LINAC2014 - List of Authors (Vikharev, A.A.)

Paper

Title

Page

Helical Waveguides for Short Wavelength Accelerators and RF Undulators

248

S.V. Kuzikov, A.V. Savilov, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia
A.V. Savilov
NNGU, Nizhny Novgorod, Russia

The short wavelength accelerating structure can combine properties of a linear accelerator and a damping ring simultaneously. It provides acceleration of straight on-axis beam as well as cooling of this beam due to the synchrotron radiation of particles. These properties are provided by specific slow eigen mode which consists of two partial waves, TM01 and TM11. The flying RF undulator introduces a high-power short pulse, propagating in a long helically corrugated waveguide where the -1st space harmonic with negative phase velocity is responsible for particle wiggling. High group velocity allows providing long interaction of particles with RF pulse. Calculations show that RF undulator with period 5 mm, undulator parameter 0.1 is possible in 1 GW 10 ns pulse at frequency 30 GHz. The eigen mode in a helical undulator might have 0th harmonic phase velocity equal to light velocity. Such wave can be excited by relativistic drive bunch in the waveguide where witness bunch follows after the drive bunch, wiggles in wakefields, and generates X-rays at whole waveguide length. Helical waveguides can also be used in order to channel low-energy bunches in RF undulator of THz FEL.

Poster MOPP083 [2.139 MB]

MOPP084

Nondestructive Diagnostics of Proton Beam Halo and Transverse Bunch Position by Cerenkov Slow Wave Structures

251

MOPOL08

use link to see paper's listing under its alternate paper code

S.V. Kuzikov, M.B. Goykhman, A.V. Gromov, A.V. Palitsin, Yu.V. Rodin, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

An appearance of the halo around bunch of particles is very undesirable destructive phenomenon in high-intensity proton accelerators. We suggest using built-in short BWO section in form of the corrugated metallic waveguide, in order to control particle distribution in real time. In BWO low velocity proton bunch has synchronism with slow spatial harmonic of TM01 wave. Fields of slow harmonic sharply grow in direction from axis to walls and rf power, generated by flying bunch of the given charge, critically depends on transverse bunch size. Results of the simulation, carried out for 20 pC proton bunch of 10 ps duration, show that in 5 GHz BWO of 30 cm length the output rf pulse of several nanosecond duration is varied from mW- level (for 1 mm transverse bunch size) to several tens of mW (for bunch of 20 mm radius). This power level is high enough to control halo appearance in each single proton bunch. The producible rf power in a BWO is also dependent on bunch deflection from axis. This effect we plan to use, in order to provide transverse bunch position monitoring by means of two additional rectangular slow wave section which have corrugations on mutually perpendicular walls.

Poster MOPP084 [0.732 MB]

Paper	Title	Page
MOPP083	Helical Waveguides for Short Wavelength Accelerators and RF Undulators	248
	S.V. Kuzikov, A.V. Savilov, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia A.V. Savilov NNGU, Nizhny Novgorod, Russia
	The short wavelength accelerating structure can combine properties of a linear accelerator and a damping ring simultaneously. It provides acceleration of straight on-axis beam as well as cooling of this beam due to the synchrotron radiation of particles. These properties are provided by specific slow eigen mode which consists of two partial waves, TM01 and TM11. The flying RF undulator introduces a high-power short pulse, propagating in a long helically corrugated waveguide where the -1st space harmonic with negative phase velocity is responsible for particle wiggling. High group velocity allows providing long interaction of particles with RF pulse. Calculations show that RF undulator with period 5 mm, undulator parameter 0.1 is possible in 1 GW 10 ns pulse at frequency 30 GHz. The eigen mode in a helical undulator might have 0th harmonic phase velocity equal to light velocity. Such wave can be excited by relativistic drive bunch in the waveguide where witness bunch follows after the drive bunch, wiggles in wakefields, and generates X-rays at whole waveguide length. Helical waveguides can also be used in order to channel low-energy bunches in RF undulator of THz FEL.
	Poster MOPP083 [2.139 MB]

MOPP084	Nondestructive Diagnostics of Proton Beam Halo and Transverse Bunch Position by Cerenkov Slow Wave Structures	251
MOPOL08	use link to see paper's listing under its alternate paper code
	S.V. Kuzikov, M.B. Goykhman, A.V. Gromov, A.V. Palitsin, Yu.V. Rodin, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	An appearance of the halo around bunch of particles is very undesirable destructive phenomenon in high-intensity proton accelerators. We suggest using built-in short BWO section in form of the corrugated metallic waveguide, in order to control particle distribution in real time. In BWO low velocity proton bunch has synchronism with slow spatial harmonic of TM01 wave. Fields of slow harmonic sharply grow in direction from axis to walls and rf power, generated by flying bunch of the given charge, critically depends on transverse bunch size. Results of the simulation, carried out for 20 pC proton bunch of 10 ps duration, show that in 5 GHz BWO of 30 cm length the output rf pulse of several nanosecond duration is varied from mW- level (for 1 mm transverse bunch size) to several tens of mW (for bunch of 20 mm radius). This power level is high enough to control halo appearance in each single proton bunch. The producible rf power in a BWO is also dependent on bunch deflection from axis. This effect we plan to use, in order to provide transverse bunch position monitoring by means of two additional rectangular slow wave section which have corrugations on mutually perpendicular walls.
	Poster MOPP084 [0.732 MB]