IPAC2012 - List of Authors (Kashikhin, V.S.)

Paper	Title	Page
MOPPC081	Simulation of RF Cavity Dark Current in Presence of Helical Magnetic Field	325
	G.V. Romanov, V.S. Kashikhin Fermilab, Batavia, USA
	In order to produce muon beam of high enough quality to be used for a Muon Collider, its large phase space must be cooled several orders of magnitude. This task can be accomplished by ionization cooling. Ionization cooling consists of passing a high-emittance muon beam alternately through regions of low-Z material, such as liquid hydrogen, and very high accelerating RF cavities within a multi-Tesla solenoidal focusing channel. But first high power tests of an RF cavity with beryllium windows in a solenoidal magnetic field showed a dramatic drop in accelerating gradient due to RF breakdowns. It has been concluded that external magnetic fields parallel to the RF electric field significantly modifies the performance of RF cavities. However, the magnetic field in a Helical Cooling Channel has a strong dipole component in addition to a solenoidal one. The dipole component essentially changes electron motion in a cavity compared to a pure solenoidal case, making dark current less focused at field emission sites. The simulation of a dark current dynamic in HCC performed with CST Studio Suite is presented in this paper.

TUPPD010	Helical Muon Beam Cooling Channel Engineering Design	1425
	G. Flanagan, R.P. Johnson, G.M. Kazakevich, F. Marhauser, M.L. Neubauer Muons, Inc, Batavia, USA V.S. Kashikhin, M.L. Lopes, G.V. Romanov, M.A. Tartaglia, K. Yonehara, M. Yu, A.V. Zlobin Fermilab, Batavia, USA
	Funding: Supported in part by DOE STTR Grant DE-SC0006266 The Helical Cooling Channel (HCC), a novel technique for six-dimensional (6D) ionization cooling of muon beams, has shown considerable promise based on analytic and simulation studies. However, the implementation of this revolutionary method of muon cooling requires new techniques for the integration of hydrogen-pressurized, high-power RF cavities into the low-temperature superconducting magnets of the HCC. We present the progress toward a conceptual design for the integration of 805 MHz RF cavities into a 10 T Nb3Sn based HCC test section. We include discussions on the pressure and thermal barriers needed within the cryostat to maintain operation of the magnet at 4.2 K while operating the RF and energy absorber at a higher temperature. Additionally, we include progress on the Nb3Sn helical solenoid design

THPPD017	Mu2e AC Dipole 300 kHz and 5.1 MHz Tests and Comparison of Nickel-Zinc Ferrites	3533
	L. Elementi, K.R. Bourkland, D.J. Harding, V.S. Kashikhin, A.V. Makarov, H. Pfeffer, G. Velev Fermilab, Batavia, USA
	To suppress any background events coming from the inter-bunch proton interactions during the muon transport and decay window for the Mu2e experiment, a beam extinction scheme based on two dipoles running at ~300 kHz and 5.1 MHz is considered. The effective field of these magnets is synchronized to the proton bunch spacing in such a way that the bunches are transported at the sinus nodes. Two types Ni-Zn ferrites are considered for these dipoles. Ferrites, their characteristics and ferrites selection is herein discussed through measurements performed under conditions close to operational. The excitation system and the measurement of some characteristics of the magnetic field and field shape and measurement mechanism are also presented.

Paper

Title

Page

Simulation of RF Cavity Dark Current in Presence of Helical Magnetic Field

325

G.V. Romanov, V.S. Kashikhin
Fermilab, Batavia, USA

In order to produce muon beam of high enough quality to be used for a Muon Collider, its large phase space must be cooled several orders of magnitude. This task can be accomplished by ionization cooling. Ionization cooling consists of passing a high-emittance muon beam alternately through regions of low-Z material, such as liquid hydrogen, and very high accelerating RF cavities within a multi-Tesla solenoidal focusing channel. But first high power tests of an RF cavity with beryllium windows in a solenoidal magnetic field showed a dramatic drop in accelerating gradient due to RF breakdowns. It has been concluded that external magnetic fields parallel to the RF electric field significantly modifies the performance of RF cavities. However, the magnetic field in a Helical Cooling Channel has a strong dipole component in addition to a solenoidal one. The dipole component essentially changes electron motion in a cavity compared to a pure solenoidal case, making dark current less focused at field emission sites. The simulation of a dark current dynamic in HCC performed with CST Studio Suite is presented in this paper.

TUPPD010

Helical Muon Beam Cooling Channel Engineering Design

1425

G. Flanagan, R.P. Johnson, G.M. Kazakevich, F. Marhauser, M.L. Neubauer
Muons, Inc, Batavia, USA
V.S. Kashikhin, M.L. Lopes, G.V. Romanov, M.A. Tartaglia, K. Yonehara, M. Yu, A.V. Zlobin
Fermilab, Batavia, USA

Funding: Supported in part by DOE STTR Grant DE-SC0006266
The Helical Cooling Channel (HCC), a novel technique for six-dimensional (6D) ionization cooling of muon beams, has shown considerable promise based on analytic and simulation studies. However, the implementation of this revolutionary method of muon cooling requires new techniques for the integration of hydrogen-pressurized, high-power RF cavities into the low-temperature superconducting magnets of the HCC. We present the progress toward a conceptual design for the integration of 805 MHz RF cavities into a 10 T Nb3Sn based HCC test section. We include discussions on the pressure and thermal barriers needed within the cryostat to maintain operation of the magnet at 4.2 K while operating the RF and energy absorber at a higher temperature. Additionally, we include progress on the Nb3Sn helical solenoid design

THPPD017

Mu2e AC Dipole 300 kHz and 5.1 MHz Tests and Comparison of Nickel-Zinc Ferrites

3533

L. Elementi, K.R. Bourkland, D.J. Harding, V.S. Kashikhin, A.V. Makarov, H. Pfeffer, G. Velev
Fermilab, Batavia, USA

To suppress any background events coming from the inter-bunch proton interactions during the muon transport and decay window for the Mu2e experiment, a beam extinction scheme based on two dipoles running at ~300 kHz and 5.1 MHz is considered. The effective field of these magnets is synchronized to the proton bunch spacing in such a way that the bunches are transported at the sinus nodes. Two types Ni-Zn ferrites are considered for these dipoles. Ferrites, their characteristics and ferrites selection is herein discussed through measurements performed under conditions close to operational. The excitation system and the measurement of some characteristics of the magnetic field and field shape and measurement mechanism are also presented.