<html><body><div style="color: rgb(0, 0, 0); font-family: arial,helvetica,sans-serif; font-size: 12pt;"><div>FYI<br></div><div><br></div><hr id="zwchr" data-marker="__DIVIDER__"><div data-marker="__HEADERS__"><b>From: </b>"Audrey Nichols" <anichols@jlab.org><br><b>To: </b>"acc staff" <acc_staff@jlab.org>, "Christopher Tennant" <tennant@jlab.org><br><b>Cc: </b>"anirban bhattacharyya" <anirban.bhattacharyya@physics.uu.se><br><b>Sent: </b>Thursday, June 11, 2015 9:04:29 AM<br><b>Subject: </b>[Accelerator_staff] Accelerator Seminar: Anirban Bhattacharyya - 6/12/15<br></div><div><br></div><div data-marker="__QUOTED_TEXT__"><div style="color: rgb(0, 0, 0); font-family: tahoma,new york,times,serif; font-size: 12pt;" data-mce-style="font-family: tahoma,new york,times,serif; font-size: 12pt; color: #000000;"><div>ACCELERATOR SEMINAR<br></div><br><div>Optimal Charging of Accelerating Superconducting Cavities for Reflected Energy Minimization<br></div><br><div>Anirban Bhattacharyya<br></div><div>Uppsala University<br></div><br><div><p style="margin: 0px; text-align: justify; vertical-align: baseline; unicode-bidi: embed; direction: ltr;" data-mce-style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="color: black; font-family: Arial; font-size: 13pt; language: en-US;" data-mce-style="font-size: 13.0pt; font-family: Arial; color: black; language: en-US;">The two big accelerator complexes being built on the outskirts of the city of Lund, to the south of Sweden, are MAX IV, a synchrotron facility, and The European Spallation Source (ESS), to be the brightest Neutron source on the planet. It is going to be a unique location with both X-Ray and Neutron sources at close proximity. The Facility for Research Instrumentation and Accelerator Development (FREIA), at Uppsala University in Sweden has both a cryogenic facility and an RF facility, capable of testing the ESS Accelerator prototype components at an operational 352 MHz, and a peak power of 350 kW, which will serve to certify them for fabrication. In my seminar I will introduce the FREIA Laboratory, talk about it's capabilities and the activities going on there, and then concentrate on my contribution to such </span><span style="color: black; font-family: Arial; font-size: 13pt; language: en-US;" data-mce-style="font-size: 13.0pt; font-family: Arial; color: black; language: en-US;">efforts.</span></p><p style="margin: 0px; text-align: justify; vertical-align: baseline; unicode-bidi: embed; direction: ltr;" data-mce-style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="color: black; font-family: Arial; font-size: 13pt; language: en-US;" data-mce-style="font-size: 13.0pt; font-family: Arial; color: black; language: en-US;"><br></span></p><p style="margin: 0px; text-align: justify; vertical-align: baseline; unicode-bidi: embed; direction: ltr;" data-mce-style="margin: 0px; text-align: justify; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="color: black; font-family: Arial; font-size: 13pt; language: en-US;" data-mce-style="font-size: 13.0pt; font-family: Arial; color: black; language: en-US;">The </span><span style="color: black; font-family: Arial; font-size: 13pt; language: en-US;" data-mce-style="font-size: 13.0pt; font-family: Arial; color: black; language: en-US;">radio frequency cavities, used to accelerate charged particle beams, need to be charged to their nominal voltage after which the beam can be injected into them. The standard procedure for such cavity filling is to use a step charging profile. However, during initial stages of such a filling process a substantial amount of the total energy is wasted in reflection for superconducting cavities because of their extremely narrow bandwidth. In my talk I will present a novel strategy to charge cavities, which reduces total energy reflection. Practical aspects (saturation, efficiency and gain characteristics) of power sources (tetrodes, IOTs and solid state power amplifiers) are also considered and </span><span style="color: black; font-family: Arial; font-size: 13pt; language: en-US;" data-mce-style="font-size: 13.0pt; font-family: Arial; color: black; language: en-US;">analysed</span><span style="color: black; font-family: Arial; font-size: 13pt; language: en-US;" data-mce-style="font-size: 13.0pt; font-family: Arial; color: black; language: en-US;">. The motivation of the talk is to present a methodology to successfully identify the optimal charging scheme for different power sources to minimize total energy requirement.</span></p></div><br><div>Friday, June 12, 2015<br></div><div>11:00 a.m.<br></div><div>CEBAF Center, Room L102<br></div><br><div><span style="color: rgb(0, 0, 0);" data-mce-style="color: #000000;">Seminar archives are found here:</span> <span class="Object" id="OBJ_PREFIX_DWT1428_com_zimbra_url"><span class="Object" id="OBJ_PREFIX_DWT1437_com_zimbra_url"><a href="https://www.jlab.org/accel/seminars.html" target="_blank" data-mce-style="" data-mce-href="https://www.jlab.org/accel/seminars.html">https://www.jlab.org/accel/seminars.html</a></span></span><br></div><br><div><div>------<br><b><span style="font-size: small;" data-mce-style="font-size: small;">Audrey N. Barron</span></b><br><span style="font-size: small;" data-mce-style="font-size: small;">Administrative Assistant</span><br><span style="font-size: small;" data-mce-style="font-size: small;">Center for Advanced Studies of Accelerators</span><br><span style="font-size: small;" data-mce-style="font-size: small;">Jefferson Lab</span><br><span style="font-size: small;" data-mce-style="font-size: small;">757-269-7327</span><br><span style="font-size: small;" data-mce-style="font-size: small;"><a href='http://<a href="mailto:anichols@jlab.org">anichols@jlab.org</a>Email Me</a> ' target="_blank" data-mce-href='http://<a href="mailto:anichols@jlab.org">anichols@jlab.org</a>Email Me</a> '>anichols@jlab.org</a></span> / <span style="font-size: small;" data-mce-style="font-size: small;"><a href="http://www.jlab.org" target="_blank" data-mce-href="http://www.jlab.org">www.jlab.org</a></span> <br><br><img style="border: 0px currentColor; border-image: none;" src="cid:a60da4fa8cfcd1cc33062ef960b643dd5a14aad8@zimbra" data-mce-style="border: 0px none;" data-mce-src="cid:a60da4fa8cfcd1cc33062ef960b643dd5a14aad8@zimbra"><br></div></div></div><br>_______________________________________________<br>Accelerator_staff mailing list<br>Accelerator_staff@jlab.org<br>https://mailman.jlab.org/mailman/listinfo/accelerator_staff<br></div></div></body></html>