Download or read book A Search for Coupled bunch Instability in the Fermilab Main Injector written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the Fermilab Main Injector (MI) we are planning to double the bunch intensity from its design value by slip stacking. The accelerator consists of 18 rf cavities which operate at a harmonic number of 588. These cavities are known to have many higher ordered resonances. Longitudinal coupled-bunch instability induced by excitation of the rf cavities may be an important issue to be addressed in the intensity upgrade. Here we have carried out some simulation studies of the longitudinal coupled bunch instability to investigate bunch intensity limits. The results are presented in this paper.

Download or read book Study of a Longitudinal Coupled bunch Instability in the Fermilab Main Ring written by Xianping Lu and published by . This book was released on 1994 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Longitidunal Coupled bunch Instability in the Fermilab Booster written by King-Yuen Ng and published by . This book was released on 1987 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Longitudinal Coupled bunch Instability in the Fermilab Booster written by King-yuen Ng and published by . This book was released on 1987 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Coupled Bunch Instability in Fermilab Booster written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The physical presence of vacuum structures can be expressed in terms of a coupling impedance experienced by the beam. The beam environment considered here consist of parasitic higher order modes of the r.f. cavities. These resonances may have high enough Q's to allow consecutive bunches to interact through mutually induced fields. The cumulative effect of such fields as the particles pass through the cavity may be to induce a coherent buildup in synchrotron motion of the bunches, i.e., a longitudinal coupled-bunch instability. The colliding mode operation of the present generation of high energy synchrotrons and the accompanying r.f. manipulations, make considerations of individual bunch area of paramount importance. Thus, a longitudinal instability in one of a chain of accelerators, while not leading to any immediate reduction in the intensity of the beam in that accelerator, may cause such a reduction of beam quality that later operations are inhibited (resulting in a degradation performance). In this paper we employ a longitudinal phase-space tracking code (ESME) as an effective tool to simulate specific coupled bunch modes arising in a circular accelerator. One of the obvious advantages of the simulation compared to existing analytic formalisms, e.g., based on the Vlasov equation, is that it allows consideration of the instability in a self-consistent manner with respect to the changing accelerating conditions. Furthermore this scheme allows to model nonlinearities of the longitudinal beam dynamics, which are usually not tractable analytically. 5 refs., 3 figs.

Download or read book Coherent Instability Limitations of Fermilab s Upgrades written by and published by . This book was released on 1990 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study is motivated by the proposed upgrades of a whole sequence of Fermilab's accelerators; Linac, Booster, Main Ring or Main Injector and the Tevatron. Two leading high-luminosity collider upgrade scenarios involve larger numbers of colliding bunches of higher intensity. This obviously raises a question of coherent instabilities, which was already quite vital in the present fixed target and collider scenarios. Furthermore, multi-bunch instability limitations due to the resistive wall impedance are studied for the fixed target mode. The same question of coupled bunch instabilities is also addressed for new collider schemes involving large number of colliding bunches (up to 100 on 100 bunches), where the inter-bunch communication may become important. 4 refs.

Download or read book COHERENT INSTABILITY LIMITATIONS OF FERMILABS UPGRADES written by S.A. BOGACZ and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simulation of Coupled Bunch Mode Growth Driven by a High Q Resonator written by and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this article the use of a longitudinal phase-space tracking code, ESME, to simulate the growth of a coupled-bunch instability in the Fermilab Booster is examined. A description of the calculation of the resonant response is given, and results are presented for the growth of the coupled bunch instability in a ring in which all of the rf buckets are equally populated and in one in which several consecutive buckets are empty. 4 refs., 6 figs.

Download or read book Single Few Bunch Space Charge Effects at 8 GeV in the Fermilab Main Injector written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: For Project X, it is planned to inject a beam of 3 1011 particles per bunch into the Main Injector. Therefore, at 8 GeV, there will be increased space charge tune shifts and an increased incoherent tune spread. In preparation for these higher intensity bunches exploratory studies have commenced looking at the transmission of different intensity bunches at different tunes. An experiment is described with results for bunch intensities between 20 and 300 109 particles. To achieve the highest intensity bunches coalescing at 8 GeV is required, resulting in a longer bunch length. Comparisons show that similar transmission curves are obtained when the intensity and bunch length have increased by similar factors. This indicates the incoherent tune shifts are similar, as expected from theory. The results of these experiments will be used in conjugation with simulations to further study high intensity bunches in the Main Injector.

