NDLI: Pulsed power supply for magnetic field to generate HPM from slow wave structures

Content Provider	IEEE Xplore Digital Library
Author	Parmar, N. Deshpande, P. Choyal, Y. Maheshwari, K.P. Bhat, K.S.
Copyright Year	2011
Description	Author affiliation: Microwave Tube Research and Development Centre, BEL Complex, Jalahalli, Bangalore, India (Bhat, K.S.) \|\| School of Physics, D.A. University, Khandwa Road Campus, Indore, India (Parmar, N.; Deshpande, P.; Choyal, Y.) \|\| Vardhman Mahaveer Open University, Kota, India (Maheshwari, K.P.)
Abstract	A strong axial magnetic field is required to guide a relativistic pulsed electron beam. The magnetic field can be supplied either by a permanent magnet or an electromagnet. In a backward wave oscillator (BWO) experiment, as the required field is 0–1.2 T in a cylindrical volume having radius of a couple of centimeters and length of about 10–12 cm, an electromagnet is preferred. A large pulsed current is passed into a solenoid to generate a pulsed magnetic field. This current is provided by a capacitor bank. In the paper, development of a pulsed magnetic field system is described. The generated magnetic field is of strength 1.25T with the pulse duration of 2 ms. Inner diameter of solenoid is 5 cm and length is 12 cm. The magnetic field guides a relativistic electron beam that excites a slow wave structure to generate high power microwaves. To generate a unidirectional magnetic field, we must have a unidirectional current pulse. This is obtained by discharging a charged capacitor into an inductor with a resistor in between them. For critical damping, we get a unidirectional pulse. Assuming inductance L and resistance R, a maximum occurs att = 2L/R where the maximum current is t = 0.74V /R. The pulse duration is The experimental set up is as follows: Secondary of a step-up transformer gives a peak voltage of 2.5 kV. After half wave rectification, a capacitor bank having capacity of 450µF is charged through a 800 ohm hand woven resistor. Charging time of the capacitor bank is 3 sec. Charged capacitor bank is discharged into a solenoid, inductance L, through pulse forming non-inductive resistance R=1.3 Ω. A small resistance R=0.125Ω is in series for measurements. A spherical spark gap having 2 cm sphere diameter acts as a self breaking switch. As soon as the instantaneous value of current overshoots a predefined strength, the corresponding voltage that drops across the resistor R exceeds the comparing voltage on a comparator. This causes a timer circuit to give a turn on a relay that controls switching of a Marx capacitor bank for relativistic electron beam $generation^{1}.$ The voltage across R, therefore give us the information of current pulse as well as controls the triggering of electron beam system. Peak current is controlled by the pulse forming resistor R. Table 1 given below shows various values of R and corresponding value of voltage on R. Measured current, pulse duration and magnetic field are given in last three columns.
Starting Page	467
Ending Page	468
File Size	70868
Page Count	2
File Format	PDF
ISBN	9781424486625
e-ISBN	9781424486618
DOI	10.1109/IVEC.2011.5747078
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2011-02-21
Publisher Place	India
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Magnetic fields Electron beams Capacitors Microwave oscillators Resistors Voltage measurement Solenoids slow wave structures Relativistic electron beam capacitor bank HPM generation
Content Type	Text
Resource Type	Article

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in