RuPAC-2012

A.V.Feschenko, A.I.Kvasha,V.L.Serov

STATUS OF INR DTL RF SYSTEM

INR Linac is in regular operation since 1993. The accelerator incorporates DTL and DAW structures operating at 198.2 MHz and 991 MHz correspondingly. Initially two types of high power vacuum tubes specially designed for INR linac (GI-54A for final amplifier and GI-51A for intermediate amplifier) were used in DTL RF power system. However production of these tubes has been terminated resulting in a need of DTL RF system upgrade. The main goal of the recent upgrade is replacement of the old tubes by modern ones. The difficulty of replacement arises due to a need to minimize mechanical changes of the existing equipment. Another goal is improving of operational reliability. The reliability depends on vacuum tube reliability and to a large extent - on crowbar operation. The results and the experience of INR DTL RF system upgrade are presented.

S. Bragin, A. Feschenko, S. Gavrilov,

A. Mirzojan, P. Reinhardt-Nickoulin, I. Vasilyev, O. Volodkevich

EMITTANCE MEASUREMENTS ON OUTPUT PROTON BEAM OF INR ras LINAC

For operation of INR linac in wide range of beam intensities and energies it is need reliable system of beam diagnostic instruments. The beam parameters measurement system on output beam of INR linac has a few modes for emittance measurements: a) by means of beam transverse profiles measurements in a few locations of wire scanners (WS), b) by means of quadrupole lenses strength variation with simultaneous measurements of beam profiles by WS or ionization beam cross section monitor (BCSM) that was developed and used on proton linac of INR RAS to provide non-intercepting measurements of transverse beam parameters. These measurement modes are compared and emittance reconstruction methods are discussed. The BCSM enables to observe beam cross section and extract from it beam profiles within required wide range of beam intensities and energies. Results of emittance measurements at the linac output are presented.

P. Reinhardt-Nickoulin, S. Bragin,V. Gaidash,

O. Grekhov, A. Feschenko, Yu. Kiselev, N.Lebedeva, A. Mirzojan, A. Naboka, I.Vasilyev, O. Volodkevich.

NEW ELECTRONICS FOR BCT SYSTEM ON INR LINAC PROTON BEAM

New electronics of automatic BCTs system was developed and tested to provide beam intensity measurements along INR Linear Accelerator. New BCT analog electronics was developed and installed. This electronics was tested in high radiation conditions of experimental areas successfully. New BCT electronics details are described. The available results of beam pulse measurements are given.

P. Reinhardt-Nickoulin, A. Feschenko, S. Gavrilov*, I. Vasilyev.

*Moscow Institute of Physics & Technology (SU), Dolgoprudny

SIMULATION OF ionization beam cross-section monitor MEASUREMENT Errors

Ionization beam cross-section monitor (BCSM) for measurements of INR linac proton beam parameters has some specific errors due to monitor electrode geometry and field distortions. Besides that BCSM has limitations of spatial resolution due to random errors and final resolution of electro-optical MCP converter also. Results of numerical simulation of beam images registration process and estimations of its distortions, which are caused by these distortions and limitations are presented, possible applications of BCSM on different beams are discussed

A.N. Drugakov, A.V. Feschenko, A.I. Kvasha, A.N. Naboka, V.L. Serov

INVESTIGATION OF INR LINAC DTL rf SISTEM OPERATION AT 100Hz REPETITION RATE

INR Linac has been operating with 50 Hz beam repetition rate so far. Increasing the repetition rate up to 100 Hz is of importance as it results in doubling of the beam intensity. To solve the task several accelerator systems must be modernized but the most critical one is the DTL rf system (up to 100 MeV). The problems related to the DTL rf system repetition rate increasing are described. One of the problems is a 50 Hz modulation of a 100 Hz rf pulse sequence. Though the instabilities of accelerating field due to the modulation are reduced by the feedback systems, nevertheless exploration of the effect and its minimizing is of importance. The analysis of the effect is given and the results of experimental studies are presented.

V. Paramonov, L. Kravchuk, P. Orlov INR,

K. Floettmann, DESY

STANDING WAVE RF DEFLECTOR WITH MINIMIZED ABERRATIONS

Deflecting structures are now widely used for bunch phase space manipulations either with bunch rotation for special bunch diagnostic or in emittance exchange experiments. Even if the field of synchronous harmonic is aberration free, the higher space harmonics provide non linear additives in the field distribution, leading to emittance growth during phase space manipulation. Standing wave operation is more RF efficient for short deflectors. The criterion of the field quality estimation and results is of deflecting structure consideration for minimization of non linear additives are presented. The solutions for dispersion correction together with end cells optimization are described too.

 

A.S.Belov, O.T.Frolov, E.S.Nikulin, V.P.Yakushev, V.N.Zubets

 

STUDY OF PROTON INJECTOR BEAM TRANSVERSE PHASE SPACE VARIATIONS
DURING ACCELERATING VOLTAGE PULSE

The proton injector of INR RAS linac provides a pulsed beam with the following parameters: current up to 100÷120 mA; duration 200 usec; pulse repetition rate 50 Hz; energy of ions 400 keV. The results of numerical calculations and experimental study of beam phase space variations during injector high voltage pulse are presented. It is shown that these variations are caused by instabilities of both beam current and accelerating tube intermediate electrode potential. Instability of beam current has been minimized by using of noiseless mode of operation for the pulsed duoplasmatron and by stabilization of ion source discharge current. The high voltage pulse stability is now better than 0.1%. High frequency oscillations at high voltage pulse plateau have been diminished by both decreasing of high voltage pulse generator artificial line characteristic impedance and filtration of high frequency component of the diode-capacitor stabilizer current. The beam transverse normalized emittance for 90% of beam current has been measured to be of 0.08p cmmrad. Variations of the emittance during the high voltage pulse are in limits of 4% value.