Download or read book The Nature of Transverse Beam Instabilities at Injection in the Fermilab Main Ring written by Ping-Jung Chou and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analytical and Numerical Evaluation of Landau Cavities in the Fermilab Booster written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Longitudinal coupled bunch instability has been observed in the Fermilab Booster at high intensity. It is a cause for concern due to its effect on the Tevatron collider performance. We study this phenomenon using initial value technique to correctly account for the underlying transient nature. Analytic result is obtained for any mode and comparison is made between ordinary harmonic potential and higher harmonic (Landau) cavity potential. A computer program is developed to facilitate the calculation. The result shows that the merit of Landau cavity is best realized in cases where the resonance is of a broad band nature. 5 refs., 4 figs., 3 tabs.

Download or read book Transition Crossing in the Fermilab Main Ring Past and Present written by and published by . This book was released on 1993 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: A recent installation of passive mode dampers in the Booster has eliminated most of the longitudinal emittance blowup of intense bunches due to coupled-bunch instabilities. As a result, high intensity effects (negative-mass instability) dominate the present transition crossing in the Main Ring for the high-intensity cycles. A negative-mass stability limit is derived for transition crossing in the Main Ring and recent observations of high frequency signals around transition is presented. Finally, some predictions about the effect of the negative mass instability on the transition in the Main Ring with the future upgrades are attempted.

Download or read book Study of Stability of Beam in the Fermilab Main Injector written by and published by . This book was released on 1993 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Fermilab Main Injector is a new 150 GeV proton synchrotron, designed to replace the Main Ring and improve the high energy physics potential of Fermilab. The status of the Fermilab accelerator complex upgrade will be discussed. Study of the stability of the beam in the Main injector will be discussed. Detuning and corrector scheme to improve the dynamic aperture of the Main Injector will be presented. Tune modulation caused by octupolar detuning will be discussed.

Download or read book Bunch Lengthening in the Fermilab Main Ring During Storage written by and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: There are two known current dependent effects which can increase the length of stored bunched beams: (1) a reduction of the potential well of the applied rf focusing system; and (2) induced unstable oscillations of the bunches, which can stabilize at a longer length by the process of Landau damping. In the first case, the current distribution in the bunches, interacting with induced electromagnetic fields in the walls, leaves a wake field which acts back on the bunches. A new equilibrium bunch shape results, different from that due to the applied rf, and this new equilibrium bunch shape will slowly establish itself as the particles within the bunch move on their new trajectories. The second form of bunch instability is the single bunch type. These are characterized by high frequency (i.e. within bunch) oscillations in the microwave region and fast growth rates. The coherent effects are very difficult to observe and such instabilities tend to simulate an incoherent growth in the bunch. An attempt is made to describe the observation of bunch lengthening in the main ring in terms of both potential well distortion and induced microwave fields. It is found that the increase in bunch size is in qualitative agreement with an induced microwave instability if the wall (i.e. chamber discontinuities) couples to beam with a broad resistive impedance in the microwave region of the order of Z/n approximately 75 OMEGA (n is the mode number of the oscillation of frequency f = nf/sub rev/).

Download or read book Improving the Fermilab Booster Emittance written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Demand of high luminosity in the Tevatron collider in Fermilab makes the small beam emittance coming out of the 8 GeV Booster a highly desirable feature. This is because Booster bunches with small emittance, when eventually coalesced into Main Ring bunches, will ensure a high luminosity in the collider. Efforts have been made to identify factors limiting the phase space density in both transverse and longitudinal dimensions. The experimental result points to space charge induced tune spread at low energy as the main factor limiting the transverse phase space density, and the space charge induced phase space dilution at transition and longitudinal coupled bunch instability as the factors limiting the longitudinal phase space density. To counteract these factors, a set of harmonic correction sextupoles and skew sextupoles were implemented to reduce the third order resonances in the transverse case. In the longitudinal case a .gamma./sub t/-jump system was implemented to ease the bunch tumbling after transition, and various schemes to damp the longitudinal coupled bunch instability are either implemented or being reviewed. Future plans and efforts will be mentioned briefly at the end of this article. 3 refs., 8 figs., 1 tab.

Download or read book Tuin en milieuserie written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt: