source: PSPA/madxPSPA/doc/usrguide/Introduction/rfmultipole.html @ 430

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3  <head>
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5    <meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
6    <title>MULTIPOLE</title>
7    <!-- Changed by: Chris ISELIN, 27-Jan-1997 -->
8    <!-- Changed by: Hans Grote, 17-Jun-2002 -->
9    <!-- Changed by: Frank Schmidt, 28-Aug-2003 -->
10  </head>
11  <body bgcolor="#ffffff">
12    <h2>RFMULTIPOLE: Thin Radio-Frequency Multipole</h2>
13    <div class="plaintext">
14      <pre>Label:  RFMULTIPOLE, VOLT=real, LAG=real,
15  HARMON=integer, FREQ=real,
16  LRAD=real, TILT=real,
17  KNL:={k0nl, k1nl, k2nl, ... },  ! Normal coefficients
18  KSL:={k0sl, k1sl, k2sl, ... },  ! Skew coefficients
19  PNL:={p0n,  p1n,  p2n,  ... },  ! Normal phases [2pi]
20  PSL:={p0s,  p1s,  p2s,  ... };  ! Skew phases [2pi]
21    </pre>
22    </div>
23    <div class="plaintext"> A RFMULTIPOLE is a thin-lens element which
24      exhibits the properties of an RF-cavity and of a magnet of
25      arbitrary order oscillating the a certain frequency:
26      <p> </p>
27      <ul>
28        <li>L: The length of the rfmultipole (DEFAULT: 0 m) </li>
29        <li>LAG: The phase lag [2pi] (DEFAULT: 0) </li>
30        <li>FREQ: The frequency [MHz] (no DEFAULT). Note that if the RF
31          frequency is not given, it is computed from the harmonic
32          number and the revolution frequency f0 as before. However, for
33          accelerating structures this makes no sense, and the frequency
34          is mandatory. </li>
35        <li>HARMON: The harmonic number h (no DEFAULT). Only if the
36          frequency is not given. </li>
37        <li>LRAD: A fictitious length, which was originally just used to
38          compute synchrotron radiation effects. A non-zero LRAD in
39          conjunction with the OPTION thin_foc set to a true logical
40          value takes into account of the weak focussing of bending
41          magnets. </li>
42        <li>TILT: The roll angle about the longitudinal axis (default: 0
43          rad). A positive angle represents a clockwise rotation of the
44          multipole element.
45          <p><b>Please note that contrary to MAD8 one has to specify the
46              desired TILT angle, otherwise it is taken as 0 rad. We
47              believe that the MAD8 concept of having individual TILT
48              values for each component and on top with default values
49              led to considerable confusion and allowed for excessive
50              and unphysical freedom. Instead, in MAD-X the KNL/KSL
51              components can be considered as the normal or skew
52              multipole components of the magnet on the bench, while the
53              TILT attribute can be considered as an tilt alignment
54              error in the machine.</b> </p>
55        </li>
56        <li>KNL: The normal rfmultipole coefficients from order zero to
57          the maximum; the parameters are positional, therefore zeros
58          must be filled in for components that do not exist. Example of
59          a thin-lens sextupole: ms:rfmultipole, knl:={0, 0, k2l}; </li>
60        <li>KSL: The skew rfmultipole coefficients from order zero to
61          the maximum; the parameters are positional, therefore zeros
62          must be filled in for components that do not exist. Example of
63          a thin-lens skew octupole:
64          <p> </p>
65        </li>
66      </ul>
67      <pre>     ms: rfmultipole, ksl:={0, 0, 0, k3sl};</pre>
68      <blockquote>Both KNL and KSL may be specified for the same
69        multipole. </blockquote>
70      <ul>
71        <li>VOLT: The peak RF voltage (DEFAULT: 0 MV). The effect of the
72          cavity is </li>
73        <li>delta(E) = VOLT * sin(2 pi * (LAG - HARMON * f0 t)). </li>
74        <li>PNL: The phase for each normal rfmultipole coefficients from
75          order zero to the maximum; the parameters are positional,
76          therefore zeros must be filled in for components that do not
77          exist. </li>
78        <li>PSL: The phase for each skew rfmultipole coefficients from
79          order zero to the maximum; the parameters are positional,
80          therefore zeros must be filled in for components that do not
81          exist. </li>
82      </ul>
83      A rfmultipole requires the particle energy (ENERGY) and the
84      particle charge (CHARGE) to be set by a BEAM command before any
85      calculations are performed. Notice that, contrary to the regular
86      multipole where the dipole component has no effect on the
87      reference orbit, an RF-Multipole that includes a dipole component
88      bends also the reference orbit.
89    </div>
90    <p>
91    </p>
92    <address>&nbsp;
93      <a
94href="https://phonebook.cern.ch/foundpub/Phonebook/index.html?search=latina#id=PE525753">Andrea
95        Latina</a>, September 28, 2012 </address>
96  </body>
97</html>
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