the Tandem van de Graaff, and accommodation by the AGS main magnet and RF systems allow the possibility for a wide range of options. The yearly physics run provides the opportunity for exploration of these options with the resulting significant evolution in the acceleration plan. This was particularly true in 1994 with strategies involving three different charge states and low and high acceleration rates employed in the Booster. The present status of this work will be presented.

The booster-to-AGS beam transfer fast kicker modulators

The authors describe modulator developments for the Brookhaven booster extraction and the Alternating Gradient Synchrotron (AGS) injection fast kickers. To achieve the design specifications, an extensive development effort has been pursued, including distributed parameter estimation and measurement, computer aided analysis and design, pulse shaping and tail-biting circuit test, prototype construction, etc. The test results are presented. The modulators are projected for both proton and heavy ion operation. The equivalent load inductance is about 2.1 to 2.3 mu H for each modulator. The pulse-forming network (PFN) voltage is required to be below 40 kV for operation in air. The rise time of the pulse for proton beam transfer is 120 ns up to 97% of full current (1000A), and for heavy ion beam transfer, the requirement is 160 ns up to 98% of full current (1615 A). During the fourth batch transfer of the proton beam from the booster to the AGS, the pulse fall time of the AGS injection fast kicker has to be very fast (<140 ns), so that it does not appreciably deflect the first batch of injected protons that is circulating in the AGS.<<ETX>>

First results of proton injection commissioning of the AGS booster synchrotron

Beam performance results for the injection phase of proton beam commissioning of the Alternating Gradient Synchrotron (AGS) booster synchrotron are presented. The beam from the 200 MeV LINAC is transported through a new beam line into the booster. This LINAC-to-booster (LTB) beam line includes a 126 degrees bend and brings the injected beam onto the Booster injection orbit through the backleg of a main-ring dipole magnet. Transfer of the beam from the LINAC to the booster, the spiralling beam, and closing of the orbit in the booster ring are discussed. Injection and transport through one sector of the ring were accomplished.<<ETX>>

AGS booster tune meter kickers

The AGS (Alternating Gradient Synchrotron) booster tune meter kicker system consists of two identical kickers for horizontal and vertical tune measurements, and a control unit utilizing a programmable logic controller. The kicker modulators are line-type pulsers. The pulse energy stored in the PFN (pulse forming network) is discharged through a set of matched cables to the load magnet and a matching terminating resistor. Some RC compensation networks are used to obtain the fast rising pulse waveforms. The booster will cover a wide range of revolution frequencies. To cover this wide range, tunes will be measured by kicking the beams with two different pulse lengths. A switch mode power supply with fast command tracking speed is used for PFN charging and enables the kickers to change pulse amplitudes on a pulse-by-pulse basis. The pulse repetition rate can reach up to a maximum of 200 pulses per second (p.p.s.) at 20 kV and 2000 p.p.s. at 2.5 kV.<<ETX>>