IPAC2013 - List of Authors (Samulyak, V.)

Paper	Title	Page
TUPFI058	Simulation of Beam-induced Gas Plasma in High Gradient RF Field for Muon Colliders	1478
	K. Yonehara, M. Chung, A.V. Tollestrup Fermilab, Batavia, USA B.T. Freemire IIT, Chicago, Illinois, USA R.P. Johnson, T.J. Roberts Muons. Inc., USA R.D. Ryne LBNL, Berkeley, California, USA V. Samulyak BNL, Upton, Long Island, New York, USA K. Yu SBU, Stony Brook, USA
	There is a strong limit of available RF gradient in a vacuum RF cavity under magnetic fields because the magnetic field enhances a dark current density due to electron focusing and increases probability of an electric breakdown. This limits the cooling performance. A dense hydrogen gas filled RF cavity can break this limit because the gas acts as a buffer of dark current. However, RF power loading due to a beam-induced plasma in a dense gas filled RF cavity (plasma loading effect) is crucial to design the practical cavity. Experiment shows that the plasma loading can be mitigated in denser hydrogen gas and by doping a small amount of electronegative gas in the cavity. A complicate plasma chemical reaction should be dominated in such a dense hydrogen gas condition. A beam-induced plasma is simulated by taking into account the plasma chemistry to reproduce the condition by using the supercomputer at LBNL. We will also investigate the space charge effect in a dense gas in this effort.

Paper

Title

Page

Simulation of Beam-induced Gas Plasma in High Gradient RF Field for Muon Colliders

1478

K. Yonehara, M. Chung, A.V. Tollestrup
Fermilab, Batavia, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
R.P. Johnson, T.J. Roberts
Muons. Inc., USA
R.D. Ryne
LBNL, Berkeley, California, USA
V. Samulyak
BNL, Upton, Long Island, New York, USA
K. Yu
SBU, Stony Brook, USA

There is a strong limit of available RF gradient in a vacuum RF cavity under magnetic fields because the magnetic field enhances a dark current density due to electron focusing and increases probability of an electric breakdown. This limits the cooling performance. A dense hydrogen gas filled RF cavity can break this limit because the gas acts as a buffer of dark current. However, RF power loading due to a beam-induced plasma in a dense gas filled RF cavity (plasma loading effect) is crucial to design the practical cavity. Experiment shows that the plasma loading can be mitigated in denser hydrogen gas and by doping a small amount of electronegative gas in the cavity. A complicate plasma chemical reaction should be dominated in such a dense hydrogen gas condition. A beam-induced plasma is simulated by taking into account the plasma chemistry to reproduce the condition by using the supercomputer at LBNL. We will also investigate the space charge effect in a dense gas in this effort.