source: PSPA/madxPSPA/doc/usrguide/Introduction/crabcavity.html @ 489

Last change on this file since 489 was 430, checked in by touze, 11 years ago

import madx-5.01.00
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1<head>
2<title>CRABCAVITY</title>
3<!-- Added by: R. Calaga, Sep 2010 -->
4</head>
5
6<body bgcolor="#ffffff">
7
8<center>
9EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH
10<IMG SRC="http://cern.ch/madx/icons/mx7_25.gif" align=right>
11<h2>CRAB Cavity</h2>
12</center>
13
14<pre>
15
16label: CRABCAVITY, L=real,VOLT=real,LAG=real,FREQ=real,
17rv1=integer, rv2=integer, rv3=integer, rv4=integer,
18rph1=integer, rph2=integer,lagf=real;
19                  <!-- HARMON=integer, BETRF=real,PG=real,
20                 FREQ=real,SHUNT=real,TFILL=real; -->
21</pre>
22An CRABCAVITY has ten real attributes and seven integer attributes:
23<ul>
24<li>L:
25The length of the cavity (default: 0 m)
26<li>VOLT:
27The peak RF voltage (default: 0 MV).
28The effect of the cavity is
29<p>
30delta(<i>px</i>)  = VOLT * sin( &phi; - &omega * t) <br>
31delta(<i>E</i>)  = -  VOLT * &omega * x * cos(&phi; - &omega * t) <br>
32(where, &phi =  sin(2 &pi; * (LAG - HARMON * <i>f<sub>0</sub> t</i>))) <br>
33<!--- delta(<i>E</i>) = VOLT *
34sin(2 pi * (LAG - HARMON * <i>f<sub>0</sub> t</i>)). -->
35<p>
36
37<li>LAG:
38The initial phase lag [2pi] (default: 0).
39<li>FREQ:
40The frequency [MHz] <i>fenergy</i>(no default).
41Note that if the RF frequency is not given, it is
42computed from the harmonic number
43and the revolution frequency <i>f<sub>0</sub></i> as before. However,
44for deflecting structures this makes no sense,
45and the frequency is mandatory. <br>
46
47<li>RV1:
48Number of initial turns with zero voltage(default: 0).
49<li>RV2:
50Number of turns to ramp voltage from zero to nominal(default: 0).
51<li>RV3:
52Number of turns with nominal voltage (default: VOLT).
53<li>RV4:
54Number of turns to ramp voltage from nominal to zero(default: 0).
55<br>
56<li>RPH1:
57Number of initial turns with nominal phase (default: 0).
58<li>EPHASE:
59Value of the final crab RF phase [2pi] with respect to  nominal value (default: 0).
60<li>RPH2:
61Number of turns to ramp phase [2pi] from nominal to specified value(default: 0).
62<br>
63<li>HARMON:
64The harmonic number <i>h</i> (no default). Only if the frequency is not given.
65<!-- <li>BETRF:
66RF coupling factor (default: 0).
67<li>PG:
68The RF power per cavity (default: 0 MW).
69<li>SHUNT:
70The relative shunt impedance (default: 0 MOhm/m).
71<li>TFILL:
72The filling time of the cavity T<sub>fill</sub>
73(default: 0 microseconds). -->
74<li><font color=ff0000><i> Please take note, that the following
75MAD8 attributes: BETRF, PG, SHUNT and TFILL are currently not
76implemented in MAD-X!</i><
77<li><i> Note that crab cavities are only implemented for tracking
78purposes. TWISS will ignore any effect of the crab cavity.
79<!-- as well that twiss is 4D only. As a consequence the TWISS
80parameters in the plane of non-zero dispersion may not close as
81expected. Therefore, it is best to perform TWISS in 4D only, i.e. with
82cavities switched off. If 6D is needed one has to use the
83
84<a href="../ptc_twiss/ptc_twiss.html">ptc_twiss</a> command. -->
85</i></font>
86</ul>
87A cavity requires the particle energy
88(<a href="beam.html#energy">ENERGY</a>)
89and the particle charge
90(<a href="beam.html#charge">CHARGE</a>)
91to be set by a <a href="beam.html">BEAM</a> command
92before any calculations are performed.
93<p>
94Example:
95<pre>
96BEAM, PARTICLE=PROTON, ENERGY=7000.0;
97CAVITY:  CRABCAVITY, L=10.0, VOLT=5.0, LAG=0.0, FREQ=400,
98rv1=0, rv2=50, rv3=1000, rv4=50, rph1=100, rph2=500,lagf=0.125;
99
100</pre>
101The <a href="local_system.html#straight">straight reference system</a>
102for a cavity is a cartesian coordinate system.
103<p>
104<address>
105<a href="http://www.cern.ch/rcalaga">R. Calaga</a>,
106September 2010
107</address>
108
109</body>
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