Mona Gehlot

Bi-harmonic free electron laser gain with variably polarizing undulator

A variably polarizing undulator free electron laser at higher harmonics is proposed. Analytical theory of the spectral feature of the radiation and the free electron laser gain for the higher harmonics are presented. The analytical results are supported by a numerical procedure.

Magnetic Measurements of a Third Harmonic Table-Top Undulator for Free Electron Lasers

We describe the measurement studies of a third harmonic undulator. The harmonic undulator is fabricated by placing shims at suitable locations along the length of a table-top six-period planar undulator. The undulator field is measured with a Hall probe and pulsed wire bench. The pulsed wire data show good agreement with the Hall probe data.

Characterization study of a hybrid undulator

In this paper, we describe the design details of a prototype DEVU25.20h, a 9 mm minimum gap, hybrid undulator designed, built, and measured in house at the IDD Laboratory, DAVV, Indore, India. The undulator is a NdFeB-based hybrid undulator with 25 period and 20 mm each period length. Low-cost M35 grade cobalt steel is used as the pole material of the undulator. The magnet size is 6.25 mm in width, 6.25 mm in height, and 50 mm in length. The pole size is 3.75 mm in width, 4.7 mm in height, and 50 mm in length. The gap is manually driven. The 20 periods are arranged in 112 mm wide and 500 mm long 316 steel jaws. The two jaws are held in a rigid variable gap support structure giving a minimum gap of 9 mm. The hybrid undulator is designed as asymmetric structure, i.e., one end starts with a magnet and terminates with a pole at the other end. The measured performance and characteristics of the undulator are evaluated with RADIA.

Magnetic performance of DEVU25.20h undulator at IDDL, DAVV,India

In this paper, we describe the design development and magnetic performance of a prototype DEVU25.20h, variable gap hybrid undulator at IDD laboratory, DAVV, Indore, India. The undulator is NdFeB based hybrid undulator with twenty five period and 20 mm each period length. Low cost M35 grade cobalt steel is used as the pole material of the undulator. The abc coefficients of the new pole material is prescribed and the measured performance and characteristics of the undulator is evaluated using RADIA. The detailed design parameters and performance indicators are summarized in Table 1 and Table 2 respectively.

Design and fabrication of PPM and hybrid undulator for free electron laser applications

Two undulators for free electron laser applications are under fabrication at Insertion Device Development & Measurement Laboratory, DAVV, Indore. The first one is of PPM type with twenty periods, 50 mm each period. The second one is a hybrid undulator with twenty five periods, 20 mm each period. NdFeB magnets of rectangular cross section 12.5mm, 12.5mm & 6.25 mm, 6.25 mm will be used for the undulators respectively. Each magnet length is of 50 mm. Each magnet is scanned by a laser micrometer to ensure gap uniformity along the length of the undulator. In this paper we describe the technical design details of both the undulators.

An overview of the undulator field measurement studies at insertion device lab, DAVV

This paper describes undulator field measurement procedures by hall probe and the pulsed wire method. The Hall probe method gives the direct field mapping and calculates the field integrals through double numerical integration. A pulsed wire magnetic measurement method is an optical method which has been independently developed by DAVV. It gives directly the field integrals and calculates the field mapping via a double numerical differentiation. The measurement methods are illustrated with field measurement of a six period PPM undulator and a third harmonic undulator.