HB2014 - List of Authors (Eldred, J.S.)

Paper

Title

Page

Slip-stacking Dynamics and the 20 Hz Booster

50

J.S. Eldred
Indiana University, Bloomington, Indiana, USA
J.S. Eldred, R.M. Zwaska
Fermilab, Batavia, Illinois, USA

Slip-stacking is an accumulation technique used at Fermilab since 2004 which nearly doubles the proton intensity. The Proton Improvement Plan II intensity upgrades require a reduction in slip-stacking losses by approximately a factor of 2. We study the single-particle dynamics that determine the stability of slip-stacking particles. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We show the particle loss as a function of time. We calculate the injection efficiency as a function of longitudinal emittance and aspect-ratio. We demonstrate that the losses from RF single particle dynamics can be reduced by a factor of 4-10 (depending on beam parameters) by upgrading the Fermilab Booster from a 15-Hz cycle-rate to a 20-Hz cycle-rate. We recommend a change in injection scheme to eliminate the need for a greater momentum aperture in the Fermilab Recycler.

THO4LR04

Fast Transverse Instability and Electron Cloud Measurements in Fermilab Recycler

419

J.S. Eldred, P. Adamson, D. Capista, N. Eddy, I. Kourbanis, D.K. Morris, J.C.T. Thangaraj, M.-J. Yang, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
J.S. Eldred
Indiana University, Bloomington, Indiana, USA
Y. Ji
IIT, Chicago, Illinois, USA

A new transverse instability is observed that may limit the proton intensity in the Fermilab Recycler. The instability is fast, leading to a beam-abort loss within two hundred turns. The instability primarily affects the first high-intensity batch from the Fermilab Booster in each Recycler cycle. This paper analyzes the dynamical features of the destabilized beam. The instability excites a horizontal betatron oscillation which couples into the vertical motion and also causes transverse emittance growth. This paper describes the feasibility of electron cloud as the mechanism for this instability and presents the first measurements of the electron cloud in the Fermilab Recycler. Direct measurements of the electron cloud are made using a retarding field analyzer (RFA) newly installed in the Fermilab Recycler. Indirect measurements of the electron cloud are made by propagating a microwave carrier signal through the beampipe and analyzing the phase modulation of the signal. The maximum betatron amplitude growth and the maximum electron cloud signal occur during minimums of the bunch length oscillation.

Slides THO4LR04 [1.608 MB]

THO4LR04

Fast Transverse Instability and Electron Cloud Measurements in Fermilab Recycler

419

J.S. Eldred, P. Adamson, D. Capista, N. Eddy, I. Kourbanis, D.K. Morris, J.C.T. Thangaraj, M.-J. Yang, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
J.S. Eldred
Indiana University, Bloomington, Indiana, USA
Y. Ji
IIT, Chicago, Illinois, USA

A new transverse instability is observed that may limit the proton intensity in the Fermilab Recycler. The instability is fast, leading to a beam-abort loss within two hundred turns. The instability primarily affects the first high-intensity batch from the Fermilab Booster in each Recycler cycle. This paper analyzes the dynamical features of the destabilized beam. The instability excites a horizontal betatron oscillation which couples into the vertical motion and also causes transverse emittance growth. This paper describes the feasibility of electron cloud as the mechanism for this instability and presents the first measurements of the electron cloud in the Fermilab Recycler. Direct measurements of the electron cloud are made using a retarding field analyzer (RFA) newly installed in the Fermilab Recycler. Indirect measurements of the electron cloud are made by propagating a microwave carrier signal through the beampipe and analyzing the phase modulation of the signal. The maximum betatron amplitude growth and the maximum electron cloud signal occur during minimums of the bunch length oscillation.

Slides THO4LR04 [1.608 MB]

Paper	Title	Page
MOPAB12	Slip-stacking Dynamics and the 20 Hz Booster	50
	J.S. Eldred Indiana University, Bloomington, Indiana, USA J.S. Eldred, R.M. Zwaska Fermilab, Batavia, Illinois, USA
	Slip-stacking is an accumulation technique used at Fermilab since 2004 which nearly doubles the proton intensity. The Proton Improvement Plan II intensity upgrades require a reduction in slip-stacking losses by approximately a factor of 2. We study the single-particle dynamics that determine the stability of slip-stacking particles. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We show the particle loss as a function of time. We calculate the injection efficiency as a function of longitudinal emittance and aspect-ratio. We demonstrate that the losses from RF single particle dynamics can be reduced by a factor of 4-10 (depending on beam parameters) by upgrading the Fermilab Booster from a 15-Hz cycle-rate to a 20-Hz cycle-rate. We recommend a change in injection scheme to eliminate the need for a greater momentum aperture in the Fermilab Recycler.

THO4LR04	Fast Transverse Instability and Electron Cloud Measurements in Fermilab Recycler	419
	J.S. Eldred, P. Adamson, D. Capista, N. Eddy, I. Kourbanis, D.K. Morris, J.C.T. Thangaraj, M.-J. Yang, R.M. Zwaska Fermilab, Batavia, Illinois, USA J.S. Eldred Indiana University, Bloomington, Indiana, USA Y. Ji IIT, Chicago, Illinois, USA
	A new transverse instability is observed that may limit the proton intensity in the Fermilab Recycler. The instability is fast, leading to a beam-abort loss within two hundred turns. The instability primarily affects the first high-intensity batch from the Fermilab Booster in each Recycler cycle. This paper analyzes the dynamical features of the destabilized beam. The instability excites a horizontal betatron oscillation which couples into the vertical motion and also causes transverse emittance growth. This paper describes the feasibility of electron cloud as the mechanism for this instability and presents the first measurements of the electron cloud in the Fermilab Recycler. Direct measurements of the electron cloud are made using a retarding field analyzer (RFA) newly installed in the Fermilab Recycler. Indirect measurements of the electron cloud are made by propagating a microwave carrier signal through the beampipe and analyzing the phase modulation of the signal. The maximum betatron amplitude growth and the maximum electron cloud signal occur during minimums of the bunch length oscillation.
	Slides THO4LR04 [1.608 MB]

THO4LR04	Fast Transverse Instability and Electron Cloud Measurements in Fermilab Recycler	419
	J.S. Eldred, P. Adamson, D. Capista, N. Eddy, I. Kourbanis, D.K. Morris, J.C.T. Thangaraj, M.-J. Yang, R.M. Zwaska Fermilab, Batavia, Illinois, USA J.S. Eldred Indiana University, Bloomington, Indiana, USA Y. Ji IIT, Chicago, Illinois, USA
	A new transverse instability is observed that may limit the proton intensity in the Fermilab Recycler. The instability is fast, leading to a beam-abort loss within two hundred turns. The instability primarily affects the first high-intensity batch from the Fermilab Booster in each Recycler cycle. This paper analyzes the dynamical features of the destabilized beam. The instability excites a horizontal betatron oscillation which couples into the vertical motion and also causes transverse emittance growth. This paper describes the feasibility of electron cloud as the mechanism for this instability and presents the first measurements of the electron cloud in the Fermilab Recycler. Direct measurements of the electron cloud are made using a retarding field analyzer (RFA) newly installed in the Fermilab Recycler. Indirect measurements of the electron cloud are made by propagating a microwave carrier signal through the beampipe and analyzing the phase modulation of the signal. The maximum betatron amplitude growth and the maximum electron cloud signal occur during minimums of the bunch length oscillation.
	Slides THO4LR04 [1.608 MB]